Chapter 3 Physiological Processes Of Life Photosynthesis Summary
- Plant physiology is a field of botany, that deals with the physiological functioning of plants.
- Several fundamental processes such as photosynthesis, mineral nutrition, transpiration, transportation, etc. are included within plant physiology.
- The mode of nutrition in higher green plants is autotrophic and plants meet this need of nutrition through the process of photosynthesis.
- Photosynthesis is the most important biological phenomenon.
- It is a biochemical process in which light energy is converted into chemical energy and stored in organic compounds.
- The general simplified chemical equation of photosynthesis is\(6 \mathrm{CO}_2+12 \mathrm{H}_2 \mathrm{O} \frac{\text { Sunlight }}{\text { Chlorophyll }} \longrightarrow \mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6+6 \mathrm{H}_2 \mathrm{O}+6 \mathrm{O}_2 \uparrow\)
- The term photosynthesis was introduced by Charles Barnes in the year 1893.
- The word ‘photosynthesis’ is derived from the Greek word ‘photos’ means light and ‘synthesis’ means building up.
- Mesophyll tissue in the leaf is the site for photosynthesis.
- Other green parts of plants that contain chlorophyll are also capable of performing photosynthesis.
- The basic components necessary for photosynthesis are CO2, water, sunlight, and photosynthetic pigments.
- Chlorophyll molecules and the other accessory pigments, like carotenes and xanthophylls, absorb light energy and then transfer it to the reaction center.
- ADP, NADP, and RuBP are some organic substances that play important role in photosynthesis.
- The whole process of photosynthesis involves two distinct phases, viz., light-dependent reaction or simply light reaction (photochemical phase) and light independent reaction or simply dark reaction (biosynthetic phase).
- Chlorophyll gets energized after getting hit by photon particles of sunlight.
- This chlorophyll now helps in the dissociation of water.
- Carbon atom of CO2 is assimilated within the cell as organic compounds.
- Glucose is the end product of photosynthesis.
- It is synthesized in the cytosol of mesophyll cells.
- Trapping and transformation of solar energy, synthesis of food for the entire living world, and maintaining a balance between O2 and CO2 in the environment are the significances of photosynthesis.
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Chapter 3 Physiological Processes Of Life Photosynthesis Short Answer Type Questions
Question 1. Mention the components, necessary for photosynthesis.
Answer:
The materials required for photosynthesis are as follows:
1. Raw material and carbon dioxide
2. Pigments-Chlorophyll and carotenoids (carotene and xanthophyll)
3. Energy-Light (sunlight or bright artificial light).
WBBSE Class 9 Life Science Solutions
Question 2 Where does photosynthesis occur?
Answer:
Photosynthesis Occur:-
Photosynthesis occurs in the chloroplast-containing parenchyma (chlorenchyma) tissues known as mesophyll tissue of higher green plants. These tissues are distributed in leaves and all other tenders, green parts of the plants, like stems (in herbs), sepals of flowers, petals (water lily and custard apple flower), bracts (Adhatoda sp.), stipule (pea plant), root (orchid, Tinospora), etc.
WBBSE Class 9 Photosynthesis Solutions
Question 3. How do plants absorb water for photosynthesis?
Answer:
Plants Absorb Water For Photosynthesis:-
Terrestrial plants absorb water from the soil with the help of their roothairs. Aquatic plants absorb water from the surrounding water medium through their body surface by the process of simple diffusion. Epiphytes (plants growing on other plants) like orchids, have special spongy tissue called velamen, in their aerial roots. These roots with a thick hygroscopic outer coating of velamen absorb rainwater and moisture from the air to fulfill the need for water.
Question 4 Define photosynthesis.
Answer:
Photosynthesis:-
Photosynthesis is a photochemical process in which green plants and certain chlorophyll-containing organisms utilize water and carbon dioxide as raw materials to synthesize monosaccharide (glucose) in their body by entrapped-ing light energy (especially sunlight) within it and releasing oxygen in the environment as a byproduct.
Key Questions on Photosynthesis for Class 9
Question 5. How do plants absorb CO2 for photosynthesis?
Answer:
Plants Absorb CO2 For Photosynthesis:-
All terrestrial plants absorb CO2 from the atmosphere through stomata on the leaves. Aquatic plants absorb dissolved CO2 from surrounding water by simple diffusion through the body surface.
Partially submerged plants absorb CO2 through stomata on their aerial portion of the body and the submerged portion get CO2 by diffusion from the surrounding water medium.
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Question 6. What do photosynthetic pigments in plants do?
Answer:
Photosynthetic Pigments In Plants Do:-
In plants, there are two types of photosynthetic pigments, namely, chlorophyll and carotenoids. Chlorophyll helps in the dissociation of water and the formation of energy-packed ATP molecules. Carotenoids (carotene and xanthophyll) entrap light energy and transfer it to the reaction center of chlorophylls for further proceedings.
Question 7. Why photosynthesis is known as an anabolic process?
Answer:
Photosynthesis Is Known As An Anabolic Process:-
In photosynthesis, a new substance (glucose) is produced from raw materials (CO2, H2O, light). and due to this dry weight of the plant cell’s protoplasm is increased and energy is also stored as potential energy. For all these reasons, photosynthesis is termed as an anabolic process.
Question 8 Why photosynthesis is called an oxidation-reduction reaction?
Answer:
Photosynthesis Is Called An Oxidation-Reduction Reaction:-
Photosynthesis involves the reduction of carbon dioxide into sugars and the oxidation of water into molecular oxygen. That is why photosynthesis is also called an oxidation-reduction reaction.
Practice Questions for Chapter 3 Photosynthesis
Question 9. Why photosynthesis does not occur in plant roots? Name one exceptional plant.
Answer:
Reason For Photosynthesis Does Not Occur In Plant Roots :
Photosynthesis occurs in chloroplasts which are absent in roots. Moreover, the light can’t reach the root because of its underground position. For all these reasons, most plant roots can’t do photosynthesis.
Exception: Roots of Gulancha, Tinospora and Trapa.
Question 10 What is meant by mesophyll tissue? Write its significance.
Answer:
Mesophyll tissue:
Mesophyll is the internal ground tissue located between the two epidermal cell layers of the leaf and is mostly composed of two kinds of chloroplast-containing tissues that are responsible for performing photosynthesis.
These tissues are the palisade parenchyma which is present on the upper side of the leaf, is made up of elongated chlorenchyma cells and the spongy parenchyma which is found on the lower side of the leaf, which is made up of spherical or ovoid cells.
Significance:
The most important role of the mesophyll cells is to perform photosynthesis. Mesophyll cells provide large intercellular spaces which allow carbon dioxide to move freely within the leaf.
WBBSE Class 9 Life Science Solutions
Question 11. Name the different factors influencing photosynthesis.
Answer:
Photosynthesis is influenced by a number of factors, which can be classified in the following two groups:
1. External or Environmental factors:
1. Light,
2. Carbon dioxide,
3. Temperature,
4. Water,
5. Oxygen.
2. Internal Factors:
1. Chlorophyll contents of leaves,
2. Protoplasmic factors,
3. Accumulation of stored food,
4. Anatomy of leaf,
5. Enzymes.
Question 12 Mention the role of water and carbon dioxide in photosynthesis.
Answer:
Role of water in photosynthesis:
1. Water molecule is broken up (photolysis) into H+ and OH ions by means of activated chlorophyll. From the OH ion, oxygen is formed and later it is liberated.
2. During the light-independent reactions of photosynthesis, hydrogen of water is used to reduce CO2 to synthesize glucose.
Role of carbon dioxide in photosynthesis:
The carbon of CO2 in the atmosphere is utilized in the preparation of glucose (C6H12O6) during photosynthesis. Due to the inclusion of carbon in the cell component (glucose), photosynthesis is called carbon assimilation.
Important Concepts in Photosynthesis for Class 9
Question 13 Why photosynthesis occurs in the daytime, not at night?
Answer:
Photosynthesis Occurs In The Daytime, Not At Night:-
Being a light-dependent process, photosynthesis takes place mainly during the daytime
Because:
1. Sunlight is available during the daytime in nature. Thus, activation of chlorophyll takes place during day time only.
2. Moreover, the stomata of some plants, like grapes, apples, etc., never open during the night. So, CO2 can’t be absorbed.
Question 14 What do you mean by grana and thylakoids? Write its significance.
Answer:
Grana:
The stacked structures found within the matrix that help to trap the light energy to carry light-dependent reactions of photosynthesis are called grana (singular: Granum).
Thylakoids: Each stack of granum is composed of membrane-bound, disc-like structures, which are called thylakoids.
Significance: The light-dependent phase of photosynthesis occurs at the thylakoid membrane of grana.
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Question 15 What is stroma? State its significance.
Answer:
Stroma: The matrix present within the inner membrane of chloroplast and is made up of protein is called the stroma.
Significance: Light-independent phase of photosynthesis takes place in the stroma.
Question 16 ‘Green plants entrap solar energy and convert it into potential energy’ Explain the sentence along with a diagram.
Answer:
The source of all the different forms of energy found on Earth is sunlight. The chlorophyll present in mesophyll cells of green plants absorbs the photon particles of the sunlight and stores it in the form of chemical energy in ATP molecules through various biochemical reactions.
This is known as the ‘entrapping of solar energy’. Later, the chemical energy of ATP is converted into the potential energy which remains stored within the glucose which is synthesized by the reduction of CO2. This is known as the ‘conversion of solar energy into potential energy!
Question 17 Write the differences between photosynthesis and carbon assimilation.
Answer:
Differences between photosynthesis and carbon assimilation are:
Question 18 Write the differences between cyclic photophosphorylation and non-cyclic photophosphorylation.
Answer:
Differences between cyclic photophosphorylation and non-cyclic photophosphorylation are:
Understanding Light Reactions and Dark Reactions for Solutions
Question 19 What is meant by the absorption spectrum of photosynthesis?
Answer:
Absorption Spectrum Of Photosynthesis:-
The specific wavelength of the visual spectrum, which is absorbed by certain plant pigments and used in photosynthesis, is called the absorption spectrum of that particular pigment.
Question 20 What is meant by the action spectrum of chlorophyll?
Answer:
Action Spectrum Of Chlorophyll:-
Out of the seven colors of the visible spectrum of light, chlorophyll molecules strongly absorb red (650-760 nm) and blue (430-470 nm) light which is most effective for photosynthesis. Therefore, this region of the visible spectrum denotes the action spectrum of chlorophyll.
Question 21 Why does Calvin’s cycle named C, Cycle?
Answer:
The first stable carbon compound of the Calvin Cycle is 3-phosphoglyceric acid (3 PGA) which is a 3-carbon compound. That’s why the Calvin cycle is also known as the C3 cycle.
Question 22 What is meant by photolysis or ionization of water?
Answer:
Ionization Of Water:-
Being hit by photons, chlorophyll molecules get excited and dissociate water molecules into protons (H+) and hydroxyl ions (OH–). This light-dependent dissociation of water molecules is called photolysis of water. This reaction is popularly known as the ‘Hill reaction’ as scientist Robin Hill’s first observation process in the plant.
Question 23 What is meant by the reduction of NADP+?
Answer:
Reduction Of NADP+
NADP+ is a proton acceptor, which is present in chloroplast. During the light-dependent phase of photosynthesis, a proton (H+) is produced during the photolysis of water, and an electron (e–) is released from an excited chlorophyll molecule. NADP+, present in the photosynthetic cells, reduces to form NADPH+H+. This reaction step is known as the reduction of NADP+.
⇒ \(\mathrm{NADP}^{+}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{NADPH}+\mathrm{H}^{+}\)
Question 24 How is O2 produced during photosynthesis?
Answer:
O2 Produced During Photosynthesis:-
During the photolysis of water, protons (H+) and hydroxyl ions (OH–) are produced. These hydroxyl ions then release one electron each and are transformed into hydroxyl radicals [OH].
Four such radicals combine to form two molecules of water (H2O) and one oxygen (O2) molecule. Thus, O2 is produced during the light-dependent phase of photosynthesis, which is a byproduct.
⇒ \(4 \mathrm{OH}^{-} \rightarrow 4[\mathrm{OH}]+4 \mathrm{e}^{-} \rightarrow 2 \mathrm{H}_2 \mathrm{O}_2 \rightarrow 2 \mathrm{H}_2 \mathrm{O}+\mathrm{O}_2 \uparrow\)
WBBSE Class 9 Life Science Solutions
Question 25 What is meant by photophosphorylation?
Answer:
Photophosphorylation:-
During the light-dependent phase of photosynthesis, the energized electrons released from photons hit chlorophylls, helping to combine adenosine diphosphate (ADP) and inorganic phosphate (iP) to produce an energy-rich compound, adenosine triphosphate (ATP). This reaction is known as photosynthetic phosphorylation or photophosphorylation.
Question 26 Why is it better to designate the second phase of photosynthesis as a light-independent phase rather than a dark phase?
Answer:
The term dark phase apparently indicates events occurring in the dark, but reactions of photosynthesis never occur in the absence of light. The second phase of photosynthesis does not need direct light but some byproducts of the light phase like ATP and NADPH + H+, come to act here. Therefore, it is better to designate this phase as a light-independent phase rather than a dark phase.
Question 27 What is meant by carbon assimilation? Cite an example.
Answer:
Carbon assimilation:
The physiological process in which inorganic carbon from the environment gets assimilated in the cell as an organic carbon compound in the presence or absence of light is called carbon assimilation.
Example:
CO2, absorbed from the atmosphere by photosynthetic plants, reacts with RuBP, a five-carbon compound, present in the stroma of chloroplast, to produce phosphoglyceric acid (PGA) in the presence of an enzyme, called RuBisCO2. In this reaction, the carbon atom of CO2 is assimilated within the cellular organic compounds. This reaction is known as carbon assimilation.
Question 28 What are the sources of the components of carbon assimilation?
Answer:
Sources Of The Components Of Carbon Assimilation:-
The sources of the components of carbon assimilation are:
1. CO2 – The source of CO2 is air
2. RuBP-Source of RuBP is the mesophyll tissue of the leaf
3. NADPH + H+Source of NADPH + H+ is NADP+, present in the chlorophyll of the leaf. NADP+ reacts with the H+ ion produced by the photolysis of water to form NADPH + H+
4. ATP-ATP is formed by the combination of ADP and inorganic phosphate in the leaf during photophosphorylation.
Question 29 How does the reduction of PGA occur in the light-independent phase of photosynthesis?
Answer:
Reduction Of PGA Occur In The Light-Independent Phase Of Photosynthesis:-
After the production of PGA during the assimilation of carbon, two products of the light-dependent phase, namely NADPH+H+ and ATP come into action. NADPH+H+ reacts with PGA and reduces it to produce phosphoglyceraldehyde (PGAld). ATP supplies the necessary chemical energy for this reaction.
⇒ \(\mathrm{PGA}+\mathrm{NADPH}+\mathrm{H}^{+}+\mathrm{ATP} \underset{\text { PGAld }+\mathrm{NADP}^{+}+\mathrm{ADP}}{\longrightarrow}\)
WBBSE Class 9 Life Science Solutions
Question 30 How is glucose synthesized in the light-independent phase of photosynthesis?
Answer:
Glucose Synthesized In The Light-Independent Phase Of Photosynthesis As Follows:-
During the light-independent phase of photosynthesis, RuBP is carboxylated to form PGA, which is reduced to phosphoglyceraldehyde (PGAld) with the help of NADPH + H+ and ATP. Out of the total 12 molecules of PGAld, 10 molecules undergo a cycle of reactions and resynthesize RuBP and the rest 2 molecule PGAld then undergo a series of reactions to produce 1 molecule of glucose.
Question 31 Why are green plants considered the food producers of the ecosystem?
Answer:
Green Plants Considered The Food Producers Of The Ecosystem:-
By the process of photosynthesis, inorganic materials like water and carbon dioxide combine to produce a monosaccharide, called glucose. It is the basic component of all food matters on earth.
From this glucose, all other carbohydrates, proteins, and lipids are produced through various metabolic processes within the plant body, which is consumed by the other organisms. This is why, green plants are considered food producers of the ecosystem.
Question 32. How does solar energy enter living organisms?
Answer:
Solar Energy Enter Living Organisms As Follows:-
During photosynthesis, light energy from the sun is trapped by the chlorophyll molecules. This energy is then transformed into chemical potential energy by the formation of glucose. In the end, this energy is transferred to different consumers or heterotrophic organisms and decomposers through food chain. This is how solar energy enters living organisms.
Question 33 Write the differences between the light-dependent and light-independent phases of photosynthesis.
Answer:
The differences between light-dependent and light-independent phases of photosynthesis are:
Chapter 3 Physiological Processes Of Life Photosynthesis Answer In A Single Word Or Sentence
Question 1. Name the scientist who coined the term ‘photosynthesis’.
Answer: Barnes coined the term ‘photosynthesis’.
Question 2. Name a vascular land plant, which photosynthesizes through its roots.
Answer: Stylites andicola is a vascular land plant, which photosynthesizes through its roots.
Question 3 What does NADP stand for?
Answer: NADP stands for Nicotinamide Adenine Dinucleotide Phosphate.
Question 4. From which of the raw materials does glucose get its oxygen during photosynthesis?
Answer: Glucose, the end product of photosynthesis, gets its oxygen from CO2.
Question 5. Which element is taken up by green plants from the environment in the form of an oxide?
Answer: Carbon is absorbed by green plants from the environment in the form of an oxide, viz. carbon dioxide.
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Question 6 Which biocatalyst is essential for photosynthesis?
Answer: Chlorophyll is a biocatalyst, which is essential for photosynthesis.
Question 7 Which pigments are necessary for photosynthesis, other than chlorophyll?
Answer: Other than chlorophyll, carotenoids are the pigments that are necessary for photosynthesis.
Question 8 Name two members under kingdom Protista, which are capable of synthesizing their own food by photosynthesis.
Answer: Euglena sp. and Chrysamoeba sp. are the two members of the kingdom Protista, which are capable of synthesizing their own food by photosynthesis.
Question 9 Name an enzyme, necessary for the assimilation of carbon during the light-independent phase of photosynthesis.
Answer: The enzyme RuBisCO is necessary for the assimilation of carbon during the light-independent phase of photosynthesis.
Question 10 What is the full form of the enzyme RuBisCO?
Answer: The full form of RuBisCO is Ribulose Bisphosphate Carboxylase Oxygenase.
Question 11 Which of the raw materials of photosynthesis is oxidized during the process?
Answer: Water molecule is oxidized during the process of photosynthesis.
Question 12 Which of the raw materials of photosynthesis is reduced during the process?
Answer: Carbon dioxide reduced photosynthesis.
Question 13 In the case of terrestrial plants, which process reduces the content of CO2 and increases the content of O2 in the atmosphere?
Answer: In the case of terrestrial plants, the process of photosynthesis reduces the content of CO2 and increases the content of O2 in the atmosphere.
Question 14 Where do plants generally store their food?
Answer: Plants generally store their food in roots, stems, and fruits.
Question 15 What are the end products of photosynthesis?
Answer: Glucose, oxygen, and water are the end products of photosynthesis.
Question 16 Name the following reaction:
Answer: This reaction is named photolysis or ionization of water.
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Question 17 Name the following reaction:
Answer: This reaction is called photophosphorylation.
Question 18 Who discovered that oxygen, which evolved during photosynthesis, comes from water?
Answer: British scientist Robin Hill discovered that oxygen, which evolved during photosynthesis, comes from water.
Question 19 Who discovered the reaction path of carbon assimilation?
Answer: Scientist Blackmannn discovered the reaction path of carbon assimilation.
Question 20 Who discovered the reaction path of glucose synthesis and regeneration of RuBP from PGA?
Answer: Scientist Melvin Calvin and his co-workers discovered the cyclic reaction path of glucose synthesis and regeneration of RuBP from PGA.
Question 21 How many phosphoglyceraldehydes (PGAId) molecules are required to produce a glucose molecule?
Answer: phosphoglyceraldehyde (PGAld) molecules are required to produce one molecule of glucose.
Question 22 Which co-enzyme carries hydrogen for the reduction of PGA?
Answer: NADP carries hydrogen for the reduction of PGA.
Question 23 Which compound supplies chemical energy for the reduction of PGA?
Answer: Adenosine triphosphate (ATP) supplies chemical energy for the reduction of PGA.
Question 24 Out of 12 PGAId molecules, how many take part in the synthesis of RuBP in the Calvin cycle?
Answer: Out of 12 PGAld molecules, 10 molecules take part in the synthesis of RuBP in the Calvin cycle.
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Question 25 What are the end products of the light-dependent phase of photosynthesis?
Answer: Oxygen, ATP, and NADPH + H+ are the end products of the light-dependent phase of photosynthesis.
Question 26 Which of the end products of the light-dependent phase take part in the reactions of the light-independent phase of photosynthesis?
Answer: ATP and NADPH + H+ are the end products of the light-dependent phase, which take part in the reactions of the light-independent phase of photosynthesis.
Question 27 Which reactant of the light-independent phase of photosynthesis is received from the environment?
Answer: CO2 is the only reactant of the light-independent phase of photosynthesis which is received from the environment.
Question 28 What are the essential components, necessary for light-independent reactions of photosynthesis?
Answer: CO2, ATP, NADPH, and RuBP are the essential components, which are necessary for the light-independent reactions of photosynthesis.
Question 29 Which instrument is used to measure the absorption spectrum of chlorophyll?
Answer: The absorption spectrum of chlorophyll is measured with the help of a spectrophotometer.
Concepts Related to Chlorophyll and Pigments for Class 9 Solutions
Question 30 Due to excessive heat from the sun, the process of photosynthesis stops. What is this condition called?
Answer: The condition, in which the process of photosynthesis stops due to excessive heat from the sun, is called solarisation.
Question 31 Under what temperature does photosynthesis occur at its best?
Answer: Photosynthesis occurs at its best at an optimum temperature ranging between 25°C-35°C.
Question 32 Name a bacteria which can prepare its own food without performing photosynthesis.
Answer: Thiobacillus sp. is a bacteria that can prepare its own food without performing photosynthesis.
Question 33 In green plants, what percentage of the total stored water is used during photosynthesis?
Answer: During photosynthesis, only 1% of the total stored water is used up by green plants.
Question 34 Name the pigment present in green plants which helps in photosynthesis.
Answer: In green plants, carotenoids act as a pigment, which helps in photosynthesis.
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Question 35 What is the absorption spectrum of carotenoids?
Answer: The absorption spectrum of carotenoids is blue-green.
Question 36 Why photosynthesis does not occur in animal cells?
Answer: Photosynthesis does not occur in animal cells because they lack chloroplast and hence the photosynthetic pigment chlorophyll.
Question 37 Which compound is both a raw material and a byproduct, in the process of photosynthesis?
Answer: Water is both a raw material as well as a byproduct, in the process of photosynthesis.
Question 38 How do completely submerged aquatic plants absorb necessary CO2 for photosynthesis?
Answer: Completely submerged aquatic plants absorb necessary CO2 through their entire body surface by the process of diffusion.
Question 39 Give an example of a natural and an artificial Hill reagent.
Answer: An example of a natural Hill reagent is NADP, and an example of an artificial Hill reagent is potassium ferric oxalate.
Question 40 What are the two types of photophosphorylation?
Answer:
The two types of photophosphorylation are:
1. Cyclic photophosphorylation
2. Non-cyclic photophosphorylation.
WBBSE Class Nine Life Science
Chapter 3 Physiological Processes Of Life Photosynthesis Fill In The Blanks
1 Chlorenchyma/ Mesophyll is the photosynthetic tissue of green plants.
2 Reactions of the light-independent phase occur in Stroma the chloroplast.
3 Scientists Blackman proved that photosynthetic reactions occur in two phases.
4 ATP is considered the energy currency of the cells.
5 In plant cells, starch is stored in Leucoplast.
6 Green plants absorb Carbon dioxide gas to synthesize glucose during photosynthesis.
7 RuBP is a cellular compound that reacts with atmospheric CO2 to produce phospho- glyceric acid.
8 RuBisCO is the enzyme that is necessary for the synthesis of PGA in the light-independent phase.
9 Photosynthesis is an Anabolic process.
10 In photosynthesis, water is oxidized and CO2 is reduced to carbohydrates.
11 Photosynthesis occurs in the Mesophyll tissue of leaves.
12 All the pigments are located in Thylakoid the membrane of the chloroplast.
13 The distinct photosynthetic unit is called Quantasome
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14 Synthesis of ATP using light energy in photosynthesis is Photophosphorylation
15 In the Calvin cycle, the primary acceptor of CO2 is RuBP
16 Bacteriochlorophyll present in Photosynthetic bacteria
17 Chlorophyll molecule captures Photon particles of sunlight.
18 Emerson defined red drop as a decline in the quantum yield of photosynthesis at wavelength 680 mm.
19 Red and blue colors are absorbed chiefly, measured by Spectrophotometer
20 Orange colors containing photosynthetic pigments are Carotene
Chapter 3 Physiological Processes Of Life Photosynthesis True Or False
Question 1 Aquatic plants absorb CO2 from water through root hair.
Answer: False
Question 2 ATP stands for Adenosine Tri Phenol.
Answer: False
Question 3 Blue-green algae like Nostoc, Anabaena, etc. can synthesize their own food.
Answer: True
Question 4 Ionisation of water is known as Blackmann’s reaction.
Answer: False
Question 5 NADP is an artificial Hill reagent.
Answer: False
Question 6 Out of 12 PGAld molecules, only 2 take part in glucose synthesis.
Answer: True
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Question 7 RuBisCO is used in the light-dependent phase of photosynthesis.
Answer: False
Question 8 Photosynthesis stops due to excessive heat from the sun.
Answer: True
Question 9 Light-independent phase of photosynthesis is also known as Blackmann’s reaction.
Answer: True
Chapter 3 Physiological Processes Of Life Photosynthesis Match The Columns
Answer: 1-D; 2-E; 3-A; 4-C; 5-G; 6-F
Answer: 1-C; 2-F; 3-E; 4-A; 5-B; 6-G
Answer: 1-B; 2-D; 3-E; 4-A; 5-F; 6-C
Chapter 3 Physiological Processes Of Life Photosynthesis Find The Odd One Out
Question 1 Chlorella, Euglena, Rhodospirillum, Mono-tropa
Answer: Monotropa
Question 2 Photosynthesis, Chlorophyll, Mitochondria, Starch
Answer: Mitochondria
Question 3 Thylakoid, Gulancha, Chrysamoeba, Amoeba
Answer: Amoeba
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Question 4 Chlorophyll, Carotene, Haemoglobin, Xanthophyll
Answer: Haemoglobin
Question 5 Light phase, Calvin cycle, Krebs’ cycle, Carbohydrate synthesis
Answer: Krebs’ cycle
Question 6 Feredoxin, Reduction of NADP+, Photolysis, Blackmann’s reaction
Answer: Blackmannn’s reaction
Chapter 3 Physiological Processes Of Life Photosynthesis Fill In The Blanks By Looking At The First Pair
1 Plant root: H2O:: Stomata: CO2
2 Chloroplast: Chlorophyll:: Sunlight: Photon
3 Protein: Nitrogen:: Chlorophyll: Magnesium
4 Photolysis:: Light phase of photosynthesis:: Dark phase of photosynthesis: Calvin cycle
5 Respiration: Catabolic:: Photosynthesis: Anabolic
6 Supplies of O2 in photosynthesis: H2O Supplies of carbon in glucose: CO2
Chapter 3 Physiological Processes Of Life Photosynthesis Among The Four Concepts Given, Three Of Them Belong To One. Find That
Question 1 Water, CO2, Mesophyll tissue, Photosynthesis
Answer: Photosynthesis
Question 2 Chlorophyll, Photosynthetic pigments, Carotene, Xanthophyll
Answer: Photosynthetic pigments
Question 3 Photophosphorylation, Photolysis, Light-dependent phase, O, evolution
Answer: Light-dependent reaction
Question 4 Grana, Thylakoid, Chloroplast, Light reaction
Answer: Chloroplast
WBBSE Class Nine Life Science
Question 5 Carbon assimilation, Redox reaction, Photosynthesis, Autotrophic nutrition
Answer: Photosynthesis
Question 6 Resynthesis of RuBP, Glucose synthesis, Reduction of PGA, Light-independent phase
Answer: Light-independent phase
Chapter 3 Physiological Processes Of Life Photosynthesis Mineral Nutrition
1. The inorganic materials obtained mainly from soil that are used as raw materials by plants are called mineral nutrients.
2. Plants collect a large quantity of mineral nutrients from three different sources, viz., soil, water, and atmosphere.
3. However, only 20 elements are essential for normal plant growth and metabolism.
4. The process of nutrition by which mineral nutrients are absorbed from the environment, distributed, and used in the metabolic activities of the plant, is called mineral nutrition.
5. The mineral elements those act as important structural and physical components are known as essential elements, e.g.-N, P, K, Ca, Mg, S, etc.
6. Macroelements are required in large quantities, whereas, microelements are required in fewer amounts for proper growth, development, structure, and metabolic activities of the plant.
7. Inadequate supply of any one of the essential elements leads to deficiency symptoms in plant bodies which may even lead to plant death.
8. Mineral nutrients help in the synthesis of enzymes (as cofactors), and act as electron carriers for redox reactions.
9. Moreover, these elements maintain water balance in plants, help in chlorophyll synthesis, and control buffer action.
Chapter 3 Physiological Processes Of Life Photosynthesis Long Answer Type Questions
Question 1 Write the characteristic features of macronutrients and micronutrients.
Answer:
Characteristic features of macronutrients:
1. These elements are present in larger quantities (1-10 mg per g dry weight of plants, or more).
2. They are mainly involved in the synthesis of structural components of plant cells.
3. They also participate in maintaining the osmotic potential of the plants.
Characteristic features of micronutrients:
1. The elements are present in minute quantities (0.1 mg per g dry weight of plant or less).
2. High concentrations of micronutrients may prove to be toxic for the plants.
3. They mainly participate in electron transport mechanisms and act as cofactors for various enzymes.
Question 2. Mention the general functions of different nutrients in plants.
Answer:
Functions of different nutrients in plants:
The general functions of different nutrients in plants are as follows:
1 Formation of protoplast: Various nutrients, such as C, H, O, S, N, P, Mg and Fe play a prominent role in the formation of chemical constituents of protoplasm.
2 Structure of enzyme: Nutrients, such as Ca, Mg, K, Zn, Cl, Cu, Ni, etc. are involved in the formation of various enzymes or act as cofactors.
3 Oxidation-reduction reaction: Elements such as Fe and Cu, take part in electron transfer and thus, bring about an oxidation-reduction reaction.
4 Osmotic balance: The presence of inorganic salts (such as CI, PO, SO, etc.) in the cell sap is involved in maintaining the osmotic balance of the cell.
5 Formation of chlorophyll: Elements, such as O, N, H, C, and Mg play a prominent role in the formation of chlorophyll. Iron (Fe) helps in this process.
6 Buffer effect: Certain salts, like phosphates, bicarbonates, and carbonates may act as buffers and thus, resist marked changes in pH.
7 Growth: Mineral elements, such as Zn, Mn, B, etc. maintain normal growth of stem and root.
Question 4. Mention the importance of any macronutrients in plants.
Answer:
Importance of any five macronutrients in plants:
1 Carbon (C):
1. It is the basic constituent of protoplasm.
2. It plays the role of chief component for the synthesis of carbohydrates, protein, fat, enzymes, vitamins, etc.
2 Hydrogen (H):
1. It is the basic constituent of protoplasm.
2. It is needed for the synthesis of carbohydrates, protein and fat.
3 Oxygen (O):
1. It helps in the synthesis and oxidation of food.
2. It is needed for normal functioning metabolic activities.
3. It is needed for the synthesis of carbohydrates, protein, and fat.
4 Nitrogen (N):
1. It is the chief ingredient of protein.
2. It helps in building cellular structure, proper growth, and development of the body.
3. It is needed for the synthesis of chlorophyll.
5 Phosphorus (P):
1. It plays an important role in protein synthesis.
2. It acts as a component of ATP, NADP, and the membrane of cells and other organelles.
3. It prevents premature shedding of leaves and blackening of fruits and leaves.
6 Sulphur (S):
1. It is the major constituent of certain amino acids, vitamins, and co-enzyme A.
2. It helps in the formation of chlorophyll and the development of roots.
3. It also prevents the hardening of stems and plays an important role in growth and metabolism.
7 Potassium (K):
1. It takes part in protein and carbohydrate synthesis.
2. It acts as a co-enzyme and helps in the stomatal movement.
3. Potassium maintains normal growth and color of leaves.
8 Calcium (Ca):
1. It helps in cell division by spindle formation.
2. It helps in nitrogen and carbohydrate metabolism.
3. It helps in the formation of the cell membrane and the middle lamella of the cell wall in plants.
4. It maintains the normal blooming of flowers.
9 Magnesium (Mg):
1. It acts as the primary metallic constituent of chlorophyll.
2. It helps in enzyme activation.
3. It prevents scorching and discoloration of leaves.
4. It helps in nucleic acid synthesis and controls fat and carbohydrate metabolism.
Question 4 Mention the deficiency symptoms of the macronutrients phosphorus, sulfur, and magnesium in plants. Mention the deficiency symptoms of the micronutrients copper, manganese, and boron in plants.
Answer:
Symptoms due to deficiency of P, S, and Mg:
Phosphorus (P):
1. Leaves and stems turn bluish-green in color.
2. Necrosis occurs in leaves.
3. Plants become weak and stunted.
2 Sulphur (S):
1. Curling of leaves occurs followed by necrosis.
2. Nodule formation in leguminous plants is hampered.
3. Overall growth of plants is hampered.
3 Magnesium (Mg):
1. Chlorosis of matured leaves occurs.
2. Retarded growth of plants is seen.
3. Carbohydrate formation is hampered.
Symptoms due to deficiency of Cu, Mn, and B:
1 Copper (Cu):
1. Necrosis occurs in tender leaves.
2. Nitrogen metabolism is hampered.
3. Dieback disease (rotting) occurs in the tender portions of stems.
2 Manganese (Mn):
1. Necrosis of leaves occurs.
2. Leaves become yellowish and intervenous chlorosis takes place.
3 Boron (B):
1. Rotting of apical portions of stems and roots, followed by necrosis.
2. Margins of leaves dry up and as a result, the leaves curl up.
3. Drought spot disease occurs in apples.
Question 5 Mention the importance of different micronutrients in plants.
Answer:
Importance of different micronutrients in plants:
Iron (Fe):
1. It helps in the formation of chlorophyll and chromatin reticulum.
2. It acts as a structural element of electron carriers and helps in ion absorption.
2 Copper (Cu):
1. It acts as a structural component of some enzymes and helps in the reduction of nitrates.
2. It takes part in electron transportation in photosynthesis.
3. It prevents necrosis of leaves in cereals and pulses.
3 Molybdenum (Mo):
1. It helps in the fixation and assimilation of nitrogen.
2. It acts as a cofactor for enzymes involved in nitrogen fixation.
3. It helps in normal flowering and coloration of leaves.
4. It also helps in protein synthesis.
4 Zinc (Zn):
1. It helps in the synthesis of auxins and certain proteins,
2. It activates various enzymes by acting as a cofactor.
3. It also maintains normal growth of the stems and roots.
5 Manganese (Mn):
1. It acts as an enzyme activator.
2. It takes part in chlorophyll and protein synthesis.
3. It helps in the normal growth of shoots and prevents necrosis of leaves.
6 Boron (B):
1. It helps in the formation and growth of flowers and leaves.
2. It takes part in protein synthesis.
3. Boron helps in the metabolism of calcium and potassium.
4. It also helps in the elongation of the pollen tube.
7 Chlorine (CI):
1. Chloride ions, in the cell sap, help in maintaining the osmotic balance of the cell.
2. It helps in the opening and closing of the stomata.
3. It plays a passive role in photosynthesis.
8 Nickel (Ni):
1. Nickel is a component of some plant enzymes, most notably urease, which metabolizes urea into ammonia.
2. It also acts as a catalyst of enzymes, that help legumes to fix nitrogen.
Question 6 Distinguish between macronutrients and micronutrients.
Answer:
Differences between macronutrients and micronutrients:
Chapter 3 Physiological Processes Of Life Photosynthesis Short Answer Type Questions
Question 1. What is meant by macronutrients?
Answer:
Macronutrients:-
The elements, that are required in larger quantities for growth, development, and normal physiological activities of plants, are called macronutrients, Example-Carbon (C), Nitrogen (N), Phosphorus (P), etc.
Question 2 What is meant by micronutrients?
Answer:
Micronutrients:-
The elements, that are required in minute quantities for normal physiological activities of plants, are called micronutrients. Example Molybdenum (Mo), Boron (B), Zinc (Zn), etc.
Question 3 How are mineral nutrients associated with the survival of plants?
Answer:
Mineral Nutrients Associated With The Survival Of Plants As Follows:-
For normal growth, proper formation of cells and tissues, and proper operation of all physiological functions, plants need different minerals. Minerals act as structural components of protoplasm, cofactors of various enzymes controlling several biochemical reactions within the cells, etc. That is how mineral nutrients are associated with the survival of plants.
Question 4. How do different elements take part in the formation of a plant cell?
Answer:
Different Elements Take Part In The Formation Of A Plant Cell As Follows:-
Various elements, such as C, H, O, S, Mg, P, N, and Fe, play a prominent role in the formation of protoplasmic chemical constituents of a cell. All cellular matter is basically composed of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N).
Proteins need sulfur (S), nucleic acids need phosphorus (P), chlorophylls need magnesium (Mg) and the middle lamella of cell needs calcium (Ca) other than C, H, O, and N.
Question 5. Which elements play a role in maintaining osmotic balance in plant cells?
Answer:
Different inorganic salts of potassium (K) and sodium (Na) play an important role in maintaining the osmotic balance of the cells in plants. The elements remain as chloride (CI–), phosphate \(\left(\mathrm{PO}_4^{3-}\right)\), sulfate \(\left(\mathrm{SO}_4^{2-}\right)\), etc. which help to maintain the osmotic concentration within the plant cells.
Study Guide for Class 9 Life Science Photosynthesis Questions
Question 6 How do salts play a role in maintaining the pH of a cellular fluid?
Answer:
Salts Play A Role In Maintaining The PH Of A Cellular Fluid:-
Certain ions, like phosphate \(\left(\mathrm{PO}_4^{3-}\right)\), bicar- donate \(\left(\mathrm{HCO}_3^{-}\right)\) and carbonate
\(\left(\mathrm{CO}_3^{2-}\right)\) may act as buffers and thus resist marked change in pH. Thus, inorganic salts help to regulate pH of any cellular fluid.
Question 7 What are the symptoms that occur due to the deficiency of potassium?
Answer:
The distinct symptoms that occur due to the deficiency of potassium are:
1. Discoloration of leaves
2. The slow growth of roots and seeds
3. Curling of older leaves.
Question 8 What are the symptoms that occur due to oms that occur due to deficiency of zinc?
Answer:
The distinct symptoms that occur due to a deficiency of zinc are:
1. Retarded growth of roots, stems, and leaves
2. Delayed seed formation
3. Discoloration of leaves.
Question 9 What is necrosis?
Answer:
Necrosis:-
When specific zones, like-tips, margins, and areas between the veins become discolored due to deficiency of any particular mineral nutrient (viz.-Cl, Mn, Cu) resulting in drying up and cell death, then the situation is called necrosis.
Question 10 Name the metallic elements which are essential for plants. which are
Answer:
The metallic elements which are essential for plants are-Magnesium (Mg), Potassium (K), Calcium (Ca), Manganese (Mn), Iron (Fe), Zinc (Zn), Copper (Cu), Molybdenum (Mo), Cobalt (Co), Nickel (Ni), Sodium (Na), etc.
Question 11 Write the source of carbon (C), oxygen (O), and hydrogen (H) in plants.
Answer:
Source Of Carbon (C), Oxygen (O), And Hydrogen (H) In Plants:-
In the plant body, the source of carbon is the CO2 gas, present in the atmosphere. Hydrogen is obtained from the water vapor present in the atmosphere and also from the water present in the soil. Oxygen is taken up by plants directly from the air.
Question 12 What is chlorosis?
Answer:
Chlorosis:-
The yellowing of leaf tissue due to deformed chlorophyll or destruction of chlorophyll caused by high alkalinity or nutrient deficiency is called chlorosis. This deficiency syndrome occurs due to a lack of N, K, Mg, S, Fe, Mn, Zn, and Mo.
Question 13 Define mottling and wilting.
Answer:
Mottling:
Different patterns of irregular marks, spots, streaks, blotches, or patches of different. shades of color because of anthocyanin pigmentation when appearing on leaves due to nutrient deficiency, is called mottling.
Wilting:
Wilting is the loss of turgor pressure of non-lignified plant cells causing drooping of plant parts, like leaves, and branches, due to nutrient deficiency.
Chapter 3 Physiological Processes Of Life Photosynthesis Answer In A Single Word Or Sentence
Question 1. Which type of nutrients mainly take part in the structural formation of protoplasm?
Answer: Macronutrients take part mainly in the structural formation of protoplasm.
Question 2 Which type of elements act mainly as cofactors of enzymes?
Answer: Microelements mainly act as cofactors of enzymes.
Question 3 What is the functional similarity between Fe and Cu in the life process of an organism?
Answer: Both Fe and Cu take part in the oxidation-reduction process of photosynthesis and respiration.
Question 4. What is the functional similarity between Zn and Mg in biochemical activities?
Answer: Both Zn and Mg act as cofactors of enzymes.
Question 5 Which metallic element is actively present in electron carriers like cytochrome and ferredoxin?
Answer: Iron (Fe) is actively present in electron carriers like cytochrome and ferredoxin.
Question 6 Mention a deficiency symptom of sulphur in plants.
Answer: In case of sulphur deficiency, young twigs become weak.
Question 7 Mention one metallic macronutrient and one micronutrient, essential for plants.
Answer: Magnesium is a metallic macronutrient and iron is a metallic micronutrient, essential for plants.
Question 8 Name any two gaseous macroelements essential for all living organisms.
Answer: Oxygen and nitrogen are two gaseous macro-elements essential for all living organisms.
Question 9. Which macroelements take part in the structural formation of protoplasm?
Answer: The macroelements which take part in the structural formation of protoplasm are C, H, O, N, P, Mg, and S.
Question 10 Which macronutrient is essential for the formation of the plasma membrane?
Answer: Calcium is an essential macronutrient that helps in the formation of plasma membranes.
Chapter 3 Physiological Processes Of Life Photosynthesis Fill In The Blanks
1 Fruit cracking appears mainly due to the deficiency of Calcium.
2 Most plants receive nitrogen from the soil, in the form of Nitrates.
3. Macronutrients are essential in larger quantities for the proper health of plants.
4 Micronutrients show indistinct deficiency symptoms.
5 Presence of inorganic salts in the cell sap is involved in maintaining the Micronutrient balance of the cell.
6 Nickel is an example of Osmotic.
7 Phosphates and carbonates act as Buffers and thus resist marked changes in pH.
8 High concentrations of micronutrients may prove to be toxic.
9 Dead spots are observed due to a deficiency of Zinc
10 Drought spot of apples is caused by the deficiency of Boron
Chapter 3 Physiological Processes Of Life Photosynthesis State True Or False
Question 1 Due to the deficiency of phosphorus, leaves and stems turn bluish-green in color.
Answer: True
Question 2 The metallic component of chlorophyll is zinc.
Answer: False
Question 3 Iron is an enzyme activator.
Answer: True
Question 4 There are 9 macronutrients, which are essential for plants.
Answer: True
Question 5 Magnesium is the metallic component of anthocyanin.
Answer: False
Question 6 Sulphur is an important constituent of co-enzyme A.
Answer: True
Question 7 Chlorosis develops due to nitrogen and sulphur deficiency.
Answer: True
Question 8 Whiptail disease of cauliflower is caused by the deficiency of molybdenum.
Answer: True
Question 9 K+ ions involve in stomatal regulation.
Answer: True
Question 10 The main component of chlorophyll is C, H, O, N, and Mg.
Answer: True
Chapter 3 Physiological Processes Of Life Photosynthesis Match The Columns
Answer: 1-D; 2-E; 3-A; 4-B; 5-G; 6-F
Answer: 1-B; 2-G; 3-F; 4-A; 5-D; 6-C
Chapter 3 Physiological Processes Of Life Photosynthesis Find The Odd One Out
Question 1 Chlorosis, Mottling, Whiptail, Transpiration
Answer: Transpiration
Question 2 Hydrogen, Nitrogen, Magnesium, Molybdenum
Answer: Molybdenum
Question 3 Manganese, Copper, Zinc, Carbon
Answer: Carbon
Question 4 Boron, Calcium, Manganese, Zinc
Answer: Calcium
Question 5 Nitrogen, Chlorosis, Magnesium, Necrosis
Answer: Necrosis
Chapter 3 Physiological Processes Of Life Photosynthesis Fill In The Blanks By Looking At The First Pair
1 Nitrogen: Macronutrient:: Copper: Micronutrient
2 Chlorosis: Magnesium:: Whiptail: Molybdenum
3 Necrosis: Phosphorus:: Heart rot: Boron
4 Chlorophyll Magnesium:: Cytochrome: Iron
5 Opening and closing of stomata: Potassium:: Synthesis of chlorophyll: Magnesium
Chapter 3 Physiological Processes Of Life Photosynthesis Among The Four Concepts Given, Three Of Them Belong To One. Find That
Question 1 Magnesium, Calcium, Phosphorus, Macronutrients
Answer: Macronutrients
Question 2 Zinc, Copper, Iron, Trace element
Answer: Trace element
Question 3 Potassium, Water balance, Sodium, Calcium
Answer: Water balance
Question 4 Nitrogen, Phosphorus, Non-metallic macronutrients, Sulphur
Answer: Non-metallic macronutrients
Question 5 Mn, Mo, Metallic micronutrients, Zn
Answer: Metallic micronutrients
Question 6 Scald disease of beans, Molybdenum, Whiptail disease of cauliflower, Nitrite production
Answer: Molybdenum
Chapter 3 Physiological Processes Of Life Photosynthesis Transpiration
1. Transpiration is a physiological process by which the excess water drawn by the roots of plants is eliminated in the form of water vapor through the aerial parts of plants, especially leaves.
2. In both the process of evaporation and transpiration, water is evaporated from the surface to the atmosphere in the form of water vapor.
3. But both processes are different from each other.
4. Evaporation is a physical process whereas transpiration is a biological process.
5. Stomata are the primary site of transpiration.
6. Though cuticles and lenticels, present on stems, also take part in transpiration.
7. Stomata are small openings, present on leaf surfaces, that are bordered with guard cells.
8. Stomata take an active part in transpiration and gaseous exchange in the plant body.
9. Transpiration is affected by several internal and external factors.
10. The external factors are temperature, humidity, wind speed, light intensity, etc. and the internal factors are leaf area, structural peculiarities of leaf, stomatal density, etc.
11. Transpiration provides the plant with evaporative cooling, nutrient flow, carbon dioxide entry, and pulling of water from root to tip.
12. Though transpiration is an inevitable process, an excess rate of transpiration leads to wilting, serious desiccation, and a shortage of water.
13. Because of this reason, transpiration is called ‘necessary evil.
14. The transpiration rate of plants can be measured by a number of devices like a lysimeter, pyrometer, heat balance sap flow gauge, etc.
Chapter 3 Physiological Processes Of Life Photosynthesis Long Answer Type Questions
Question 1. What is transpiration? Mention the differences between transpiration and evaporation.
Answer:
Transpiration:
Transpiration is a physiological process by which the excess water, drawn by the roots of plants is eliminated in the atmosphere in the form of water vapor through the aerial parts of plants, especially leaves.
Differences between transpiration and evaporation:
Question 2. How do plants eliminate excess water from their body? Write down the differences between transpiration and guttation.
Answer:
Elimination of excess water from plant body:
Plants eliminate the maximum amount of excess water from their body in the form of water vapor by the process of transpiration. This occurs through the stomata, cuticular pores, and lenticels. Some herbs release excess water as droplets through small pores, present at the edges of their leaves, called hydathodes. This process of disposal of water by plants is known as guttation.
Differences between transpiration and guttation:
Sample Solutions from WBBSE Class 9 Life Science Chapter 3
Question 3 Mention one difference between stomata and hydathodes. Give a brief account of different types of transpiration of plants, stomata
Answer:
Difference between stomata and hydathodes:
One difference between stomata and hydathodes is that stomata usually open during the day and remain closed during the night (in some desert plants, like Aloe vera, it remains closed during the day, and open during the night), whereas, hydathodes remain open all the time. This opening and closing of stomata can be controlled by the guard cells, but there is no such mechanism to close hydathodes.
1. Different types of transpiration:
Transpiration occurs through three different parts of the plant body stomata, lenticels and cuticle. Based on this, the process is divided into the following types.
Stomatal transpiration: Stomata are small pores, present mainly on leaves and a few other parts of plants. Each of these pores is surrounded by two guard cells, that help to open and close the stomatal pores subsequently during the day and at night. The maximum amount of excess water (about 90-97%) is eliminated from the plant body through the stomata.
2 Cuticular transpiration:
Cuticle is a layer of waxy coating present on the epidermis of leaves. Very Site of transpiration-[A] Stomata, [B] Lenticel little amout of water (about 3-10%) is eliminated through the minute pores of the cuticle.
3 Lenticular transpiration:
Lenticels are permanent, lens-shaped, minute pores, found on the cracked bark of the trees. Negligible amount of water (about 0.1%) is transpired through these pores.
Question 4 Mention the roles of different external factors regulating the rate of transpiration.
Answer:
External factors regulating transpiration:
Various external factors control the rate of transpiration.
These are discussed below:
1 Intensity of light:
The most important external factor which regulates the rate of transpiration is the intensity of light. In nature, stomata open during the daytime in the presence of sunlight and close at night. Thus, light controls transpiration by regulating the opening and closing of stomata. An increase in the intensity of light, increases the rate of transpiration, and a decrease in light intensity decreases the rate of transpiration..
2 Temperature:
The rate of transpiration increases with the rise in temperature. But when the temperature rises above 35°C, the stomata start to close, in order to prevent excess water loss.
3 Humidity:
An increase in relative humidity decreases the rate of transpiration and vice versa. That means transpiration is inversely proportional to the relative humidity.
4 Flow of wind:
In an airy environment, transpiration occurs at a faster rate. Therefore, the flow of wind is directly proportional to the rate of transpiration.
5 Density of carbon dioxide:
The rate of transpiration also depends on the density of CO2 in the atmosphere. When the density of CO2 increases in the atmosphere to a certain extent, as well as, more CO2 accumulates in leaves, stomatal pores close, and the rate of transpiration decreases. Similarly, when the density of CO2 is less, the rate of transpiration increases. Thus, the density of CO2 in the atmosphere is inversely proportional to the rate of transpiration.
Question 5 Mention the roles of different internal factors regulating the rate of transpiration.
Answer:
Internal factors regulating transpiration:
Various internal factors control the process of transpiration.
These are discussed below:
1 Surface area and number of stomata in the leaves:
Leaves with larger surface area possess more number of stomata. Therefore, the transpiration rate is higher in plants with broader and larger leaves.
2 Size of stomata:
The size of stomata is directly proportional to the rate of transpiration of a plant.
3 Position of stomata:
Stomata, present on the surface of leaves, facilitate transpiration, but in some plants, stomata is slightly sunken below the surface of leaves. This type of stomata helps to reduce the rate of transpiration.
4 Cuticle:
A plant with a thick and waxy cuticle reduces cuticular transpiration. On the other hand, a thin and porous cuticle enhances the transpiration rate.
5 Age of leaves:
As the leaves grow older stomata get clogged which lessens the rate of transpiration. So the age of leaves is inversely proportional to the rate of transpiration.
6 Protoplasm:
Increased density of cellular protoplasm results in an increase in the rate of transpiration and vice versa. Thus, the density of protoplasm in the cell is directly proportional to the rate of transpiration.
7 Presence of hormones:
Hormones, such as abscisic acid, control the rate of transpiration by regulating the opening and closing of stomata.
Question 6 Explain the beneficial effects of transpiration. Mention its harmful effects.
Answer:
Beneficial effects of transpiration:
The beneficial effects of transpiration are as follows:
1 Ascent of sap:
Transpiration results in transpiration pull, by which water and minerals reach the top leaves of the trees.
2 Elimination of excess water:
By transpiration, excess water from the plant body is removed. It eases the physiological activities within the cells.
3 Cooling plant body:
Through this process, latent heat of evaporation is lost from the plant body, which cools the plant.
4 Maintaining water balance:
Due to the removal of excess water from the plant body, water balance is maintained within it.
Harmful effects of transpiration:
The harmful effects of transpiration are as follows:
1 Drying of leaves and twigs:
Excess transpiration reduces water content in plant cells. As a result, leaves and other softer parts of plants become dry.
2 Wilting:
In case of excess transpiration, the cells lose turgidity and shrink. Hence, leaves and tender branches droop. This is called wilting. If the whole plant wilts and remains in that state for several hours, it may die.
3 Wastage of energy:
The plant utilizes only about 5% of the total absorbed water for various functions of its body. The rest (about 95% ) is given out by transpiration. Thus, there is a waste of energy.
4 Inhibition of gaseous exchange:
Due to excess stomatal transpiration, gaseous exchange during photosynthesis and respiration through stomata is inhibited.
Chapter 3 Physiological Processes Of Life Photosynthesis Short Answer Type Questions
Question 1 What are stomata?
Answer: The tiny openings, present generally on the epidermis of leaves and surrounded by the guard cells, are called stomata. They help plants in gaseous exchange and transpiration.
Question 2 What is meant by stomatal apparatus?
Answer: The tiny openings on the epidermis of leaves are known as stomata. Stomata, two bean-shaped guard cells) and subsidiary cells (ie., the specialized epidermal cells surrounding guard cells) together form the stomatal apparatus.
Question 3 How do guard cells control the opening and closing of stomata?
Answer: In the presence of light, hygroscopic pressure increases inside the guard cells. Due to the unequal thickness and elasticity of cell walls of the two opposite sides of each guard cell, the cells bend like beans. As a result, the space between the two guard cells widens and the stomata open. In the absence of light, hygroscopic pressure decreases inside the guard cells and the stomata close.
Question 4 Why are the stomata of the lotus plant present on the dorsal surface of the leaves?
Answer: The lotus leaves float on the water surface and the stomata are present on the dorsal surface to keep direct contact with air. This typical placement of stomata helps lotus leaves to maintain gaseous exchange with the atmosphere and thus, perform transpiration.
Question 5 Why do plants with wider leaves wilt in summer but a pine tree remains unaffected?
Answer: Plants with wider leaves have more stomata, through which they lose excess water in the form of vapor due to transpiration on summer days. This loss of water makes the cells flaccid and the protoplasm shrinks. This results in wilting of these plants. Whereas, a pine tree possesses needle-like leaves with very little number of sunken stomata. Therefore, pine trees lose much less water by transpiration and remain unaffected even on a summer day.
Question 6 Why is transpiration called a necessary evil?
Answer: Transpiration helps plants in the ascent of sap, removal of excess water, cools the plant body, and maintains the water balance. On the other hand, excessive transpiration causes a decrease in protoplasmic water content and thus, results in shrinkage of cells followed by wilting of leaves and tender branches. This is why, transpiration is called a necessary evil.
Question 7 If all the leaves of a plant are applied with a layer of vaseline, what will happen to it?
Answer: If all the leaves of a plant are applied with a layer of vaseline, the stomatal openings will be sealed completely. In this situation, gaseous exchange for photosynthesis and respiration will be ceased. The excess water in the plant body will not be released into the atmosphere. This will affect many necessary physiological activities of the cells and the cells will die and eventually will the whole plant.
Question 8 How does transpiration control environmental conditions?
Answer: By transpiration, water vapor is released into the atmosphere. This increases the relative humidity, which in turn helps in the formation of clouds. Therefore, transpiration initiates rainfall in an area and thus, regulates atmospheric temperature and soil water content of that environment.
Question 9 What are hydathodes? What is the function of hydathodes?
Answer: Hydathodes: Several plants, especially herbs, possess small pores on the apices and edges of their leaves. These small pores are known as hydathodes.
Function: Hydath- odes help the plants to dispose of excess water Guttation through hydathodes from the body in the form of droplets, by a process called guttation but they do not take part in tran- spiration.
Question 10 What is wilting?
Answer: In case of excess transpiration during the daytime in summer, the plants lose large amounts of water. As a result, the protoplasm of cells loses turgidity and shrinks. Hence, leaves and tender branches droop. This is called wilting. If the whole plant wilts and remains in that state for several hours, it may die.
Question 11 State the relationship between transpiration and root-shoot ratio.
Answer: The rate of transpiration is reduced if the root-shoot ratio is low, i.e., the root system is less branched and less deep or the shoot is larger in size.
Chapter 3 Physiological Processes Of Life Photosynthesis Answer In A Single Word Or Sentence
Question 1. Which cells control the opening and closing of stomata?
Answer: Guard cells
Question 2. Name the small lens-shaped pores present on the stems of plants, which serve as sites of transpiration.
Answer: Lenticels
Question 3. Which layer on the leaf surface prevents transpiration in desert plants?
Answer: Cuticle layer
Question 4. Why does transpiration occur mainly during the daytime?
Answer: Light helps in opening of the stomata, therefore, transpiration occurs mainly during the daytime.
Question 5 Why do the stomata of some desert plants open at night?
Answer: To prevent excess water loss during the daytime, the stomata of some desert plants open at night.
Question 6 In which season of the year does transpiration in terrestrial plants reach the peak?
Answer: In dry summer season, transpiration in terrestrial plants reaches the peak.
Question 7 Why are the leaves of many desert plants modified into spines?
Answer: The leaves of many desert plants are modified into spines in order to prevent water loss by transpiration.
Question 8 Why do many desert plants possess dense hairs on the body surface?
Answer: Dense hairs prevent direct air contact on the leaf surface and thus, reduce the rate of transpiration. Therefore, many desert plants possess dense hairs on the body surface.
Question 9 Why is the rate of transpiration high on the ventral surface of the leaves of dicotyledonous plants?
Answer: Leaves of dicotyledonous plants possess more stomata on the ventral surface. Therefore, the rate of transpiration is higher on that side.
Question 10 Which instrument is used to measure the rate of transpiration?
Answer: Ganong’s Potometer
Question 11 Mention the phenomenon through which plants give out excess water in the form of droplets.
Answer: Guttation
Question 12 How is the rate of transpiration affected on a rainy day?
Answer: Since the percentage of water vapor is high in the atmosphere on a rainy day, the rate of transpiration decreases.
Question 13 On which side of an isobilateral leaf, do we find more stomata?
Answer: In an isobilateral leaf, stomata are distributed equally on both sides of the leaf.
Question 14 What are the subsidiary cells?
Answer: Plant epidermal cells, surrounding the guard cells, are called subsidiary cells.
Question 15 Give an example of a plant where sunken stomata are present.
Answer: Nerium sp.
Question 16 Who described the mechanism of active K+ exchange of opening and closing of stomata?
Answer: Levitt
Chapter 3 Physiological Processes Of Life Photosynthesis Fill In The Blanks
1 Minimum rate of transpiration occurs through Lenticels.
2 Potassium ions help in the opening of stomata.
3 Xerophytic plants possess Sunken stomata.
4 In dorsiventral leaves, a maximum number of stomata is seen on the Ventral side.
5 Abscisic acid is an example of anti-transpirant.
6 In the airy environment, the rate of transpiration Increases.
7 A thin and porous cuticle Enhances transpiration rate.
8 Transpiration is a slow and controlled process in plants.
9 Drooping of plant, due to excess transpiration is called Wilting.
10 Turgor pressure of the guard cell is responsible for the opening of the stomata.
Chapter 3 Physiological Processes Of Life Photosynthesis State True Or False
Question 1 Ganong’s photometer is used to measure the rate of respiration.
Answer: False
Question 2 Plants give out excess water as vapors by a process called evaporation.
Answer: False
3 Transpiration is a physiological process.
Answer: True
4 Maximum rate of transpiration occurs through the cuticle.
Answer: False
5 Relative humidity is one of the main controlling factors of evaporation.
Answer: True
6 Excess transpiration causes wilting of plants.
Answer: True
7 High CO2 concentration causes the opening of stomata.
Answer: False
8 Stomata is the chief site of the transpiration of plants.
Answer: True
Chapter 3 Physiological Processes Of Life Photosynthesis Match The Columns
Answer: 1-C; 2-A; 3-E; 4-B
Answer: 1-G; 2-F; 3-B; 4-A; 5-C; 6-D .
Answer: 1-B; 2-D; 3-E; 4-C; 5-A; 6-G
Chapter 3 Physiological Processes Of Life Photosynthesis Find The Odd One Out
Question 1 Lenticel, Stomata, Cuticle, Hydathode
Answer: Hydathode
Question 2 Humidity of air, Temperature, Number of stomata, Velocity of air
Answer: The Number of stomata
Question 3 Wax, Water, Silicon, oil
Answer: Water
Question 4 Wilting, Reduction of Water content, Loss of energy, Photosynthesis
Answer: Photosynthesis
Chapter 3 Physiological Processes Of Life Photosynthesis Fill In The Blanks By Looking At The First Pair
1 Transpiration Physiological process:: Evaporation: Physical process
2 Stomata transpiration: 80-90%:: Lenticular transpiration: 1%
3 Presence of stomata on both surfaces of leaves: Isobilateral leaves: Stomata on the lower surface of leaves: Dorsiventral leaves
4 Larger surface area: Higher transpiration rate:: A plant with thick cuticle: Reduced transpiration rate
Chapter 3 Physiological Processes Of Life Photosynthesis Among The Four Concepts Given, Three Of Them Belong To One. Find That
Question 1 Wind velocity, Factors affecting transpiration, Humidity of air, Temperature
Answer: Factors affecting transpiration
Question 2 Structure of leaf, Factors affecting transpiration, Light intensity, the humidity of the air
Answer: Factors affecting transpiration
Question 3 Stomata, Lenticel, Site of transpiration, Cuticle
Answer: Site of transpiration
Chapter 3 Physiological Processes Of Life Photosynthesis Movement Of Water Minerals Food And Gases
1. Movement of substances like water, gases, minerals, hormones, organic solutes, etc. within the plant body, occurs not only from one cell to another or from one tissue to another (short distances) but also from roots to the top of plants or from leaves to the tip of roots (long distances).
2. The movement of materials (transport) within a plant body, over long distances, through the vascular system i.e., xylem and phloem, is called transportation.
3. Transport of substances over short distances occurs via the process of diffusion, cytoplasmic streaming, and active transport.
4. Water is absorbed by root hairs and it moves through the xylem via two pathways-apoplastic and symplastic pathways.
5. A hydrostatic pressure, existing in roots pushes the water up through xylem vessels.
6. This pressure is called root pressure.
7. The excess water absorbed by plant roots is lost in the atmosphere through leaves by the process of transpiration.
8. It helps in the ascent of sap.
9. As a result, it also increases the absorption of mineral nutrients from the soil.
10. Transpiration-driven ascent of sap through the xylem depends on physical forces like cohesion, adhesion, and surface tension.
11. Transpiration creates a transpirational pull for the absorption and transport of water in plants.
12. Active and passive transport helps in ion absorption through plant roots.
13. The active uptake of ions requires ATP energy.
Chapter 3 Physiological Processes Of Life Photosynthesis Long Answer Type Questions
Question 1 Mention the role of different factors in controlling diffusion.
Answer:
Role of different factors in controlling diffusion:
Various factors play an important role in controlling the rate of diffusion.
These are mentioned below:
1 Temperature:
With the increase in temperature of the medium, the movement of diffusible molecules increases. Therefore, an increase in temperature enhances the rate of diffusion.
2 Size of diffusible molecules:
The larger size of the diffusible molecules restricts their movement. Therefore, larger molecules show a slower diffusion rate.
3 Extent of concentration gradient:
The rate of diffusion also depends upon the concentration gradient of molecules of both media. The greater the difference in concentration, the more rapid the diffusion. The closer the distribution of both molecules gets to equilibrium, the slower the rate of diffusion becomes.
4 Solubility:
A molecule with a higher rate of solubility diffuses quickly in a given medium.
5 Viscosity of the medium:
The rate of diffusion is inversely proportional to the viscosity of the medium. That is, if the viscosity of the medium is high, then the rate of diffusion will be lower and vice versa.
Question 2 Mention the salient features of diffusion. Give two examples of diffusion in plants.
Answer:
The salient features of diffusion:
The salient features of diffusion are as follows:
1. Diffusible molecules of solid, liquid, or gaseous substances can diffuse within either liquid or in gaseous. medium.
2. Diffusible molecules move from a region of higher concentration to a region of lower concentration.
3. Diffusion of molecules continues until homogeneity is attained, i.e. the concentration of molecules in both directions becomes the same.
4. It is a passive process, i.e. does not require any metabolic energy.
Example of diffusion in plants:
Two examples of diffusion in plants are:
1. Passive absorption of ions
2. Absorption of O2 a CO2 in cells.
Question 3 What is meant by plasmolysis and deplasmolysis? What happens when a living cell is placed in a solution with a concentration identical to its protoplasm?
Answer:
Plasmolysis:
If a cell with an intact cell membrane is placed in a hypertonic solution, i.e. a solution with a concentration higher than the concentration of the protoplasm of the cell, water from the protoplasm will gradually move out from the cell through its cell membrane by exosmosis.
In this case, the protoplasm of the cell will shrink and the cell will appear wrinkled. This phenomenon is called plasmolysis.
Deplasmolysis:
If a plasmolyzed cell is placed in a hypotonic solution, i.e., a solution with a concentration lower than the concentration of the protoplasm of the cell, water from the outer medium will enter into the protoplasm through the cell membrane by endosmosis.
In this case, the protoplasm will get more water and the cell will be distended. This phenomenon is called deplasmolysis.
The fate of living cells in isotonic solution:
If a living cell is placed in a solution with a concentration identical to its protoplasm, i.e., isotonic solution, water from the outer medium and from the protoplasm will move through the cell membrane at the same rate against each other. Therefore, no change will appear in the cell.
Question 4. Mention the salient features of osmosis. Mention three roles of osmosis in the plant body.
The salient features of osmosis:
The salient features of osmosis have been mentioned below:
1. Osmosis occurs only in a liquid medium.
2. This process of the Solute molecule involves the presence of a semi-permeable membrane.
3. Solvent molecules move from a region of its higher concentration to a region of lower concentration across the semi-permeable membrane. The movement of solutes does not occur in osmosis.
4. The movement of solvent molecules continues until homogeneity is attained. In osmosis, the rate of movement of solvent molecules on either side of the semi-permeable membrane becomes the same.
5. It is a passive process, i.e. does not require any metabolic energy.
Role of osmosis in plant body:
In plants, osmosis helps in:
1. Absorption of water
2. Opening and closing of the stomata
3. Maintaining turgidity of the cell.
Question 5 Briefly describe the characteristic features of active transport. Mention the importance of cell-to-cell transport.
Answer:
The characteristic features of active transport:
The characteristic features of active transport have been briefly described below:
1. In this process, the movement of substances occurs from a region of lower concentration to a region of higher concentration.
2. The cell membrane has different carrier proteins that remain suspended in its lipid bilayer. The substances to be transported, first bind to a specific carrier protein and then pass from one side of the membrane to another.
3. The movement of substances against the concentration gradient requires the involvement of energy, which is supplied by ATP. In plants, active transport occurs during the absorption of mineral ions by plant roots, loading of sugar into the phloem, etc.
4. Active transport requires a semi-permeable membrane.
Importance of cell-to-cell transport:
The importance of cell-to-cell transport is as follows:
1. Diffusible materials like O2, CO2, etc., move from one cell to the next, by cell-to-cell diffusion.
2. Water passes from one cell to another, by cell-to-cell osmosis.
3. Sugar is loaded into the phloem cells from the leaf cells by means of cell-to-cell active transport.
Question 6 How does the ascent of sap occur in a plant?
Answer:
Ascent of sap:
Transpiration is the process that acts as a driving force for the ascent of sap, from roots to the top of a tree, via xylem vessels.
The sequence of events during the ascent of sap occurs in the following order:
1. Release of water through stomata by transpiration.
2. Lowering of turgor pressure of leaf cells due to loss of water.
3. The uptake of water by leaf cells from the xylem elements causes a vacuum in the xylem vessels.
4. Generation of a vertically upward suction force on the water column in the xylem vessel, called transpiration pull.
5. Cohesive and adhesive forces of water molecules maintain the uninterrupted water column within the xylem vessels.
6. Roots absorb water and minerals from the soil by imbibition and endosmosis, which moves through the endodermis and pressure in the cells surrounding the xylem vessels.
7. The mounting root pressure pushes sap into xylem vessels and starts to drive it against gravity towards the leaves upwards.
Question 7 How is food transported in different parts of the plant body?
Answer:
Transportation of food in plant body:
Transportation of food in plants occurs through sieve tubes of phloem. The cells of the sieve tube are arranged one after the other forming a continuous structure.
Regarding the mechanism of this process, the ‘pressure flow hypothesis’ by Ernst Munch, is the most accepted one. According to this hypothesis, the following events occur during food transport in plants.
1 Transfer of food from mesophyll tissue to sieve tube:
In mesophyll tissues, glucose produced by photosynthesis is soon converted into a larger sugar (sucrose). The sucrose solution is then transferred to the sieve tube via bundle sheath cells, phloem parenchyma and companion cells by cell to cell transport.
2 Creation of pressure within sieve tube:
With the entry of sucrose, the cytoplasm of the sieve tube becomes denser. As a result, a concentration gradient develops between the sieve tube & neighboring xylem vessels. Due to this, water moves into the sieve tube from xylem vessels by osmosis, thereby, creating additional pressure within the sieve tubes.
3 Flow of food:
This mounting pressure produced within the sieve tube pushes the food solution to different parts of the plant body. Finally, the sucrose solution enters into the tissue cells from the sieve tube.
Question 8 Write the importance of diffusion and osmosis in the living body.
Answer:
Importance of diffusion in the living body:
1. All physiological processes in living bodies are directly or indirectly dependent on diffusion.
2. Intake of different gases like CO2, and O2, from the atmosphere and movement of gases in inter-cellular spaces take place by this process.
3. Loss of molecules like CO2, O2, water vapor, etc., from the plant body during respiration, photosynthesis, and transpiration respectively take place by the process of diffusion.
4. Oxygen and carbon dioxide, dissolved in water, are exchanged by diffusion in the lungs of animals.
Importance of osmosis in the living body:
1. Plants absorb water by root hairs from the soil by osmosis.
2. Osmosis maintains turgidity in meristematic cells that are required for cell division and growth.
3. Osmosis controls the movement of guard cells and helps in the opening and closing of stomata.
4. Osmosis controls the entry of water into animal cells and its movement in intercellular space.
Chapter 3 Physiological Processes Of Life Photosynthesis Short Answer Type Questions
Question 1 What is meant by transport?
Answer:
The process by which food materials, mineral salts, hormones, and various gases reach the cells of living organisms and different harmful metabolic waste matters are sent from tissues to
respective excretory organs through a liquid medium are called transport.
Question 2 How is facilitated diffusion different from simple diffusion?
Answer:
In facilitated diffusion, a carrier molecule or a channel protein in the membrane helps the entry of the diffusible molecules through it, but in simple diffusion, the carrier protein is not required.
Question 3 What is meant by passive transport?
Answer:
Passive transport is a process by which any molecule or ion of a substance passes through the cell membrane along a concentration gradient without consuming any metabolic energy.
Example: Diffusion and osmosis.
Question 4 What is meant by active transport?
Answer:
Active transport is a process in which any molecule or ion, with the help of some metabolic energy, passes through a cell membrane with the help of carrier protein, against a concentration gradient.
Example: Intake of glucose molecules by a cell.
Question 5 What is diffusion?
Answer:
The physical process by which molecules or ions of any substance, move from a region of higher with the help of their own kinetic energy, is called concentration to a region of lower concentration, diffusion.
Example: The aroma of incense sticks spreads to all corners of the room by diffusion.
Question 6 What is meant by osmosis?
Answer:
Osmosis:-
If two solutions of different concentrations, prepared from the same liquid solvent, are separated by a semi-permeable membrane, the solvent molecules move from the region of higher solvent concentration towards the region of lower solvent concentration, until equilibrium is attained. This physical phenomenon is known as osmosis. Example-Raisins swell in water due to osmosis.
Question 7 What is meant by facilitated diffusion?
Answer:
Facilitated diffusion is a type of diffusion, where diffusible molecules pass through a cell membrane with the help of some channel proteins present in it. In this process, no metabolic energy is needed.
Question 8 What is meant by root pressure? Mention the importance of root pressure.
Answer:
Root pressure: The cumulative turgor pressure created in the cells, surrounding the xylem vessels of the root, due to absorption of sap is known as root pressure.
Importance: Root pressure pushes the sap into the xylem vessels through their thick cell wall and drives the sap upward.
Question 9 What is cohesive force? What is meant by adhesive force?
Answer:
Cohesive force: The force of attraction between two particles or molecules of the same substance, is called cohesion force. Inside the xylem vessels, water droplets remain attached to each other by cohesive force.
Adhesive force: The force of attraction between the particles of different substances, is called the adhesive force. The water droplets remain attached to the wall of the xylem vessel by adhesive force.
Question 10 What is transpiration pull?
Answer:
In xylem vessels, uninterrupted water column. is formed by cohesive-adhesive force. These columns extend from the roots to the stomata of the leaves. During transpiration, when a molecule of water leaves the stomatal opening, it applies an upward pulling force on the receding water column, which is known as transpiration pull.
Question 11 What is meant by the ascent of sap?
Answer:
Ascent Of Sap:-
The transport of water and minerals, known as sap, from root to the leaves through xylem vessels against the force of gravity, is known as the ascent of sap.
Question 12 The fragrance of a perfume, sprayed at one corner of a room, can be felt in the entire. room after some time. Which phenomenon is responsible for this?
Answer:
The fragrance of a perfume, sprayed at one corner of a room, can be felt in the entire room after some time due to a phenomenon called diffusion.
Question 13 Name the forces which control the ascent of sap in plants.
Answer:
The forces which control the ascent of sap in plants are:
1. Root pressure
2. Transpiration pull
3. Adhesive force
4. Cohesive force.
Question 14 Give two examples of liquid-liquid diffusion.
Answer:
Two examples of liquid-liquid diffusion are:
1. Diffusion between water and ink
2. Diffusion between water and sugar syrup.
Question 15 Give two examples of liquid-solid diffusion.
Answer:
Two examples of liquid-solid diffusion are:
1. Diffusion between water and sugar crystal
2. Diffusion between water and copper sulfate (CuSO4) crystals.
Question 16 Give two examples of solid-gas diffusion.
Answer:
Two examples of solid-gas diffusion are:
1. Diffusion between asafoetida and air
2. Diffusion between camphor and air.
Question 17 Give two examples of gas-gas diffusion.
Answer:
Two examples of gas-gas diffusion are:
1. Diffusion between air and ammonia gas and
2. Diffusion between air and smoke of incense stick.
Question 18 Mention two examples of carrier proteins that help in active transport.
Answer:
Two examples of carrier proteins that help in active transport are:
1. Sodium-Potassium pump (Na+K+-ATPase pump)
2. Proton pump (H+- ATPase pump).
Question 19 Define hypertonic solution.
Answer:
Hypertonic Solution:-
A solution that has a higher concentration of solutes on the outer side of a cell in Cell- comparison to the inner side of it, is known as a hypertonic solution.
Question 20 What is an isotonic solution?
Answer:
Isotonic Solution:-
A solution that has an identical concentration of solutes on both the outer and inner sides of a cell, is Cell-known as an isotonic solution. If a cell is placed in this solution there will be no net flow of water into or out of the cell.
Question 21 Define a hypotonic solution.
Answer:
Hypotonic Solution:-
A solution that has a lower concentration of solutes on the outer side of a cell in comparison to Cell- the inner side of it, is known as a hypotonic solution.
Question 22 What is absorption in plants?
Answer:
Absorption In Plants:-
The physical process by which water and mineral salts enter the plant body through root hair by the process of endosmosis is called absorption.
Question 23 Why the water potential of any solution is always negative?
Answer:
Water Potential Of Any Solution Is Always Negative:-
The water potential of pure water is zero. Thus, solute mixed with any solution always has negative water potential.
Question 24 What are the major components of phloem sap?
Answer:
Major Components Of Phloem Sap:-
The major components of phloem sap are- carbohydrates, amino acids, minerals, organic acids, and water.
Question 25 Mention the differences between active transport and passive transport.
Answer:
The differences between active transport and passive transport are:
Question 26 Mention the differences between diffusion and osmosis.
Answer:
The differences between diffusion and osmosis are:
Question 27 Write the differences between plasmolysis and deplasmolysis.
Answer:
The differences between plasmolysis and deplasmolysis are:
Question 28 Write the differences between endosmosis and exosmosis.
Answer:
The differences between endosmosis and exosmosis are:
Question 29 Define impermeable membrane, permeable membrane, semipermeable membrane, and selectively permeable membrane.
Answer:
Impermeable membrane:
The membrane through which both solute and solvent molecules cannot pass is called an impermeable membrane. e.g. suberised walls of plant cells, sheets of rubber, etc.
Permeable membrane:
The membrane through which both solute and solvent molecules can pass is called a permeable membrane, e.g. plant cell wall, filter paper, etc.
Semipermeable membrane: The membrane through which only solvent molecules can pass through but not solute molecules is called a semi-permeable membrane, e.g. parchment paper.
Selectively permeable membrane: The membrane through which both solute and solvent molecules can pass through but in a selective manner is called a selectively permeable membrane, e.g. cell membrane. 30
Question 30. Define turgor pressure.
Answer:
Turgor Pressure:-
As a result of the entry of water into a cell (endosmosis) pressure is developed in the protoplasm which presses the cell membrane against the cell wall. This pressure is called turgor pressure (TP).
Question 31 Write the features which are influencing the Dixon and Jolly theory.
Answer:
Cohesion-Tension was originally proposed by Dixon and Jolly in 1894.
The theory is based on the following features:
1. Cohesive and adhesive properties of water molecules form a continuous water column in the xylem.
2. Transpiration pull is exerted on this water column.
3. The continuity of the water column in the xylem vessels is maintained.
Question 32 Mention the role of root pressure in the ascent of sap in herbaceous plants. Or, Why root pressure is largely responsible for ascent of sap in herbaceous plants?
Answer:
Root pressure is defined as pressure developing in the tracheary elements of the xylem due to the metabolic activities of the root. The pressure is caused due to diffusion pressure gradient and is maintained by the activity of living cells.
This is why, if the stem of a plant is cut near its base, xylem sap is seen to flow out through the cut end. This root pressure is an osmotic phenomenon. So, the living cells of roots are involved in the phenomenon of the ascent of sap.
Question 33 Mention the cohesion-adhesion force in the force in the ascent of sap mechanism.
Answer:
Water molecules make a continuous column in the xylem because of forces of adhesion and cohesion among the molecules. Cohesion is the force of attraction between molecules of the same substance and adhesion is the force of attraction between molecules of different substances.
Water molecules stick together because of the force of cohesion. Water molecules stick to a surface because of the force of adhesion.
Question 34 Write the role of transpiration pulls in the ascent of sap.
Answer:
Role Of Transpiration Pulls In The Ascent Of Sap:-
Evaporation of water molecules through the stomata of a leaf creates a suction that pulls water from the xylem cells of roots. Thus, transpiration helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves.
Question 35 State the path of the ascent of sap in plants.
Answer:
The path of the ascent of sap in plants is as follows:
Question 36 What do you mean by source and sink?
Answer:
Source And Sink:-
In plants, food is mainly synthesized in the leaves and also in young stems. The leaves, therefore, serve as the source. The synthesized food is translocated to the growing regions and also to the storage organs of the plants. So, these regions serve as sinks.
Question 37 Write the direction of translocation of organic solutes.
Answer:
Translocation of organic solutes can occur in the following directions:
1. Downward translocation
2. Upward translocation
3. Lateral translocation
4. Bidirectional translocation.
Question 38 What do you mean by sodium-potassium pump?
Answer:
Sodium-Potassium Pump
The sodium-potassium pump system moves sodium and potassium ions against large concentration gradients. It transfers two potassium ions into the cell where potassium levels are high and pump three sodium ions out of the cell and into the extracellular fluid.
Question 39 What do you mean by imbibition?
Answer:
Imbibition
Imbibition is the absorption of water by the particles of a solid, without forming a solution. It only occurs in the presence of imbibing. Heat is released.
Question 40 What do you mean by hygroscopic water and capillary water?
Answer:
Hygroscopic Water And Capillary Water:-
Hygroscopic water is found in close association with colloidal soil particles and is not available to plants. Capillary water is present in small spaces of soil particles and is easily absorbed by the root.
Chapter 3 Physiological Processes Of Life Photosynthesis True Or False
Question 1. The rate of diffusion increases with the
- Increase in temperature of the medium
- Increase in viscosity of the medium
- Decrease in relative difference in concentration of two media
- All of these
Answer: 1. Increase in temperature of the medium
Question 2. Which type of transport never needs any carrier?
- Simple diffusion
- Osmosis
- Both 1 and 2
- Ion absorption
Answer: 3. Both 1 and 2
Question 3. In the diffusion of molecules, the main driving force is the
- Electrical gradient
- Concentration gradient
- Both 1 and 2
- None of these
Answer: 3. Both 1 and 2
Question 4. O2is absorbed in the living cells by
- Diffusion
- Osmosis
- Active absorption
- None of these
Answer: 1. Diffusion
Question 5. The main cause of diffusion pressure is
- Size of diffusible molecules
- The velocity of the diffusible molecules
- Weight of the diffusible molecules
- The viscosity of the medium
Answer: 2. The velocity of the diffusible molecules
Question 6. The phloem element which helps in the transport of food material, is
- Sieve tube
- Companion cells
- Both 1 and 2
- None of these
Answer: 3. Both 1 and 2
Question 7. An increase in the size of diffusible molecules results into
- The slower rate of diffusion
- The faster rate of diffusion
- No change in diffusion rate
- Stoppage of diffusion
Answer: 1. The slower rate of diffusion
Question 8. Increase in viscosity of the medium
- Has no role in the diffusion
- Has a negative role in the diffusion rate
- Has a positive role in the diffusion rate
- Stops diffusion completely
Answer: 2. Has a negative role in the diffusion rate
Question 9. If a living cell is placed in a hypertonic solution, the protoplasm
- Shrinks
- Swells
- Remains as it is
- Gets dissolved in the solution
Answer: 1. Shrinks
Question 10. In active transport, sodium, and potassium ions
- Joined enter into a cell through the cell membrane
- Move against each other through the cell membrane
- Never enter a cell through the cell membrane
- Sodium ion enters but potassium ion does not enter in a cell
Answer: 2. Move against each other through the cell membrane
Question 11. During deplasmolysis
- A cell with shrunken protoplasm swells
- Protoplasm shrinks
- Cell membrane swells
- Cell membrane shrinks
Answer: 1. Protoplasm shrinks
Question 12. Select the correct statement.
- Diffusion is possible only in liquid medium
- Osmosis occurs through a permeable membrane.
- The semipermeable membrane allows solvent molecules to pass through it
- All cell membranes are semi-permeable in nature
Answer: 3. The semipermeable membrane allows solvent molecules to pass through it
Question 13. In active transport, ATP
- Carries the ions with it
- Pushes the ions through the membrane
- Binds to the carrier protein
- Provides physical energy
Answer: 3. Binds to the carrier protein
Question 14. The transport of molecules with the help of a carrier protein but without any role of ATP through a cell membrane is called
- Facilitated diffusion
- Diffusion
- Passive transport
- Active transport
Answer: 1. Facilitated diffusion
Question 15. If a flower is cut and immersed in dilute Nacl solution, then
- Exosmosis occurs
- Endosmosis occurs
- Absorption of solutes inside the cells of the flower occurs
- None of diese
Answer: 2. Endosmosis occurs
Chapter 3 Physiological Processes Of Life Photosynthesis Answer In A Single Word Or Sentence
Question 1. By which process do water molecules enter through the cell membrane of root hair cells?
Answer: Endosmosis
Question 2. How do cells of aquatic plants absorb dissolved CO2 from water?
Answer: By diffusion
Question 3. How is facilitated diffusion different from active transport?
Answer: In active transport, chemical energy is needed in the form of ATP but facilitated diffusion does not need energy.
Question 4. In which type of active transport, do two different diffusible molecules or ions move against each other at the same time?
Answer: Antiport
Question 5. In which type of active transport, a single type of ion or molecule moves through the cell membrane?
Answer: Uniport
Question 6 In which type of active transport, do two different ions or molecules move together in the same direction through a cell membrane?
Answer: Symport
Question 7. Name two biomolecules, which pass through the cell membrane by active transport.
Answer: Glucose and amino acids
Question 8. Mention two matters, which are taken into a cell by passive transport.
Answer: Oxygen and water
Question 9 Diffusion pressure deficit increases in leaves during daytime due to which phenomenon?
Answer: Transpiration
Question 10. How does sap pass through the cells of the cortex of the root?
Answer: By cell-to-cell osmosis
Question 11. Which pressure is created within the xylem vessels by the inflow of sap from the root?
Answer: Root pressure
Question 12. Which force pulls the sap up from the roots to the leaves of tall plants?
Answer: Transpiration pull
Question 13. How much pulling force may transpiration pull create in a xylem vessel?
Answer: About 20 atmospheric pressure
Question 14. How does the size of diffusible molecules affect the rate of diffusion?
Answer: The larger size of diffusible molecules reduces the rate of diffusion and vice versa.
Question 15. How does the density of diffusible molecules affect the rate of diffusion?
Answer: Higher density of diffusible molecules increases the rate of diffusion.
Question 16. Due to which pressure do young meristematic cells grow in size?
Answer: Turgor pressure
Question 17. Name the scientist who proposed the ‘Root Pressure Theory’.
Answer: British scientist Stephen Hales
Question 18. Who proposed the ‘Transpiration pull and Cohesion Tension Theory’ to explain the ascent of sap?
Answer: Scientists Dixon and Joly
Question 19. Give an example of an impermeable membrane.
Answer: Plastic sheet
Question 20. Give an example of a permeable membrane.
Answer: Cell wall
Question 21. By which type of active transport, two different diffusible molecules are carried by a single carrier protein?
Answer: Coupled transport
Question 22 Give an example of a semi-permeable membrane.
Answer: Parchment paper
Question 23 Name the components of the xylem, which play a major role in the transport of water.
Answer: Tracheid and trachea
Question 24 What is osmotic pressure?
Answer: Osmotic pressure is the minimum pressure that needs to be applied to a solution to prevent the inward flow of its pure solvent across a semi-permeable membrane.
Chapter 3 Physiological Processes Of Life Photosynthesis Fill In The Blanks
1 Water does not need any metabolic energy for transportation.
2 In osmosis, the molecules of Solvent move from a region of low concentration to a region of high concentration.
3 Diffusion occurs due to differences in the Density of the two media.
4 The physiological process for which a semi-permeable membrane is required, is called Osmosis
5 The process which helps herbs to stand erect on the ground, is Osmosis
6 The pressure flow hypothesis was given by scientist Munch
7 The cell membrane of a living cell is usually a kind of Selectively permeable membrane.
8 The passage of water from one cell to the next is called Intercellular osmosis.
9 When a cell is placed in a hypotonic solution, water moves into the cell, this flow is called Endosmosis
10 The most acceptable theory of the ascent of sap is Cohesion-tension
Chapter 3 Physiological Processes Of Life Photosynthesis State True Or False
Question 1 ‘Root Pressure Theory’ was proposed by Curtis.
Answer: False
Question 2 Transpiration pull helps in the ascent of sap.
Answer: True
Question 3 Acell shrinks when placed in a hypotonic solution.
Answer: False
Question 4 Air bladder of fish is an example of a semi-permeable membrane.
Answer: True
Question 5 Symport and antiport are types of coupled transport.
Answer: True
Question 6 Only the downward transport of food materials takes place in the phloem.
Answer: False
Question 7 Swelling of the protoplasm of a flaccid cell by endosmosis is called deplasmolysis.
Answer: True
Question 8 Call wall is a selectively permeable membrane.
Answer: False
Question 9 Diffusion is a random movement of individual molecules from a region of lower concentration to a region of higher concentration.
Answer: False
Question 10 Grapes, placed in concentrated sugar solution shrink due to exosmosis.
Answer: True
Question 11 Transporter proteins are called channel proteins.
Answer: True
Chapter 3 Physiological Processes Of Life Photosynthesis Match The Columns
Answer: 1-D; 2-C; 3-A; 4-B
Answer: 1-B; 2-C; 3-A; 4-E
Chapter 3 Physiological Processes Of Life Photosynthesis Find The Odd One Out
Question 1 Parchment membrane, Inner membrane of eggshell, Filter paper, Cell membrane
Answer: Cell membrane
Question 2 Endosmosis, Exosmosis, Plasmolysis, Diffusion
Answer: Diffusion
Chapter 3 Physiological Processes Of Life Photosynthesis Fill In The Blanks By Looking At The First Pair
1 Endosmosis:Deplasmolysis::Exosmosis: Plasmolysis
2 Osmosis: Passive transport:: Na-K pump: Active transport
3 Transport of solute particles with density: Diffusion: Transport of solvent molecules with density: Osmosis
Chapter 3 Physiological Processes Of Life Photosynthesis Among The Four Concepts Given, Three Of Them Belong To One. Find That
Question 1 Diffusion, Osmosis, Facilitated diffusion, Passive transport
Answer: Passive transport
Question 2 Rate of diffusion, Temperature, Size of molecules, Medium
Answer: Rate of diffusion
Question 3 Plasmolysis, Cell to cell water transport, Osmosis, Deplasmolysis
Answer: Osmosis
Question 4 Osmosis, Semipermeable membrane, Solvent diffusion, Difference in density (concentration)
Answer: Osmosis
Question 5 Uses of ATP, Carrier molecule, Against concentration gradient, Active transport
Answer: Active transport
