Photosynthesis in Higher Plants Questions and Answers AP Inter 1st Year Botany Chapter 8

Andhra Pradesh BIEAP AP Inter 1st Year Botany Study Material 8th Lesson Photosynthesis in Higher Plants Class 11 Textbook Exercise Questions and Answers.

Photosynthesis in Higher Plants Class 11 Questions and Answers AP Inter 1st Year Botany 8th Lesson

I. Photosynthesis in Higher Plants Multiple Choice Questions (1 Mark)

Question 1.
Who discovered oxygen ?
(1) Joseph Priestly
(2) T. Engelmann
(3) Jan Ingenhousz
(4) Van Neil
Answer:
(1) Joseph Priestly

Question 2.
Chloroplast is ………..
(1) single membrane bound organelle
(2) double membrane bound organelle
(3) triple membrane bound organelle
(4) membrane lacking organelle
Answer:
(2) double membrane bound organelle

Question 3.
Which is the most abundant plant pigment in the world ?
(1) Chlorophyll a
(2) Chlorophyll b
(3) Carotenoids
(4) Xanthophylls
Answer:
(1) Chlorophyll a

Question 4.
Maximum absorption by chlorophyll a occurs in ……………..
(1) blue & green region
(2) red & green region
(3) blue & red region
(4) yellow & red region
Answer:
(3) blue & red region

Question 5.
LHC stands for ……………..
(1) Late Harvesting Complex
(2) Light Harvesting Complex
(3) Light Hanging Complex
(4) Late Hanging Complex
Answer:
(2) Light Harvesting Complex

Question 6.
During photosynthesis the O₂is released in……………..
(1) lumen of thylakoid
(2) outer side of thylakoid
(3) stroma
(4) cytoplasm
Answer:
(1) lumen of thylakoid

Question 7.
For formation of 1 glucose molecule, how many turns of Calvin cycle is/are needed?
(1) 3
(2) 1
(3) 2
(4) 6
Answer:
(4) 6

Question 8.
The most crucial step of Calvin cycle is ……….
(1) carbonation
(2) carboxylation
(3) reduction
(4) regeneration
Answer:
(2) carboxylation

Question 9.
The first stable product during CO₂ fixation in C₄ cycle is ……………..
(1) RBP
(2) PEP
(3) OAA
(4) PGA
Answer:
(3) OAA

II. Photosynthesis in Higher Plants Fill in the Blanks (1 Mark)

Question 1.
………… in 1770 performed a series of experiments that revealed the essential role of air in the growth of green plants.
Answer:
Joseph Priestley

Question 2.
Chlorophyll ………… is the chief pigment associated with photosynthesis.
Answer:
Chlorophyll a

Question 3.
In PS-I the reaction centre chlorophyll-a has an absorption peak at ………… nm.
Answer:
700

Question 4.
The splitting of water is associated with the PS- …………
Answer:
PS II

Question 5.
The ………… enzyme is located on the stroma side of the membrane.
Answer:
NADP reductase

Question 6.
Chemiosmosis is helpful for the synthesis of …………
Answer:
ATP

Question 7.
The products of light reaction are ATP, NADPH and …………
Answer:
Oxygen

Question 8.
RuBP carboxylase also has an oxygenation activity, so it would be more correct to call it …………
Answer:
RUBISCO

Question 9.
‘Kranz’ anatomy is characteristic feature of ………… plants.
Amswer:
C₄ plants

Question 10.
………… is the major limiting factor for photosynthesis.
Answer:
CO₂

III. Photosynthesis in Higher Plants One Word Answer Questions (1 Mark)

Question 1.
What is the primary acceptor of CO₂ in C₃ plants ?
Answer:
RuBP/Ribulose 1-5- Bis Phosphate

Question 2.
Which is the first formed compound in C₃ plants ?
Answer:
3 PGA

Question 3.
What is the primary acceptor of CO₂ in C₄ plants?
Answer:
PEP

Question 4.
Name the first formed compound in C₄ plants.
Answer:
OAA

Question 5.
Where does photolysis of water take place in Chloroplast ?
Answer:
Lumen of thylakoid

Question 6.
Who proposed law of limiting factor in photosynthesis ?
Answer:
Blackman

Question 7.
How many ATP are required for synthesis of one glucose in C₃ plants ?
Answer:
18 ATP

Question 8.
Where does light reaction takes place in chloroplast ?
Answer:
Grana or Thylakoids

Question 9.
Where does dark reaction takes place in chloroplast ?
Answer:
Stroma

Question 10.
Name the first enzyme that is involved in carboxylation process in C₃ Plants.
Answer:
RUBISCO

IV. Photosynthesis in Higher Plants Very Short Answer Questions (2 Marks)

Question 1.
Name the processes which take place in grana and stroma regions of chloroplast.
Answer:
In the grana region of the chloroplast, the light reactions (also called photochemical reactions) take place. These include light absorption, water splitting, oxygen release, and synthesis of ATP and NADPH. In the stroma region, the dark reactions (also called carbon reactions or biosynthetic phase) occur. These involve CO₂ fixation and sugar synthesis using ATP and NADPH.

Question 2.
Where does the photolysis of H₂O occur ? What is its significance ?
Answer:
Photolysis of H₂O occurs on the inner side of the thylakoid membrane in Photosystem II. It provides electrons for PS II, protons for the proton gradient, and releases oxygen. Oxygen is the basis of all organisms.

Question 3.
Where is the enzyme NADP reductase located ? What is released if the proton gradient breaks down?
Answer:
The enzyme NADP reductase is located on the stroma side of the thylakoid membrane. When the proton gradient across the thylakoid membrane breaks down, ATP is synthesized through the action of the ATP synthase enzyme.

Question 4.
Explain the terms:
(a) PEP Carboxylase
(b) Bundle sheath cells
Answer:
(a) PEP Carboxylas: Enzyme in C₄ plants responsible for fixing CO₂ with PEP to form oxaloacetic acid (OAA) in mesophyll cells.
(b) Bundle sheath cells : Cells surrounding vascular bundles in C₄ plants, rich in RuBisCO, thick walled and site of Calvin cycle.

Question 5.
Mention the components of ATPase enzyme. What is their location ? Which part of the enzyme shows conformational change ?
Answer:

The ATPase enzyme consists of two components : CF₀, which is embedded in the thylakoid membrane, and forms a trans-membrane channel that carries out facilitated diffusion of protons across the membrane.
CF₁, which protrudes on the stroma side. The CF₁ part undergoes conformational change to synthesize ATP.

Question 6.
Distinguish between action spectrum and absorption spectrum.
Answer:

Absorption spectrum : A graph shows the rate of photosynthesis at different wavelengths of light absorbed by pigments.
Action spectrum : A graph shows the absorption of photosynthetic pigments at different light wavelengths.

Question 7.
Out of the basic raw materials of photosynthesis, What is reduced ? What is oxidized?
Answer:
In phbtosynthesis, carbon dioxide (CO₂) is reduced to form glucose, while water (H₂O) is oxidized to release oxygen (O₂).

Question 8.
Define the law of limiting factors proposed by Blackman.
Answer:
If a process is conditioned as to its rapidly by a number of separate factors, the rate of the process is limited by the factor that is present in a relative minimum value.

Question 9.
What is the primary accepter of CO₂ in C₃ plants ? What is first stable compound formed in Calvin cycle ?
Answer:
In C₃plants, the primary acceptor of CO₂ is RuBP (Ribulose-1,5-bisphosphate), and the first stable compound formed in the Calvin cycle is PGA (3-phosphoglyceric acid).

Question 10.
What is the primary acceptor of CO₂ in C₄ plants? What is the first compound formed as a result of primary carboxylation in the C₄ pathway?
Answer:
In C₄ plants, the primary acceptor of CO₂ is PEP (Phosphoenolpyruvate), and the first stable compound formed after primary carboxylation is OAA (Oxaloacetic acid).

V. Photosynthesis in Higher Plants Short Answer Questions (4 Marks)

Question 1.
Differentiate between C₃ and C₄ plants.
Answer:

C₃ Plants	C₄ Plants
1. Predominantly found in temperate and tropical regions.	1. Mostly grow in tropical and subtropical regions.
2. Leaves lack Kranz anatomy.	2. Leaves exhibit Kranz anatomy.
3. Chloroplasts are not dimorphic.	3. Chloroplast dimorphism is present.
4. RUBP is the primary CO₂ acceptor.	4. PEPA (phosphoenolpyruvate) is the initial CO₂ acceptor.
5. The first stable product formed is PGA (Phosphoglyceric acid).	5. The first stable product formed is OAA (Oxaloacetic acid).
6. CO₂ utilization is relatively inefficient.	6. CO₂ utilization is highly efficient.
7. Photorespiration is high.	7. Photorespiration is absent or negligible.
8. Optimum temperature for photosynthesis is between 15 – 25°C.	8. Optimal temperature for photosynthesis is between 30 – 45°C.
9. Photosynthetic efficiency is comparatively low.	9. Photosynthetic yield is high.
10. Requires 18 ATP to produce one molecule of glucose.	10. Requires 30 ATP to synthesize one glucose molecule.
11. Water usage is relatively low.	11. Water use efficiency is high.
12. CO₂ compensation point is high.	12. CO₂ compensation point is low.

Question 2.
Write short notes on photorespiration.
Answer:

Photorespiration is a metabolic process where oxygen binds to the enzyme RuBisCO instead of carbon dioxide, resulting in the release of carbon dioxide.
RUBISCO has a much greater affinity for CO₂ when the CO₂and O₂ are nearly equal.
In C₃ plants, Some O₂ binds with RUBISCO and hence CO₂ fixation is reduced.
RUBP Binds with Oxygen to form one molecule of Phosphoglycerate and phosphoglycolate (2C). So called C₂
In this process, release of CO₂ with the utilization of ATP occurs.
No synthesis of ATP or NADPH.
It is a wasteful process.
In C₄ plants, photorespiration does not occur, because they have a mechanism that increases the concentration of CO₂ at the enzyme site.
In C₄ plants, C₄ acid from the mesophyll is broken down in the bundle sheath cells to release CO₂.
This results in increasing the intracellular concentration of CO₂
In turn this ensures that the RUBISCO functions as a carboxylase minimising the oxygenase activity.
So C₄ plants are more effective in productivity and yield and also show tolerance to higher temperatures than C₃

Question 2.
Describe the mechanism of C₄Answer:

Researchers Kortschak, Hartt, and Burr discovered that in sugarcane, the first product of photosynthesis is not 3-PGA but rather four-carbon compounds such as malic acid and aspartic acid.
Hatch and Slack later confirmed these findings, leading to the identification of the C₄ pathway, named after its four-carbon intermediate.
Plants using this pathway are known as C₄
The pathway is also referred to as the Hatch-Slack pathway or Beta-Carboxylation pathway.

Steps of the C₄ Pathway:
In Mesophyll Cells:

Initial CO₂ Fixation : Carbon dioxide (as bicarbonate, HCO₃ ) is fixed by a 3-carbon molecule, phosphoenol pyruvic acid (PEP), in the presence of PEP carboxylase and water. This reaction forms oxaloacetic acid and phosphoric acid (H₃POr).
CO₂ + PEP + H₂O ? Oxaloacetic acid + H₃PO^–₄

Reduction to Malic Acid : Oxaloacetic acid is reduced to malic acid using NADPH + H⁺, facilitated by malic dehydrogenase.
Oxaloacetic acid + NADPH + H⁺ → Malic acid + NADP⁺

In Bundle Sheath Cells:
Transport and Decarboxylation : Malic acid is transported to the bundle sheath chloroplasts, where it undergoes oxidative decarboxylation by the enzyme malic enzyme, forming pyruvic acid (3C), CO₂, and NADPH + H⁺.
Malic acid + NADP⁺ → Pyruvic acid + NADPH + H⁺ + CO₂

CO₂ Utilization : The released CO₂ is fed into the Calvin cycle to produce sugars.

Regeneration of PEP : The pyruvic acid is transported back to the mesophyll chloroplasts, where it is converted into PEP using pyruvate dikinase and ATP.
Pyruvic acid + 2ATP + Pi → PEP + 2AMP + 2Pi

The C₄pathway involves two carboxylation reactions and one decarboxylation, allowing efficient CO₂ fixation, especially under conditions of high light intensity and temperature, while minimizing photorespiration.

Question 4.
Draw neat labelled diagram of chloroplast.
Answer:

Questuion 5.
Differentiate between cyclic and non cyclic photophosphorylation.
Answer:

Cyclic Photophosphorylation	Non-Cyclic Photophosphorylation
1. Only Photosystem I (PS I) is involved.	1. Both Photosystem I (PS I) and Photosystem II (PS II) are involved.
2. Electrons released from PS I cycle back to PS I.	2. Electrons flow from PS II to PS I and then to NADP⁺, not returning to the original PS.
3. Only ATP is produced.	3. ATP and NADPH + H⁺ are both produced.
4. It does not occur, hence no O₂evolution.	4. It occurs, leading to O₂ release.
5. It occurs in the stroma lamellae, where PS II and NADP⁺ reductase are absent.	5. It takes place in the grana thyla- koid membranes, where both PS I and PS II are present.
6. Electrons are accepted and cycled back to PS I.	6. Electrons are transferred to NADP⁺ to form NADPH.
7. To compensate ATP shortage, especially when more ATP than NADPH is needed in Calvin Cycle.	7. To generate both ATP and NADPH for use in the Calvin Cycle.

VI. Photosynthesis in Higher Plants Long Type Questions (8 Marks)

Question 1.
Describe the process of reactions in Calvin cycle.
Answer:
i) The Calvin cycle, also known as the C₃ pathway, is the biosynthetic phase of photosynthesis where CO₂ is fixed into carbohydrates using the ATP and NADPH produced during the light reactions.
ii) This cycle occurs in the stroma of chloroplasts and was first worked out by Melvin Calvin and his associates Andrew Benson and James Basham.
iii) The Calvin cycle operates in three main phases :
1. Carboxylation
2. Reduction
3. Regeneration.

1. Carboxylation Phase:

CO₂ is fixed by the 5-carbon sugar RuBP (Ribulose-1,5-bisphosphate).
This reaction is catalyzed by the enzyme RuBisCO (RuBP carboxylase-oxygenase).
The product is two molecules of 3-PGA (3-phosphoglyceric acid), a 3-carbon compound.
It is the most crucial step in the cycle.

2. Reduction Phase:

Each molecule of 3-PGA is converted into triose phosphate (G3P).
This step requires :
2 ATP for phosphorylation
2 NADPH for reduction per CO₂ molecule fixed
Six turns of the cycle (fixing 6 CO₂) are needed to form one glucose molecule.

3. Regeneration Phase:

To continue the cycle uninterrupted, regeneration of RUBP is crucial. It requires one ATP for phosphorylation to form RUBP.
Hence for every CO, molecule entering the Calvin cycle, 3 molecules of ATP and 2 molecules of NADPH are required.
To meet this difference in the number of ATP and NADPH used in dark reactions, cyclic phosphorylation takes place.
To synthesize one Glucose molecule, 18 ATP and 12 NADPH+H⁺ are required.

Photosynthesis in Higher Plants Class 11 Extra Questions and Answers

I. Multiple Choice Questions (1 Mark)

Question 1.
According to the chemiosmotic theory given by Mitchell, ATPs are synthesised on the membranes of chloroplast due to
(1) K+ gradient
(2) H +gradient
(3) e-gradient
(4) Na+ gradient
Answer:
(2) H +gradient

Question 2.
Which of the following steps consume ATP ?
(1) Carboxylation
(2) Reduction
(3) Regeneration
(4) Both 2 and 3
Answer:
(4) Both 2 and 3

Question 3.
How many molecules of ATP would be consumed in 5 turns of the Calvin cycle?
(1) 5
(2) 10
(3) 15
(4) 20
Answer:
(3) 15

Question 4.
Enzyme responsible for primary CO₂ fixation in C₆ plants is
(1) RUBisCO
(2) PEPCase
(3) Oxaloacetate
(4) Phenolase
Answer:
(2) PEPCase

Question 5.
Which of the following statements is not correct?
(1) The antennae pigments protect the chief pigment against photooxidative damage.
(2) The LHC allows wider usage of the spectrum for improving photosynthetic efficiency.
(3) The accessory pigments absorb and transfer photons to the reaction centres.
(4) The reaction centres do not differ from each other in their absorption maxima.
Answer:
(4) The reaction centres do not differ from each other in their absorption maxima.

Question 6.
Who discovered oxygen and when ?
(1) Joseph Priestly (1770)
(2) T. Engelmann (1770)
(3) Jan Ingenhousz (1787)
(4) Joseph Priestly (1774)
Answer:
(4) Joseph Priestly (1774)

Question 7.
Cladophora is ………….
(1) Purple and green bacteria
(2) Green bacteria
(3) Red algae
(4) Green algae
Answer:
(4) Green algae

Question 8.
The colour of leaf is due to ………….
(1) Chlorophyll only
(2) Chlorophyll, carotenoids only
(3) Chlorophyll, carotenoids, xanthophyll
(4) None of these
Answer:
(3) Chlorophyll, carotenoids, xanthophyll

Question 9.
Which is the most abundant plant pigment in the world ?
(1) Chlorophyll a
(2) Chlorophyll b
(3) Carotenoids
(4) Xanthophylls
Answer:
(1) Chlorophyll a

Question 10.
Leaf pigments are separated by………….
(1) Crystallization
(2) Gel electrophoresis
(3) Blotting
(4) Paper chromatography
Answer:
(4) Paper chromatography

Question 11.
End product of Z-scheme is………….
(1) ATP
(2) Glucose
(3) NADH+H⁺
(4) Both 1 & 3
Answer:
(4) Both 1 & 3

Question 12.
The products of light reaction are
(1) ATP only
(2) ATP, NADPH
(3) ATP, NADPH, O₂
(4) NADPH only
Answer:
(3) ATP, NADPH, O₂

Question 13.
Calvin discovered that first CO₂ fixation product in C₃ plants is …………
(1) 3-carbon organic acid
(2) 4-carbon organic acid
(3) 5-carbon organic acid
(4) 6-carbon organic acid
Answer:
(1) 3-carbon organic acid

II. Fill in the Blanks (1 Mark)

Question 1.
Chlorophyll contains …………
Answer:
Mg

Question 2.
Solar energy is converted into ATP in …………
Answer:
Chloroplast

Question 3.
The formula of chlorophyll ‘a’ is …………
Answer:
C₃₅H₂₂O₅N₄Mg

Question 4.
………… (element) is a component of ferredoxin.
Answer:
Iron

Question 5.
The primary acceptor of electron is located on the (inner/outer) side of the membrane …………
Answer:
Outer

Question 6.
The Calvin cycle starts with ………… ends with …………
Answer:
RUBP, regeneration of RUBP

Question 7.
Reduction involves use of ………… molecules of NADPH to reduce fixed CO₂.
Answer:
2

Question 8.
For formation of 1 glucose molecule, ………… turns of Calvin cycle is needed?
Answer:
6

Question 9.
Light saturation occurs at ………… of full sunlight.
Answer:
10%

Question 10.
NADP reductase enzyme is located on ………… of thylakoid membrane.
Answer:
Stroma side (outer side)

III. One Word Answer Questions (1 Mark)

Question 1.
Biosynthetic phase of photosynthesis is………….
Answer:
Dark reaction

Question 2.
Kranz anatomy is seen in………………..
Answer:
Tropical grass plants like Sugarcane, Maize and Sorghum.

Question 3.
Jan Ingenhousz did an experiment with an aquatic plant and concluded that all parts of plant release CO₂.
Answer:
Only green parts of plant release O₂.

Question 4.
Who demonstrated that O₂ during photosynthesis by using purple and green bacteria in their experiments ?
Answer:
Cornelius Van Niel

Question 5.
Law of limiting factor was proposed by…………..
Answer:
Blackmann

Question 6.
For chlorophyll formation in plants elements needed are………….
Answer:
Iron and magnesium

Question 7.
In C₃ plants, the first stable product of photosynthesis during the dark reaction is………….
Answer:
3-phosphoglyceric acid

Question 8.
Cyclic photophosphorylation occurs when……….
Answer:
Only light of wavelengths beyond 680 nm is available.

Question 9.
Accessory pigments are…………..
Answer:
Chlorophyll-b, carotenoids

Photosynthesis in Higher Plants Class 11 Questions and Answers AP Inter 1st Year Botany 8th Lesson

Photosynthesis in Higher Plants Class 11 Extra Questions and Answers

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