Photosynthesis in Higher Plants MCQ – Best 100 MCQs

Photosynthesis in Higher Plants MCQ – Best 100 MCQs. These 100 Multiple Choice Questions with Answer and Explanation will help you score full marks in your class 11 Biology exam.

What Do We Know about Photosynthesis in Higher Plants?

Question 1: Which of the following is NOT a basic requirement for photosynthesis?

A. Chlorophyll

B. Light

C. Oxygen

D. Carbon dioxide

Question 2: The presence of starch in a leaf indicates that:

A. The leaf has been exposed to light.

B. The leaf contains chlorophyll.

C. Photosynthesis has occurred.

D. All of the above.

Question 3: In a variegated leaf experiment, which part of the leaf would test positive for starch after exposure to light?

A. The green parts

B. The non-green parts

C. Both green and non-green parts

D. Neither green nor non-green parts

 Early Experiments – Photosynthesis in Higher Plants MCQs

Question 4: Which scientist is credited with discovering oxygen in 1774?

A. Joseph Priestley

B. Jan Ingenhousz

C. Julius von Sachs

D. Cornelius van Niel

Question 5: Ingenhousz’s experiments demonstrated that:

A. Plants restore to the air whatever breathing animals and burning candles remove.

B. Sunlight is essential for plants to purify the air.

C. The green parts of plants release oxygen in the presence of sunlight.

D. Glucose is produced and stored as starch during plant growth.

Question 6: Julius von Sachs’s studies revealed that:

A. Photosynthesis is a light-dependent reaction.

B. The oxygen evolved during photosynthesis comes from water.

C. Glucose is produced during photosynthesis and stored as starch.

D. The first CO2 fixation product is a 3-carbon organic acid.

Question 7: Cornelius van Niel’s research on purple and green bacteria led to the understanding that:

A. Photosynthesis primarily occurs in the blue and red regions of the light spectrum.

B. Photosynthesis is a process where hydrogen from a suitable compound reduces carbon dioxide to carbohydrates.

C. The oxygen released during photosynthesis comes from carbon dioxide.

D. The first stable product of CO2 fixation in some plants is a 4-carbon organic acid.

 Where Does Photosynthesis Take Place? – Photosynthesis in Higher Plants MCQ

Question 8: The primary sites of photosynthesis in plants are:

A. Green leaves only

B. Roots and stems

C. Green leaves and other green parts of the plant

D. Flowers and fruits

Question 9: Which cells in leaves are specialized for photosynthesis?

A. Epidermal cells

B. Guard cells

C. Mesophyll cells

D. Xylem cells

Question 10: The internal membrane system within chloroplasts is organized into:

A. Grana, stroma lamellae, and stroma

B. Thylakoids, cristae, and matrix

C. Vacuoles, cytoplasm, and nucleus

D. Cell wall, plasma membrane, and endoplasmic reticulum

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Question 11: Light reactions of photosynthesis involve:

A. The synthesis of sugars

B. The fixation of carbon dioxide

C. Light absorption, water splitting, and ATP and NADPH formation

D. The release of carbon dioxide

Question 12: Dark reactions (carbon reactions) of photosynthesis:

A. Occur only in the absence of light

B. Are independent of the products of light reactions

C. Utilize ATP and NADPH to synthesize sugars

D. Release oxygen

 How Many Pigments are Involved in Photosynthesis? – Photosynthesis in Higher Plants MCQ

Question 13: The color of leaves is due to:

A. A single pigment called chlorophyll

B. A combination of four pigments: chlorophyll a, chlorophyll b, xanthophylls, and carotenoids

C. The presence of anthocyanins

D. The reflection of all wavelengths of light

Question 14: Paper chromatography is used to:

A. Measure the rate of photosynthesis

B. Separate and identify the different pigments present in leaves

C. Determine the absorption spectrum of chlorophyll a

D. Study the structure of chloroplasts

Question 15: The most abundant plant pigment in the world is:

A. Chlorophyll a

B. Chlorophyll b

C. Xanthophylls

D. Carotenoids

Question 16: The absorption spectrum of chlorophyll a shows maximum absorption in the:

A. Green and yellow regions

B. Blue and red regions

C. Violet and orange regions

D. Infrared region

Question 17: The action spectrum of photosynthesis:

A. Shows the wavelengths of light at which maximum photosynthesis occurs

B. Is identical to the absorption spectrum of chlorophyll a

C. Indicates that only chlorophyll a is involved in photosynthesis

D. Demonstrates that plants absorb all wavelengths of light equally

Question 18: Accessory pigments like chlorophyll b, xanthophylls, and carotenoids:

A. Play no role in photosynthesis

B. Absorb light and transfer the energy to chlorophyll a

C. Protect chlorophyll a from photo-oxidation

D. Both B and C

 What is Light Reaction? – Photosynthesis in Higher Plants MCQ

Question 19: The light reaction of photosynthesis involves:

A. The synthesis of sugars from carbon dioxide and water

B. The fixation of carbon dioxide into organic molecules

C. Light absorption, water splitting, oxygen release, and the formation of ATP and NADPH

D. The breakdown of glucose to release energy

Question 20: Photosystems I and II are:

A. Protein complexes involved in the electron transport chain

B. Light-harvesting complexes containing pigments

C. Reaction centers where light energy is converted into chemical energy

D. All of the above

Question 21: The reaction center chlorophyll a in photosystem I (PS I) is called P700 because:

A. It absorbs light with a wavelength of 700 nm

B. It is the 700th chlorophyll a molecule in the photosystem

C. It has a molecular weight of 700

D. It was discovered in the year

Question 22: The Z scheme in photosynthesis represents:

A. The absorption spectra of different pigments

B. The flow of electrons during the light reactions

C. The Calvin cycle

D. The structure of a chloroplast

Question 23: The primary electron donor in photosystem II (PS II) is:

A. Water

B. Carbon dioxide

C. Chlorophyll a

D. NADPH

Question 24: The final electron acceptor in the non-cyclic electron transport chain is:

A. Oxygen

B. NADP+

C. ATP

D. Carbon dioxide

Question 25: The movement of electrons through the electron transport chain is driven by:

A. Differences in redox potential

B. ATP hydrolysis

C. Light energy

D. Concentration gradients

Question 26: The energy released during electron transport is used to:

A. Split water molecules

B. Generate a proton gradient

C. Reduce NADP+ to NADPH

D. All of the above

Question 27: In photosystem I (PS I), the reaction center chlorophyll a:

A. Absorbs light at 680 nm

B. Is called P680

C. Absorbs light at 700 nm

D. Is the primary electron donor

Question 28: During non-cyclic photophosphorylation:

A. Only ATP is synthesized

B. Only NADPH is synthesized

C. Both ATP and NADPH are synthesized

D. Neither ATP nor NADPH is synthesized

Question 29: Cyclic photophosphorylation:

A. Involves both PS I and PS II

B. Occurs in the grana lamellae

C. Generates only ATP

D. Produces NADPH

Question 30: The conditions that favor cyclic photophosphorylation include:

A. Low light intensity

B. High light intensity

C. Presence of only wavelengths beyond 680 nm

D. Both A and C

Question 31: The primary function of the electron transport chain in photosynthesis is to:

A. Generate oxygen

B. Fix carbon dioxide

C. Transfer energy from light to ATP and NADPH

D. Synthesize glucose

Question 32: The Z scheme gets its name from:

A. The shape of the electron transport chain when plotted on a redox potential scale

B. The zigzag movement of electrons between photosystems

C. The involvement of zinc ions in the process

D. The discovery of the pathway by a scientist named Z

 Splitting of Water – Photosynthesis in Higher Plants MCQ

Question 33: Water splitting is associated with:

A. Photosystem I

B. Photosystem II

C. Both photosystems I and II

D. Neither photosystem

Question 34: The products of water splitting are:

A. Protons, electrons, and carbon dioxide

B. Protons, electrons, and oxygen

C. Oxygen, carbon dioxide, and ATP

D. ATP, NADPH, and oxygen

Question 35: The electrons released during water splitting:

A. Are used to reduce NADP+ to NADPH

B. Replace the electrons lost from the reaction center chlorophyll in PS II

C. Are transferred to PS I

D. Combine with carbon dioxide to form glucose

Question 36: The oxygen released during photosynthesis originates from:

A. Carbon dioxide

B. Water

C. Glucose

D. Chlorophyll

 Cyclic and Non-cyclic Photo-phosphorylation – Photosynthesis in Higher Plants MCQ

Question 37: The process of synthesizing ATP from ADP and inorganic phosphate in the presence of light is called:

A. Oxidative phosphorylation

B. Substrate-level phosphorylation

C. Photophosphorylation

D. Chemiosmosis

Question 38: The key difference between cyclic and non-cyclic photophosphorylation lies in:

A. The involvement of photosystems

B. The production of ATP

C. The production of NADPH

D. All of the above

Question 39: Which photosystem is involved in both cyclic and non-cyclic photophosphorylation?

A. Photosystem I

B. Photosystem II

C. Both photosystems I and II

D. Neither photosystem

Question 40: The primary location for cyclic photophosphorylation is:

A. Grana lamellae

B. Stroma lamellae

C. Stroma

D. Thylakoid lumen

Question 41: Which of the following conditions favors cyclic photophosphorylation?

A. High light intensity

B. Abundance of NADPH

C. Wavelengths of light beyond 680 nm

D. Low ATP levels

Question 42: The main advantage of cyclic photophosphorylation is:

A. Production of both ATP and NADPH

B. Increased efficiency of light energy capture

C. Additional ATP synthesis to meet the demands of the Calvin cycle

D. Oxygen evolution

 Chemiosmotic Hypothesis – Photosynthesis in Higher Plants MCQ

Question 43: The chemiosmotic hypothesis explains the mechanism of:

A. ATP synthesis in chloroplasts

B. Water splitting

C. Electron transport

D. Carbon fixation

Question 44: The proton gradient across the thylakoid membrane is created by:

A. Water splitting on the inner side of the membrane

B. Proton pumping during electron transport

C. Removal of protons from the stroma during NADP+ reduction

D. All of the above

Question 45: The breakdown of the proton gradient leads to:

A. ATP synthesis

B. Water splitting

C. NADPH formation

D. Carbon fixation

Question 46: ATP synthase consists of two parts:

A. CF0 and CF1

B. PS I and PS II

C. LHC I and LHC II

D. RuBisCO and PEPcase

Question 47: The energy for ATP synthesis is provided by:

A. The breakdown of the proton gradient

B. Light energy directly

C. The oxidation of glucose

D. The reduction of NADP+

Question 48: Chemiosmosis in chloroplasts differs from that in mitochondria in terms of:

A. The direction of proton pumping

B. The involvement of ATP synthase

C. The source of energy for proton pumping

D. All of the above

 Where are the ATP and NADPH Used? – Photosynthesis in Higher Plants MCQ

Question 49: The biosynthetic phase of photosynthesis, also known as the dark reaction, primarily involves:

A. The absorption of light energy

B. The splitting of water molecules

C. The synthesis of sugars using ATP and NADPH

D. The release of oxygen

Question 50: Melvin Calvin’s work with radioactive 14C led to the discovery that the first stable product of CO2 fixation in photosynthesis is:

A. Glucose

B. RuBP

C. PGA (3-phosphoglyceric acid)

D. OAA (oxaloacetic acid)

Question 51: The distinction between C3 and C4 plants is based on:

A. The presence or absence of chlorophyll

B. The type of primary CO2 acceptor

C. The first stable product of CO2 fixation

D. The ability to perform photosynthesis

 The Primary Acceptor of CO2 – Photosynthesis in Higher Plants MCQ

Question 52: The primary acceptor of CO2 in the Calvin cycle is:

A. RuBP (ribulose bisphosphate)

B. PEP (phosphoenolpyruvate)

C. PGA (3-phosphoglyceric acid)

D. OAA (oxaloacetic acid)

Question 53: The identification of RuBP as the primary CO2 acceptor was:

A. A straightforward process

B. Initially assumed to be a 2-carbon compound

C. A result of Melvin Calvin’s experiments

D. Both B and C

Question 54: The enzyme responsible for catalyzing the reaction between CO2 and RuBP is:

A. RuBisCO

B. PEP carboxylase

C. ATP synthase

D. NADP reductase

 The Calvin Cycle – Photosynthesis in Higher Plants MCQ

Question 55: The Calvin cycle can be divided into three stages:

A. Carboxylation, reduction, and regeneration

B. Light absorption, electron transport, and ATP synthesis

C. Glycolysis, Krebs cycle, and oxidative phosphorylation

D. Carbon fixation, sugar synthesis, and oxygen release

Question 56: During the carboxylation stage of the Calvin cycle:

A. CO2 is fixed to RuBP, forming two molecules of PGA

B. ATP and NADPH are used to reduce PGA to G3P

C. RuBP is regenerated from G3P

D. Glucose is synthesized

Question 57: The reduction stage of the Calvin cycle involves:

A. The fixation of CO2 to RuBP

B. The conversion of PGA to G3P using ATP and NADPH

C. The regeneration of RuBP

D. The release of oxygen

Question 58: The regeneration stage of the Calvin cycle is essential for:

A. The continuation of the cycle

B. The synthesis of glucose

C. The fixation of carbon dioxide

D. The release of oxygen

Question 59: How many turns of the Calvin cycle are required to produce one molecule of glucose?

A. 1

B. 3

C. 6

D. 12

Question 60: The enzyme RuBisCO is unique because:

A. It is the most abundant enzyme on Earth

B. It can bind to both CO2 and O2

C. It catalyzes the first step of the Calvin cycle

D. All of the above

Question 61: The overall input of the Calvin cycle includes:

A. Six CO2, 18 ATP, and 12 NADPH

B. One glucose, 18 ADP, and 12 NADP+

C. Six CO2, 12 ATP, and 18 NADPH

D. One glucose, 12 ADP, and 18 NADP+

Question 62: The overall output of the Calvin cycle includes:

A. Six CO2, 18 ATP, and 12 NADPH

B. One glucose, 18 ADP, and 12 NADP+

C. Six CO2, 12 ATP, and 18 NADPH

D. One glucose, 12 ADP, and 18 NADP+

Question 63: For each CO2 molecule entering the Calvin cycle, how many ATP and NADPH molecules are required?

A. 1 ATP and 1 NADPH

B. 2 ATP and 2 NADPH

C. 3 ATP and 2 NADPH

D. 2 ATP and 3 NADPH

Question 64: The Calvin cycle occurs in:

A. All photosynthetic plants

B. Only C3 plants

C. Only C4 plants

D. Neither C3 nor C4 plants

 The C4 Pathway – Photosynthesis in Higher Plants MCQ

Question 65: C4 plants are adapted to:

A. Cold, high-altitude environments

B. Dry, tropical regions

C. Temperate forests

D. Aquatic habitats

Question 66: Which of the following is NOT a characteristic of C4 plants?

A. Special leaf anatomy (Kranz anatomy)

B. Tolerance to high temperatures

C. High rates of photorespiration

D. Greater productivity of biomass

Question 67: The primary CO2 acceptor in C4 plants is:

A. RuBP

B. PEP

C. PGA

D. OAA

Question 68: The enzyme responsible for fixing CO2 to PEP in C4 plants is:

A. RuBisCO

B. PEP carboxylase

C. ATP synthase

D. NADP reductase

Question 69: The 4-carbon compound formed in mesophyll cells of C4 plants is transported to bundle sheath cells in the form of:

A. Malic acid or aspartic acid

B. Pyruvate

C. Glucose

D. RuBP

Question 70: In C4 plants, the Calvin cycle takes place in:

A. Mesophyll cells

B. Bundle sheath cells

C. Both mesophyll and bundle sheath cells

D. Neither mesophyll nor bundle sheath cells

Question 71: Bundle sheath cells in C4 plants are characterized by:

A. A large number of chloroplasts

B. Thick walls impervious to gaseous exchange

C. No intercellular spaces

D. All of the above

Question 72: The 3-carbon molecule released after the breakdown of C4 acids in bundle sheath cells is:

A. PEP

B. Pyruvate

C. Glucose

D. RuBP

Question 73: Kranz anatomy refers to:

A. The arrangement of mesophyll cells around the vascular bundle sheath in C4 plants

B. The structure of chloroplasts in C3 plants

C. The presence of large vacuoles in plant cells

D. The arrangement of stomata on leaves

Question 74: The main advantage of the C4 pathway over the C3 pathway is:

A. Increased water loss

B. Reduced light absorption

C. Minimized photorespiration and enhanced CO2 fixation under high temperatures

D. Lower biomass productivity

 Photorespiration – Photosynthesis in Higher Plants MCQ

Question 75: Photorespiration is a process where:

A. RuBisCO binds to CO2 and initiates the Calvin cycle

B. RuBisCO binds to O2, leading to the breakdown of RuBP and release of CO2

C. ATP and NADPH are synthesized

D. Glucose is produced

Question 76: In C3 plants, photorespiration is:

A. Absent

B. More likely to occur at low light intensities

C. More likely to occur at high CO2 concentrations

D. More likely to occur at high temperatures and low CO2 concentrations

Question 77: C4 plants avoid photorespiration by:

A. Increasing the concentration of CO2 at the RuBisCO enzyme site

B. Decreasing the concentration of O2 in bundle sheath cells

C. Using PEP carboxylase instead of RuBisCO for initial CO2 fixation

D. All of the above

Question 78: The biological function of photorespiration is:

A. Well understood

B. To generate additional ATP

C. To release excess oxygen

D. Not yet fully known

Question 79: Compared to C3 plants, C4 plants:

A. Have higher rates of photorespiration

B. Are less productive

C. Are more tolerant to high temperatures

D. Are better adapted to cold climates

Question 80: The oxygenase activity of RuBisCO:

A. Is beneficial for photosynthesis

B. Increases CO2 fixation

C. Leads to the formation of PGA and phosphoglycolate

D. Occurs only in C4 plants

 Factors Affecting Photosynthesis – Photosynthesis in Higher Plants MCQ

Question 81: The rate of photosynthesis is influenced by:

A. Internal factors (plant-related)

B. External factors (environmental)

C. Both internal and external factors

D. Neither internal nor external factors

Question 82: Which of the following is an internal factor affecting photosynthesis?

A. The amount of chlorophyll

B. Temperature

C. Carbon dioxide concentration

D. Sunlight availability

Question 83: Blackman’s Law of Limiting Factors states that:

A. The rate of a process is determined by the factor present in the highest amount

B. The rate of a process is determined by the factor nearest to its minimal value

C. All factors affect a process equally

D. External factors are more important than internal factors

 Light – Photosynthesis in Higher Plants MCQ

Question 84: The intensity of light at which the rate of photosynthesis no longer increases is called the:

A. Compensation point

B. Saturation point

C. Light optimum

D. Light maximum

Question 85: Light saturation in plants typically occurs at:

A. 1% of full sunlight

B. 10% of full sunlight

C. 50% of full sunlight

D. 100% of full sunlight

Question 86: Excessive light can lead to:

A. Increased photosynthesis

B. Breakdown of chlorophyll

C. Enhanced CO2 fixation

D. Increased plant growth

 Carbon dioxide Concentration – Photosynthesis in Higher Plants MCQ

Question 87: The current concentration of CO2 in the atmosphere is:

A. Limiting for C3 plants

B. Limiting for C4 plants

C. Optimal for both C3 and C4 plants

D. Damaging to plants

Question 88: C4 plants show saturation of CO2 fixation at a _____ concentration compared to C3 plants.

A. Lower

B. Higher

C. Same

D. Variable

Question 89: CO2 enrichment is sometimes used in greenhouses to:

A. Increase crop yields

B. Reduce photorespiration

C. Decrease water loss

D. Control pests

 Temperature – Photosynthesis in Higher Plants MCQ

Question 90: The dark reactions of photosynthesis are:

A. Temperature-independent

B. Temperature-controlled due to their enzymatic nature

C. More sensitive to temperature than light reactions

D. Less sensitive to temperature than light reactions

Question 91: C4 plants have a _____ temperature optimum for photosynthesis compared to C3 plants.

A. Lower

B. Higher

C. Same

D. Variable

 Water – Photosynthesis in Higher Plants MCQ

Question 92: Water stress affects photosynthesis primarily by:

A. Directly inhibiting the light reactions

B. Causing stomatal closure and reducing CO2 availability

C. Increasing the rate of photorespiration

D. Damaging chloroplasts

Question 93: Besides affecting CO2 availability, water stress also:

A. Increases leaf surface area

B. Enhances metabolic activity

C. Causes leaves to wilt, reducing their surface area and metabolic activity

D. Promotes chlorophyll synthesis

Question 94: The effect of water as a factor on photosynthesis is mainly:

A. Direct, by influencing the light reactions

B. Indirect, through its impact on stomatal opening and leaf physiology

C. Negligible, as water is abundant in most environments

D. Primarily related to its role as a reactant in the dark reactions

Question 95: The optimal temperature for photosynthesis:

A. Is the same for all plants

B. Varies depending on the plant’s habitat and adaptations

C. Is always higher for C4 plants than C3 plants

D. Is not affected by the type of photosynthesis (C3 or C4)

Question 96: Which of the following statements about the effect of light on photosynthesis is FALSE?

A. At low light intensities, there is a linear relationship between light intensity and CO2 fixation rate.

B. Light saturation occurs at 100% of full sunlight.

C. Beyond the saturation point, further increases in light intensity do not increase the rate of photosynthesis.

D. Excessive light can damage chlorophyll and decrease photosynthesis.

Question 97: The main limiting factor for photosynthesis in natural environments is usually:

A. Light

B. Carbon dioxide concentration

C. Temperature

D. Water

Question 98: Which of the following is NOT an external factor affecting photosynthesis?

A. Temperature

B. Carbon dioxide concentration

C. The number of chloroplasts

D. Water availability

Question 99: When a plant experiences water stress:

A. The stomata open wider to allow more CO2 uptake

B. The rate of photosynthesis increases

C. The leaves wilt, reducing their surface area and metabolic activity

D. The plant switches from C3 to C4 photosynthesis

Question 100: The primary way water influences photosynthesis is by:

A. Acting as a reactant in the light reactions

B. Affecting the plant’s ability to regulate CO2 uptake and maintain leaf function

C. Directly influencing the activity of RuBisCO

D. Providing a medium for nutrient transport