Plant Physiology MCQ with Answers Pdf
Plant Physiology MCQ: Plant physiology studies the processes that occur within plants. As a living being, a plant performs the three basic vital functions required to survive, and to do so, it carries out several internal processes, which are carried out by different parts of its body. As autotrophic organisms, they must produce their own food, and to do so, they perform a very important function called photosynthesis, which we will discuss later.
Because some of these processes will be covered in more depth in other resources, in this resource we’ll name them and study what each process entails. Let’s take a look at the processes that occur in plants:
Plants also perform the process of respiration , where they take oxygen from the air and transform it into carbon dioxide. This is because plant cells also need oxygen, just like animal cells.
Finally, plants perform the function of reproduction , through which new organisms of that species are produced. Plant reproduction varies depending on the type of plant and can be sexual, involving both female and male cells (eggs and pollen), or asexual, where sex cells are not required. This process will be developed in another resource.
Plant Physiology MCQ with Answers Pdf
Plant Physiology is a crucial sub-discipline of Botany that deals with the internal functions and vital processes of plants at the molecular and cellular levels. It explores how plants grow, develop, and respond to their environment, integrating knowledge from ecology, biochemistry, and structural biology. As NEET 2025 approaches, mastering Plant Physiology can significantly enhance a student’s performance in the Biology section, which carries a major weightage.
Practicing multiple choice questions (MCQs) on Plant Physiology not only sharpens conceptual clarity but also aids in quick revision of key topics like photosynthesis, respiration, plant hormones, and water transport. In this article, we present a curated set of MCQs from various important sections of Plant Physiology to support last-minute NEET preparation effectively.
1) Water potential is equal to___________
a) Ts + O.P
b) = T.P.
c) π + Ψ
d) Zero
Answer: d) Zero
Explanation: Pure water has a water potential of zero. Solutes lower the water potential, making it negative.
2) Transpiration is least in_____
a) good soil moisture
b) high wind velocity
c) dry environment
d) high atmospheric humidity
Answer: d) high atmospheric humidity
Explanation: High humidity reduces the water vapor gradient, decreasing transpiration.
3) Phenyl mercuric acetate (PMA) results in_________
a) reduced photosynthesis
b) reduced transpiration
c) reduced respiration
d) killing of plants
Answer: b) reduced transpiration
Explanation: PMA is an anti-transpirant; it partially closes stomata, reducing water loss.
4) Stomata open and close due to_______
a) circadian rhythm
b) genetic clock
c) pressure of gases inside the leaves
d) turgor pressure of guard cells
Answer: d) turgor pressure of guard cells
Explanation: Turgor pressure changes in guard cells control stomatal movement.
6) Phytochrome is involved in________
a) phototropism
b) photorespiration
c) photoperiodism
d) geotropism
Answer: c) photoperiodism
Explanation: Phytochrome detects light duration, regulating flowering and biological rhythms.
7) Which of the following is responsible for the opening and closing of stomata in plants?
a) Chlorophyll
b) Gibberellin
c) Abscisic acid
d) Auxin
Answer: c) Abscisic acid
Explanation: Abscisic acid promotes stomatal closure during water stress.
8) What is the primary function of auxins in plants?
a) Stimulating stem elongation
b) Promoting root growth
c) Inducing flowering
d) Enhancing photosynthesis
Answer: a) Stimulating stem elongation
Explanation: Auxins promote cell elongation, particularly in shoots.
9) Which of the following pigments is responsible for the red coloration of leaves in autumn?
a) Chlorophyll
b) Carotenoids
c) Anthocyanins
d) Xanthophylls
Answer: c) Anthocyanins
Explanation: Anthocyanins give red, blue, and purple hues in plant tissues.
10) Phytohormones are________
a) chemical regulation of flowering
b) chemical regulation of secondary growth
c) hormones regulating growth from seed to adulthood
d) regulators synthesized by plants and influencing physiological processes
Answer: d) regulators synthesized by plants and influencing physiological processes
Explanation: Phytohormones regulate various plant functions like growth, dormancy, and development.
11) Highest auxin concentration occurs__________
a) in growing tips
b) in leaves
c) at the base of plant organs
d) in the xylem and phloem
Answer: a) in growing tips
Explanation: Auxins are synthesized in shoot apices and promote apical dominance.
12) Kranz anatomy is typical of__________
a) C4 plants
b) C3 plants
c) C2 plants
d) CAM plants
Answer: a) C4 plants
Explanation: C4 plants have Kranz anatomy, with bundle sheath and mesophyll cell arrangement for efficient CO₂ fixation.
13) Which of the following processes involves the conversion of light energy into chemical energy in plants?
a) Transpiration
b) Respiration
c) Photosynthesis
d) Translocation
Answer: c) Photosynthesis
Explanation: Photosynthesis converts solar energy into chemical energy stored in glucose.
14) Which of the following is not a factor that affects the rate of photosynthesis in plants?
a) Temperature
b) Light intensity
c) Carbon dioxide concentration
d) Soil pH
Answer: d) Soil pH
Explanation: While soil pH affects nutrient uptake, it does not directly affect photosynthesis.
15) Which of the following plant hormones is responsible for initiating the formation of roots in cuttings?
a) Cytokinins
b) Ethylene
c) Abscisic acid
d) Auxins
Answer: d) Auxins
Explanation: Auxins stimulate adventitious root formation in stem cuttings.
16) What is the primary function of gibberellins in plants?
a) Inhibiting stem elongation
b) Promoting leaf growth
c) Promoting seed germination
d) Regulating stomatal closure
Answer: c) Promoting seed germination
Explanation: Gibberellins stimulate seed germination by breaking seed dormancy and promoting the synthesis of enzymes needed for growth.
17) Which of the following is a key component of the electron transport chain during photosynthesis?
a) NADP⁺
b) ATP
c) CO₂
d) H₂O
Answer: a) NADP⁺
Explanation: NADP⁺ acts as the final electron acceptor in the light-dependent reactions of photosynthesis, forming NADPH.
18) Which of the following is responsible for transporting water and nutrients from the roots to the leaves in plants?
a) Xylem
b) Phloem
c) Stomata
d) Epidermis
Answer: a) Xylem
Explanation: Xylem is a vascular tissue that conducts water and minerals absorbed from the soil up to the aerial parts of the plant.
19) Which of the following is a plant hormone that is involved in promoting cell division and differentiation?
a) Gibberellin
b) Ethylene
c) Cytokinin
d) Abscisic acid
Answer: c) Cytokinin
Explanation: Cytokinins promote cell division and influence various developmental processes including shoot and root morphogenesis.
20) Which of the following is the process by which plants release water vapor through stomata?
a) Osmosis
b) Transpiration
c) Respiration
d) Photosynthesis
Answer: b) Transpiration
Explanation: Transpiration is the evaporation of water from plant leaves through stomata, helping in cooling and nutrient uptake.
21) Which of the following gases is absorbed during photosynthesis?
a) Oxygen
b) Nitrogen
c) Carbon dioxide
d) Hydrogen
Answer: c) Carbon dioxide
Explanation: During photosynthesis, plants absorb carbon dioxide from the atmosphere and use it to produce glucose and oxygen.
22) Which of the following is a C3 plant?
a) Maize
b) Sugarcane
c) Wheat
d) Sorghum
Answer: c) Wheat
Explanation: Wheat is a C3 plant where the first stable product of photosynthesis is a 3-carbon compound (3-PGA).
23) Which among the following hormones is a gaseous plant hormone?
a) Auxin
b) Cytokinin
c) Ethylene
d) Abscisic acid
Answer: c) Ethylene
Explanation: Ethylene is a gaseous hormone involved in fruit ripening and senescence.
24) What is the end product of photosynthesis?
a) Glucose and oxygen
b) Oxygen and nitrogen
c) Water and carbon dioxide
d) ATP and NADPH
Answer: a) Glucose and oxygen
Explanation: Photosynthesis converts carbon dioxide and water into glucose (sugar) and oxygen using sunlight.
25) Which pigment is responsible for capturing light energy during photosynthesis?
a) Xanthophyll
b) Chlorophyll
c) Anthocyanin
d) Carotene
Answer: b) Chlorophyll
Explanation: Chlorophyll absorbs sunlight energy which is used in the photosynthesis process.
26) Which plant hormone is known as the ‘stress hormone’?
a) Ethylene
b) Auxin
c) Cytokinin
d) Abscisic acid
Answer: d) Abscisic acid
Explanation: Abscisic acid helps plants cope with stress by inducing stomatal closure and inhibiting growth.
27) CAM plants open their stomata at:
a) Night
b) Morning
c) Afternoon
d) Noon
Answer: a) Night
Explanation: CAM (Crassulacean Acid Metabolism) plants open stomata at night to reduce water loss during photosynthesis.
28) Which of the following helps in closing of stomata?
a) High turgor pressure in guard cells
b) Low turgor pressure in guard cells
c) High light intensity
d) High CO₂ concentration in atmosphere
Answer: b) Low turgor pressure in guard cells
Explanation: When guard cells lose turgidity, stomata close to conserve water.
29) Which is the site of light reaction in chloroplast?
a) Stroma
b) Grana
c) Matrix
d) Inner membrane
Answer: b) Grana
Explanation: Grana (stacked thylakoids) are the site for light-dependent reactions in chloroplasts.
30) Which of the following mineral is required for chlorophyll synthesis?
a) Magnesium
b) Iron
c) Calcium
d) Potassium
Answer: a) Magnesium
Explanation: Magnesium is an essential component of the chlorophyll molecule and is crucial for its formation.
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