Free Forms and Functions of Plants MCQs with Answers
272 Forms and Functions of Plants MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Plant nutrition and transport cover mineral uptake, photosynthesis, xylem movement of water and minerals, and phloem translocation of sugars. Plant growth regulators include auxins, gibberellins, cytokinins, abscisic acid and ethene, whose effects on cell division, elongation, dormancy, fruit ripening and tropic responses should not be confused with mineral nutrition.
Last updated
272 questions · page 3 of 28
21. Leaf fall can be prevented with the help of:
- A. Abscisic Acid
- B. Auxins
- C. Florigen
- D. Cytokinins
Explanation: Cytokinins delay senescence, maintaining chlorophyll/protein content.
Correct answer: Cytokinins22. Which one increases in the absence of light?
- A. Uptake of minerals
- B. Uptake of water
- C. Elongation of internodes
- D. Ascent of sap
Explanation: Etiolation → rapid internode elongation in darkness.
Correct answer: Elongation of internodes23. Phytochromes are involved in:
- A. Phototropism
- B. Photorespiration
- C. Photoperiodism
- D. Geotropism
Explanation: Phytochrome senses day length → regulates flowering.
Correct answer: Photoperiodism24. Movement of leaves of sensitive plant (Mimosa pudica) is due to:
- A. Thermonasty
- B. Seismonasty
- C. Hydrotropism
- D. Chemonasty
Explanation: Mechanical stimulus → turgor loss in pulvini → leaves fold.
Correct answer: Seismonasty25. The process in which a seed develops into a new plant is:
- A. Plasmolysis
- B. Deplasmolysis
- C. Fertilization
- D. Germination
Explanation: Germination = emergence of young plant under favorable conditions.
Correct answer: Germination26. In the higher plants, growth is confined to certain regions called the:
- A. Meristems
- B. Epistems
- C. Peristems
- D. Mesostems
Explanation: Meristems = actively dividing cells at root/shoot tips or sides.
Correct answer: Meristems27. The increase in thickness of stems and roots due to the activity of lateral meristems is called:
- A. Primary Growth
- B. Secondary Growth
- C. Tertiary Growth
- D. Both A and B
Explanation: Secondary growth = thickening by vascular & cork cambium.
Correct answer: Secondary Growth28. Secondary growth is the increase in diameter of stems and roots due to activity of:
- A. Xylem
- B. Phloem
- C. Cambium
- D. Cortex
Explanation: Vascular & cork cambium produce secondary tissues → thickening.
Correct answer: Cambium29. The phase restricted to root and shoot tips, where cells divide continuously, is:
- A. Formative Phase
- B. Elongation Phase
- C. Maturation Phase
- D. Differentiation Phase
Explanation: Formative phase in meristems → active cell division.
Correct answer: Formative Phase30. Plant hormone "AUXIN" is:
- A. Acetic Acid
- B. Ethyl Acetic Acid
- C. Methyl Acetic Acid
- D. Indole Acetic Acid
Explanation: Naturally occurring auxin = Indole-3-acetic acid (IAA). Regulates cell elongation, apical dominance, phototropism, root initiation, and callus formation.
Correct answer: Indole Acetic Acid