Free Forms and Functions of Plants MCQs with Answers

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.

22. 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.

23. Phytochromes are involved in:

• A. Phototropism
• B. Photorespiration
• C. Photoperiodism
• D. Geotropism

Explanation: Phytochrome senses day length → regulates flowering.

24. 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.

25. 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.

26. 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.

27. 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.

28. 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.

29. 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.

30. 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.