Free Forms and Functions of Plants MCQs with Answers

31. The most common correlation found in plants is:

• A. Seed Dominancy
• B. Shoot Dormancy
• C. Apical Dormancy
• D. Peduncle Dormancy
• E. None of these

Explanation: Apical bud suppresses lateral buds → conserves energy and maintains vertical growth.

32. The removal of apex releases the lateral buds from apical dominance is called:

• A. Inhibitory Effects
• B. Compensatory Effects
• C. Compression Effects
• D. Comprehensive Effect

Explanation: Removing apical bud allows lateral buds to grow → compensatory effect.

33. In higher plants, the phase that lies behind the region of elongation is:

• A. The Formative Phase
• B. Elongation Phase
• C. Maturation Phase
• D. Ovulation Phase

Explanation: Maturation zone → cells complete differentiation into xylem, phloem, and epidermis.

34. Vernalization is related to:

• A. Very High Temperature
• B. High Temperature
• C. Moderate Temperature
• D. Low Temperature
• E. Optimum Temperature

Explanation: Vernalization = induction of flowering after prolonged cold exposure.

35. Promotion of flowering by a cold treatment given to the imbibed seeds or young plants is:

• A. Vernalization
• B. Imbibition
• C. Photoperiodism
• D. Apoptosis
• E. Germination

Explanation: Ensures flowering occurs only after cold exposure, preventing premature reproduction.

36. Passive processes for the movement of molecules across the cell surface membrane are:

• A. Facilitated diffusion and osmosis
• B. Diffusion and exocytosis
• C. Pinocytosis and facilitated diffusion
• D. Osmosis and phagocytosis

Explanation: Facilitated diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration with the help of specific transport proteins present in the cell membrane. It allows larger or polar molecules, such as glucose or ions, to pass through the membrane without energy expenditure.Osmosis is the passive movement of water molecules through a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration, aiming to balance solute levels on both sides of the membrane.Both processes are passive because they occur along the concentration gradient and do not require energy input from the cell.

37. Excess water is forced out in the form of droplets through

• A. Stomata
• B. Cuticle
• C. Hydathodes
• D. Lenticles
• E. All of the above

Explanation: Excessive water is removed from the plant body by the process of transpiration. Hydathodes are special glands that remove water in the form of droplets.

38. Which element has function in opening and closing of stomata?

• A. K
• B. Mg
• C. Cu
• D. Fe

Explanation: Potassium (K+) plays a crucial role in the opening and closing of stomata in plants. Stomata are small pores found on the surfaces of leaves, stems, and other plant organs. They are responsible for gas exchange, allowing plants to take in carbon dioxide (CO2) for photosynthesis while releasing oxygen (O2) and water vapor. Hence option A is correct.

39. Stomata of a plant opens due to

• A. Influx of potassium ions
• B. Efflux of potassium ions
• C. Influx of hydrogen ions
• D. Influx of calcium ions

Explanation: The correct answer is the influx of potassium ions into the guard cells of the stomata. When light is available, potassium ions are actively transported into these cells, leading to an increase in turgor pressure. This pressure causes the guard cells to swell and bend, resulting in the opening of the stomata for gas exchange. The other options are incorrect: the efflux of potassium ions would decrease turgor pressure and close the stomata, while the influx of hydrogen or calcium ions does not directly cause the stomatal opening mechanism.

40. The main force that draws water from the soil for plants is caused by:

• A. Evaporation
• B. Transpiration pull
• C. Guttation
• D. Wilting

Explanation: Water evaporates from leaves, creating a suction force that pulls water upward through xylem from roots.