Free Forms and Functions of Plants MCQs with Answers

61. In most of the plants, intercalary meristems are situated at the

• A. Root apex
• B. Shoot apex
• C. Base of internodes
• D. Lateral sides of shoots

Explanation: Intercalary meristems are primarily found at the base of internodes in many plants and are responsible for the elongation of plant sections such as stems and leaves. This is especially common in grasses and monocots where growth needs to occur from the base upwards. The root apex and shoot apex are sites for apical meristems, which facilitate root and shoot elongation respectively. The lateral sides of shoots, however, are associated with lateral meristems, which are involved in the thickening of the plant stem or trunk (secondary growth).

62. Consider the given molecules.I.NADPHII. ATPIII. CO2In the process of photosynthesis, these molecules are used as inputs in the:

• A. Krebs cycle
• B. Calvin cycle
• C. Cyclic electron flow
• D. Non-cyclic electron flow

Explanation: The Calvin cycle is integral to the process of photosynthesis. It occurs in the stroma of chloroplasts and is sometimes referred to as the light-independent reactions or the dark reactions. This cycle uses ATP and NADPH produced in the light-dependent reactions, along with CO2 from the atmosphere, to synthesize glucose.

63. Insectivorous plants are autotrophs which grow in the soil that is deficient in

• A. Nitrogen
• B. Potassium
• C. Phosphorus
• D. Magnesium

Explanation: Insectivorous plants grow in nitrogen-deficient soil, so they catch insects to obtain nitrogen. Deficiency of potassium, phosphorus, or magnesium does not cause insect-eating behaviour, so those options are incorrect.

64. One of the characteristics of lenticels in woody plants is that they:

• A. Have cells containing chloroplast
• B. Are located in the stem epidermis
• C. Are permanent pores that always remain open
• D. Are openings in the stem of shrubs that are regulated

Explanation: Unlike stomata, which open and close to regulate gas exchange, lenticels are permanent openings in the bark of woody plants.So option C is correct.

65. In plants, the option that shows the range of environmental temperature and CO2 to O2 ratio which favours photorespiration is:

• A. Low, Low
• B. Low, High
• C. High, Low
• D. High, High

Explanation: Photorespiration is a process in plants where the enzyme RuBisCO oxygenates RuBP, leading to a decrease in photosynthetic output. This process is most active at high temperatures and when the CO2 to O2 ratio is low, as RuBisCO has a higher affinity for oxygen under these conditions. Therefore, option C is correct as it describes a high temperature with a low CO2 to O2 ratio, both of which promote photorespiration.

66. The pathway through which water moves from root hair cells to the xylem in plants are/is:I. apoplastII. symplastIII. vacuolar

• A. I only
• B. I and II
• C. III only
• D. II and III

Explanation: The vacuolar pathway involves water moving from one cell's vacuole to the next, and it is a key pathway in transporting water to the xylem.

67. Given is the sequence of events that lead to the opening of stomata in plants during day light:Accumulated of substances X and Y in the guard cell→increase solute concentration in the guard cells→water potential of guard cells→endosmosis of water in the guard cells→ increased turgidity of the guard cells→stomata opens.The letter X, Y and Z represent:

• A. Carbon dioxide, Potassium ions, decreases
• B. Glucose, Potassium ions decreases
• C. Carbon dioxide, Hydrogen ions increaes
• D. Glucose, Hydrogen ions increases

Explanation: As concentration of glucose and potassium ions increases, water potential decreases. This causes opening of stomata. So option B is correct.

68. The graph which illustrates the relation between wind speed and the rate of transpiration is:

• A. Graph A
• B. Graph B
• C. Graph C
• D. Graph D

Explanation: We know that as the wind speed increases, rate of transpiration increases.B option is the correct graphical representation of it.

69. The given diagram shows the microscopic view of a permanent slide.This slide is CORRECTLY identified as the transverse section of a:

• A. Dicot root
• B. Dicot stem
• C. Monocot root
• D. Monocot stem

Explanation: The given picture is microscopic view of dicot stem. It has epidermis, cortex, vascular bundles and pith.so option B is correct.

70. Photosynthesis in C3 plants is reduced in the presence of excessive:

• A. Oxygen
• B. Rubisco
• C. Carbon dioxide
• D. Glyceraldehyde-3-phosphate

Explanation: In C3 plants, photosynthesis can be reduced by high levels of oxygen due to a process known as photorespiration. During photorespiration, rubisco, the enzyme responsible for fixing carbon dioxide, can instead bind to oxygen, leading to a less efficient conversion of energy. This reduces the overall efficiency of photosynthesis.