Free Forms and Functions of Plants MCQs with Answers

81. Consider the given reaction which occurs in the leaves of C4 plants.

• A. Option A
• B. Option B
• C. Opion C
• D. Option D

Explanation: The C4 cycle, also known as the Hatch-Slack pathway, has two main steps: initial carbon fixation in mesophyll cells and the subsequent Calvin cycle in bundle sheath cells. As this reaction shows initial carbon fixation, it must occur in mesophyll cells. So D is correct.

82. Venus flytrap is an insectivorous plant in which the organ specialised to trap insects is

• A. Leaves
• B. Buds
• C. Roots
• D. Branches

Explanation: The correct answer is Leaves. The Venus flytrap is known for its specialized leaves that act as traps. These leaves snap shut when trigger hairs are stimulated by the presence of an insect, allowing the plant to trap and digest its prey for nutrients. The other options are incorrect as follows: Buds are involved in the growth of new plant parts; Roots are involved in nutrient uptake and are not used for trapping; Branches support other structures but do not trap insects.

83. The given diagram shows the water potentials of a plant cell and the solution in which it wasimmersed for 10 minutes:

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: In general, water moves from an area of higher water potential to an area of lower water potential. So water will move from the solution into cell, water potential of cell will become higher and cell will become turgid.So, option A is correct.

84. If a plant cell with a solute potential of −0.65 kPa is placed in a solution having water potentialof −3.65 kPa, then its pressure potential will be:

• A. 3.0 kPa
• B. 4.3 kPa
• C. −3.0 kPa
• D. −4.3 kPa

Explanation: Water potential = solute potential + pressure potential-3.65+(-0.65)= pressure potentialPressure potential = -3.0kpaSo C is correct option.

85. Presence of aerenchyma in the leaves, stem and roots of plants is an anatomical adaptation inI. hydrophytesII. mesophytesIII. halophytes

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

Explanation: The correct answer is 'I only.' Aerenchyma is a type of tissue with large air spaces that facilitates gas exchange, particularly in aquatic environments. This adaptation is common in hydrophytes, which are plants that grow in water. Mesophytes, which grow in moderate environments, and halophytes, which are adapted to saline conditions, do not typically have aerenchyma as a significant anatomical adaptation. Therefore, the presence of aerenchyma is specifically an adaptation for hydrophytes.

86. Following are the characteristics of a plant tissue.I. It has angular thickening in its primary cell wall.II. It provides support to young herbaceous parts of the plant.The plant tissue with these characteristics is identified as

• A. Sclereid
• B. Tracheid
• C. Parenchyma
• D. Collenchyma

Explanation: The correct answer is collenchyma. Collenchyma tissues are specialized for providing support to young, growing parts of the plant, such as stems and leaves, which aligns with the characteristic of providing support to young herbaceous parts. They are characterized by their uneven or angular thickening of the primary cell walls, which helps them support and strengthen these parts without hindering growth.On the other hand, sclereids are a form of sclerenchyma with heavily lignified walls, contributing to hardness and rigidity, not the flexible support described. Tracheids are involved in water transport and structural support but do not match the description of angular thickening or support specifically for young herbaceous parts. Parenchyma cells are generally thin-walled and involved in various functions like storage and photosynthesis, not specifically support with angular thickening.

87. The given diagram shows the transverse section of a leaf.The plant having such leaves will be MAINLY found in a:

• A. Pond
• B. River
• C. Desert
• D. Polar region

Explanation: The correct answer is Option D: polar region.The transverse section of the leaf likely shows adaptations like thick cuticles or reduced surface area, which are typical for plants in polar regions to conserve heat and protect against freezing temperatures.

88. The given diagram shows the transverse section of a stem.With reference to osmoregulation the plant that has shown anatomical feature is

• A. Sunflower plant
• B. Water lily
• C. Cactus
• D. Pinus

Explanation: Aerenchyma is a specialized plant tissue characterized by large air spaces within its structure, primarily found in waterlogged plants e.g water lily. So option B is correct. Sunflower, cactus and pinus doesn't grow in such environment so A,C and D are incorrect.

89. In dicot plants, vascular cambium is a cylinder of actively dividing cells between

• A. Primary xylem and Primary phloem
• B. Primary xylem and Secondary xylem
• C. Primary xylem and secondary phloem
• D. Primary phloem and secondary phloem

Explanation: In a dicot stem, the vascular cambium is located between the primary xylem and primary phloem. So option A is correct. All other options give wrong combinations.

90. The given diagram shows the cross-sectional view of a woody stem.Based on the examination of annual rings, it can be inferred that the age of this tree is

• A. 10 years
• B. 12 years
• C. 14 years
• D. 16 years

Explanation: The age of a tree can be determined by counting its annual rings, which are visible in the cross-sectional view of the woody stem. Each ring represents one year of growth. In the given diagram, there are 12 distinct annual rings, indicating that the tree is 12 years old. So option B is correct. Option A,C and D give incorrect age.