Which of the following is a characteristic of the stems of desert plants like cactus? 1. They are covered with a thick waxy layer. 2. They lack chlorophyll and cannot perform photosynthesis. 3. They are modified to store water. Select the correct answer using the code given below:

The correct option is (c). Explanation Desert plants, scientifically known as xerophytes, evolve specific morphological and physiological adaptations to survive in arid environments with scarce water. These adaptations primarily aim to minimize water loss (transpiration) and maximize water storage. - Statement 1 is Correct: The stems of desert plants are typically covered with a thick waxy cuticle. This waxy layer acts as a waterproof barrier, significantly reducing the rate of water loss through evaporation from the stem surface. - Statement 2 is Incorrect: In plants like cacti, the leaves are modified into spines to reduce the surface area available for transpiration. To compensate for the lack of leaves, the stem becomes green and contains chlorophyll. Therefore, the stem actively performs photosynthesis. These modified photosynthetic stems are called phylloclades. - Statement 3 is Correct: The stems of desert plants are often modified into fleshy, swollen structures known as succulents. These stems contain specialized parenchymatous tissues designed to store large quantities of water, allowing the plant to survive prolonged dry periods. Key Takeaway: In xerophytes like cacti, the stem takes over the function of leaves; it becomes a phylloclade (green, photosynthetic, and flattened) and is succulent (water-storing), while leaves are reduced to spines to prevent water loss.

Which of the following is a characteristic of the... - NCERT Class 6 Science MCQ

Solution

The correct option is (c).

Explanation

Desert plants, scientifically known as xerophytes, evolve specific morphological and physiological adaptations to survive in arid environments with scarce water. These adaptations primarily aim to minimize water loss (transpiration) and maximize water storage.

Statement 1 is Correct: The stems of desert plants are typically covered with a thick waxy cuticle. This waxy layer acts as a waterproof barrier, significantly reducing the rate of water loss through evaporation from the stem surface.
Statement 2 is Incorrect: In plants like cacti, the leaves are modified into spines to reduce the surface area available for transpiration. To compensate for the lack of leaves, the stem becomes green and contains chlorophyll. Therefore, the stem actively performs photosynthesis. These modified photosynthetic stems are called phylloclades.
Statement 3 is Correct: The stems of desert plants are often modified into fleshy, swollen structures known as succulents. These stems contain specialized parenchymatous tissues designed to store large quantities of water, allowing the plant to survive prolonged dry periods.

Key Takeaway: In xerophytes like cacti, the stem takes over the function of leaves; it becomes a phylloclade (green, photosynthetic, and flattened) and is succulent (water-storing), while leaves are reduced to spines to prevent water loss.

NCERT Class 6 Science — Chapter 4: The living organisms - characteristics and habitats

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