Adaptation of Plants to Different Habitats

Free sample questions

Adaptation of Plants to Different Habitats — sample Biology questions with answers

1. Question 1

   Why does the lotus leaf (Nymphaea) have stomata only on the upper surface of the leaf?

   • AStomata on the lower surface would be submerged in water and unable to function for gas exchange.
   • BStomata on the lower surface are blocked by a thick waxy layer.
   • CLotus leaves do not have stomata because they live in water.
   • DThe lower surface of the lotus leaf is covered with fine hairs that cover the stomata.

   Answer: A. Stomata on the lower surface would be submerged in water and unable to function for gas exchange.

   Lotus leaves float on the water surface. Stomata only on the upper (adaxial) surface allow direct gas exchange with the air, because the lower surface is constantly in contact with water.

2. Question 2

   Which of the following is a structural adaptation of the leaf of xerophytic plants like cactus?

   • ABroad and thin leaves to absorb light.
   • BLeaves modified into spines to reduce water loss.
   • CLarge leaves with many stomata to cool the body.
   • DLeaves with a thick waxy layer to absorb rainwater.

   Answer: B. Leaves modified into spines to reduce water loss.

   Cacti modify their leaves into spines to reduce surface area and thus reduce transpiration. This is an important adaptation in dry habitats.

3. Question 3

   Halophytic plants like mangrove (Rhizophora) have pneumatophores (aerial roots) that function to:

   • AAbsorb salt water from the soil.
   • BSupport the stem above the mud.
   • CObtain oxygen from the air because the muddy soil lacks oxygen.
   • DStore fresh water in the roots.

   Answer: C. Obtain oxygen from the air because the muddy soil lacks oxygen.

   Pneumatophores grow upward from underground roots to take in oxygen from the air, because the muddy swamp soil has low oxygen content.

4. Question 4

   Which of the following characteristics is NOT found in hydrophytes (aquatic plants)?

   • AAir spaces in tissues (aerenchyma) for buoyancy.
   • BThick cuticle to reduce water loss.
   • CFloating leaves with stomata on the upper surface.
   • DPoorly developed roots because water is easily absorbed.

   Answer: B. Thick cuticle to reduce water loss.

   Hydrophytes do not need a thick cuticle because water loss is not a problem; instead, they may have a thin or absent cuticle. Thick cuticle is a xerophytic adaptation.

5. Question 5

   Why do epiphytic plants like orchids have thick, fleshy roots (velamen)?

   • ATo attach to the host tree trunk.
   • BTo store water absorbed from humid air.
   • CTo absorb nutrients from the host trunk.
   • DFor photosynthesis because the roots are green.

   Answer: B. To store water absorbed from humid air.

   Velamen roots on epiphytes have a spongy layer that absorbs water and moisture from the air and rain, allowing the plant to survive without soil.