Question

Xerophytes have very small leaves or spines to.

• A. Reduce weight
• B. Reduce loss of water
• C. Reduce volume
• D. Be beautiful

Answer 1

The correct option is B Reduce loss of water

Xerophytes have very small leaves or spines to reduce loss of water.

A xerophyte is a species of plant that has adapted to survive in an environment with little liquid water, such as a desert or an ice- or snow-covered region.

Morphologically and physiologically the xerophytes are adapted to conserve water and also to store large quantities of water in the dry periods. Some species are adapted to survive long periods of dehydration in their tissues. During the periods of dehydration the metabolic activity of them may be shut down.

Morphological Adaptations in xerophytic plants

Almost all the xerophytic plants have similar shapes, structure and forms and they look very similar though these plants are not genetically related. This process of evolution is known as convergent evolution.

Reduction of Surface Area

• Xerophytic plants usually have less surface area than other plants, this reduces the area that is exposed to the air and helps in reducing water loss by evaporation process.
  
• These plants have smaller leaves and few branches than other plants.
  

Reduction in Air Flow

• Some xerophytes plants have tiny hairs on their surface; this provides a wind break and reduces air flow, which reduces the rate of evaporation.
  
• In such environments the region under the leaves/spines is the place of transpiration and this place is more saturated than the normal water vapor.
  
• If there is less movement of air, there is reduced potential gradient of the water vapor hence reducing transpiration.
  
• Spines trap moisture and also slow the movement of air over the tissues.
  

Reflectivity

• The color of these plants or of the waxes or hairs on its surface may help to reflect sunlight and reduce evaporation.
  
• Physiological Adaptations of Xeropyhtes
  
• Some xerophytic plants store water in structures like roots, trunks, stems and leaves. Water is stored in swollen parts of the plant known as succulence. A swollen trunk part or the root part at the ground level of a plant is called caudex.
  
• Stomata are tiny pores on the surface of xerophytic plants; they stay open only at night to reduce evaporation.
  
• These plants may secrete resins and waxes on their surface which reduce evaporation.
  
• Some plants drop their leaves in the times of dryness or they modify the leaves produced so that they are smaller and less surface area of the plants is exposed.
  
• Xerophytic plants may go dormant and stop growing during dry periods; they may also change the kind of photosynthesis or they may change the storage allotment of the products of photosynthesis by growing new leaves to the roots.
  
• Seeds also may be modified to require excessive amount of water before the process of germination, so to ensure that there is sufficient supply of water for the survival of the seedling.
• So, the correct answer is 'Reduce loss of water'