Question

In xerophytes, photosynthesis, often occurs through
(a)Root
(b)Modified stem
(c)Stomata
(d)Scaly leaves

Answer 1

Hint: Xerophytes are plants found in xerophytic conditions i.e. places with a scarcity of water such as deserts or snow-covered mountains. Water constitutes 70% of a cell and is essential for its proper functioning. Thus, these xerophytic plants have certain adaptations to conserve water loss.

Complete answer:
The adaptations of xerophytic plants include converting their leaves into spine shaped needles as this will reduce the surface area of the leaves from which evaporation will take place. So by doing this, less amount of water is lost through evaporation. Now as leaves are not available for performing photosynthesis, the stem of such xerophytic plants becomes swollen and green in color. Swollen stem increases the area for photosynthesis to occur and green color has chlorophyll pigments in it to trap the energy of sunlight. Thus, photosynthesis occurs through the stem.

Additional Information: Let us look at some more adaptations in xerophytic plants.
-They have sunken stomata i.e. the stomata are hidden inside deep pits or crypts.
-Leaves have a thick cuticle to ensure less transpiration.
-These plants follow the CAM pathway instead of the ${ C }_{ 3 }$ or ${ C }_{ 4 }$ cycle. In such plants photosynthesis occurs at night so that the stomata won’t be open during the daytime.
-Leaves are covered with silvery hair to reflect back the sunlight.
So, the correct option is ‘Modified stem’.

Note: -Stem modifications are also seen in the form of the rhizome of ginger which grows underground.
-To differentiate whether an underground modification is a root or stem, we need to look for nodes and internodes. Only stems have nodes and internodes.
-Internodes are the spaces between two nodes.