Question

In Opuntia, the stem is modified into a flattened green structure to perform the function of leaves (i.e., photosynthesis). Cite some other examples of modifications of plant parts for the purpose of photosynthesis.

Answer 1

Leaves are known to be the kitchen of the plant as it is the site for the production of plant food. This occurs through a process called photosynthesis which utilizes sunlight and carbon dioxide to make starch. Various modifications of plant parts occur to conduct photosynthesis in plants based on the habitat in which they live.

Complete answer: Photosynthesis is an essential process for the growth and development of any plant species. It is a vital life process that uses sunlight energy, carbon dioxide, and water to form plant food in the form of starch. The starch is further broken down into energy molecules required for various cellular processes of the plant. Together all of these events aid in the growth and sustainability of the plant. Usually, it is the leaves of the plant that performs photosynthesis. Leaves contain a green pigment called chlorophyll which helps in photosynthesis. When leaves open their pores to collect carbon dioxide water is also lost. In Opuntia, the leaves are absent as it is a desert plant and will lose water due to leaves. Thus, its stem is modified to form flattened structures that help in photosynthesis without water loss. Some other plants that show modifications of their body parts to perform photosynthesis are Euphorbia and Acacia. In Euphorbia, the stem modifies to form a fleshy cylindrical structure that consists of chlorophyll. Due to the presence of chlorophyll, the stem performs the function of leaves. On the other hand, in Acacia, the petiole which is a stalk responsible for joining stem to leaf takes up the function of a leaf. It is modified into a lamina structure and leaves get highly reduced.

Note: Modifications in plants enable them to adapt to harshest of conditions. The desert plants are an example of excessive modifications. These plants have leaves modified into spikes, stems modified to swollen structures to store water, and roots being very deep. All these adaptations allow them to survive in the conditions close to droughts.