Question

How does Carbon dioxide diffuse in submerged plants?

Answer 1

Normally, atmospheric carbon dioxide ${CO}_{2}$ is diffused into plants through stomata. While in submerged plants, the level and movement{ of carbon dioxide gas is less, as compared to the atmosphere. Thus the diffusion takes place through a complicated procedure.

Complete answer:
The submerged plants grow inside water. Only a small part of their vegetative body is present above the water. Unlike the land plants, they do not possess stomata, as there are chances that excess water might enter through the stomatal pores. Thus gaseous exchange in submerged plants doesn't occur through stomata. On the other hand, the ocean has absorbed a high amount of carbon dioxide (${CO}_{2}$) from the atmosphere. Thus submerged plants depend on water as a source of carbon dioxide.
There are some special adaptations in submerged plants for the process of carbon dioxide diffusion. They are:
-Submerged plants have thin and edgy leaves that help in the flow of carbon dioxide over them.
-The leaves are surrounded by thin porous cuticles, through which carbon dioxide enters into plants.
-The light weight spongy aerenchyma tissues are present in the floating leaves of submerged plants. It contains air pores that allow smooth gaseous exchange.
-In between the spaces of aerenchyma cells of plants, water flows freely and diffusion of carbon dioxide takes place.

Note:
-Gases diffuse faster in air than water.
-Along with water, plants must need Carbon dioxide (${CO}_{2}$) in order to carry out the photosynthesis process.
-In submerged plants, there is no air to be absorbed.