Question

Answer the following question based on your observations about aquatic plants in the laboratory.
A. Why do they float on water?

Answer 1

Plants that are adapted to the water habitats are called aquatic plants, and these plants may be either freshwater or saltwater, and they also referred to as hydrophytes, and they can also be called as Macrophytes, and to distinguish them from algae that live in water to other plants, that grow near in or near the water.

Complete answer:
The plants that grow in water are present in any form such as emergent, submergent, or floating.
In the aquatic areas, these plants provide shelter for many organisms, and these plants produce plenty of oxygen which can be utilized by all other aquatic animals, and these plants act as food for some fish and other aquatic life.
These are primary producers in the food web, as they can synthesize their food by photosynthesis, and these plants have a significant effect on soil chemistry and light levels, and there are so many sediments in water, where some of them can be absorbed by the plants.
Aquatic plants require the special adaptation for living submerged in water or on the surface of the water, where the most common adaptation is the presence of air cells such as aerenchyma, which are nothing but Spongy cells that are light in weight and packed internally by air, so because of this reason, they can have buoyancy which means having the ability to float on water.
The largest aquatic plant in the world is the Amazon water lily and the smallest aquatic plant is duckweed.
And based on morphology, plants are classified into different types such as Amphiphytes, Elodeids, and Isoetids, etc.

Note: Plants have different habitats, and the plants that are grown in water are called aquatic plants and they can float on water which is an adaptation, and this is due to the presence of spongy cells that are filled with air.