Question

Transportation in the living organisms is necessary, because of the following reasons

• A. Food, oxygen, water and other essential substances are distributed through this system
• B. It displaces the excretory wastes from the cells of the body to the excretory organs from where they are expelled out
• C. Temperature and pressure throughout the body are kept uniform
• D. All of the above

Answer 1

The correct option is D All of the above

All living cells have to be provided with nutrients, O${}_2$, and other essential substances. Also, the waste or harmful substances produced, have to be removed continuously for the healthy functioning of tissues. Different groups of animals have evolved different methods for this transport. Simple organisms like sponges and coelenterates circulate water from their surroundings through their body cavities to facilitate the cells to exchange these substances. More complex organisms use special fluids within their bodies to transport such materials. Blood is the most commonly used body fluid by most of the higher organisms including humans for this purpose. Another body fluid, lymph, also helps in the transport of certain substances. Blood also plays an important role in the regulation of body temperature. Thus playing a role in the maintenance of homeostasis. As a major constituent of blood is water, blood is incompressible and helps maintain a uniform pressure throughout the body.

So, the correct answer is option D.