Question

F. Give reasons for the following questions.
1. Transportation of substances in living organisms.
2. The heart gives away impure blood through an artery.
3. Arteries have thick elastic walls.
4. We feel cool in summer while sweating.
5. If plants do not get enough water, they drop and wilt.​

Answer 1

1. Substances like food,oxygen etc needs to be transported around the body as all organs require certain substances to do a certain task like muscles require food and oxygen to use energy and not only muscles require these but all organs,tissues,cells etc require food and oxygen.
2. The reason is that the impure pumped away from heart so that is goes to kidney/lung for purification/oxidation and then it comes again and then pumped to the rest of the body. So this thing is known as double circulation as the blood is pumped two times for a single beat.
3. Because arteries are the first vessels that the heart pumps blood through, they experience the highest blood pressure, so they have thick elastic walls to withstand the high pressures.
4. So sweat helps cool you down two ways. First, it makes your skin feel cooler when it's wet. And when it evaporates it removes some heat. But sweat will only evaporate in an environment where there isn't much water in the air.
5. The water keeps plants fresh and turgid. When a plant does not get enough water, it wilts and droops due to loss of turgidity by decrease in the amount of water in plant cells/parts .