Question 1

Urine output increases in winter. Why?

Accepted Answer

During winter, the surrounding temperature will be very low. There will not be any sweating and no evaporation losses. To keep the body temperature constant, the blood capillaries in the skin get constricted and the blood pressure is increased. The result is that our body gets warmed up. In order to maintain the blood pressure normal, the excess water along with the wastes is excreted mostly in the form of urine. This is the reason for more urine output and frequent urination in winter.

Question 2

Terrestrial animals are generally either ureotelic or uricotelic, not ammonotelic, why?

Accepted Answer

Terrestrial animals are either ureotelic or uricotelic, and not ammonotelic. This is because of the following two main reasons:(a) Ammonia is highly toxic in nature. Therefore, it needs to be converted into a less toxic form such as urea or uric acid.(b) Terrestrial animals need to conserve water. Since ammonia is soluble in water, it cannot be eliminated continuously. Hence, it is converted into urea or uric acid. These forms are less toxic and also insoluble in water. This helps terrestrial animals conserve water.

Question 3

Explain why the composition of glomerular filtrate is not the same as urine.

Accepted Answer

When the volume of the filtrate is compared with that of the urine that is formed per day, which is 180 litres and 1.5. Litres respectively, most of the filtrate needs to be reabsorbed by the renal tubules, the phenomenon is referred to as reabsorption. Substances such as amino acids, Na+, glucose are actively reabsorbed in the filtrate hence, are not found in urine.

Question 4

The glomerular filtrate in the loop of Henle gets concentrated in the descending and then gets diluted in the ascending limbs. Explain.

Accepted Answer

The descending limb of Henle's loop is more permeable to water and almost impremeable to electrolytes. As a result, filtrate gets concentrated as it moves down the descending limb of Henle's loop.The ascending limb of Henle's loop is impermeable to water but permeable to electrolytes. As a result, the filtrate gets diluted as it moves up the ascending limb of Henle's loop.

Question 5

Why is right kidney slightly lower in position compared to the left kidney?

Accepted Answer

Humans have a pair of kidneys, with one placed on the left and the other on the right side of the abdominal cavity But the position of the right kidney is slightly lower than the left kidney due to the presence of the liver on the right side placed anterior to the kidney. To accommodate the liver the position of the right kidney Is slightly lower than the left kidney.

Question 6

In desert animals

Accepted Answer

The loop of Henle functions to reabsorb water, therefore, the longer the loop of Henle, the more water that can be reabsorbed. It is especially important for animals in arid environments to preserve as much water as possible and minimise loss through urine and sweating.

Excretory Products And Their Elimination