Question

Salmon regulates its internal water and salt concentrations during its swimming in the ocean and migrates to freshwater to spawn, is described by
A. In salt water the salmon loses water by osmosis; it drinks salt water and disposes of excess salt through its gills. In fresh water, the salmon gains water by osmosis; its kidneys excrete large quantities of urine along with some salts, and it replenishes the loss of salts through uptake by its gills and digestive system.
B. In salt water, the salmon gains water by osmosis; it drinks salt water and disposes of excess salt through its gills. In fresh water, the salmon loses water by osmosis; it's kidneys secretes large quantities of urine along with some salts , and it replenishes the lost salts through uptake by its gills and digestive system.
C. In salt water, the salmon loses water by osmosis; it drinks salt water and stores excess salt in its body cavity. In fresh water, the salmon gains water by osmosis; it's kidneys secretes large quantities of urine and salts.
D. In salt water, the salmon gains water by osmosis; it drinks salt stores excess salt in its body cavity. In fresh water, the salmon loses water by osmosis; it's kidneys secretes large quantities of urine and salts.
E. In salt water, the salmon gains water by osmosis and loses salt by diffusion. In fresh water, the salmon loses water by osmosis and gains salt through diffusion.

Answer 1

Hint:-Salmon is a fish which has capacity to regulate salt and ions from salt water to fresh water as it starts its life in fresh water and spend their life in salt water where their body regulates the process of osmosis and again it returns to the same area where they were hatched and came out of the egg as they are capable of remembering the taste and smell of that particular area.

Complete step-by-step solution:-
Salmon’s life starts at the upstream of the fresh water where its egg hatches and they starts traveling downstream(salt water) which takes several months for them to reach, here they remain for about 3 to 5 years of their life and then again when they become adult they travel towards the upstream( fresh water) where they hatched as mentioned above salmon remembers the taste and smell of area finally they reaches the upstream where they spawn and die this is the lifecycle of a salmon, but this travel includes the process of osmosis through their body and gills due to change of water i.e. from fresh water to salt water and again to fresh water. They rely on the process of osmoregulation where they have a control over their body to deal with the change of external environment from their body. In salt water the salmon drinks several litres of water and stores it as it does not drink fresh water it only goes inside its body when it engulfs the food. As by the above statement we come to know that salmon consume a lot of sodium chloride from salt water as a result it disposes of extra salt through its gills, whereas in fresh water it does not drink water at all and excretes the diluted urine to maintain ionic balance within the body.
Hence the correct option is (A) In salt water the salmon loses water by osmosis; it drinks salt water and disposes of excess salt through its gills. In fresh water, the salmon gains water by osmosis; its kidneys excrete large quantities of urine along with some salts, and it replenishes the loss of salt through uptake by its gills and digestive system.

Note:- Osmoregulation is the process in which the osmotic pressure is detected by the osmoreceptors within the organism’s body to maintain the water and ionic balance or homeostasis, i.e. the fluid concentration along with required electrolytes for the survival during the change of external environment to that of internal environment