The hormone that does the opposite of calcitonin is
a) insulin.
b) glucagon.
c) growth hormone.
d) parathyroid hormone.
e) thyroid hormone.

D) parathyroid hormone

Explanation:

Calcitonin and parathyroid hormones work against each other. Calcitonin is secreted by thyroid gland and parathyroid hormone is secreted by parathyroid gland. They both regulate serum calcium levels by affecting kidney, bone and intestine.

Calcitonin decreases calcium level when it has crossed its normal level. It is produced by parafollicular cells of the thyroid gland. Parathyroid hormone increases calcium level. It increases blood calcium level by simulating osteoclasts which release calcium from bone.

there’s no image attached but i can if you want: )

it has to be understood that the sea water contains a huge amount of sodium and chlorine ions and if they enter the cell of the atlantic cod fish, the cell will shrivel and the fish will die. to avoid such a condition, the fish uses active transport for the purpose of removing the ions against the gradient.

explanation:

the atlantic cod is not a maritime osmoconformer. its native application of salts is less than that of the seawater it lives in. it is continually falling water from the gills to the ocean via osmosis.

countering that, the fish is going to be swallowing seawater. but since its internal collection of salts is lower than seawater, the fish will want to go free of excess salt, and since that's going upon a gradient, then active transport, requiring energy, must be used to pump out the salt. much marine fish use the organs to filter out the salt and these fish discharge very straight urine.