Question

Which process in the nephron is least selective?

(A) filtration

(B) reabsorption

(C) active transport

(D) secretion

Short answer

(A) The option “filtration” is true.

(B) The option “reabsorption” is false.

(C) The option “active transport” is false.

(D) The option “secretion” is false.

Step-by-step solution

Nephron

The nitrogenous waste and excess substance in the blood are filtered in the active part of the kidney called nephrons. The regulation of water and soluble materials is maintained in the body with the help of nephrons. These structures regulate blood pressure and blood volume in the body.

Explanation of option (A)

Filtration is least selective because hydrostatic pressure forces the entry of water and solutes to the glomerulus. All the body fluids undergo a filtration mechanism. Negative charges and effective size of the pores present on the glomerulus membrane make the filtration least selective.

Therefore, filtration in nephrons is least selective as it filters the whole blood in the body.

Thus, the given option is true.

Explanation of option (B)

Reabsorption is the process in which essential substances are absorbed again in the proximal tubule. The substance which is only needed for the body is transferred to the plasma.

Therefore, reabsorption is a highly selective process.

Thus, the given option is false.

Explanation of option (C)

Active transport is a selective process because the molecules which need to transfer against concentration gradient are transferred through active transport. Reabsorption is one such active transport that occurs in nephrons.

Therefore, active transport is a selective process.

Thus, the given option is true.

Explanation of option (D)

In the secretion process, the waste material is transferred to the lumen of the renal tubule.

Therefore, secretion is a selective process.

Thus, the given option is false.