Question

Assertion- Ions are absorbed from the soil by active transport only.
Reason-
The proteins present in the membranes of root hair cells passively pump ions from the soil into the cytoplasm of the epidermal cells.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect.
D. Both Assertion and Reason are incorrect.

Answer 1

Hint: The process of uptake of minerals is known as mineral absorption and it is the method through which the minerals in the ionic form enter the cellular environment. The mineral ions are taken inside the cells just as the way water is taken in. In plants, the roots are the way of entrance of the mineral ions.

Complete answer:
The development and growth of the plants may depend upon the availability of certain types of minerals present in the soil. The roots are the organs through which the minerals are taken up by the plants. Plants absorb minerals in the form of ions and the process of absorption of mineral ions are known as mineral absorption. The minerals in plants can enter either by diffusion through the cells or by the process of active transport. The root hair cells are present in the roots of the plants which contain specific proteins. These specific proteins pump the ions from the soil to enter the cellular environment.

The movement of the mineral ions across the plasma membrane generally taken up by the chemiosmotic mechanism. The transport protein present in the cells of the endodermis allows the passage of some types of ions but it also restricts the movement of many other types of ions. The plants absorb a variety of ions and each ion may bear different charges. The ions with different charges face problems while crossing the plasma membrane which is already charged.

The plants actively absorb the mineral ion by active transport and this process requires energy. The process occurs by the creation of an electrochemical gradient across the plasma membrane and it causes the positive ions to flow and enter the cells. This process takes place due to the utilization of ATP by the proton pump which sets up the electrochemical gradient and allows movement of ions carrying the positive charge. In case of the negative ions, they are carried across the membrane in addition to the $H+$ ions due to the diffusion of $H+$ ions down the concentration gradient.

Thus, ions are absorbed by both active and passive types of transport and it depends upon the charge present on the mineral ions. Hence, the assertion is incorrect. The proteins are specific in their cation and cause transportation of the mineral ions through the active transport and the assertion is also incorrect.

Hence, The correct answer is option (D).

Note: Mineral absorption is an important process and the roots are the site of absorption of the mineral ions that are present in the surrounding soils. The ions are actively transported by the specific proteins that are present in the roots of the plants. Also the transport proteins only allow the transfer of specific proteins while others are not allowed to pass through. The process of active transportation occurs by expenditure of energy by the plant cells.