NEET 2023 Biology Solved Paper Code C4 (Manipur)

(A) BOD (Biochemical Oxygen Demand) is indeed inversely related to dissolved oxygen. BOD is a measure of the quantity of oxygen used by microorganisms while decomposing organic matter in water. The more organic matter there is (i.e., the higher the BOD), the lower the amount of dissolved oxygen will be.
(B) Low dissolved oxygen levels and high BOD can lead to the loss of aquatic life. When dissolved oxygen levels in water are low, it can create a condition known as hypoxia, which can be harmful or lethal to aquatic organisms.
(C) High BOD does not lead to high dissolved oxygen. As explained above, high BOD usually leads to low levels of dissolved oxygen because the oxygen is consumed in the process of breaking down organic material. So, this statement is false.
(D) Both BOD and dissolved oxygen are indeed indicators of the health of a water body. High levels of BOD and low levels of dissolved oxygen can indicate pollution, often from organic waste.
(E) Both BOD and dissolved oxygen are affected by the amount of organic matter in the water body. The more organic matter there is in the water, the higher the BOD will be and the lower the level of dissolved oxygen will be, due to microbial decomposition of the organic matter.