Which of the following is an example of a biological macromolecule?

The digestive system breaks down complex food substances into small and less complex absorbable compounds. Proteins, for instance, are broken down to constituent amino acids through a digestion process that combines mastication and enzymatic breakdown.

ATP is produced by a series of reactions that occur in the mitochondria. The mitochondria have a double membrane structure, with an inner membrane that is folded into cristae. These cristae contain the enzymes and proteins that are involved in the process of cellular respiration, which converts glucose and oxygen into ATP and carbon dioxide.

A gene is a segment of DNA that codes for a specific protein or polypeptide.

Helper T cells are important cells that stimulate the action of other immune cells. For instance, they not only help activate B cells to secrete antibodies and macrophages to destroy ingested microbes, but they also help activate cytotoxic T cells to kill infected target cells.

The complementary strand of DNA is formed by pairing complementary bases. In DNA, adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C). Additionally, RNA uses uracil (U) instead of thymine.

Given the sequence 5' AGCTAGCGT 3', the complementary strand would read:

3' TCGATCGCA 5'

Correlation does not imply causation. Even if two processes are found to be correlated, it does not necessarily mean that one causes the other. It could be that they are both influenced by a third factor, or the correlation could be coincidental. Therefore, the study does not indicate a causal relationship between the processes.

Rationale

Chromatin refers to a complex of DNA and proteins in human cells. This material is packaged by histones to make up the chromosomes. The chromosomes then contain genetic information that is heritable.

The kidneys are the primary organs involved in the excretion of nitrogenous wastes. Nitrogenous wastes are mostly products of protein metabolism in the liver. One of the common nitrogenous waste products is urea, which is excreted through the kidneys.

The endocardium lines the interior structures of the heart. It is a thin, innermost layer of the heart wall that lines the heart chambers and valves. It is composed of subendocardial connective tissue and endothelial cells that are continuous with blood vessel endothelium.

The gray matter of the brain primarily consists of neuron cell bodies, along with dendrites, glial cells, and unmyelinated axons. It appears gray because it lacks the white fatty myelin sheath that covers many nerve fibers.