Correct Answer: B

Rationale: The dendrites are the part of the neuron that receive incoming signals from other neurons and conduct them toward the cell body. They play a crucial role in integrating signals received from other neurons. The dendrites are covered in synapses, which are the junctions where communication between neurons occurs. The axon, on the other hand, is responsible for transmitting signals away from the cell body. The synapse is the gap between neurons where neurotransmitters are released to facilitate communication. Lastly, the myelin sheath is a fatty layer that insulates and speeds up signal transmission along the axon, helping in the efficient conduction of nerve impulses.

Correct Answer: D

Rationale: Genomic medicine is the scientific discipline that specifically focuses on the study of genes and their involvement in disease processes. It seeks to understand how variations in an individual's genes can influence their predisposition to certain diseases or affect their response to treatment. This field plays a crucial role in personalized medicine by utilizing genetic information to tailor healthcare decisions and interventions to individual patients. Molecular biology, biochemistry, and evolutionary biology, while related to genetics in various ways, do not have the primary focus on the role of genes in disease as genomic medicine does.

Correct Answer: A

Rationale: Parathyroid hormone (PTH) is the correct answer. PTH stimulates the release of calcium from bones, leading to increased blood calcium levels. It acts on the bones to release calcium into the bloodstream, facilitates the kidneys' reabsorption of calcium, and triggers vitamin D activation to boost calcium absorption from the intestines. Choice B, Calcitonin, is incorrect as it works in opposition to PTH by decreasing blood calcium levels through inhibiting calcium release from bones. Choices C and D, Growth hormone and Testosterone, are not directly involved in calcium homeostasis and do not regulate blood calcium levels through bone calcium release mechanisms.

Correct Answer: D

Rationale: Amino acids are linked together by covalent bonds to form proteins. Specifically, the bond that links amino acids together is called a peptide bond, which is a type of covalent bond. The peptide bond forms between the amino group of one amino acid and the carboxyl group of another amino acid, resulting in the formation of a peptide chain. While hydrogen bonds, ionic bonds, and disulfide bonds are important for protein structure and stability, the primary bond responsible for linking amino acids in a protein chain is the covalent peptide bond. Hydrogen bonds are involved in maintaining the secondary structure of proteins, such as alpha helices and beta sheets. Ionic bonds and disulfide bonds contribute to tertiary and quaternary structures of proteins by stabilizing interactions between different parts of the protein or between different protein subunits, respectively.

Correct Answer: B

Rationale: Testosterone and estrogen are the primary sex hormones responsible for the development of male and female sex organs, respectively, and the emergence of secondary sex characteristics during puberty. Growth hormone, insulin, and thyroid hormone do not directly influence the development of sex organs and secondary sex characteristics during puberty. Growth hormone primarily regulates growth and metabolism, insulin regulates blood sugar levels, and thyroid hormone controls metabolism and energy levels. Therefore, choices A, C, and D are incorrect for this question.