Correct Answer: C

Rationale: Testosterone is the hormone crucial for stimulating sperm production in males. It is primarily produced in the testes and plays a significant role in the development of male reproductive tissues, including the testes and prostate, as well as promoting secondary sexual characteristics such as facial hair growth and deepening of the voice. Estrogen and progesterone are female sex hormones responsible for regulating the menstrual cycle and other female reproductive functions. Insulin, on the other hand, is involved in regulating blood sugar levels and glucose metabolism, not directly related to sperm production in males.

Correct Answer: B

Rationale: The spleen is located in the abdomen, specifically in the upper left part of the abdomen, under the ribcage and above the stomach. It is an important organ in the lymphatic system responsible for filtering blood, storing blood cells, and fighting infection. It is not located in the chest, pelvis, or head and neck regions. Therefore, the correct answer is 'B: Abdomen.' Choices 'A: Chest,' 'C: Pelvis,' and 'D: Head and neck' are incorrect as the spleen is not situated in these anatomical areas.

Correct Answer: B

Rationale: - Amino acids are the building blocks of proteins, not DNA. - Nucleotide is the correct building block of DNA. A nucleotide consists of a sugar (deoxyribose in DNA), a phosphate group, and a nitrogenous base (adenine, thymine, cytosine, or guanine). - The option 'C) Phosphate group' is incorrect as it is only part of a nucleotide, not the complete building block of DNA. - Fatty acids are not the building blocks of DNA; they are a type of lipid molecule.

Correct Answer: C

Rationale: The main function of the pancreas is to produce digestive enzymes that aid in breaking down carbohydrates, fats, and proteins in food. These enzymes are essential for the digestion and absorption of nutrients in the small intestine. While the pancreas also plays a role in regulating blood sugar levels by producing insulin and glucagon, its primary function is to produce enzymes for food digestion. Options A and B are incorrect as the pancreas is not involved in storing food or absorbing nutrients into the bloodstream.

Correct Answer: B

Rationale: The correct answer is B: 23. Humans have 23 pairs of chromosomes, totaling 46 chromosomes. Each pair consists of one chromosome inherited from the mother and one from the father, making a total of 46 chromosomes in a human cell. Choice A (46) is incorrect as it represents the total number of chromosomes, not pairs. Choice C (64) and D (32) are incorrect as they do not reflect the accurate number of chromosome pairs in a human cell.