Which of the following brain structures is responsible for emotions, emotional behavior, and motivation?

Correct Answer: A

Rationale: The correct answer is the amygdala. The amygdala is a key brain structure involved in processing emotions, emotional behavior, and motivation. It plays a crucial role in fear responses, emotional memories, and social behaviors. The cerebellum (Choice B) is primarily responsible for coordination and balance, not emotions. The hypothalamus (Choice C) regulates basic survival functions like hunger, thirst, and body temperature, but it is not primarily responsible for emotions. The pons (Choice D) is involved in functions such as sleep, respiration, and bladder control, but it is not the main center for emotions, emotional behavior, or motivation.

Correct Answer: D

Rationale: The pia mater is the correct answer. It is a thin, innermost layer of the meninges that contains numerous nerves and blood vessels, providing nourishment to the underlying brain cells and spinal cord. The arachnoid mater (Choice A) is the middle layer of the meninges and does not contain as many nerves and blood vessels as the pia mater. The dura mater (Choice B) is the tough, outermost layer of the meninges and is not responsible for supplying nourishment. The periosteum (Choice C) is a connective tissue membrane covering bones, not part of the meninges.

Correct Answer: B

Rationale: The correct answer is B: 2. During aerobic respiration, each molecule of FADH2 produces 2 ATP molecules. FADH2 enters the electron transport chain and contributes to the generation of ATP. Choice A (1), Choice C (3), and Choice D (4) are incorrect because FADH2 specifically yields 2 ATP molecules per molecule in the process of aerobic respiration.

Correct Answer: C

Rationale: The ultimate end product of glucose breakdown in glycolysis is pyruvic acid. During glycolysis, glucose is broken down into pyruvic acid through a series of enzymatic reactions. ATP is produced as an energy carrier during glycolysis, but it is not the final end product. NADPH is not a direct product of glycolysis; it is mainly produced in the pentose phosphate pathway. Oxygen is not a product of glycolysis but is used as an electron acceptor in the electron transport chain of cellular respiration.

Correct Answer: C

Rationale: The correct answer is IgG. IgG is the only antibody that can cross the placenta, providing passive immunity to the developing fetus. IgA, IgD, and IgM do not cross the placenta. IgA is mainly found in mucosal secretions, IgD is involved in the activation of B cells, and IgM is the first antibody produced in response to an infection, but it does not cross the placental barrier.