What is the role of the hypothalamus in the body?

Correct Answer: B

Rationale: The correct answer is B: 'To regulate hormones.' The hypothalamus plays a crucial role in regulating hormones and maintaining homeostasis by controlling various functions such as hunger, thirst, body temperature, and sleep-wake cycles. While digestion, body temperature, and the immune system are important bodily functions, they are not primarily controlled by the hypothalamus. Therefore, choices A, C, and D are incorrect as they do not accurately represent the primary function of the hypothalamus.

Correct Answer: A

Rationale: The correct answer is A: 'To break down food into nutrients.' The primary function of the digestive system is to break down food into nutrients that can be absorbed by the body for energy, growth, and repair. The digestive system is not responsible for absorbing oxygen (Choice B), as that is the role of the respiratory system. While the digestion process does release energy from nutrients, the primary function is not to produce energy (Choice C), but rather to extract nutrients for energy production. Regulating body temperature (Choice D) is primarily handled by the thermoregulatory mechanisms in the body, such as the skin and sweat glands, not the digestive system.

Correct Answer: B

Rationale: The correct answer is B: Neuron. Neurons are indeed the basic structural and functional units of the nervous system. Neurons are specialized cells that transmit signals throughout the nervous system, enabling communication and coordination of various functions within the body. While axons, dendrites, and synapses are all essential components of neurons and neural function, the neuron as a whole is considered the fundamental building block responsible for signal transmission. Choice A, Axon, is incorrect because an axon is a part of a neuron responsible for transmitting electrical signals away from the cell body. Choice C, Dendrite, is incorrect because dendrites are extensions of a neuron that receive signals from other neurons. Choice D, Synapse, is incorrect because a synapse is the junction between two neurons where signals are transmitted.

Correct Answer: B

Rationale: The correct answer is B: To transport oxygen. Red blood cells play a crucial role in carrying oxygen from the lungs to all the tissues and organs in the body. This oxygen transport is essential for cellular respiration, where oxygen is used in the production of energy. Red blood cells do not primarily transport nutrients, fight infection, or produce antibodies. Choice A is incorrect because while red blood cells do carry some nutrients, their primary function is to transport oxygen. Choice C is incorrect because immune cells, not red blood cells, are responsible for fighting infections. Choice D is incorrect as antibody production is mainly carried out by specialized white blood cells, not red blood cells.

Correct Answer: B

Rationale: Mitosis is the correct type of cell division responsible for growth and repair. During mitosis, a cell divides to produce two identical daughter cells, contributing to growth and tissue repair in multicellular organisms. Meiosis, on the other hand, is involved in the formation of gametes (sperm and egg cells) for sexual reproduction. Binary fission is a form of asexual reproduction in single-celled organisms, and osmosis is the movement of water molecules across a selectively permeable membrane. Therefore, choices A, C, and D are incorrect as they are not directly related to growth and repair in multicellular organisms.