Which structure connects the two hemispheres of the brain, allowing communication and coordination between them?

Correct Answer: A

Rationale: The correct answer is the corpus callosum. It is a thick band of nerve fibers that connects the two hemispheres of the brain, facilitating communication and coordination between them. The thalamus acts as a relay station for sensory information, the hypothalamus regulates basic functions like hunger and thirst, and the medulla oblongata controls vital functions such as breathing and heart rate. Therefore, choices B, C, and D are incorrect as they do not specifically connect the two hemispheres of the brain as the corpus callosum does.

Correct Answer: B

Rationale: Progesterone, produced by the ovaries, is responsible for the development of the uterine lining during the menstrual cycle and supports early pregnancy. While estrogen also plays a crucial role in the menstrual cycle, progesterone is specifically known for its role in preparing the uterus for pregnancy and maintaining the uterine lining. Testosterone is primarily a male sex hormone and not directly involved in these processes. Prolactin is a hormone that is mainly associated with milk production and not related to the development of the uterine lining or early pregnancy.

Correct Answer: C

Rationale: The correct answer is systemic arteries. Systemic arteries carry oxygenated blood from the heart to the rest of the body to provide oxygen and nutrients to tissues. Pulmonary arteries carry deoxygenated blood from the heart to the lungs for oxygenation. Pulmonary veins transport oxygenated blood from the lungs back to the heart. Systemic veins return deoxygenated blood from the body tissues to the heart for reoxygenation. Therefore, choices A, B, and D are incorrect as they do not carry oxygenated blood away from the heart to the body.

Correct Answer: B

Rationale: The correct answer is B: To increase lung compliance. Surfactant is a substance produced by type II alveolar cells in the lungs that reduces surface tension in the alveoli. This reduction in surface tension helps to increase lung compliance, making it easier for the lungs to expand and contract during breathing. Improved lung compliance is essential for efficient gas exchange in the respiratory system, facilitating oxygen uptake and carbon dioxide removal. Choices A, C, and D are incorrect because surfactant does not trap dust particles, produce mucus, or generate oxygen during respiration. Instead, its primary function lies in reducing surface tension to prevent alveolar collapse and improve lung compliance for optimal gas exchange.

Correct Answer: D

Rationale: The correct answer is D, the cell wall. The cell wall is the structure in plant cells that provides rigidity and support. It is a tough, rigid structure located outside the cell membrane. Composed primarily of cellulose, the cell wall offers structural support to the cell, helping it maintain its shape and protect it from damage. The other choices, such as the cell membrane (choice A), Golgi apparatus (choice B), and plastid (choice C) do not provide rigidity and support to plant cells. The cell membrane is a selectively permeable barrier, the Golgi apparatus is involved in processing and packaging proteins, and plastids are organelles responsible for functions like photosynthesis and storage, but they do not provide the structural support that the cell wall does.