What is the role of the hypothalamus in the body?
- A. To regulate digestion
- B. To regulate hormones
- C. To regulate body temperature
- D. To regulate the immune system
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.
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What is the name for the smallest amount of an element that can exist independently and retain its chemical properties?
- A. Atom
- B. Molecule
- C. Compound
- D. Mixture
Correct Answer: A
Rationale: The correct answer is 'Atom.' An atom is the fundamental unit of an element that can exist independently and retain its unique chemical properties. It consists of a nucleus containing protons and neutrons, surrounded by electrons. Choice B, 'Molecule,' is incorrect because a molecule is a combination of two or more atoms bonded together. Choice C, 'Compound,' is incorrect as a compound is a substance formed by the chemical combination of two or more different elements. Choice D, 'Mixture,' is incorrect since a mixture is a blend of two or more substances physically combined, but the individual components retain their properties.
Which of the following is the smallest unit of matter?
- A. Molecule
- B. Atom
- C. Compound
- D. Element
Correct Answer: B
Rationale: An atom is the fundamental building block of matter, while molecules are formed by the combination of atoms.
Which protein complex in the sarcomere is responsible for the thick filament?
- A. Actin
- B. Myosin
- C. Tropomyosin
- D. Troponin
Correct Answer: B
Rationale: Myosin is the protein complex responsible for the thick filament in the sarcomere. It interacts with actin, another protein in the sarcomere, to generate the sliding movement that results in muscle contraction. Actin is a thin filament protein that interacts with myosin to create the sliding filament mechanism. Tropomyosin and troponin are regulatory proteins that regulate muscle contraction by controlling the interaction between actin and myosin, rather than directly being responsible for the thick filament.
Which of the following best describes the term homeostasis?
- A. The ability to maintain a constant body temperature
- B. The ability to maintain a stable internal environment
- C. The ability to increase body temperature when cold
- D. The ability to regulate blood glucose levels
Correct Answer: B
Rationale: The correct answer is B, 'The ability to maintain a stable internal environment.' Homeostasis refers to the body's ability to regulate and maintain a stable internal environment, which includes variables like body temperature, pH levels, and fluid balance. It involves processes that help keep the body's internal conditions within a narrow range, despite external changes. While maintaining body temperature is a component of homeostasis, it is not the complete definition of the term. Choice C, 'The ability to increase body temperature when cold,' is incorrect as homeostasis aims to maintain stability rather than promoting temperature increases in response to external conditions. Choice D, 'The ability to regulate blood glucose levels,' is also incorrect as this is a specific function related to glucose homeostasis, which is a part of overall homeostatic processes but not the sole definition of homeostasis itself.
What are the finger-like projections that increase the surface area for absorption in the small intestine called?
- A. Crypts of Lieberk¼hn
- B. Goblet cells
- C. Villi
- D. Paneth cells
Correct Answer: C
Rationale: A) Crypts of Lieberk¼hn are small pits in the lining of the small intestine that contain cells involved in the production of intestinal juices, but they do not increase the surface area for absorption.
B) Goblet cells are specialized cells that secrete mucus to protect the lining of the digestive tract, but they do not increase the surface area for absorption.
C) Villi are finger-like projections in the small intestine that increase the surface area available for nutrient absorption. Each villus contains blood vessels and lacteals (lymphatic vessels) that help absorb nutrients from digested food.
D) Paneth cells are specialized cells found in the small intestine that secrete antimicrobial substances, but they do not increase the surface area for absorption.