Nokea
Which gland produces the hormone responsible for the 'fight-or-flight' response in stressful situations?
- A. Thyroid gland
- B. Pituitary gland
- C. Adrenal gland
- D. Pancreas
Correct Answer: C
Rationale: The correct answer is C: Adrenal gland. The hormone responsible for the 'fight-or-flight' response in stressful situations is produced by the adrenal gland. This hormone is called adrenaline (epinephrine) and is released in response to stress, preparing the body to either fight the stressor or flee from it. The other choices are incorrect because the thyroid gland primarily produces hormones that regulate metabolism, the pituitary gland produces various hormones that control other endocrine glands, and the pancreas produces insulin and glucagon to regulate blood sugar levels.
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Homologous structures are similar structures in different organisms that have a common evolutionary origin. An example is:
- A. Butterfly wings and bird wings (analogous structures with different origins)
- B. The arm of a human, the wing of a bat, and the flipper of a whale
- C. The eyes of an octopus and a human (convergent evolution with different origins)
- D. The stinger of a bee and the barb of a cactus (unrelated structures)
Correct Answer: B
Rationale: Homologous structures are similar structures found in different organisms that share a common evolutionary origin. The arm of a human, the wing of a bat, and the flipper of a whale are all examples of homologous structures. Despite serving different functions, they share a common underlying structure due to their evolutionary relationship, evidencing a shared ancestry. These structures are modified over time to suit the specific needs of each species. Option A (Butterfly wings and bird wings) refers to analogous structures with different origins. Option C (The eyes of an octopus and a human) describes convergent evolution where traits evolve independently. Option D (The stinger of a bee and the barb of a cactus) are unrelated structures.
Which part of the brain is responsible for regulating body temperature, hunger, and thirst, and is considered a key player in the endocrine system?
- A. Amygdala
- B. Hippocampus
- C. Hypothalamus
- D. Thalamus
Correct Answer: C
Rationale: The hypothalamus is responsible for regulating body temperature, hunger, and thirst, making it a vital component in maintaining homeostasis. It also plays a crucial role in the endocrine system by controlling the release of hormones from the pituitary gland. The amygdala primarily processes emotions, the hippocampus is associated with memory formation, and the thalamus acts as a relay station for sensory information. Therefore, the hypothalamus is the correct answer as it directly regulates the physiological processes mentioned in the question.
Bile, stored in the gallbladder, aids in the digestion of which nutrient?
- A. Carbohydrates
- B. Proteins
- C. Fats
- D. Vitamins
Correct Answer: C
Rationale: Bile, produced by the liver and stored in the gallbladder, aids in the digestion of fats. Bile emulsifies fats, breaking them down into smaller droplets to increase the efficiency of fat digestion by enzymes like lipase. This process enhances the absorption of fats in the small intestine, facilitating the body's utilization of essential fatty acids and fat-soluble vitamins. Carbohydrates are primarily broken down by enzymes like amylase, proteins by pepsin and other proteases, and vitamins have varying digestion and absorption processes, which do not involve bile. Therefore, the correct answer is fats as they are directly influenced by bile in the digestion process.
During gas exchange in the alveoli, what happens to oxygen?
- A. Oxygen is released from the alveoli into the bloodstream.
- B. Oxygen is absorbed from the alveoli into the bloodstream.
- C. Oxygen is converted into carbon dioxide.
- D. Oxygen is stored in the alveoli for later use.
Correct Answer: B
Rationale: During gas exchange in the alveoli, oxygen is absorbed from the alveoli into the bloodstream. This process occurs due to the difference in partial pressures of oxygen between the alveoli and the bloodstream, causing oxygen to move from an area of higher concentration (alveoli) to an area of lower concentration (bloodstream). Oxygen is then transported by red blood cells to tissues throughout the body for cellular respiration. Choice A is incorrect as oxygen moves from the alveoli into the bloodstream, not the other way around. Choice C is incorrect as oxygen is not converted into carbon dioxide during gas exchange. Choice D is incorrect as oxygen is not stored in the alveoli but rather continuously exchanged with carbon dioxide during respiration.
Which structure in the respiratory system serves as a passageway for both air and food, with a flap-like structure that prevents food from entering the trachea during swallowing?
- A. Larynx
- B. Pharynx
- C. Trachea
- D. Bronchi
Correct Answer: B
Rationale: The pharynx is the correct answer. The pharynx is a structure in the respiratory system that serves as a passageway for both air and food. It contains a flap-like structure called the epiglottis, which prevents food from entering the trachea during swallowing by covering the opening to the trachea. The larynx, although important in the respiratory system, is located below the pharynx and contains the vocal cords. The trachea is a tube that carries air to and from the lungs, while the bronchi are the two main branches that lead from the trachea into the lungs.