Which hormone is responsible for lowering blood sugar levels?
- A. Glucagon
- B. Insulin
- C. Adrenaline
- D. Cortisol
Correct Answer: B
Rationale: Insulin is the hormone responsible for lowering blood sugar levels. It is produced by the pancreas and facilitates the entry of glucose into cells, thereby reducing blood sugar levels. Glucagon, adrenaline, and cortisol have roles in increasing blood sugar levels through various mechanisms. Glucagon raises blood sugar levels by stimulating the liver to release stored glucose, adrenaline increases blood sugar in fight-or-flight responses, and cortisol raises blood sugar levels as part of the stress response. Therefore, in the context of lowering blood sugar levels, insulin is the correct answer.
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What is the acceleration of an object moving at a constant speed of 20 m/s if it comes to a complete stop within 5 seconds?
- A. 0 m/s² (no acceleration)
- B. 4 m/s²
- C. -4 m/s²
- D. Insufficient information
Correct Answer: C
Rationale: To find the acceleration, we use the formula: acceleration = (final velocity - initial velocity) / time. Given that the final velocity is 0 m/s (as the object stops), the initial velocity is 20 m/s, and the time taken is 5 seconds. Substituting these values into the formula, we get acceleration = (0 m/s - 20 m/s) / 5 s = -20 m/s / 5 s = -4 m/s². Therefore, the acceleration is -4 m/s², indicating that the object decelerated at a rate of 4 m/s² to come to a complete stop. Choice A is incorrect because the object does experience acceleration as it changes its speed from 20 m/s to 0 m/s. Choice B is incorrect as it represents acceleration in the wrong direction, considering the object is decelerating. Choice D is incorrect as there is sufficient information provided to calculate the acceleration based on the given data.
Which of the following statements about fungi is FALSE?
- A. They can be unicellular or multicellular
- B. They are all parasitic and cause disease in humans
- C. They play a vital role in decomposition and nutrient cycling
- D. Some are used in food production, like mushrooms
Correct Answer: B
Rationale: A) This statement is true. Fungi can exist in both unicellular (yeast) and multicellular (molds and mushrooms) forms.
B) This statement is false. While some fungi can be parasitic and cause diseases in humans, not all fungi exhibit this behavior. Many fungi are beneficial and play essential roles in ecosystems.
C) This statement is true. Fungi are crucial for decomposition and nutrient cycling in ecosystems. They break down organic matter and recycle nutrients back into the environment.
D) This statement is true. Some fungi, like mushrooms, are used in food production and are consumed by humans.
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.
Which of the following is responsible for the body's fight-or-flight response?
- A. Pancreas
- B. Adrenal glands
- C. Thyroid gland
- D. Pituitary gland
Correct Answer: B
Rationale: The correct answer is B: Adrenal glands. The adrenal glands are responsible for the body's fight-or-flight response. During stressful situations, the adrenal glands release hormones like adrenaline and noradrenaline, initiating the fight-or-flight response. These hormones prepare the body to either confront or flee from a perceived threat.\nChoice A - Pancreas: The pancreas is primarily responsible for producing insulin and regulating blood sugar levels, not the fight-or-flight response.\nChoice C - Thyroid gland: The thyroid gland is responsible for producing hormones that regulate metabolism, not directly involved in the fight-or-flight response.\nChoice D - Pituitary gland: The pituitary gland regulates various endocrine functions by releasing hormones, but it is not the primary gland responsible for the fight-or-flight response.
What is the definition of 'acceleration' in terms of motion?
- A. Change in velocity over time
- B. Speed in a straight line
- C. Distance covered in a given time
- D. Force applied to an object
Correct Answer: A
Rationale: Acceleration is defined as the rate of change of velocity of an object over time. It represents how an object's velocity is changing, either by speeding up, slowing down, or changing direction. Option B, 'Speed in a straight line,' actually refers to velocity, not acceleration. Option C, 'Distance covered in a given time,' is more related to speed, as it measures how much ground is covered in a specific time period. Option D, 'Force applied to an object,' is not the definition of acceleration; it is a force exerted on an object that can cause acceleration.