Nokea
Which enzyme breaks down carbohydrates like starches and sugars in the mouth?
- A. Pepsin
- B. Lipase
- C. Amylase
- D. Trypsin
Correct Answer: C
Rationale: The correct answer is Amylase. Amylase is the enzyme responsible for breaking down carbohydrates like starches and sugars in the mouth. Pepsin is a digestive enzyme that breaks down proteins in the stomach, lipase breaks down fats, and trypsin is another enzyme that breaks down proteins in the small intestine. Therefore, choices A, B, and D are incorrect for this question.
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How does RNA polymerase differ from DNA polymerase?
- A. Both enzymes are identical in function and structure.
- B. RNA polymerase does not require a primer to initiate RNA synthesis.
- C. RNA polymerase can synthesize both RNA and DNA.
- D. RNA polymerase can only synthesize RNA, unlike DNA polymerase.
Correct Answer: B
Rationale: Rationale:
A) This statement is incorrect. RNA polymerase and DNA polymerase are not identical in function and structure. They have different roles in the cell.
B) This statement is correct. Unlike DNA polymerase, RNA polymerase does not require a primer to initiate RNA synthesis. RNA polymerase can start the synthesis of RNA de novo.
C) This statement is incorrect. RNA polymerase is specialized for synthesizing RNA, not DNA. DNA polymerase is responsible for synthesizing DNA.
D) This statement is correct. RNA polymerase can only synthesize RNA, while DNA polymerase is responsible for synthesizing DNA.
Which vitamin plays a vital role in muscle function and helps prevent muscle weakness and fatigue?
- A. Vitamin A
- B. Vitamin B12
- C. Vitamin D
- D. Vitamin E
Correct Answer: C
Rationale: Vitamin D is the correct answer as it plays a crucial role in muscle function by helping prevent muscle weakness and fatigue. It is essential for maintaining muscle strength and function, as well as supporting overall bone health. Vitamin D deficiency can lead to muscle weakness and fatigue, emphasizing its significance for muscle health. Vitamin A does not directly impact muscle function in the same way as Vitamin D. Although Vitamin B12 is important for neurological function and red blood cell production, it is not primarily known for its role in muscle function. Vitamin E is more commonly associated with its antioxidant properties and its role in protecting cells from damage, but it is not specifically linked to muscle function and preventing muscle weakness and fatigue.
Which of the following is an example of a chemical property of matter?
- A. Boiling point
- B. Flammability
- C. Density
- D. Conductivity
Correct Answer: B
Rationale: Flammability is an example of a chemical property of matter because it describes how a substance reacts with oxygen in the air to produce heat and light. Chemical properties involve the ability of a substance to undergo a chemical change or reaction, such as burning. Boiling point, density, and conductivity are examples of physical properties, not chemical properties. Boiling point is the temperature at which a substance changes from a liquid to a gas, density is the mass of a substance per unit volume, and conductivity is the ability to conduct electricity. Therefore, flammability best exemplifies a chemical property as it pertains to the substance's reaction with oxygen, while the other options are physical properties that describe characteristics without changing the substance's chemical composition.
The neutral theory of molecular evolution proposes that:
- A. Most mutations in DNA are selectively neutral and do not affect an organism's fitness.
- B. All mutations are beneficial and contribute to the adaptation of a population.
- C. The rate of evolution is primarily driven by strong directional selection pressures.
- D. Genetic drift plays a negligible role in shaping genetic variation within populations.
Correct Answer: A
Rationale: Rationale:
A) The neutral theory of molecular evolution, proposed by Motoo Kimura in the 1960s, suggests that the majority of mutations that occur in DNA are selectively neutral, meaning they do not have a significant impact on an organism's fitness. These neutral mutations are not subject to natural selection and are allowed to accumulate in populations over time. This theory helps explain the high levels of genetic variation observed within populations.
B) Option B is incorrect because not all mutations are beneficial. Mutations can be neutral, harmful, or beneficial, and the neutral theory specifically focuses on the idea that many mutations are neutral in their effects.
C) Option C is incorrect because the neutral theory suggests that evolution is not primarily driven by strong directional selection pressures. Instead, it emphasizes the role of genetic drift and the accumulation of neutral mutations in shaping genetic variation.
D) Option D is incorrect because
A car is moving in a circle at a constant speed. Which of the following is NOT true about its motion?
- A. It has a constant centripetal acceleration
- B. Its tangential velocity remains constant
- C. It experiences a force directed towards the center of the circle
- D. It covers the same distance in equal time intervals along its circular path
Correct Answer: B
Rationale: In circular motion at a constant speed, the car has a constant centripetal acceleration (choice A), experiences a force directed towards the center of the circle (choice C), and covers the same distance in equal time intervals along its circular path (choice D). However, the tangential velocity of an object in circular motion at a constant speed changes continuously as it moves around the circle, so it is not constant (choice B). The change in tangential velocity allows the car to maintain its motion in a circular path despite moving at a constant speed. Choice A is incorrect because centripetal acceleration is indeed present to keep the car moving in a circular path. Choice C is incorrect as a force towards the center is required to keep the car in circular motion. Choice D is incorrect because the car covers equal distances in equal time intervals to maintain its circular trajectory.