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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.
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Which type of joint allows for rotational movement around a single axis?
- A. Ball-and-socket joint
- B. Pivot joint
- C. Hinge joint
- D. Saddle joint
Correct Answer: B
Rationale: The correct answer is a Pivot joint. A pivot joint, like the joint in the neck, enables rotational movement around a single axis. This type of joint is crucial for allowing the head to turn from side to side. Choice A, Ball-and-socket joint, allows for movement in multiple axes due to its spherical structure, not limited to single-axis rotation. Choice C, Hinge joint, allows movement in one plane like a door hinge, but not rotational movement around a single axis. Choice D, Saddle joint, allows movement in multiple directions but is not specifically designed for rotational movement around a single axis.
What is the difference between the atomic number and the mass number of an atom?
- A. The atomic number is the number of protons in the nucleus, while the mass number is the total number of protons and neutrons in the nucleus.
- B. The atomic number is the number of electrons in an atom, while the mass number is the total number of protons and neutrons in the nucleus.
- C. The atomic number is the number of neutrons in the nucleus, while the mass number is the total number of protons and electrons in an atom.
- D. The atomic number is the number of protons and neutrons in the nucleus, while the mass number is the total number of electrons in an atom.
Correct Answer: A
Rationale: The atomic number of an atom represents the number of protons in its nucleus, which defines the element's identity. On the other hand, the mass number corresponds to the total sum of protons and neutrons in the nucleus. Therefore, the key distinction between the atomic number and the mass number lies in the fact that the atomic number specifically counts the protons, whereas the mass number encompasses both protons and neutrons. Choice B is incorrect because the atomic number is not related to the number of electrons but rather to the number of protons. Choice C is incorrect because the atomic number is not the number of neutrons but the number of protons. Choice D is incorrect because the atomic number does not include neutrons; it is solely the number of protons.
Which type of cell division is responsible for growth and repair?
- A. Meiosis
- B. Mitosis
- C. Binary fission
- D. Osmosis
Correct Answer: B
Rationale: Mitosis is the correct type of cell division responsible for growth and repair. During mitosis, a cell divides to produce two identical daughter cells, contributing to growth and tissue repair in multicellular organisms. Meiosis, on the other hand, is involved in the formation of gametes (sperm and egg cells) for sexual reproduction. Binary fission is a form of asexual reproduction in single-celled organisms, and osmosis is the movement of water molecules across a selectively permeable membrane. Therefore, choices A, C, and D are incorrect as they are not directly related to growth and repair in multicellular organisms.
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.
What is the primary function of the small intestine?
- A. To absorb water
- B. To absorb nutrients
- C. To store waste
- D. To produce enzymes
Correct Answer: B
Rationale: The correct answer is B: "To absorb nutrients." The small intestine's primary function is to absorb nutrients from digested food. It plays a crucial role in the digestion and absorption of nutrients such as proteins, carbohydrates, fats, vitamins, and minerals, which are essential for the body's functions and energy production. Choice A, "To absorb water," is incorrect because the absorption of water primarily occurs in the large intestine. Choice C, "To store waste," is incorrect as waste is stored in the large intestine before elimination. Choice D, "To produce enzymes," is incorrect because while the small intestine does receive enzymes from other organs to aid in digestion, its primary role is not enzyme production.