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What is the primary cause of acne vulgaris, commonly known as acne?
- A. Dry skin
- B. Clogged pores and excess oil production
- C. Bacterial infection alone
- D. Vitamin deficiency
Correct Answer: B
Rationale: The primary cause of acne vulgaris is clogged pores and excess oil production. Acne develops when hair follicles become clogged with oil and dead skin cells, creating an environment for bacteria to thrive, leading to inflammation and acne breakouts. While dry skin, bacterial infection alone, and vitamin deficiency can contribute to acne, they are not the main underlying cause. Therefore, the correct answer is clogged pores and excess oil production, as they form the basis for the development of acne vulgaris.
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In the electron cloud model, electrons occupy specific energy levels around the nucleus with varying probabilities. This model depicts electrons existing in distinct energy levels, not fixed orbits, with probabilities of finding them in specific regions.
- A. 2 protons and 6 neutrons
- B. 2 filled s orbitals and 6 filled p orbitals
- C. 2s orbitals with 2 and 6 electrons, respectively
- D. 4 filled electron shells
Correct Answer: C
Rationale: The electron cloud model describes electrons existing in distinct energy levels, not fixed orbits. Option C correctly describes the electron configuration of an atom with 2s orbitals containing 2 electrons and 6 electrons in the 2p orbitals. This configuration aligns with the electron cloud model where electrons are found in specific energy levels with varying probabilities. Options A, B, and D do not accurately represent the electron cloud model.
Which functional group is commonly found in ketones?
- A. Hydroxyl
- B. Carbonyl
- C. Ester
- D. Amine
Correct Answer: B
Rationale: Ketones contain a carbonyl functional group, which consists of a carbon atom double-bonded to an oxygen atom. This distinguishes ketones from other functional groups such as hydroxyl, ester, and amine. The presence of the carbonyl group, not hydroxyl (choice A), ester (choice C), or amine (choice D), is characteristic of ketones, making choice B, 'Carbonyl', the correct answer.
Which property of matter refers to the measure of the force of gravity acting on an object?
- A. Mass
- B. Weight
- C. Density
- D. Volume
Correct Answer: B
Rationale: The correct answer is 'Weight.' Weight is the measure of the force of gravity acting on an object. Mass refers to the amount of matter in an object, density is the mass per unit volume of a substance, and volume is the amount of space an object occupies. In this context, the question specifically asks for the property related to the force of gravity, making 'Weight' the correct choice. 'Mass' is the measure of the amount of matter in an object, 'Density' is the mass per unit volume of a substance, and 'Volume' is the space occupied by an object, none of which directly measure the force of gravity on an object.
Which of the following is NOT a characteristic of mitosis?
- A. The replication of DNA
- B. The condensation of chromosomes
- C. The separation of sister chromatids
- D. The formation of haploid cells
Correct Answer: D
Rationale: Rationale:
A) The replication of DNA is a characteristic of mitosis. Before cell division occurs, the DNA is replicated to ensure that each daughter cell receives a complete set of genetic information.
B) The condensation of chromosomes is a characteristic of mitosis. During mitosis, the chromosomes condense and become visible under a microscope as distinct structures.
C) The separation of sister chromatids is a crucial step in mitosis. During anaphase, the sister chromatids are pulled apart and move to opposite poles of the cell to ensure that each daughter cell receives a complete set of chromosomes.
D) The formation of haploid cells is NOT a characteristic of mitosis. Mitosis results in the formation of two identical diploid daughter cells, each containing the same number of chromosomes as the parent cell. Haploid cells are typically formed through the process of meiosis, not mitosis.
A ball is thrown upwards. Which of the following statements is TRUE about its potential energy and kinetic energy at the peak of its trajectory?
- A. Both potential and kinetic energy are zero.
- B. Potential energy is maximum and kinetic energy is minimum.
- C. Potential energy is minimum and kinetic energy is maximum.
- D. Both potential and kinetic energy remain constant.
Correct Answer: B
Rationale: At the peak of its trajectory, the ball momentarily stops moving before falling back down. This means its kinetic energy is at a minimum because it has come to a stop. At the same time, its potential energy is at a maximum because it is at the highest point in its trajectory, where it has the most potential to fall and convert that potential energy into kinetic energy as it descends. Choice A is incorrect because at the peak, the ball still has potential energy due to its height. Choice C is incorrect because kinetic energy is at a minimum when the ball is momentarily at rest. Choice D is incorrect because the energy conversion between potential and kinetic energy occurs at different points in the trajectory.