Nokea
Which vitamin requires intrinsic factor for proper absorption?
- A. Vitamin A
- B. Vitamin C
- C. Vitamin D
- D. Vitamin B12
Correct Answer: D
Rationale: Vitamin B12 requires intrinsic factor, a glycoprotein secreted by the parietal cells of the stomach, for proper absorption in the small intestine. Intrinsic factor binds to vitamin B12 and facilitates its absorption in the ileum. Deficiency in intrinsic factor can lead to pernicious anemia, a condition characterized by a lack of vitamin B12 absorption. Options A, B, and C are incorrect. Vitamin A is absorbed in the small intestine with the help of bile salts; Vitamin C is absorbed in the small intestine via active transport; Vitamin D is absorbed in the small intestine through a process involving bile salts and micelles. It is essential for students to understand this relationship as it highlights the importance of intrinsic factor in the absorption of specific vitamins and the consequences of its deficiency.
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The largest level of ecological organization is a:
- A. Population
- B. Community
- C. Ecosystem
- D. Biome
Correct Answer: D
Rationale: A) Population: A population consists of individuals of the same species living in the same area. It is a smaller level of ecological organization compared to a biome.
B) Community: A community consists of populations of different species living and interacting in the same area. It is a larger level of organization than a population but smaller than an ecosystem or biome.
C) Ecosystem: An ecosystem includes all living organisms (biotic factors) and their physical environment (abiotic factors) interacting in a particular area. It is a larger level of organization than a community but smaller than a biome.
D) Biome: The correct answer is D - Biome. A biome is the largest level of ecological organization and encompasses a large geographic area characterized by a specific climate, vegetation, and animal life. Biomes can be found on multiple continents and are defined by similar abiotic and biotic factors. Therefore, it is the largest level of ecological organization among the options provided, making it the correct answer.
Which of the following terms refers to a muscle that lengthens while another muscle contracts to produce movement?
- A. Synergist
- B. Agonist
- C. Antagonist
- D. Flexor
Correct Answer: C
Rationale: The correct answer is 'Antagonist.' An antagonist muscle is a muscle that lengthens while another muscle (agonist) contracts to produce movement. The antagonist muscle relaxes to allow the agonist muscle to contract effectively. In this scenario, the antagonist muscle works in opposition to the agonist muscle, providing control and precision to movement. The other choices are incorrect because a synergist muscle assists the agonist muscle in performing a movement, an agonist muscle is the primary muscle responsible for generating movement, and a flexor muscle is a muscle that decreases the angle at a joint.
What is a temporary loss of consciousness due to insufficient blood flow to the brain called?
- A. Stroke
- B. Seizure
- C. Syncope (fainting)
- D. Coma
Correct Answer: C
Rationale: Syncope, also known as fainting, is a temporary loss of consciousness caused by insufficient blood flow to the brain. It results from a brief interruption in the brain's blood supply, leading to a temporary loss of consciousness. The correct answer is C. A stroke, option A, is caused by a blockage or rupture of blood vessels in the brain, not insufficient blood flow. Seizure, option B, involves a sudden surge of electrical brain activity, not reduced blood flow. Coma, option D, is characterized by prolonged unconsciousness, not a temporary loss of consciousness due to insufficient blood flow.
Adaptive radiation refers to the evolutionary process where:
- A. A single ancestral species diversifies into multiple descendant species due to ecological pressures in a heterogeneous environment.
- B. Two unrelated species evolve similar adaptations in response to similar environments, leading to convergent evolution.
- C. A population becomes increasingly well-adapted to its current environment through continued natural selection.
- D. The fossil record exhibits gaps or missing links in the evolutionary history of a lineage.
Correct Answer: A
Rationale: - Adaptive radiation is a process where a single ancestral species diversifies into multiple descendant species to exploit different ecological niches within a heterogeneous environment.
- This diversification occurs due to the different selective pressures present in various habitats, leading to the evolution of distinct traits and adaptations in different descendant species.
- Option A accurately describes the process of adaptive radiation, where the initial species undergoes rapid speciation to occupy different ecological roles and adapt to diverse environmental conditions.
- Options B, C, and D do not accurately describe adaptive radiation but refer to other evolutionary processes such as convergent evolution, natural selection, and gaps in the fossil record, respectively.
What happens when an atom loses an electron?
- A. It forms a molecule.
- B. It gains a positive charge and becomes an ion.
- C. It alters its elemental identity.
- D. No change occurs; it remains neutral.
Correct Answer: B
Rationale: When an atom loses an electron, it gains a positive charge and becomes an ion. This occurs because the number of protons in the atom exceeds the number of electrons, leading to a positive charge. Therefore, the atom undergoes a transformation into an ion by losing an electron. Choice A is incorrect because losing an electron does not result in the formation of a molecule, as molecules are made up of bonded atoms. Choice C is incorrect because losing an electron does not change the fundamental identity of the atom; it only changes its charge. Choice D is incorrect because losing an electron causes the atom to become positively charged, altering its neutrality.