Nokea
What is a submicroscopic entity that is considered nonliving because it lacks cellular structure and consists of nucleic acids encapsulated in a protein coat called a capsid?
- A. Bacteria
- B. Fungus
- C. Virus
- D. Protozoa
Correct Answer: C
Rationale: The correct answer is C: Virus. Viruses are not considered living organisms because they lack cellular structure. Instead, they are composed of nucleic acids (either DNA or RNA) enclosed in a protein coat called a capsid. Bacteria (choice A), fungus (choice B), and protozoa (choice D) are all living organisms with cellular structures, unlike viruses. Therefore, they are incorrect choices for this question.
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Which of the following correctly describes mitosis?
- A. Mitosis occurs in germ cells.
- B. Mitosis occurs in somatic cells.
- C. Mitosis involves the reduction of chromosome number by half.
- D. Mitosis produces four genetically different cells.
Correct Answer: B
Rationale: The correct answer is B. Mitosis occurs in somatic cells where a single cell divides to produce two identical daughter cells. Germ cells undergo meiosis, not mitosis. Choice C is incorrect as mitosis results in the preservation of the same chromosome number in daughter cells. Choice D is inaccurate as mitosis produces genetically identical cells, not genetically different ones.
Which of the following is a chief difference between evaporation and boiling?
- A. Liquids boil only at the surface, while they evaporate equally throughout the liquid.
- B. Evaporating substances change from liquid to gas, while boiling substances change from gas to liquid.
- C. Evaporation can happen below a liquid's boiling point.
- D. Evaporation happens in nature, while boiling is a man-made phenomenon.
Correct Answer: C
Rationale: The chief difference between evaporation and boiling is that evaporation can happen below a liquid's boiling point, while boiling only occurs at the liquid's boiling point. Evaporation is the process of a liquid turning into a gas at any temperature, while boiling specifically refers to the rapid vaporization that occurs when a liquid reaches its boiling point. Choice A is incorrect because liquids evaporate throughout the liquid, not just at the surface. Choice B is incorrect as evaporating substances change from liquid to gas, while boiling substances change from liquid to gas. Choice C is incorrect as boiling is not a man-made phenomenon; in fact, it is a natural process based on temperature changes. Choice D is incorrect because evaporation can happen naturally and is not limited to man-made processes.
What is the role of the spleen in the body?
- A. To produce bile
- B. To filter blood and remove old red blood cells
- C. To produce red blood cells
- D. To store fat
Correct Answer: B
Rationale: The correct answer is B. The spleen acts as a blood filter, removing old or damaged red blood cells. It also plays a role in immune responses, storing blood reserves, and helping to fight infection. The production of bile is primarily associated with the liver, not the spleen. While the bone marrow is responsible for red blood cell production, the spleen's main functions do not include this process. Storing fat is not a primary function of the spleen.
What is the function of valves in arteries?
- A. To maintain high blood pressure for the proper diffusion of nutrients in capillaries.
- B. To prevent backflow of blood due to high pressure away from the heart.
- C. As a vestigial trait from evolution, like the appendix, that serves no purpose.
- D. Valves are absent in arteries but present in veins.
Correct Answer: B
Rationale: Valves in arteries serve the crucial function of preventing backflow of blood. Arteries carry blood at high pressure away from the heart, and the valves ensure that blood flows in one direction, towards the capillaries, to maintain efficient circulation. Without these valves, there would be a risk of blood flowing backward, compromising the effectiveness of blood circulation in the body. Choices A, C, and D are incorrect. Choice A incorrectly suggests that valves maintain high blood pressure for nutrient diffusion in capillaries, which is not their function. Choice C inaccurately compares valves to vestigial traits, like the appendix, implying they serve no purpose, which is untrue. Choice D is incorrect as valves are indeed present in arteries to regulate blood flow, not just in veins.
Which of the following is an example of a pivot joint?
- A. Hip
- B. Neck
- C. Shoulder
- D. Elbow
Correct Answer: B
Rationale: The correct answer is B: Neck. A pivot joint, as found in the neck, allows for rotational movement around a single axis. This type of joint is essential for movements like shaking your head 'no' or looking left and right. Choices A, C, and D are incorrect because the hip, shoulder, and elbow joints are examples of ball-and-socket joints, which allow for a wide range of motion in multiple directions, not just rotational movement around a single axis like a pivot joint.