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What are Mendel's laws?
- A. Law of inheritance, law of expression
- B. Law of segregation, law of independent assortment
- C. Law of dominance, law of recessiveness
- D. Law of mutation, law of crossing over
Correct Answer: B
Rationale: The correct answer is B. Mendel's laws consist of the law of segregation, which states that each parent passes one allele for each trait, and the law of independent assortment, which explains that genes for different traits are inherited independently. Choice A is incorrect because 'law of expression' is not one of Mendel's laws. Choice C is incorrect because 'law of dominance' and 'law of recessiveness' do not represent the two main laws proposed by Mendel. Choice D is incorrect because 'law of mutation' and 'law of crossing over' are not part of Mendel's original laws.
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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 structures in the body is responsible for protecting the lungs and heart?
- A. Rib cage
- B. Pelvis
- C. Femur
- D. Vertebral column
Correct Answer: A
Rationale: The rib cage is the correct answer. It plays a crucial role in protecting vital organs like the lungs and heart. The rib cage forms a protective barrier around these organs, shielding them from external trauma or injuries. It acts as a sturdy cage, offering structural support and safeguarding the delicate tissues and structures of the lungs and heart. The pelvis, femur, and vertebral column do not directly protect the lungs and heart; instead, they have other important functions in the body, such as supporting the body's weight, enabling movement, and protecting the spinal cord.
What happens to the diaphragm during inspiration?
- A. It moves upward
- B. It moves downward
- C. It expands
- D. It contracts and moves downward
Correct Answer: D
Rationale: During inspiration, the diaphragm contracts and moves downward. This action increases the volume of the thoracic cavity, which lowers the air pressure inside the lungs, allowing air to flow in. The downward movement and contraction of the diaphragm create the necessary space for the lungs to expand and fill with air. Choice A, 'It moves upward,' is incorrect as the diaphragm moves downward. Choice B, 'It moves downward,' is partially correct but misses the contraction aspect. Choice C, 'It expands,' is incorrect as the diaphragm itself does not expand during inspiration. Therefore, choice D, 'It contracts and moves downward,' is the most accurate description of the diaphragm's action during inspiration.
Which of the following inventions likely had the greatest impact on combating nutrition deficiencies in developing countries?
- A. Food products fortified with dietary vitamins and minerals
- B. Integrated statistical models of fish populations
- C. Advances enabling microscopes to use thicker tissue samples
- D. Refrigerated train cars for transportation of food
Correct Answer: A
Rationale: Food products fortified with dietary vitamins and minerals have had the greatest impact on combating nutrition deficiencies in developing countries. By fortifying food products with essential nutrients such as vitamins and minerals, it becomes easier to address specific deficiencies in populations that may not have access to a diverse range of foods. This innovation has been particularly impactful in addressing common deficiencies like vitamin A, iron, zinc, and folic acid, improving overall health outcomes in populations with limited access to nutrient-rich foods. Choices B, C, and D are incorrect. Integrated statistical models of fish populations, advances in microscopy, and refrigerated train cars, while important in their own right, do not directly address combating nutrition deficiencies in developing countries as effectively as food fortification with essential nutrients.
Which of the following is responsible for carrying electrical impulses in the nervous system?
- A. Platelets
- B. Neurons
- C. Red blood cells
- D. White blood cells
Correct Answer: B
Rationale: Neurons are the correct answer as they are specialized cells in the nervous system that transmit electrical impulses throughout the body. Neurons have structures like axons and dendrites that enable the transmission of electrical signals. Platelets are responsible for blood clotting, red blood cells carry oxygen, and white blood cells are part of the immune system; however, none of these cell types play a role in carrying electrical impulses in the nervous system.