How many minerals are known to be essential for human nutrition?

Correct Answer: C

Rationale: There are 16 essential minerals required for human nutrition. These minerals include calcium, potassium, iron, and others. Choice A (8) is incorrect as it underestimates the number of essential minerals. Choice B (12) is also incorrect as it does not encompass the full count of essential minerals. Choice D (20) is incorrect as it overestimates the number of essential minerals.

Correct Answer: D

Rationale: If a group consumes an amount of protein equal to the estimated average requirement, 50% of the people will receive insufficient amounts. The estimated average requirement is the amount of a nutrient that is estimated to meet the requirement of half the healthy individuals in a particular life stage and gender group. Therefore, 50% of the group will not be meeting their individual needs if they are consuming only the average requirement. Choices A, B, and C are incorrect because at the estimated average requirement level, a higher percentage than those values will receive insufficient amounts.

Correct Answer: A

Rationale: The correct answer is A. Vitamins are organic compounds, containing carbon, which is a key characteristic that differentiates them from minerals. Choice B is incorrect because vitamins do not provide energy; they are not a source of calories. Choice C is incorrect as both vitamins and minerals are considered micronutrients due to being essential in small amounts. Choice D is incorrect because while it is true that vitamins are needed in small amounts, this is not the characteristic that sets them apart from minerals.

Correct Answer: B

Rationale: Randomization is crucial in a scientific experiment to eliminate bias in the assignment of subjects to groups. By randomly assigning subjects, it helps ensure that any differences observed in the outcomes are due to the experimental treatment and not to preexisting differences between groups. Choice A is incorrect because randomization does not guarantee representativeness but rather minimizes the impact of confounding variables. Choice C is not entirely accurate; while randomization can contribute to accuracy and validity, its primary purpose is to reduce bias. Choice D is incorrect as the goal of randomization is not to balance the number of subjects but to prevent systematic differences between groups.

Correct Answer: C

Rationale: Peer review is crucial in scientific research to verify the accuracy and validity of research findings. By subjecting research papers to evaluation by experts in the field, peer review ensures that the study's methods, results, and conclusions are robust and reliable. This process helps to maintain high standards of quality in scientific publications, providing credibility to the research. Choices A and D are incorrect because the primary purpose of peer review is not to expedite publication or solely enhance credibility; its core function is to validate the research's accuracy and validity. Choice B, while beneficial, is not the primary reason for peer review; replication is a byproduct of the rigorous evaluation of research methods and findings.