Nokea
In experimental design, which group can be measured against the experimental group as a standard of comparison?
- A. Control
- B. Responding
- C. Manipulated
- D. Variable
Correct Answer: A
Rationale: The control group is a critical component in experimental design as it serves as a reference point for comparison with the experimental group. The control group does not receive the experimental treatment but is subjected to all other conditions. By comparing the outcomes of the experimental group with those of the control group, researchers can evaluate the impact and efficacy of the experimental treatment.
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A researcher wants to gather data on the average wing strength of all birds found in the American Northwest. The researcher only has one small net, so all large birds were excluded from the study. The researcher's results were different than expected, but he believes his data includes enough birds to estimate the strength of all birds.
Why should data be rejected in this scenario?
- A. Data contradicts the control group.
- B. Data were different from expectations.
- C. Data cannot be displayed graphically.
- D. Data are based on flawed methodology.
Correct Answer: D
Rationale: The correct answer is D because when data are based on flawed methodology, it means that the way the data were collected, analyzed, or interpreted was not done correctly. This can lead to unreliable results that do not accurately represent the population being studied. In this case, if the researcher's methodology was flawed, it would be a valid reason to reject the data as it would not provide a valid estimate of the average wing strength of all birds found in the American Northwest.
Which of the following demonstrates a chemical reaction involving water?
- A. Water and oil separate when combined
- B. Water boils to produce steam at 100 degrees Celsius
- C. Water dissolves sugar
- D. Water produces gas when reacting with sodium metal
Correct Answer: D
Rationale: The correct answer is D because when water reacts with sodium metal, it produces hydrogen gas, indicating a chemical reaction. Options A, B, and C involve physical changes or processes like separation, phase change, and dissolution, respectively, which do not involve a chemical reaction. In option A, oil and water separating is a physical change due to differences in polarity. Option B describes a physical change where water undergoes a phase change from liquid to gas. Option C involves a physical change as sugar dissolves in water through a physical process without a chemical reaction occurring.
Which of the following is a function of bone?
- A. Detoxification of alcohol
- B. Production of otoliths
- C. Storage of minerals
- D. Secretion of hormones
Correct Answer: C
Rationale: Bones serve as a crucial storage site for essential minerals like calcium and phosphorus. These minerals are indispensable for various physiological functions in the body, such as muscle contraction, nerve transmission, and blood clotting. Bones act as a reservoir for these minerals, releasing them into the bloodstream as needed to maintain appropriate mineral levels. Therefore, the correct answer is C, storage of minerals.
What is the function of a totipotent cell?
- A. Fights infection
- B. Develops into any type of cell
- C. Aids in the maturation of sex cells
- D. Carries electrical impulses
Correct Answer: B
Rationale: Totipotent cells possess the remarkable ability to differentiate into any cell type in the body, encompassing both embryonic and extraembryonic cell varieties. This quality is crucial in the early stages of embryonic development, facilitating the generation of all cell lineages and tissues. Unlike pluripotent or multipotent cells, totipotent cells exhibit the most extensive differentiation potential, playing a vital role in the organism's development from a single fertilized egg cell.
Which of the following chemicals is released by one type of immune cell to directly activate another immune cell?
- A. lysozymes
- B. cytokines
- C. perforin
- D. granzymes
Correct Answer: B
Rationale: The correct answer is B: cytokines. Cytokines are signaling molecules released by immune cells to regulate the immune response. They play a crucial role in coordinating and communicating between different immune cells. By releasing cytokines, immune cells can directly activate other immune cells, enhancing the immune response. Lysozymes are enzymes that break down bacterial cell walls, perforin is a protein involved in cell-mediated immune responses, and granzymes are enzymes that induce apoptosis in target cells, mainly used by cytotoxic T cells and natural killer cells, not for directly activating other immune cells.