Nokea
When a child is sick and has a body temperature exceeding 37Å—C, the body begins to sweat in order to lower the temperature. What is this an example of?
- A. Positive feedback loop
- B. Negative feedback loop
- C. Both
- D. None of the above
Correct Answer: B
Rationale: This scenario illustrates a negative feedback loop. In negative feedback, the body's response opposes the initial change, helping to restore equilibrium. In this case, the body's sweating is a response to reduce the elevated temperature, aiming to return the body to its normal state. This process helps regulate and maintain homeostasis, ensuring the body functions within a narrow range of optimal conditions.
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What is the first step in the process of respiration?
- A. Fermentation
- B. Krebs cycle
- C. Electron transport chain
- D. Glycolysis
Correct Answer: D
Rationale: The correct answer is Glycolysis. Glycolysis is the initial step in cellular respiration where glucose is broken down into pyruvate, producing a small amount of ATP and NADH in the cytoplasm. This step is crucial as it initiates the breakdown of glucose, setting the stage for further energy production in subsequent stages like the Krebs cycle and electron transport chain.
What is the typical result of mitosis in humans?
- A. two diploid cells
- B. two haploid cells
- C. four diploid cells
- D. four haploid cells
Correct Answer: A
Rationale: During mitosis, a cell divides to produce two identical daughter cells that are genetically identical to the parent cell. These daughter cells are diploid, meaning they contain the full set of chromosomes. Therefore, the typical result of mitosis in humans is the formation of two diploid cells (Choice A). Choices B, C, and D are incorrect as mitosis results in the production of diploid cells, not haploid cells, and typically, it results in two daughter cells, not four.
Select the cell parts that are present in plant cells but not animal cells (there may be more than one answer):
- A. Cell membrane
- B. Cell wall
- C. Ribosome
- D. Chloroplast
Correct Answer: D
Rationale: Chloroplasts are unique to plant cells and are responsible for photosynthesis, a process that converts light energy into chemical energy. Animal cells do not contain chloroplasts as they do not perform photosynthesis. Therefore, the correct answer is D - Chloroplast. The cell membrane is found in both plant and animal cells, serving as a protective barrier, while the cell wall is a rigid structure present in plant cells that provides support and protection. Ribosomes are cellular structures responsible for protein synthesis and are present in both plant and animal cells.
Which of the following is necessary for cell diffusion?
- A. water
- B. membrane
- C. ATP
- D. gradient
Correct Answer: A
Rationale: Water is necessary for cell diffusion because it serves as the medium through which particles move across cell membranes. Diffusion is the passive movement of particles from an area of higher concentration to an area of lower concentration, and water plays a crucial role in facilitating this process by dissolving molecules and allowing them to move freely. Membranes provide the barrier for diffusion to occur, ATP is not directly involved in the process of diffusion, and a gradient is the difference in concentration that drives diffusion but is not a necessary component for diffusion itself.
Phenotype refers to the.................... of an individual.
- A. Genetic makeup
- B. Actual physical appearance
- C. Recessive alleles
- D. None of the above
Correct Answer: B
Rationale: Phenotype refers to the observable physical characteristics of an individual, such as hair color, eye color, and height. It is the result of the interaction between an individual's genetic makeup (genotype) and environmental influences. Therefore, the correct answer is B, 'Actual physical appearance.' The term 'genetic makeup' (Choice A) refers to genotype, which is the actual set of genes an individual carries. 'Recessive alleles' (Choice C) are specific forms of genes that are masked by dominant alleles in heterozygous individuals and do not directly define the phenotype. 'None of the above' (Choice D) is incorrect as phenotype does refer to something among the given choices, which is the actual physical appearance.