Nokea
Which of the following is NOT a function of the endoplasmic reticulum (ER)?
- A. Synthesis of lipids (fats)
- B. Transport of materials within the cell
- C. Detoxification of harmful substances
- D. Breakdown of cellular waste products
Correct Answer: D
Rationale: The endoplasmic reticulum (ER) is not involved in the breakdown of cellular waste products; this function is primarily carried out by lysosomes. The ER is responsible for the synthesis of lipids (fats), transport of materials within the cell, and detoxification of harmful substances. Lysosomes are the organelles responsible for breaking down cellular waste products through processes like autophagy. Therefore, option D is the correct answer as it does not align with the known functions of the endoplasmic reticulum.
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In endocrine regulation, the feedback loop is a critical concept. In a negative feedback loop, high levels of a hormone can result in:
- A. Further stimulating the release of the same hormone
- B. Inhibiting the release of the hormone or its production
- C. Having no effect on the hormone's regulation
- D. Increasing the need for another hormone entirely
Correct Answer: B
Rationale: In a negative feedback loop, high levels of a hormone will inhibit the release of the hormone or its production. This mechanism is crucial for maintaining homeostasis by preventing excessive levels of hormones in the body. When a hormone reaches a certain concentration, it triggers the body to decrease its production or release, thereby ensuring a balance within the system. Choice A is incorrect because a negative feedback loop aims to counteract high hormone levels, not further stimulate them. Choice C is incorrect as high hormone levels do have an effect by triggering the feedback loop. Choice D is incorrect as the negative feedback loop operates within the same hormone system rather than increasing the need for an entirely different hormone.
When baking soda (sodium bicarbonate) reacts with vinegar (acetic acid), what type of reaction occurs?
- A. Combustion
- B. Double displacement
- C. Decomposition
- D. Synthesis
Correct Answer: B
Rationale: When baking soda (sodium bicarbonate) reacts with vinegar (acetic acid), a double displacement reaction occurs. In this reaction, the positive ions in baking soda switch places with the positive ions in vinegar to form water, carbon dioxide, and a salt. Combustion involves a reaction with oxygen to produce heat and light energy. Decomposition is the breakdown of a compound into simpler substances, which is not the case in the given reaction. Synthesis is the combination of substances to form a more complex compound, which is also not the type of reaction observed when baking soda and vinegar react.
What does the concept of punctuated equilibrium suggest?
- A. Evolution occurs gradually through the continuous accumulation of small changes over long periods.
- B. Evolution is characterized by long periods of relative stasis punctuated by rapid bursts of evolutionary change.
- C. The fossil record is a complete and accurate representation of all past life forms.
- D. Natural selection primarily favors extreme phenotypes within a population.
Correct Answer: B
Rationale: Punctuated equilibrium suggests that evolution is characterized by long periods of relative stasis punctuated by rapid bursts of evolutionary change. This concept, proposed by Stephen Jay Gould and Niles Eldredge, implies that species remain relatively unchanged for extended periods, followed by sudden bursts of rapid evolution. Option A describes the gradualism model, which is different from punctuated equilibrium. Option C is inaccurate as the fossil record is incomplete and biased. Option D is unrelated to the concept of punctuated equilibrium.
Antibiotic resistance in bacteria is an example of:
- A. Convergent evolution
- B. Divergent evolution
- C. Microevolution
- D. Macroevolution
Correct Answer: C
Rationale: Antibiotic resistance in bacteria is a classic example of microevolution (option C). Microevolution refers to changes in allele frequencies within a population over a relatively short period of time. In the case of antibiotic resistance, bacteria evolve resistance to antibiotics through the natural selection of pre-existing resistant strains. This process does not involve the formation of new species or higher taxonomic groups, which are associated with macroevolution (option D). Convergent evolution (option A) involves different species independently evolving similar traits in response to similar environmental pressures, which is not the case with antibiotic resistance in bacteria. Divergent evolution (option B) refers to related species becoming more dissimilar over time, which also does not apply to the scenario of antibiotic resistance in bacteria.
Which division of the nervous system is responsible for involuntary functions such as heart rate, digestion, and respiratory rate?
- A. Somatic nervous system
- B. Autonomic nervous system
- C. Peripheral nervous system
- D. Central nervous system
Correct Answer: B
Rationale: The autonomic nervous system is the correct answer. It is responsible for controlling involuntary functions such as heart rate, digestion, respiratory rate, and other automatic processes in the body. The somatic nervous system controls voluntary movements, making choice A incorrect. The peripheral nervous system consists of nerves outside the brain and spinal cord, which is not directly responsible for these involuntary functions, making choice C incorrect. The central nervous system includes the brain and spinal cord, but it is not primarily responsible for regulating involuntary functions, making choice D incorrect.