Nokea
If a biochemist isolates a large amount of pyruvate, which part of the cell is he working with?
- A. Chloroplasts
- B. Cytoplasm
- C. Mitochondria
- D. Nucleus
Correct Answer: B
Rationale: The correct answer is B: Cytoplasm. Pyruvate is a product of glycolysis, a metabolic pathway that takes place in the cytoplasm of the cell. Therefore, a biochemist isolating a large amount of pyruvate would be working with the cytoplasm of the cell. Choice A, Chloroplasts, is incorrect because pyruvate is not produced in chloroplasts, which are responsible for photosynthesis. Choice C, Mitochondria, is incorrect as pyruvate is produced in the cytoplasm before entering the mitochondria for further metabolism. Choice D, Nucleus, is incorrect as the nucleus is not involved in the production or isolation of pyruvate, which is a metabolic intermediate.
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A scientist wants to measure how far a person can run in 30 minutes. Which of the following units should be used to record this measurement as a small number?
- A. Gigameters
- B. Kilometers
- C. Megameters
- D. Terameters
Correct Answer: B
Rationale: Kilometers are commonly used for shorter distances and would provide a small and practical number to measure distance in this context. Gigameters, Megameters, and Terameters are much larger units of measurement and would result in very large numbers, making them impractical for measuring the distance a person can run in 30 minutes. Therefore, the correct choice is Kilometers as it is a suitable unit for measuring such distances within a reasonable range.
Which structure do cells rely on for movement?
- A. Flagellum
- B. Microtubule
- C. Pili
- D. Vesicle
Correct Answer: A
Rationale: The correct answer is A: Flagellum. Cells rely on flagella for movement, which are whip-like structures that propel the cell forward through their whipping motion. Flagella provide motility to single-celled organisms and certain cells in multicellular organisms. Microtubules, on the other hand, provide structural support to the cell and play a role in intracellular transport. Pili are short, hair-like structures used for attachment to surfaces or other cells, not for movement. Vesicles are membrane-bound sacs involved in intracellular transport, aiding in the movement of substances within the cell, but not in the movement of the cell itself.
Which type of immunity does the MMR vaccine provide?
- A. Artificial/active
- B. Artificial/passive
- C. Natural/active
- D. Natural/passive
Correct Answer: A
Rationale: The correct answer is A: Artificial/active. The MMR vaccine provides artificial/active immunity. It works by introducing a weakened or killed form of the virus to trigger the body's immune response, leading to the production of antibodies that offer long-lasting protection against measles, mumps, and rubella. Artificial immunity is obtained through medical intervention, such as vaccination, while active immunity involves the immune system's direct response to an antigen. Choices B, C, and D are incorrect because the MMR vaccine does not provide passive immunity nor is it acquired naturally; instead, it stimulates the body to actively produce its immune response.
How many electrons are typically found in each shell of a neutral aluminum atom with 13 electrons in its electron cloud?
- A. 6 in the first shell, 7 in the second shell
- B. 2 in the first shell, 11 in the second shell
- C. 2 in the first shell, 8 in the second shell, 3 in the third shell
- D. 3 in the first shell, 5 in the second shell, 5 in the third shell
Correct Answer: C
Rationale: In a neutral aluminum atom with 13 electrons, the electron distribution typically follows the electron shell filling order based on the Aufbau principle. The first shell can hold a maximum of 2 electrons, the second shell can hold up to 8 electrons, and the third shell can hold up to 8 electrons as well. Therefore, the distribution would be 2 electrons in the first shell, 8 electrons in the second shell, and 3 electrons in the third shell, totaling 13 electrons. Choice A is incorrect as it exceeds the maximum number of electrons the shells can hold. Choice B is incorrect as it does not distribute the electrons correctly among the shells. Choice D is incorrect as it also does not distribute the electrons correctly among the shells.
Which of the following is a characteristic of an interneuron?
- A. Forms neural circuits
- B. Interacts with effectors
- C. Sends impulses to the CNS
- D. Functions as an efferent nerve cell
Correct Answer: A
Rationale: The correct characteristic of an interneuron is that it forms neural circuits, connecting sensory and motor neurons within the central nervous system. Interneurons facilitate communication between different neurons in the central nervous system, helping in the processing and integration of signals. Choice B is incorrect as interneurons primarily interact with other neurons, not effectors. Choice C is incorrect as interneurons typically do not send impulses to the CNS; they operate within the CNS. Choice D is incorrect as interneurons are not efferent nerve cells; they are mainly involved in processing signals within the CNS rather than transmitting signals to effectors.