Nokea
An atom has 17 protons, 20 neutrons, and 17 electrons. What is its mass, in amu?
- A. 17
- B. 20
- C. 37
- D. 54
Correct Answer: C
Rationale: The atomic mass of an atom is the sum of the protons and neutrons in its nucleus. In this case, the atom has 17 protons and 20 neutrons, totaling 37 particles in the nucleus. Electrons are not considered in the atomic mass calculation as their mass is negligible compared to protons and neutrons. Therefore, the mass of the atom in atomic mass units (amu) is 37.
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A physician prescribes a drug to help control a person's anxiety attacks. This drug most likely targets the
- A. Amygdala.
- B. Parietal lobe.
- C. Hypothalamus.
- D. Sensory neuron.
Correct Answer: A
Rationale: The correct answer is A: Amygdala. The amygdala is a key brain structure involved in the processing of emotions, including anxiety. Medications for anxiety disorders often target the amygdala to help regulate emotional responses and control anxiety attacks. The amygdala plays a crucial role in the brain's fear circuit and is essential for the appropriate response to stress and threat perception. Choices B, C, and D are incorrect because the parietal lobe is primarily involved in sensory processing and spatial reasoning, the hypothalamus regulates basic functions like hunger, thirst, and body temperature, and sensory neurons transmit signals from sensory receptors to the central nervous system, none of which are directly related to the regulation of anxiety attacks.
What is the purpose of an electrocardiogram?
- A. Indicate the rate of blood flow
- B. Display the heart's rate and rhythm
- C. Identify a person's blood group type
- D. Determine cell type in a blood sample
Correct Answer: B
Rationale: An electrocardiogram (ECG or EKG) is used to measure and display the heart's rate and rhythm. It provides valuable information about the electrical activity of the heart, allowing healthcare providers to assess the heart's health, detect abnormalities in the heart's rhythm, and diagnose various cardiac conditions. Choices A, C, and D are incorrect. Choice A is incorrect because an ECG does not indicate the rate of blood flow but rather focuses on the heart's electrical activity. Choice C is incorrect because identifying a person's blood group type is typically done through blood typing tests, not ECG. Choice D is incorrect because determining cell type in a blood sample is unrelated to the purpose of an ECG.
In an experiment where five tropical plants are kept at varying humidity levels in a greenhouse for three months, while one plant is left outside in normal conditions, with plant height measured weekly, what serves as the control of the experiment?
- A. Plant height for each tropical plant
- B. The plant left outside in normal conditions
- C. Humidity level readings in the greenhouse
- D. Amount of time used to study plant height
Correct Answer: B
Rationale: The correct answer is B. The plant left outside in normal conditions acts as the control in the experiment. It provides a standard reference point for comparison to assess the impact of the varying humidity levels on the growth of the tropical plants. Choice A is incorrect because it refers to the dependent variable being measured, not the control. Choice C is incorrect as humidity levels in the greenhouse are part of the experimental conditions, not the control. Choice D is incorrect as the time used for studying plant height is a parameter of the experiment and not the control.
How do killer T cells recognize infected cells?
- A. The B cells flag the infected cells with amino acids.
- B. Tiny bits of the virus's RNA are left around the cell.
- C. Macrophages show up to help consume the infected cell.
- D. The T cells have receptors that recognize the proteins the virus leaves on the surface of the cell.
Correct Answer: D
Rationale: Killer T cells recognize infected cells by detecting viral proteins displayed on the surface of these cells. The T cells possess receptors specifically designed to identify these viral proteins, allowing them to target and eliminate the infected cells. Choice A is incorrect because B cells are not directly involved in the recognition process of infected cells by killer T cells. Choice B is incorrect because tiny bits of the virus's RNA being left around the cell is not how killer T cells primarily recognize infected cells. Choice C is incorrect because while macrophages play a role in immune responses, they do not directly assist in the recognition of infected cells by killer T cells.
How does the developing fetus primarily eliminate metabolic wastes?
- A. The developing fetus does not produce metabolic wastes.
- B. Fetal waste is excreted as feces, which pass into the mother's anus.
- C. Fetal waste is passed down the umbilical cord to the mother's circulatory system.
- D. Fetal waste is passed down the umbilical cord and leaves the mother's body via the vagina.
Correct Answer: C
Rationale: Metabolic wastes produced by the developing fetus are eliminated primarily by being passed down the umbilical cord to the mother's circulatory system. Once in the mother's blood, these wastes are then filtered and excreted by the mother's kidneys. Choice A is incorrect because the developing fetus does produce metabolic wastes. Choice B is incorrect as fetal waste does not pass into the mother's anus. Choice D is incorrect as fetal waste does not leave the mother's body via the vagina.