Nokea
How does the human eye focus light?
- A. Cornea
- B. Iris
- C. Lens
- D. Retina
Correct Answer: C
Rationale: The human eye focuses light by adjusting the shape of its lens. The lens changes shape to allow the eye to focus on objects at different distances, a process known as accommodation. The cornea is the transparent outer covering of the eye that helps to focus light but does not change shape like the lens. The iris controls the size of the pupil to regulate the amount of light entering the eye. The retina is the light-sensitive layer at the back of the eye that receives and processes images but does not adjust the focus of light.
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Which of the following is the MOST common symptom of angina pectoris, a condition related to insufficient blood flow to the heart?
- A. Fever and chills.
- B. Chest pain or discomfort.
- C. Sudden onset of severe shortness of breath.
- D. Numbness or tingling in the extremities.
Correct Answer: B
Rationale: Chest pain or discomfort is the most common symptom of angina pectoris. This pain is often described as squeezing, pressure, heaviness, tightness, or pain in the chest. Fever and chills, sudden onset of severe shortness of breath, and numbness or tingling in the extremities are not typical symptoms of angina pectoris. The pain associated with angina is usually triggered by physical or emotional stress and typically subsides with rest or medication, distinguishing it from other conditions.
Which of the following is NOT a typical component of healthy semen?
- A. Sperm
- B. Fructose (sugar)
- C. Prostaglandins
- D. Urine
Correct Answer: D
Rationale: Healthy semen is composed of sperm, fructose (sugar), and prostaglandins. Urine is not a typical component of semen. While semen is ejaculated during sexual activity, urine is expelled through a separate pathway in the male reproductive system. Therefore, the correct answer is 'Urine.' Choices A, B, and C are all components found in healthy semen.
Memory B cells and memory T cells are crucial for immunological memory. How does immunological memory enhance the immune response upon re-exposure to a pathogen?
- A. It increases the production of the same ineffective antibodies.
- B. It allows for a quicker and more robust immune response.
- C. It suppresses the immune system to prevent overreaction.
- D. It triggers a completely different immune response.
Correct Answer: B
Rationale: Immunological memory enhances the immune response upon re-exposure to a pathogen by allowing for a quicker and more robust immune response. Memory B cells and memory T cells are primed to recognize the pathogen quickly and mount a faster and more effective response, leading to a more efficient clearance of the pathogen. Choice A is incorrect because immunological memory does not increase the production of ineffective antibodies but rather promotes the production of specific antibodies that are effective against the pathogen. Choice C is incorrect as immunological memory does not suppress the immune system; instead, it enhances the response. Choice D is incorrect because immunological memory leads to a recall of the specific immune response mounted during the initial exposure, not a completely different response.
Which neurotransmitter is associated with mood regulation, sleep, and appetite?
- A. Acetylcholine
- B. Dopamine
- C. Serotonin
- D. GABA (Gamma-aminobutyric acid)
Correct Answer: C
Rationale: The correct answer is C: Serotonin. Serotonin is a neurotransmitter that plays a crucial role in mood regulation, sleep, and appetite. It helps regulate emotions, mood, and behavior. Imbalances in serotonin levels have been associated with conditions such as depression, anxiety, and eating disorders.
Choice A, Acetylcholine, is primarily involved in muscle control and memory functions. Choice B, Dopamine, is associated with reward, motivation, and motor control. Choice D, GABA (Gamma-aminobutyric acid), is an inhibitory neurotransmitter that helps reduce neuronal excitability and is not directly linked to mood regulation, sleep, or appetite.
Which property of a substance refers to its ability to be stretched into thin wires without breaking?
- A. Conductivity
- B. Viscosity
- C. Ductility
- D. Malleability
Correct Answer: C
Rationale: Ductility is the property of a substance that allows it to be stretched into thin wires without breaking. This property is distinct from the other options provided. Conductivity refers to the ability to conduct electricity or heat, viscosity refers to a liquid's resistance to flow, and malleability refers to the ability of a substance to be hammered or rolled into thin sheets. Therefore, the correct answer is 'Ductility.'