Nokea
Which part of the eye controls the amount of light that enters the eye?
- A. Cornea
- B. Iris
- C. Retina
- D. Lens
Correct Answer: B
Rationale: The iris is the correct answer as it controls the amount of light that enters the eye by adjusting the size of the pupil. The cornea is responsible for focusing light onto the retina, the retina detects light at the back of the eye, and the lens helps in further focusing light onto the retina. The iris, through changing the size of the pupil, regulates the amount of light reaching the eye, making it the part that controls the entry of light.
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Which of the following neurotransmitters slows down the activity of neurons, preventing them from becoming overexcited?
- A. Acetylcholine
- B. Dopamine
- C. GABA
- D. Serotonin
Correct Answer: C
Rationale: The correct answer is C: GABA (gamma-aminobutyric acid). GABA acts as an inhibitory neurotransmitter that reduces neuronal activity, thus preventing overexcitation. Acetylcholine (choice A) is involved in muscle control and cognitive function, but it is not primarily responsible for slowing down neuronal activity. Dopamine (choice B) plays a role in reward-motivated behavior and motor control, rather than inhibiting neuronal firing. Serotonin (choice D) is involved in mood regulation, sleep, and appetite but does not primarily slow down neuronal activity to prevent overexcitation.
What is the primary function of the nervous system?
- A. To produce hormones
- B. To transmit electrical impulses
- C. To carry oxygen
- D. To transport nutrients
Correct Answer: B
Rationale: The correct answer is B: To transmit electrical impulses. The primary function of the nervous system is to transmit electrical impulses and coordinate body activities. While hormones are produced by the endocrine system, not the nervous system, oxygen transportation is mainly carried out by the respiratory system, and nutrient transport is primarily the role of the circulatory system. Therefore, choices A, C, and D are incorrect as they do not align with the primary function of the nervous system.
Which of the following is an effect of high blood pressure?
- A. Smoking
- B. Excessive dietary salt
- C. Renal vessel damage
- D. Older age
Correct Answer: C
Rationale: The correct answer is C: Renal vessel damage. High blood pressure can lead to damage in blood vessels throughout the body, including the kidneys. When blood vessels in the kidneys are affected, it can impair kidney function and potentially lead to kidney disease. Smoking (Choice A) and excessive dietary salt (Choice B) can contribute to high blood pressure but are not direct effects of high blood pressure itself. Older age (Choice D) is a risk factor for developing high blood pressure but is not a direct effect of high blood pressure.
Which of the following represents the strongest scientific argument?
- A. Scientific Hypothesis
- B. Scientific Law
- C. Scientific Study Conclusion
- D. Scientific Theory
Correct Answer: D
Rationale: The correct answer is D, 'Scientific Theory.' A scientific theory is a well-substantiated explanation of an aspect of the natural world. It is based on a large body of evidence and has withstood rigorous testing and scrutiny. Scientific theories are considered the strongest scientific arguments because they have predictive power and are supported by a significant amount of empirical data. Choice A, 'Scientific Hypothesis,' is a proposed explanation for a phenomenon but lacks the extensive evidence and testing that theories undergo. Choice B, 'Scientific Law,' describes a consistent and predictable relationship between variables but does not explain why the relationship exists. Choice C, 'Scientific Study Conclusion,' may be based on a single study and lacks the comprehensive nature and validation that theories possess.
If an atom has 32 neutrons, 17 protons, and 19 electrons, what is its charge?
- A. Positive
- B. Negative
- C. Neutral
- D. Cannot be determined
Correct Answer: A
Rationale: An atom's charge is determined by the difference between the number of protons and electrons. Since the atom has 17 protons and 19 electrons, the net charge is positive. The excess of two electrons compared to protons results in a positive charge. Choice B (Negative) is incorrect because the atom has more protons than electrons, leading to a positive charge. Choice C (Neutral) is incorrect because the atom has an imbalance between protons and electrons, resulting in a charge. Choice D (Cannot be determined) is incorrect as the charge can be determined based on the given information.