Nokea
What is the feedback mechanism in the endocrine system that helps maintain hormone balance?
- A. Positive feedback, where a hormone stimulates its own release
- B. Negative feedback, where a hormone suppresses its own release
- C. Cascade effect, where one hormone triggers the release of another
- D. Dual hormone system, where two hormones work together
Correct Answer: B
Rationale: In the endocrine system, negative feedback is the mechanism by which hormone levels are regulated. When hormone levels reach a certain threshold, they signal the body to stop producing more of that hormone, thus maintaining a balance. Negative feedback (option B) is the correct answer as it helps in preventing overproduction of hormones by suppressing their own release. Positive feedback (option A) would lead to an excessive production of hormones, disrupting the balance. The cascade effect (option C) involves one hormone triggering the release of another but does not directly regulate hormone levels. The dual hormone system (option D) refers to two hormones working together but does not specifically address the feedback mechanism for maintaining hormone balance.
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Which of the following is an example of stabilizing selection?
- A. Selection that favors extreme traits in a population
- B. Selection that removes individuals with extreme traits
- C. Selection that maintains the current average trait in a population
- D. Selection that favors one specific trait over all others
Correct Answer: C
Rationale: - Stabilizing selection is a type of natural selection that favors the intermediate variants in a population, while selecting against the extreme traits. This results in the maintenance of the current average trait in the population.
- Option A is incorrect because stabilizing selection does not favor extreme traits; instead, it favors the average trait.
- Option B is incorrect because stabilizing selection does not remove individuals with extreme traits; it acts against extreme traits by favoring the intermediate variants.
- Option D is incorrect because stabilizing selection does not favor one specific trait over all others; it favors the average trait by selecting against extreme traits.
The gradual change in a species over time is called:
- A. Adaptation
- B. Evolution
- C. Speciation
- D. Natural selection
Correct Answer: B
Rationale: - Adaptation refers to the process by which a species becomes better suited to its environment over time. While adaptation is a component of evolution, it specifically refers to the changes that help a species survive and reproduce in its environment.
- Speciation is the process by which new species arise from a single ancestral species. It involves the evolution of reproductive isolation between populations.
- Natural selection is a mechanism of evolution where individuals with advantageous traits are more likely to survive and reproduce, leading to the increase in frequency of those traits in a population.
- Evolution is the gradual change in a species over time, encompassing all the processes such as adaptation, speciation, and natural selection that drive these changes.
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.
Why is maintaining good muscle strength and flexibility as we age important?
- A. To prevent headaches
- B. To prevent falls
- C. To reduce anxiety
- D. To avoid the common cold
Correct Answer: B
Rationale: Maintaining good muscle strength and flexibility as we age is crucial to prevent falls. Strong muscles and good flexibility help improve balance and stability, reducing the risk of falls, which can lead to serious injuries, especially in older adults. Falls are a significant concern for the elderly population, and preventing them through muscle strength and flexibility can enhance overall quality of life. Headaches are not directly related to muscle strength and flexibility; they can have various causes such as stress, dehydration, or underlying health conditions. Anxiety is a mental health condition and not directly prevented by muscle strength and flexibility. Similarly, the common cold is a viral infection and is not influenced by muscle strength and flexibility.
What is the periodic table?
- A. A table of elements that are arranged in order of increasing atomic number.
- B. A table of elements that are arranged in order of increasing atomic mass.
- C. A table of elements that are arranged in order of their reactivity.
- D. A table of elements that are arranged in order of their color.
Correct Answer: A
Rationale: The periodic table is a tabular arrangement of the chemical elements, organized based on their atomic number, electron configurations, and recurring chemical properties. Elements are placed in rows (periods) and columns (groups) with similar properties. The elements are listed in order of increasing atomic number, which is the number of protons in the nucleus of an atom. This arrangement reveals a periodic repetition of chemical properties, forming the basis of the periodic law. Choice B, which suggests arranging elements based on increasing atomic mass, is incorrect because the periodic table is primarily organized by atomic number, not atomic mass. Choices C and D are also incorrect as the periodic table is not based on reactivity or color of elements, but rather on atomic number and properties.