Nokea
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.
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What are the three main types of RNA?
- A. Messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA)
- B. DNA, RNA, and protein
- C. Adenine, guanine, cytosine, and thymine
- D. Deoxyribose, ribose, and phosphate
Correct Answer: A
Rationale: - Messenger RNA (mRNA) carries genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm for protein synthesis.
- Ribosomal RNA (rRNA) is a structural component of ribosomes, which are the cellular machinery responsible for protein synthesis.
- Transfer RNA (tRNA) is responsible for bringing amino acids to the ribosome during protein synthesis.
Options B, C, and D are incorrect:
- Option B lists DNA, RNA, and protein, which are biomolecules but not the three main types of RNA.
- Option C lists nitrogenous bases (adenine, guanine, cytosine, and thymine) found in DNA, not types of RNA.
- Option D lists components of nucleotides (deoxyribose, ribose, and phosphate), which are building blocks of nucleic
What phenomenon occurs when two identical waves are perfectly aligned and reinforce each other?
- A. Refraction
- B. Reflection
- C. Diffraction
- D. Constructive interference
Correct Answer: D
Rationale: Constructive interference occurs when two identical waves are perfectly aligned and reinforce each other. This results in an increase in the overall amplitude of the wave. Refraction refers to the bending of waves as they pass from one medium to another, reflection is the bouncing back of waves when they encounter a boundary, and diffraction is the bending of waves around obstacles and openings. In this scenario, the waves are not changing direction or bending but rather combining to produce a wave with a larger amplitude, which is characteristic of constructive interference.
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 element is used in semiconductors like computer chips and solar panels?
- A. Germanium
- B. Silicon
- C. Gallium
- D. Arsenic
Correct Answer: B
Rationale: Silicon is the correct answer. Silicon is widely used in semiconductors for electronic applications because of its unique properties that allow it to be manipulated to conduct or not conduct electricity effectively. Germanium is also used in semiconductors but to a lesser extent compared to silicon. Gallium and arsenic are not as commonly used in semiconductors like computer chips and solar panels, making them incorrect choices for this question.
Which part of the brain is responsible for regulating heart rate, breathing, and swallowing?
- A. Cerebrum
- B. Cerebellum
- C. Medulla oblongata
- D. Thalamus
Correct Answer: C
Rationale: The correct answer is C, the medulla oblongata. This part of the brain, located at the base of the brainstem, is primarily responsible for regulating essential functions like heart rate, breathing, and swallowing. Choices A, B, and D are incorrect. The cerebrum is associated with higher brain functions such as thinking and voluntary movements, the cerebellum controls coordination and balance, and the thalamus serves as a relay station for sensory information. Therefore, the medulla oblongata specifically governs the autonomic functions critical for survival.