Nokea
What is the primary function of ribosomes in a cell?
- A. Protein synthesis
- B. DNA replication
- C. Cell division
- D. Lipid synthesis
Correct Answer: A
Rationale: The correct answer is A: Protein synthesis. Ribosomes are the cellular organelles responsible for protein synthesis. They read the messenger RNA (mRNA) and translate the genetic information into specific proteins. This process is essential for building and maintaining the structures and functions of the cell. Choice B, DNA replication, is incorrect because ribosomes are not involved in replicating DNA; that process occurs in the nucleus. Choice C, cell division, is incorrect as ribosomes are not directly involved in cell division but rather in protein synthesis. Choice D, lipid synthesis, is also incorrect as ribosomes are not responsible for synthesizing lipids, which primarily occurs in the endoplasmic reticulum and other organelles.
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Which of the following statements is true about the dependent variable?
- A. A factor that remains constant during the experiment
- B. A factor with data typically plotted on the x-axis
- C. A factor that is measured during an experiment
- D. A factor with data typically plotted on the y-axis
Correct Answer: C
Rationale: The correct answer is C. The dependent variable is the factor that is being measured or observed in an experiment. It is the outcome that is affected by changes in the independent variable. In graphical representations, the dependent variable is usually plotted on the y-axis, not the x-axis. Choice A is incorrect because a factor that remains constant is referred to as a constant, not a dependent variable. Choice B is incorrect as the independent variable's data is typically plotted on the x-axis. Choice D is incorrect because the dependent variable's data is usually plotted on the y-axis. Therefore, choice C accurately describes the dependent variable.
Which of the following describes the term allele?
- A. A specific form of a gene that can exist at a particular locus
- B. An inheritable variation of a gene
- C. A grouping of various genes
- D. Variations of complementary base pairs
Correct Answer: B
Rationale: The correct answer is B. Alleles are different forms of a gene that can exist at a specific locus. They represent variations of a gene and are inheritable. Choice A is incorrect as it does not fully capture the concept of an allele, which is a specific form of a gene rather than a substitution. Choice C is incorrect as alleles are not a grouping of various genes but rather different forms of a single gene at a specific locus. Choice D is also incorrect as it does not accurately describe alleles; alleles are variations of genes, not base pairs.
What is the function of the alveoli in the lungs?
- A. To exchange carbon dioxide for oxygen
- B. To transport air to the lungs
- C. To filter blood
- D. To produce mucus
Correct Answer: A
Rationale: The corrected answer is A: 'To exchange carbon dioxide for oxygen.' The alveoli in the lungs are responsible for facilitating gas exchange, where oxygen from inhaled air diffuses into the bloodstream, and carbon dioxide from the bloodstream diffuses into the alveoli to be exhaled. This process is vital for respiration and maintaining proper oxygen levels in the body. Choices B, C, and D are incorrect. Choice B is incorrect because the alveoli are not involved in transporting air to the lungs; they are primarily responsible for gas exchange. Choice C is incorrect because the alveoli do not filter blood; their main function is gas exchange. Choice D is incorrect because alveoli do not produce mucus; mucus is produced by other specialized cells in the respiratory system.
Which type of blood vessel carries blood away from the heart?
- A. Vein
- B. Artery
- C. Capillary
- D. Venule
Correct Answer: B
Rationale: The correct answer is B: Artery. Arteries carry oxygen-rich blood away from the heart to various parts of the body. Veins, on the other hand, carry blood back to the heart. Capillaries are tiny blood vessels where oxygen and nutrients are exchanged with tissues. Venules are small veins that collect blood from capillaries, not from the heart, making them incorrect in this context.
Which of the following is the largest organ in the human body?
- A. Liver
- B. Brain
- C. Heart
- D. Skin
Correct Answer: D
Rationale: The skin is the largest organ in the human body. It covers the entire body, serving as a protective barrier against pathogens, UV radiation, and physical damage. Additionally, the skin plays a crucial role in regulating body temperature and synthesizing vitamin D when exposed to sunlight. Choices A, B, and C are incorrect. The liver is the largest internal organ, the brain is the control center of the body, and the heart is a vital organ responsible for pumping blood throughout the body. However, none of these organs are the largest in terms of surface area or overall size.