Nokea
Which of the following organs is covered by the pleura, a connective tissue sheath?
- A. spleen
- B. lungs
- C. heart
- D. liver
Correct Answer: B
Rationale: The pleura is a protective membrane that covers the lungs. It consists of two layers: the visceral pleura (inner layer) and the parietal pleura (outer layer). The pleural space between these layers contains a small amount of fluid that helps reduce friction during breathing movements. The spleen, heart, and liver are not covered by the pleura. Therefore, the correct answer is the lungs.
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Which of the following structures is present in both prokaryotic and eukaryotic cells?
- A. Cell membrane
- B. Chromoplast
- C. Golgi apparatus
- D. Endoplasmic reticulum
Correct Answer: A
Rationale: The correct answer is the cell membrane (choice A). The cell membrane is a vital structure present in both prokaryotic and eukaryotic cells. It plays a crucial role as a selectively permeable barrier, controlling the movement of substances into and out of the cell. On the other hand, chromoplasts, Golgi apparatus, and endoplasmic reticulum are specific organelles found only in eukaryotic cells. Chromoplasts are responsible for pigment synthesis, Golgi apparatus is involved in protein processing and packaging, and endoplasmic reticulum is crucial for lipid synthesis and protein folding. Therefore, the cell membrane is the correct choice as it is the common feature shared by both prokaryotic and eukaryotic cells.
Which of the following statements best describes the function of a buffer?
- A. It permanently binds hydrogen ions.
- B. It causes the pH of a solution to become neutral.
- C. It decreases the pH of the solution.
- D. It enables resistance to a change in pH.
Correct Answer: D
Rationale: The correct answer is D: 'It enables resistance to a change in pH.' Buffers function by resisting changes in pH when small amounts of acid or base are added to a solution, thereby maintaining a stable pH. Option A is incorrect because buffers do not permanently bind hydrogen ions; they can release or absorb them as needed to maintain pH. Option B is incorrect because buffers do not necessarily cause a solution's pH to become neutral; they stabilize the pH at a specific value. Option C is incorrect; buffers can increase or decrease pH depending on the conditions to maintain stability. Therefore, the best description of a buffer's function is its ability to resist changes in pH.
If a mother's ______ cell contains mutated DNA, this mutation can be passed to her offspring.
- A. germ
- B. white blood
- C. stem
- D. somatic
Correct Answer: A
Rationale: The correct answer is A: 'germ.' Germ cells, which include egg and sperm cells, are responsible for passing genetic information to offspring. Mutations in these cells can be inherited by the next generation. In contrast, mutations in somatic cells (D), like skin or muscle cells, are not passed on to offspring as they are not involved in reproduction. White blood cells (B) and stem cells (C) are not directly involved in transmitting genetic mutations to offspring.
What is the function of the myelin sheath for a nerve cell?
- A. Sensory perception
- B. Insulation
- C. Nutrition
- D. Regeneration
Correct Answer: B
Rationale: The myelin sheath functions as an insulator for nerve cells, enabling the rapid transmission of electrical impulses along the nerve fiber. This insulation is essential for maintaining the speed and efficiency of nerve signal conduction. Sensory perception involves detecting sensory stimuli, nutrition involves the supply of nutrients, and regeneration is the process of regrowth or repair, which are distinct functions from what the myelin sheath provides.
Which of the following vessels carries oxygenated blood?
- A. Pulmonary vein
- B. Superior vena cava
- C. Pulmonary artery
- D. Inferior vena cava
Correct Answer: A
Rationale: The correct answer is A, the pulmonary vein. The pulmonary vein carries oxygenated blood from the lungs back to the heart. It is crucial to differentiate between the pulmonary vein, which carries oxygenated blood, and the pulmonary artery, which carries deoxygenated blood. This understanding is fundamental in comprehending the flow of oxygen-rich and oxygen-poor blood within the cardiovascular system.