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From which component do RNA and DNA derive their names?
- A. From the sugar each contains
- B. From the structure of their nucleotides
- C. From the information they transfer
- D. From their formative processes
Correct Answer: A
Rationale: RNA and DNA derive their names from the sugar each contains. RNA stands for Ribonucleic Acid, with 'ribo' indicating the ribose sugar in its structure. DNA stands for Deoxyribonucleic Acid, with 'deoxyribo' referring to the deoxyribose sugar in its structure. The sugars in RNA and DNA molecules distinguish them and are the basis for their names. Choices B, C, and D are incorrect as they do not accurately explain how RNA and DNA derive their names.
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Why do high-salt content foods not require refrigeration to prevent spoilage?
- A. Osmosis
- B. Diffusion
- C. Active transport
- D. Passive transport
Correct Answer: A
Rationale: Osmosis is the natural process that prevents high-salt content foods from spoiling without the need for refrigeration. Osmosis involves the movement of water across a semi-permeable membrane from an area of lower solute concentration (water) to an area of higher solute concentration (salt). In high-salt content foods, the salt acts as a preservative by drawing moisture out of bacteria or other microorganisms, making it difficult for them to survive and spoil the food. This process helps in preserving the food and preventing spoilage even without refrigeration. Choices B, C, and D are incorrect because they do not involve the specific mechanism of water movement in response to the salt concentration in high-salt content foods.
Which light color would be most effective for growing green plants indoors?
- A. Blue
- B. Yellow
- C. Green
- D. Orange
Correct Answer: A
Rationale: Blue light is the most effective color for growing green plants indoors. Blue light has a higher energy level compared to other colors, which is crucial for promoting vegetative growth, strong stems, and lush foliage in plants. Additionally, blue light helps regulate plant growth hormones, making it essential for the overall health and development of green plants. Yellow, green, and orange light do not provide the necessary energy levels or spectrum needed for optimal plant growth, making them less effective choices for growing green plants indoors.
Which organelle is the site of energy production?
- A. Mitochondrion
- B. Vacuole
- C. Cell membrane
- D. Ribosome
Correct Answer: A
Rationale: The correct answer is A: Mitochondrion. The mitochondrion is the site of energy production in a cell. It is often referred to as the powerhouse of the cell because it is where cellular respiration occurs, generating energy in the form of adenosine triphosphate (ATP) through processes like the citric acid cycle and oxidative phosphorylation. The other organelles listed play different roles in the cell - vacuoles store materials, the cell membrane regulates the movement of substances in and out of the cell, and ribosomes are involved in protein synthesis.
How do green plants use nitrates in the nitrogen cycle?
- A. To synthesize proteins
- B. To store food
- C. To decompose ammonia
- D. To break down nitrites
Correct Answer: A
Rationale: Green plants use nitrates in the nitrogen cycle to synthesize proteins. Nitrogen is an essential component of amino acids, which are the building blocks of proteins. Plants take up nitrates from the soil through their roots and incorporate nitrogen into their proteins through the process of protein biosynthesis. This helps in their growth, development, and overall health. Choice B, 'To store food,' is incorrect because nitrates are primarily used for protein synthesis, not food storage. Choice C, 'To decompose ammonia,' is incorrect as plants do not decompose ammonia but rather utilize it through nitrification. Choice D, 'To break down nitrites,' is incorrect as plants typically convert nitrites into nitrates through a process called nitrate assimilation for protein synthesis.
What happens to glucose during glycolysis?
- A. Its energy is entirely lost.
- B. It splits into molecules of pyruvic acid.
- C. It is stored in NADH.
- D. It joins with molecules of citric acid.
Correct Answer: B
Rationale: During glycolysis, glucose undergoes a series of enzymatic reactions in the cytoplasm of the cell, resulting in its breakdown into two molecules of pyruvic acid. This process also generates ATP and NADH as energy carriers. Choice A is incorrect because glucose is not entirely lost, but rather converted into other molecules. Choice C is incorrect because NADH is a product of glycolysis, not a storage form for glucose. Choice D is incorrect as glucose does not join with molecules of citric acid during glycolysis, but rather in subsequent stages of cellular respiration.