ati teas 7 science

Correct Answer: B

Rationale: The correct answer is B: Cytoplasm. Cytoplasm is the fluid-filled, jelly-like substance within the cell that suspends the organelles. It is where many cellular processes occur. The nucleus (A) contains genetic material, not the organelles. The plasma membrane (C) is the cell's outer boundary, not the internal fluid. The Golgi apparatus (D) is an organelle involved in processing and packaging proteins, not the cell's fluid. Therefore, the correct answer is cytoplasm.

Correct Answer: B

Rationale: The correct answer is B: 23. In humans, each normal cell contains 23 pairs of chromosomes, making a total of 46 chromosomes. The pairs consist of one chromosome from each parent, ensuring genetic diversity. Choices A, C, and D are incorrect because they do not reflect the accurate number of chromosome pairs in a human cell. Option A (46) is the total number of chromosomes, not pairs. Option C (64) and D (32) are not the correct numbers of chromosome pairs in a human cell.

Correct Answer: C

Rationale: Rationale: Cytosol is the liquid component of the cytoplasm and is not membrane-bound. Mitochondrion is a membrane-bound organelle responsible for energy production. Therefore, the difference between cytosol and mitochondrion is that the mitochondrion is a membrane-bound organelle, while cytosol is not. Summary: A: Incorrect. Cytosol is not a membrane-bound organelle, and the mitochondrion is also not membrane-bound. B: Incorrect. Cytosol is part of the cytoplasm, and the mitochondrion is also located within the cytoplasm. C: Correct. The mitochondrion is a membrane-bound organelle, while cytosol is not. D: Incorrect. Both the mitochondrion and cytosol are components of the cytoplasm, but the mitochondrion is membrane-bound, unlike cytosol.

Correct Answer: B

Rationale: The correct answer is B: In a covalent bond, the shared electrons spend more time closer to the more electronegative atom. This is because the more electronegative atom attracts the electrons more strongly, causing them to be closer to that atom. This creates a partial negative charge on the more electronegative atom and a partial positive charge on the other atom. This distribution of electron density contributes to the stability of the covalent bond. Choices A, C, and D are incorrect because: A: Are completely transferred to one atom - This describes an ionic bond, not a covalent bond. C: Remain equidistant between the two atoms - Shared electrons in a covalent bond are not equidistant but are closer to one atom. D: Do not influence the bond strength - The distribution of shared electrons significantly influences the strength and properties of a covalent bond.

Correct Answer: C

Rationale: The correct answer is C: Control sleep-wake cycles. Melatonin is primarily responsible for regulating our sleep-wake cycles, also known as the circadian rhythm. This hormone is released by the pineal gland in response to darkness, signaling to the body that it is time to sleep. Melatonin helps to synchronize our internal body clock with the natural day-night cycle. Choice A (Regulate blood pressure) is incorrect because melatonin does not play a direct role in regulating blood pressure. Choice B (Stimulate the digestive system) is incorrect as melatonin is not involved in stimulating the digestive system. Choice D (Maintain bone density) is also incorrect as melatonin's primary function is not related to bone density regulation.