ati teas 7 science

Correct Answer: C

Rationale: The correct answer is C: Light energy from the sun. This is because photosynthesis, the process by which plants and other organisms convert light energy into chemical energy, is the primary source of energy in most ecosystems. Sunlight is essential for plants to produce food, which then sustains the entire food chain. Choice A (Chemical energy stored in bonds) is incorrect because this energy is a product of photosynthesis and not the primary source entering ecosystems. Choice B (Thermal energy from the Earth's core) is incorrect as it is not a significant source of energy for most ecosystems. Choice D (Kinetic energy from wind and water) is also incorrect as it is not the primary source of energy entering ecosystems, although it can play a role in some ecosystems.

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: B

Rationale: The correct answer is B because not all fungi are parasitic and harmful to humans. Some fungi are beneficial, while others are neutral. A is correct as fungi can be unicellular or multicellular. C is true as fungi are crucial in breaking down organic matter. D is accurate as some fungi, such as mushrooms, are consumed as food. Overall, choice B is false because it wrongly generalizes all fungi as harmful, which is not the case.

Correct Answer: A

Rationale: The correct answer is A: Stapes. The stapes is the smallest bone in the human body, located in the middle ear. It plays a crucial role in transmitting sound vibrations to the inner ear. The other choices are incorrect because the patella is a knee bone, phalanges are finger bones, and ribs are chest bones, none of which are the smallest bone in the body. The stapes' small size and specific location make it uniquely suited for its function in hearing.

Correct Answer: A

Rationale: The correct answer is A because polygenic inheritance refers to a trait that is influenced by multiple genes working together to produce a single phenotype. In contrast, pleiotropy occurs when a single gene has multiple effects on different traits. This distinction is crucial as it highlights the difference in the genetic basis of these phenomena. The other choices are incorrect because they either misinterpret the definitions of polygenic inheritance and pleiotropy (B and C) or provide vague statements without accurately distinguishing between the two concepts (D). The key to selecting the correct answer lies in understanding the fundamental genetic mechanisms underlying polygenic inheritance and pleiotropy.