ati teas 7 science

Correct Answer: D

Rationale: The correct answer is D, the medium's properties. The speed of a wave in a given medium is determined by the properties of that medium, such as its density and elasticity. This affects how fast the wave can travel through the medium. Amplitude (A) is the height of a wave, which does not directly impact the speed of the wave. Wavelength (B) is the distance between two consecutive points of a wave, and while it can affect the wave's behavior, it does not solely determine its speed. Frequency (C) is the number of wave cycles that pass a point in a given time, which is related to speed but not the sole determinant. Therefore, the correct answer is D as the properties of the medium directly influence the speed of the wave.

Correct Answer: B

Rationale: The correct answer is B: Bacteria. Dysentery is primarily caused by pathogenic bacteria such as Shigella or Escherichia coli. Bacteria are single-celled microorganisms that can infect the intestines and cause symptoms like bloody diarrhea and abdominal pain. Helminths are parasitic worms that typically cause different types of infections. Protozoa are single-celled organisms that can also cause intestinal infections, but they are not the primary cause of dysentery. Fungi do not typically cause dysentery; they are more commonly associated with skin infections or respiratory issues. In summary, the correct answer is B because dysentery is most commonly caused by bacterial infections in the intestines.

Correct Answer: D

Rationale: The correct answer is D because all the options are valid obstacles to achieving controlled nuclear fusion on Earth. Lack of suitable materials (A) is crucial due to extreme conditions, limited fusion fuels (B) can hinder sustained reactions, and containing plasma (C) is challenging to prevent energy loss. Therefore, all factors must be addressed for successful fusion energy production.

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: Myosin. Myosin is the protein complex responsible for the thick filament in the sarcomere. It forms cross-bridges with actin during muscle contraction. Actin (choice A) is the thin filament in the sarcomere. Tropomyosin (choice C) is a regulatory protein that covers the myosin-binding sites on actin when the muscle is at rest. Troponin (choice D) is another regulatory protein that helps regulate muscle contraction by binding calcium ions.