ati teas 7 science

Correct Answer: B

Rationale: The correct answer is B. Sunscreen protects the skin by absorbing UV rays and converting them to heat. This process prevents the UV rays from penetrating the skin and causing damage. Reflecting UV rays (A) would not be as effective as absorbing them. Blocking UV rays completely (C) is not possible with sunscreen. Stimulating melanin production (D) is not the main mechanism of how sunscreen works to protect the skin.

Correct Answer: B

Rationale: The correct answer is B: Protons and neutrons only. Electrons are not found in the nucleus, as they orbit around the nucleus in electron shells. Protons and neutrons are the subatomic particles found within the nucleus of an atom. Protons have a positive charge, while neutrons are neutral. The nucleus contains almost all of the atom's mass and is positively charged due to the presence of protons. Choice A is incorrect because electrons are not part of the nucleus. Choice C is incorrect because electrons are not present in the nucleus. Choice D is incorrect as protons and neutrons are indeed constituents of the atomic nucleus.

Correct Answer: B

Rationale: The correct answer is B: Cardiac muscle. Cardiac muscle is found exclusively in the heart, allowing it to contract rhythmically and involuntarily to pump blood throughout the body. Smooth muscle (A) is found in organs like the intestines and blood vessels, not in the heart. Skeletal muscle (C) is attached to bones and responsible for voluntary movements, while voluntary muscle (D) is a general term that refers to skeletal muscle controlled voluntarily. Therefore, the unique characteristics of cardiac muscle make it the correct answer for this question.

Correct Answer: B

Rationale: Ductility refers to the ability of a substance to be drawn into thin wires. This is because ductile materials can undergo plastic deformation without breaking when subjected to tensile stress. Conductivity (choice A) refers to the ability to conduct electricity, viscosity (choice C) refers to a fluid's resistance to flow, and malleability (choice D) refers to the ability of a substance to deform under compressive stress without breaking. Therefore, the correct answer is B as it specifically relates to the property of being drawn into thin wires.

Correct Answer: B

Rationale: The correct answer is B: Atom. An atom is the smallest unit of matter that retains the properties of an element. Atoms are made up of protons, neutrons, and electrons. A molecule (A) consists of two or more atoms bonded together. A compound (C) is a substance composed of two or more different elements chemically bonded. An element (D) is a pure substance made up of only one type of atom. Therefore, the smallest unit of matter is the atom.