ati teas 7 science

Correct Answer: C

Rationale: The correct answer is C: Vitamin D. When the skin is exposed to sunlight, a form of cholesterol in the skin is converted into Vitamin D. This vitamin plays a crucial role in calcium absorption and bone health. Vitamin A is not synthesized in the skin but obtained through diet. Vitamin C is obtained from fruits and vegetables. Vitamin E is a fat-soluble vitamin found in nuts and seeds. In summary, only Vitamin D is synthesized in the skin upon sunlight exposure, making it the correct answer.

Correct Answer: B

Rationale: In mitosis, sister chromatids are separated and move to opposite poles during Anaphase. This is when the spindle fibers shorten, pulling chromatids apart. Metaphase is when chromosomes align in the middle. Telophase is when the nuclear envelope reforms. Cytokinesis is the division of the cytoplasm. Therefore, B is correct as it specifically describes the phase where sister chromatids separate and move to opposite poles.

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: A

Rationale: The correct answer is A: Solid. Solids have both a definite volume and a definite shape because the particles are tightly packed and vibrate in fixed positions. This leads to a rigid structure and minimal movement, maintaining the shape and volume. In contrast, liquids (B) have a definite volume but take the shape of their container, gases (C) have neither a definite shape nor volume as they expand to fill the container, and plasmas (D) have no definite shape or volume due to their high energy state.

Correct Answer: B

Rationale: The correct answer is B: Autoimmune disease. In autoimmune diseases, the immune system mistakenly targets healthy cells and tissues, causing inflammation and damage. This is due to a breakdown in self-tolerance mechanisms. Immunodeficiency (A) is the opposite, where the immune system is weakened. Allergy (C) is an immune response to harmless substances, not attacking healthy tissues. Cancer (D) involves uncontrolled cell growth, not immune system attacking healthy tissues.