ATI TEAS 7 Science

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: B

Rationale: The correct answer is B: Thyroxine. Thyroxine is a hormone produced by the thyroid gland that plays a key role in regulating metabolism. It controls the body's metabolic rate, impacting energy levels and weight. Adrenaline (A) is produced by the adrenal glands and is involved in the fight-or-flight response. Cortisol (C) is produced by the adrenal glands and is known as the stress hormone. Insulin (D) is produced by the pancreas and regulates blood sugar levels, not metabolism. Thyroxine directly influences metabolism, making it the correct choice.

Correct Answer: B

Rationale: The correct answer is B: Humoral immunity. B-cells produce antibodies that circulate in bodily fluids to combat pathogens. This is a key aspect of humoral immunity. A: Cell-mediated immunity involves T-cells directly attacking infected cells, not antibody secretion by B-cells. C: Innate immunity is non-specific and does not involve B-cells producing antibodies. D: Phagocytic immunity involves phagocytes engulfing and destroying pathogens, not antibody secretion by B-cells.

Correct Answer: A

Rationale: The correct answer is A: Convergent evolution. Dinosaurs evolving feathers before birds supports convergent evolution because it shows unrelated organisms (dinosaurs and birds) developing similar traits (feathers) independently to adapt to similar environmental pressures. This scenario is not an example of divergent evolution (B) where related organisms evolve different traits. It also does not demonstrate coevolution (C) where two species influence each other's evolution. The extinction of dinosaurs due to an asteroid impact (D) is not directly related to the evolution of feathers in dinosaurs before birds.

Correct Answer: B

Rationale: When a sound wave travels from air to water, its speed decreases because sound travels faster in denser mediums. Water is denser than air, so the speed of sound decreases. This decrease occurs due to the change in the medium's properties affecting the wave propagation speed. The other choices are incorrect because the speed of sound is not dependent on frequency (choice D) and it doesn't remain the same (choice C) when transitioning between different mediums. Choice A is incorrect as an increase in density leads to a decrease in speed, not an increase.