ati teas 7 science

Correct Answer: D

Rationale: The correct answer is D because chromosomal nondisjunction can lead to various genetic disorders such as Down syndrome (A), caused by an extra chromosome 21. Nondisjunction can also result in Turner syndrome (B) in females due to the absence of one X chromosome, and Klinefelter syndrome (C) in males with one or more extra X chromosomes. Therefore, all the options are potential consequences of chromosomal nondisjunction.

Correct Answer: D

Rationale: Certainly! The correct answer is D because saltatory conduction is faster than normal nerve conduction (A), occurs from one node of Ranvier to the next (B), and only occurs in myelinated neurons (C). This process involves the rapid transmission of action potentials in myelinated axons, where the impulse "jumps" from one node of Ranvier to the next, skipping the myelinated regions in between. This allows for faster conduction speeds compared to continuous conduction in unmyelinated neurons. Therefore, all of the statements in options A, B, and C are accurate descriptions of saltatory conduction, making option D the correct choice.

Correct Answer: C

Rationale: The correct answer is C: Exceptional stability of the nucleus. Magic numbers are specific numbers of protons or neutrons that result in a more stable nucleus due to the arrangement of nucleons in energy levels. This stability is a result of closed shells, leading to lower energy states and less tendency for decay. Choices A and B are incorrect as magic numbers actually contribute to increased stability, leading to decreased nuclear instability and lower radioactive decay rates. Choice D is incorrect because magic numbers do not lead to increased instability or enhanced decay rates, but rather to exceptional stability.

Correct Answer: B

Rationale: Insulin is the correct answer as it is responsible for lowering blood sugar levels by promoting the uptake of glucose into cells. Glucagon raises blood sugar levels, adrenaline and cortisol are stress hormones that increase blood sugar levels. Therefore, the correct choice is B.

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.