ati teas 7 science

Correct Answer: A

Rationale: The correct answer is A: Nucleosome. Nucleosomes are the basic units of DNA packaging in eukaryotic cells, consisting of DNA wrapped around histone proteins. This structure helps in compacting the DNA to fit inside the nucleus. Choice B (Chromatin) is a broader term for DNA and associated proteins, not a specific packaging structure. Choice C (Histone) refers to the protein component of nucleosomes, not the packaging structure itself. Choice D (Centromere) is a region on a chromosome where the kinetochore forms during cell division, not involved in DNA packaging.

Correct Answer: D

Rationale: The correct answer is D: Pancreas. The pancreas produces insulin and glucagon, which are hormones involved in regulating blood sugar levels. Insulin helps lower blood sugar levels, while glucagon helps raise them. The salivary glands (A) produce saliva for digestion, the liver (B) plays a role in metabolism and detoxification, and the gallbladder (C) stores and releases bile to aid in digestion. Therefore, the pancreas is the correct organ responsible for producing insulin and glucagon.

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: C

Rationale: The correct answer is C: To regulate body functions through hormones. The endocrine system consists of glands that produce hormones to regulate various bodily functions like metabolism, growth, and reproduction. This system helps maintain homeostasis by communicating through chemical messengers. Choices A, B, and D are incorrect as fighting infection is primarily the role of the immune system, oxygen transportation is done by the respiratory system, and food breakdown is the function of the digestive system.

Correct Answer: B

Rationale: The correct answer is B: The ability to maintain a stable internal environment. Homeostasis is the body's ability to regulate and maintain a stable internal environment despite external changes. This includes maintaining stable levels of temperature, pH, and nutrients. Choice A is incorrect because homeostasis is not solely about body temperature. Choice C is incorrect as it does not encompass the overall concept of homeostasis. Choice D is incorrect because although regulating blood glucose levels is part of homeostasis, it does not fully capture the broad scope of maintaining a stable internal environment.