ATI TEAS Science Test

Correct Answer: C

Rationale: Weight gain when consuming excess calories is not an example of a homeostatic mechanism. Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes. The other options listed (A, B, and D) involve physiological responses aimed at restoring balance or stability within the body (e.g., regulating body temperature, blood pressure, and blood sugar levels). Shivering, increasing heart rate, and secreting insulin are mechanisms to counteract specific imbalances and maintain internal equilibrium. In contrast, weight gain due to excess calorie intake does not represent a specific regulatory mechanism but rather an outcome of energy imbalance. The body stores excess energy as fat rather than actively regulating a physiological parameter to restore balance.

Correct Answer: C

Rationale: The lateral malleolus is a bony prominence on the lateral side of the ankle and is not part of the knee anatomy. The other options - medial collateral ligament, patella, and lateral meniscus - are all structures within the knee joint. The medial collateral ligament is located on the inner side of the knee, the patella is the kneecap, and the lateral meniscus is a cartilage structure within the knee joint. Therefore, the correct answer is C, lateral malleolus.

Correct Answer: D

Rationale: Endorphins are the class of hormones most likely to be released after a serious injury. Endorphins are the body's natural pain relievers and are produced in response to stress or pain, helping to alleviate discomfort and promote a sense of well-being. Acetylcholine is a neurotransmitter, not a hormone. Oxytocin is mainly involved in childbirth and lactation. Luteinizing hormone is involved in reproductive functions such as ovulation. Therefore, choices A, B, and C are incorrect in the context of a hormone release following a serious injury.

Correct Answer: B

Rationale: In an oxidation reaction, the substance being oxidized loses electrons, not gains them. An oxidizing agent is responsible for causing oxidation in another substance by accepting electrons, hence it undergoes reduction and loses electrons. Therefore, the correct statement is 'an oxidizing agent loses electrons,' making choice B the correct answer. Choices A, C, and D are incorrect because in an oxidation reaction, the oxidizing agent does not gain electrons, a reducing agent does not gain electrons, and a reducing agent does not lose electrons.

Correct Answer: A

Rationale: The correct answer is the Tricuspid valve. This valve is located between the right atrium and the right ventricle in the heart. Its primary function is to facilitate the flow of blood from the right atrium into the right ventricle and to prevent the backflow of blood. The Pulmonic valve (choice B) is situated between the right ventricle and the pulmonary artery, not between the right atrium and ventricle, making it incorrect. The Mitral valve (choice C) is found between the left atrium and the left ventricle, not the right side, so it is incorrect. The Aortic valve (choice D) is positioned between the left ventricle and the aorta, not involved in the right atrium and ventricle connection, hence it is also incorrect.