ATI TEAS Practice Science Test

Correct Answer: C

Rationale: The correct answer is C: Hypothalamus. The hypothalamus is a major structure of the limbic system responsible for regulating various essential functions like emotions, behavior, and physiological processes. It plays a crucial role in the control of thirst, hunger, body temperature, and hormonal regulation. The brainstem (A) is involved in basic life functions like breathing and heart rate, but it is not a part of the limbic system. The spinal cord (B) primarily functions in transmitting sensory and motor signals but is not directly related to the limbic system. The cerebral cortex (D) is responsible for higher-order thinking, sensory processing, and motor functions but is not a major structure of the limbic system.

Correct Answer: A

Rationale: The correct answer is A: Adenine. Adenine forms a complementary base pair with cytosine through hydrogen bonding in DNA. This pairing is essential for maintaining the structure and stability of the DNA double helix. Adenine and cytosine form two hydrogen bonds between them. Choices B, C, and D are incorrect because cytosine does not bind with itself (B), guanine (C), or thymine (D) in DNA. Thymine pairs with adenine, while guanine pairs with cytosine. Therefore, the correct base that binds with cytosine is adenine.

Correct Answer: B

Rationale: The correct answer is B: Negative feedback. In this scenario, the body's response to a fever is an example of negative feedback mechanism. Negative feedback works to maintain homeostasis by reversing the direction of a change, in this case, reducing the fever to bring the body back to its normal temperature. This mechanism helps to regulate and stabilize bodily functions. Summary: A: Equal feedback is not a recognized type of feedback mechanism in biological systems. C: Neutral feedback does not actively regulate a response but rather allows it to continue unchanged. D: Positive feedback would amplify the fever response rather than work to reduce it and is usually seen in processes that need to be amplified, not regulated like in this scenario.

Correct Answer: A

Rationale: The correct answer is A: Cell. Cells are the most basic unit of structure in living things because they are the building blocks of all living organisms. Cells perform all the necessary functions for life, such as growth, reproduction, and energy production. Organelles are structures within cells, not the basic unit themselves. Oxygen is a vital component for life but not a structural unit. Pigments are molecules that give color and have specific functions in organisms but are not the basic unit of structure. Therefore, the correct choice is A: Cell.

Correct Answer: B

Rationale: The correct answer is B: Ribcage. The ribcage is a bony structure that surrounds and protects the lungs. It consists of ribs, sternum, and thoracic vertebrae, forming a protective cage around the vital organs in the thoracic cavity. The ribs provide a barrier against external forces and help maintain the shape and integrity of the lungs. The other choices are incorrect because the femur is a bone in the leg, the scapula is a bone in the shoulder, and the skull protects the brain, not the lungs.