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: D

Rationale: The correct answer is D: Oxygen. 1. Oxygen has 8 electrons in total, with 2 in the first shell and 6 in the second shell, following the 2-8-8 electron configuration rule. 2. Beryllium has 4 electrons with 2 in the first shell and 2 in the second shell. 3. Carbon has 6 electrons with 2 in the first shell and 4 in the second shell. 4. Helium has 2 electrons, filling the first shell. Therefore, Oxygen is the only element among the choices that fits the description of having 2 electrons in the first shell and 6 electrons in the second shell.

Correct Answer: B

Rationale: The correct answer is B (18). Ossification at the growth plate occurs during adolescence when bones undergo rapid growth and development. At around age 18, the growth plates begin to close as bone growth slows down, leading to ossification replacing cartilage. At age 5 (A), the growth plates are still actively contributing to bone growth. At age 42 (C) and 91 (D), ossification is more likely related to aging processes and repair rather than growth plate replacement.

Correct Answer: A

Rationale: The correct answer is A: Flagellum. Cells rely on flagella for movement because flagella are whip-like structures that enable cells to propel themselves through fluid environments. Flagella are composed of microtubules, which provide structural support and enable movement through their bending and contracting motion. Microtubules alone (B) do not facilitate movement; they serve as a scaffold within cells. Pili (C) are short, hair-like structures used for attachment rather than movement. Vesicles (D) are membrane-bound sacs involved in transportation within cells, not in cell movement. Therefore, flagellum is the most suitable structure for cellular movement.

Correct Answer: C

Rationale: The correct answer is C: Chromosome. A chromosome is a rod-shaped structure formed when a single DNA molecule and its associated proteins coil tightly before cell division. This coiling helps to compact the DNA and ensure it is evenly distributed to daughter cells during cell division. Centromere (A) is a specific region of a chromosome where sister chromatids are joined. Chromatid (B) refers to one of the two identical copies of a chromosome that are joined at the centromere. Gene (D) is a segment of DNA that carries the genetic information for a specific trait. Therefore, the correct answer is chromosome as it specifically describes the rod-shaped structure formed during cell division due to the coiling of DNA and proteins.