ATI TEAS Practice Science Test

Correct Answer: C

Rationale: The correct answer is C: Flexor. Flexor muscles are responsible for bending a joint by decreasing the angle between the bones they act upon. They contract to bring two body parts closer together. Cardiac muscles (A) are found in the heart and control its pumping action. Extension (B) refers to the straightening of a joint, not bending. Smooth muscles (D) are found in various organs and are not directly involved in joint movement. Therefore, the flexor muscle (C) is the correct choice for causing a joint to bend.

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.

Correct Answer: A

Rationale: The correct answer is A: Forms neural circuits. Interneurons are responsible for forming connections between sensory neurons and motor neurons, creating neural circuits that allow for complex processing and coordination of signals within the central nervous system. They do not directly interact with effectors (choice B), send impulses to the CNS (choice C), or function as efferent nerve cells (choice D). Interneurons integrate and relay information within the CNS, playing a crucial role in coordinating various functions such as reflexes, sensory processing, and motor control.

Correct Answer: D

Rationale: The correct answer is D because it specifically refers to the process of selective permeability by stating that sodium ions must travel through ion channels to enter the cell. This demonstrates that the cell membrane allows certain substances to pass through while blocking others. Receptors on the cell's surface (A) and cell communication (B) are related to cell function but do not directly confirm selective permeability. Environmental changes affecting cell size (C) are more about cell response than membrane permeability. In summary, choice D is correct because it directly addresses the concept of selective permeability, while the other choices do not provide direct evidence of this property.

Correct Answer: A

Rationale: During Prophase I of meiosis, chiasmata structures form as homologous chromosomes exchange genetic material through crossing over. This occurs after homologous chromosomes pair up during synapsis. Chiasmata play a crucial role in genetic diversity. In contrast, Prophase II is focused on preparing the cells for division, and chiasmata formation does not occur during this phase. Metaphase I is characterized by the alignment of homologous chromosomes at the metaphase plate, while Metaphase II involves the alignment of sister chromatids. Therefore, the correct answer is A: Prophase I, as it is the specific phase where chiasmata formation takes place.