ATI TEAS Science

Correct Answer: C

Rationale: The correct answer is C: The glomerulus. The glomerulus is a cluster of capillaries within the Bowman's capsule where blood filtration occurs. It functions as the main filter of the blood entering the kidney by allowing small molecules like water, glucose, and wastes to pass through while retaining larger molecules like proteins and blood cells. The Loop of Henle is responsible for water reabsorption, not blood filtration. The Bowman's capsule is the initial structure where the glomerulus is located, but it is not the main filter. The nephron is the functional unit of the kidney composed of the glomerulus, Bowman's capsule, and tubules, so it encompasses the other structures mentioned.

Correct Answer: A

Rationale: The correct answer is A because in a primary immune response, the first event is the recognition and phagocytosis of pathogens by macrophages. This is crucial for initiating the immune response by presenting antigens to T cells. Neutrophils (choice B) are important in later stages as part of the innate immune response. B lymphocytes (choice C) produce antibodies later in the response. Helper T cells (choice D) are activated by the antigens presented by macrophages and play a role in coordinating the immune response but are not the first event.

Correct Answer: D

Rationale: The correct answer is D because bones are resistant to shattering due to the intricate balance of minerals like calcium and phosphorus, along with collagen fibers. Calcium salts alone (choice A) only provide hardness, not flexibility. Collagen fibers (choice B) provide strength but not hardness. Bone marrow and blood vessels (choice C) support bone health but don't contribute directly to resistance to shattering. The combination of minerals and collagen fibers in choice D provides both hardness and flexibility, making bones resistant to shattering.

Correct Answer: A

Rationale: The correct answer is A: A control. A control in an experiment is used as a standard for comparison because it remains unchanged and is not subjected to the experimental treatment. By comparing the results of the experimental group to the control group, researchers can determine the effectiveness of the treatment. Variables (B) and constants (C) are factors that are manipulated or kept consistent, respectively, in an experiment but do not serve as a standard for comparison. Collected data (D) is the outcome of the experiment and is not used as a standard for comparison.

Correct Answer: B

Rationale: The correct answer is B: Secondary structure. Secondary structure is defined by the local folds and coils in the protein's polypeptide backbone, such as alpha helices and beta sheets. This level of structure does not involve interactions between different regions of the protein (tertiary) or multiple protein subunits (quaternary). Primary structure (A) refers to the linear sequence of amino acids. Tertiary structure (C) involves the 3D arrangement of secondary structures and other elements in a single polypeptide chain. Quaternary structure (D) pertains to the arrangement of multiple polypeptide subunits in a protein complex.