ATI TEAS 7 Science

Correct Answer: C

Rationale: The correct answer is C: RBC (Red Blood Cell). RBCs are biconcave discs that are round and flat without a nucleus. This unique shape allows for efficient gas exchange and flexibility to pass through narrow capillaries. Rationale: 1. Plasma (Choice A) is the liquid component of blood that carries various substances but does not have a specific shape or structure like RBCs. 2. Platelets (Choice B) are cell fragments involved in blood clotting and do not have the described characteristics of a biconcave disc without a nucleus. 3. WBCs (Choice D) are white blood cells responsible for immune responses and have a nucleus, unlike RBCs. In summary, RBCs are the only blood constituent among the choices that fits the description provided in the question.

Correct Answer: A

Rationale: The correct answer is A: Stapes. The stapes is the smallest bone in the human body, located in the middle ear. It plays a crucial role in transmitting sound vibrations to the inner ear. The other choices are incorrect because the patella is a knee bone, phalanges are finger bones, and ribs are chest bones, none of which are the smallest bone in the body. The stapes' small size and specific location make it uniquely suited for its function in hearing.

Correct Answer: D

Rationale: The correct answer is D: tRNA. Transfer RNA (tRNA) carries amino acids to ribosomes during protein synthesis. tRNA has an anticodon that pairs with the mRNA codon, ensuring the correct amino acid is added to the growing polypeptide chain. A: DNA carries genetic information but does not directly participate in protein synthesis. B: mRNA carries the genetic information from DNA to the ribosomes but does not carry amino acids. C: rRNA is a structural component of ribosomes and helps in protein synthesis but does not carry amino acids to the ribosomes.

Correct Answer: C

Rationale: The correct answer is C: Phagocytes. Phagocytes are white blood cells responsible for the initial attack on pathogens by engulfing and digesting them. They include neutrophils, monocytes, and macrophages. Red blood cells (A) are not involved in the immune response. Platelets (B) are responsible for blood clotting, not attacking pathogens. Lymphocytes (D) play a role in specific immune responses but are not the primary cells responsible for the initial attack on pathogens.

Correct Answer: C

Rationale: The myelin sheath is derived from nervous tissue, specifically glial cells. Glial cells, also known as neuroglia, support and protect nerve cells. They produce the myelin sheath, which insulates nerve fibers and allows for faster transmission of nerve impulses. Epithelial tissue (choice A) primarily covers and lines body surfaces, muscle tissue (choice B) is responsible for movement, and connective tissue (choice D) provides support and structure to the body. None of these tissues are involved in the production of the myelin sheath, making them incorrect choices.