TEAS Practice Test Science

Correct Answer: A

Rationale: The correct answer is A: Helicase. Helicase is responsible for unwinding the double-stranded DNA during replication by breaking the hydrogen bonds between the base pairs. This allows the DNA strands to separate and serve as templates for the synthesis of new DNA strands by DNA polymerase. Ligase is responsible for joining the DNA fragments together, nuclease is involved in DNA repair by cutting out damaged DNA, and polymerase is responsible for synthesizing new DNA strands based on the template strands. Therefore, only helicase directly unwinds the double-stranded DNA during replication.

Correct Answer: C

Rationale: The correct answer is C: Thymus. The thymus is responsible for maturing T cells, a type of white blood cell crucial for immune responses. The thymus is where immature T cells develop into functional T cells through a process called thymic education. The other choices are incorrect because the hypothalamus (A) is involved in regulating hormones, the pineal gland (B) regulates sleep-wake cycles, and the thyroid (D) produces hormones that regulate metabolism. These structures do not have a direct role in maturing T cells.

Correct Answer: B

Rationale: The correct answer is B: Larynx. The larynx houses the vocal cords, which vibrate to produce sound for voice production. The pharynx is involved in swallowing, the trachea is responsible for air passage to the lungs, and the bronchi are the airways that branch off from the trachea into the lungs. The larynx specifically contains the vocal cords, making it the structure responsible for voice production.

Correct Answer: B

Rationale: The correct answer is B: Red blood cells. Red blood cells contain hemoglobin, a protein that binds to oxygen in the lungs and carries it to tissues throughout the body. This process is essential for oxygen transport and delivery to cells for energy production. White blood cells (A), platelets (C), and plasma (D) do not have the specific function of transporting oxygen in the blood. White blood cells are involved in the immune response, platelets help in blood clotting, and plasma is the liquid component of blood that carries nutrients and waste products.

Correct Answer: A

Rationale: The correct answer is A: Femur. Long bones are characterized by their elongated shape, with the length exceeding the width. The femur, as the thigh bone, perfectly fits this description. It serves as a major weight-bearing bone and plays a crucial role in movement and support. Ribs and cranial bones (Choice B) belong to the category of flat bones. Sesamoid bones (Choice C) are small bones embedded within tendons. Vertebrae and hip bones (Choice D) are classified as irregular bones due to their complex shapes and structures.