ATI TEAS Practice Science Test

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: A

Rationale: The correct answer is A: Adenine. Adenine forms a complementary base pair with cytosine through hydrogen bonding in DNA. This pairing is essential for maintaining the structure and stability of the DNA double helix. Adenine and cytosine form two hydrogen bonds between them. Choices B, C, and D are incorrect because cytosine does not bind with itself (B), guanine (C), or thymine (D) in DNA. Thymine pairs with adenine, while guanine pairs with cytosine. Therefore, the correct base that binds with cytosine is adenine.

Correct Answer: C

Rationale: To calculate the mass of the atom, we add the number of protons and neutrons since electrons have negligible mass. In this case, 17 protons + 20 neutrons = 37. Therefore, the correct answer is C. Choice A is incorrect because it only considers the number of protons. Choice B is incorrect because it only considers the number of neutrons. Choice D is incorrect because it does not take into account the total number of protons and neutrons in the atom.

Correct Answer: B

Rationale: The correct answer is B because endocrine glands release hormones directly into the bloodstream. Therefore, an extensive network of blood vessels is necessary to facilitate the direct release of hormones into the blood for systemic circulation. The other choices are incorrect because: A: Filtering waste from the blood is the function of the kidneys, not the endocrine glands. C: Blood does not "empty" into the endocrine system; rather, hormones are released into the bloodstream. D: Endocrine glands do not filter waste; instead, they produce and release hormones into the blood for various physiological functions.

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.