ATI TEAS Practice Science Test

Correct Answer: A

Rationale: The dependent variable in a study is the outcome that is being measured or tested. In this scenario, the weight of the fish is being measured weekly as a result of being fed different amounts of food daily. The fish weight is directly influenced by the amount of food they consume, making it the dependent variable. This is the variable that changes in response to the independent variable, which is the amount of food given. Summary: A: Weight of the fish - Correct, as it is the outcome being measured. B: Type of food used - Incorrect, as this is not the variable being tested. C: Number of fish tanks - Incorrect, as this is not the variable being measured. D: Frequency of feedings - Incorrect, as this is not the outcome being tested.

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: A

Rationale: The correct answer is A: Diffusion. Gas exchange in the respiratory system occurs through diffusion, where oxygen moves from the alveoli in the lungs to the blood and carbon dioxide moves from the blood to the alveoli. This process is driven by a concentration gradient, allowing for the exchange of gases between the air and blood. Exhalation (choice B) is the process of expelling air from the lungs, not the mechanism of gas exchange. Inspiration (choice C) is the process of inhaling air into the lungs, but it is not directly involved in gas exchange. Ventilation (choice D) refers to the movement of air into and out of the lungs and is necessary for gas exchange to occur but is not the actual mechanism of gas exchange itself.

Correct Answer: D

Rationale: The correct answer is D: Melanocyte-stimulating hormone. Melanocyte-stimulating hormone stimulates the melanocytes in the skin to produce melanin, the pigment responsible for skin color. This hormone darkens the skin by increasing melanin production. A: Follicle-stimulating hormone is involved in reproductive functions, not skin color changes. B: Growth-stimulating hormone primarily affects growth and development, not skin color. C: Thyroid-stimulating hormone regulates thyroid function, not skin color.

Correct Answer: A

Rationale: The correct answer is A: Embryogenesis. During the first trimester of gestation, the developing organism goes through the process of embryogenesis, where the embryo forms and major organ systems begin to develop. Fertilization (B) occurs at the beginning of pregnancy, not during the first trimester. Meiosis (C) is the process of cell division that produces gametes, not directly related to the first trimester of gestation. Menstruation (D) is the shedding of the uterine lining if fertilization does not occur, not a developmental process during pregnancy.