ATI TEAS 7 Science

Correct Answer: B

Rationale: The correct answer is B: Alveoli. Alveoli are tiny air sacs in the lungs where gas exchange occurs between the air in the lungs and the blood. Oxygen from the air enters the blood, and carbon dioxide from the blood exits into the air. Trachea (A) is the windpipe that carries air to and from the lungs. Bronchi (C) are the main airways that branch off from the trachea. Diaphragm (D) is a muscle that helps with breathing by expanding and contracting the lungs, but it is not directly involved in gas exchange.

Correct Answer: C

Rationale: The correct answer is C: Nucleus. The nucleus is responsible for controlling the activities of the cell because it houses the cell's DNA, which contains instructions for cellular functions. It regulates gene expression and controls the production of proteins. The Golgi apparatus (choice A) is involved in processing and packaging proteins. Mitochondria (choice B) are responsible for energy production. Ribosomes (choice D) are responsible for protein synthesis. However, the nucleus is the main organelle that directly regulates and controls the activities of the cell.

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: A

Rationale: The correct answer is A: Calcitonin. Calcitonin is produced by the thyroid gland and functions to lower blood calcium levels by promoting calcium deposition in bones and inhibiting calcium reabsorption in the kidneys. This hormone opposes the action of parathyroid hormone (PTH), which increases blood calcium levels by promoting calcium release from bones and increasing calcium reabsorption in the kidneys. Thyroxine is a thyroid hormone that regulates metabolism and growth, not calcium levels. Insulin is a hormone produced by the pancreas that regulates blood sugar levels, not calcium levels. Thus, A is the correct answer as it directly regulates calcium levels in the blood through its actions on bones and kidneys.

Correct Answer: B

Rationale: The correct answer is B: Ammonia (NH₃). Ammonia is a common base found in household products due to its ability to accept protons and increase the pH of solutions. It is commonly used in cleaning products such as glass cleaners and floor cleaners. A: Sodium chloride (NaCl) is a salt and not a base. C: Vinegar is acidic due to the presence of acetic acid. D: Lemon juice is also acidic due to the presence of citric acid. Therefore, B is the correct answer as it is a common base found in household products, while the other choices are either salts or acidic substances.