Practice TEAS Science Test

Correct Answer: B

Rationale: The correct answer is B: Thyroxine. Thyroxine is produced by the thyroid gland and plays a crucial role in regulating the body's metabolism by controlling the rate at which cells use energy. Insulin is a hormone that regulates blood sugar levels, not metabolism. Melatonin is responsible for regulating sleep-wake cycles, not metabolism. Adrenaline, also known as epinephrine, is involved in the fight or flight response and does not directly regulate metabolism.

Correct Answer: B

Rationale: The correct answer is B: Hydrogen bond. Water molecules are held together by hydrogen bonds, which form between the hydrogen atom of one water molecule and the oxygen atom of another. This bond is weaker than a covalent bond but still strong enough to keep water molecules attracted to each other. Covalent bonds (choice A) involve the sharing of electrons between atoms, not present in water. Ionic bonds (choice C) involve the transfer of electrons between atoms, not applicable to water. Peptide bonds (choice D) are found in proteins, not in water molecules.

Correct Answer: B

Rationale: The correct answer is B: Protein. Proteins are macromolecules composed of amino acids, which always contain nitrogen in their structure. Amino acids have an amine group (-NH2), which is where the nitrogen is found. Fatty acids (choice A) do not contain nitrogen in their structure. Lipids (choice C) and carbohydrates (choice D) also do not contain nitrogen in their basic structure. Therefore, protein is the only macromolecule among the choices that will always contain nitrogen.

Correct Answer: B

Rationale: The correct answer is B: Hypothalamus. The hypothalamus is responsible for maintaining homeostasis in the body by regulating various bodily functions such as body temperature, thirst, hunger, sleep, and hormonal balance. It receives input from different parts of the body and initiates responses to maintain internal stability. The brainstem (A) is involved in basic life functions like breathing and heart rate but does not play a direct role in homeostasis. The medulla oblongata (C) controls involuntary functions like breathing and swallowing. The cerebrum (D) is responsible for higher brain functions like thinking and voluntary movements, not for maintaining homeostasis.

Correct Answer: B

Rationale: The correct answer is B: To fight infection. White blood cells are a vital part of the immune system and are responsible for identifying and destroying pathogens like bacteria and viruses. They play a crucial role in defending the body against infections. A: White blood cells do not transport oxygen. That is the role of red blood cells. C: Red blood cells, not white blood cells, carry oxygen throughout the body. D: While white blood cells can produce antibodies as part of the immune response, their primary function is to directly combat infections.