Practice TEAS Science Test

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: D

Rationale: The correct answer is D: Type O. Type O blood lacks both A and B antigens, making it compatible with all blood types. As a result, it can be safely transfused to individuals with any blood type, earning it the title of the universal donor. Choice A (Type A) has A antigens, Choice B (Type B) has B antigens, and Choice C (Type AB) has both A and B antigens, making them not suitable for universal donation.

Correct Answer: B

Rationale: The correct answer is B: Medulla oblongata. This part of the brain is located in the brainstem and is responsible for controlling vital involuntary functions like breathing, heart rate, and blood pressure. It contains nuclei that regulate these activities and plays a crucial role in maintaining homeostasis. The cerebellum (A) is involved in coordinating movement and balance, the cerebrum (C) is responsible for higher brain functions like thinking and decision-making, and the thalamus (D) acts as a relay center for sensory information. However, they are not directly involved in controlling involuntary actions like breathing and heart rate.

Correct Answer: B

Rationale: The primary function of white blood cells is to fight infection. They are key components of the immune system, identifying and attacking pathogens like bacteria and viruses. White blood cells produce antibodies to neutralize invaders. This function helps the body defend against illnesses and maintain overall health. Choices A, C, and D are incorrect because carrying oxygen (A) is primarily done by red blood cells, transporting nutrients (C) is mainly performed by blood plasma, and transporting waste (D) is mainly the role of the kidneys and liver.

Correct Answer: B

Rationale: Iron is the correct answer because it is an essential component of hemoglobin, the protein in red blood cells responsible for transporting oxygen throughout the body. Without iron, the body cannot produce enough hemoglobin, leading to anemia. Calcium, potassium, and sodium do not play a direct role in hemoglobin synthesis. Calcium is important for bone health, potassium is crucial for nerve and muscle function, and sodium helps regulate fluid balance. Iron is the only element among the choices that is directly involved in hemoglobin formation.