Practice TEAS Science Test

Correct Answer: C

Rationale: The correct answer is C because an allergic reaction is triggered by the release of histamine and other inflammatory molecules from mast cells, which are stimulated by Immunoglobulin E. This process leads to symptoms such as hives, itching, swelling, and difficulty breathing. Other choices are incorrect because: A: While integumentary and respiratory systems are involved in allergic reactions, they are not overactive systems but rather respond to the allergen. B: B-cells produce antibodies, not immunoglobulins directly related to allergic reactions. D: Histamine is involved in allergic reactions, but keratin and collagen are not typically associated with allergic responses.

Correct Answer: B

Rationale: The correct answer is B: Sebaceous gland. Sebaceous glands produce sebum, an oily substance that helps moisturize the skin and hair. The sudoriferous gland produces sweat, not oil. The hair follicle anchors the hair to the skin, it does not produce oil. Melanocytes are responsible for producing melanin, the pigment that gives skin its color, not oil. Therefore, the sebaceous gland is the structure responsible for producing oil to keep the skin and hair moisturized.

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: Depolarization of the SA node. The P-wave in an ECG represents atrial depolarization, which is initiated by the SA node. This electrical signal spreads through the atria causing them to contract. Choice A is incorrect because the P-wave corresponds to atrial depolarization, not repolarization. Choice C is incorrect as the QRS complex represents ventricular depolarization. Choice D is incorrect as the T-wave represents ventricular repolarization. Therefore, the SA node depolarization is accurately represented by the P-wave in an ECG.

Correct Answer: B

Rationale: The correct answer is B (2 ATP molecules produced per FADH2 molecule) in aerobic respiration. FADH2 enters the electron transport chain at a later stage compared to NADH, leading to the production of 2 ATP through oxidative phosphorylation. FADH2 donates electrons to Complex II, bypassing Complex I, resulting in a lower energy yield compared to NADH which donates electrons to Complex I. Choice A (1 ATP) is incorrect as FADH2 produces more ATP than that. Choice C (3 ATP) is incorrect as FADH2 produces 2 ATP, not 3. Choice D (4 ATP) is incorrect as FADH2 produces 2 ATP, not 4.