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: C

Rationale: The correct answer is C because not all macromolecules contain phosphorus. Macromolecules such as proteins, carbohydrates, and lipids contain carbon, hydrogen, and oxygen but not necessarily phosphorus. Proteins and carbohydrates can exist as single chains or be branched, so choices A and B are not characteristics that exclude a macromolecule. Choice D is also incorrect because not all macromolecules are used by the body, as some like cellulose are not digestible by humans.

Correct Answer: B

Rationale: The correct answer is B: Laryngopharynx. The laryngopharynx is part of the pharynx where both the respiratory and digestive systems intersect. It serves as a common passageway for both food and air. When we swallow, the epiglottis covers the larynx to prevent food from entering the trachea. A: The esophagus is solely a passageway for food from the mouth to the stomach. C: The nasopharynx is a part of the upper respiratory tract and not involved in the passage of food. D: The trachea is strictly a passageway for air to enter and exit the lungs.

Correct Answer: C

Rationale: Natural Killer Cells produce Perforin to create pores in the target cell membrane, leading to target cell rupture. Perforin forms channels in the cell membrane, allowing for the entry of granzymes that induce apoptosis in the target cell. Interferon is produced by infected cells to inhibit viral replication. Apoptosis is a programmed cell death process. Antibodies are produced by B cells in response to antigens but are not involved in the direct lysis of target cells by Natural Killer Cells.

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.