TEAS 7 practice test science

Correct Answer: A

Rationale: When hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), it forms sodium chloride (NaCl) and water (H2O) according to the following chemical equation: HCl + NaOH -> NaCl + H2O. Therefore, the correct answer is NaCl + H2O (Choice A). This reaction is a classic acid-base neutralization reaction where the acid (HCl) reacts with the base (NaOH) to form a salt (NaCl) and water (H2O). Choice B (NaOH + HCl) is incorrect because the order of the reactants matters in a chemical reaction, and in this case, HCl is the acid reacting with NaOH. Choices C (Na2Cl + H2O) and D (NaClO3 + H2) are incorrect because they do not represent the products of the reaction between HCl and NaOH as per the balanced chemical equation.

Correct Answer: C

Rationale: A) Mutations in genes can introduce new genetic variations into a population, which can be acted upon by natural selection. B) Differential survival and reproduction based on traits is a key component of natural selection, as individuals with advantageous traits are more likely to survive and pass on their genes to the next generation. C) Inheritance of acquired characteristics, also known as Lamarckism, is not a mechanism of evolution by natural selection. Traits acquired during an individual's lifetime (such as strong muscles from working out) are not passed on to offspring. D) Competition for resources in an environment can drive natural selection by favoring individuals with traits that help them better compete for limited resources. Therefore, the correct answer is C) Inheritance of acquired characteristics (like strong muscles from working out), as it is not a mechanism that can directly cause evolution by natural selection.

Correct Answer: B

Rationale: Fingernails and toenails are primarily made of a protein called keratin. Keratin is a tough, fibrous protein that provides structure and strength to nails, hair, and the outer layer of skin. Collagen, as mentioned, is found in the dermis and is not the primary component of nails. Melanin provides pigment to the skin and hair, not the structure of nails. Sebum is an oily substance produced by the skin's sebaceous glands and is not a structural component of nails.

Correct Answer: D

Rationale: The P wave on an ECG represents the depolarization of the atria. This electrical activity initiates the contraction of the atria, allowing blood to be pumped into the ventricles. The P wave is the first positive deflection seen on the ECG and signifies the beginning of atrial depolarization, which is a critical step in the cardiac cycle. Choices A, B, and C are incorrect. Option A (The repolarization of the ventricles) is represented by the T wave on the ECG. Option B (The electrical conduction through the AV node) is not represented by the P wave but rather by the PR interval on the ECG. Option C (The contraction phase of the ventricles (systole)) is more related to the QRS complex on the ECG, which represents ventricular depolarization and contraction.

Correct Answer: A

Rationale: As an object falls freely near the Earth's surface, its potential energy decreases. This decrease occurs because the gravitational potential energy is being converted into kinetic energy as the object accelerates due to gravity. According to the law of conservation of energy, the total mechanical energy (the sum of potential and kinetic energy) remains constant in the absence of non-conservative forces like air resistance. Choice B ('Potential energy increases') is incorrect because the object's potential energy is being converted into kinetic energy, leading to a decrease. Choice C ('Potential energy remains constant') is incorrect as the conversion of potential energy to kinetic energy results in a decrease in potential energy. Choice D ('Potential energy becomes zero') is incorrect because potential energy is not reduced to zero but is transformed into kinetic energy as the object falls.