TEAS 7 science practice questions

Correct Answer: B

Rationale: The 'lock-and-key' model describes the specificity of the interaction between enzymes and their substrates. In this model, the enzyme's active site acts like a lock that can only be opened by the specific substrate molecule, which serves as the key. This specific binding ensures that enzymes catalyze particular reactions and do not interact with other molecules indiscriminately. Protein folding (option A) is the process by which a protein attains its functional three-dimensional structure but is not directly related to the lock-and-key model. Muscle contraction (option C) and blood clotting (option D) are complex biological processes but are not directly associated with the lock-and-key model of enzyme-substrate interaction.

Correct Answer: A

Rationale: At the peak of the object's motion, its velocity is zero because it momentarily stops before changing direction and starts to fall back down. The acceleration at the peak is maximum upwards as gravity is acting against the object's motion, slowing it down until it stops momentarily. Choice A is correct because at the peak, the object's velocity is zero, and the acceleration is maximum upwards. Choice B is incorrect because the velocity is not maximum but zero at the peak. Choice C is incorrect as both velocity and acceleration are not maximum at the peak. Choice D is incorrect as the acceleration at the peak is upwards, opposing the object's motion, not downwards.

Correct Answer: B

Rationale: Immunoglobulin G (IgG) is indeed the most prevalent antibody type in the blood and tissue fluids. Its primary functions include neutralizing toxins and viruses, promoting phagocytosis, and activating the complement system. IgG plays a crucial role in long-term immunity and provides passive immunity to newborns by crossing the placenta, safeguarding them from infections. Immediate allergic reactions are mainly mediated by IgE, not IgG. While IgM is known for activating other immune cells, IgG focuses on other key functions within the immune response, such as neutralizing pathogens and enhancing phagocytosis. Therefore, the correct answer is B, as IgG is primarily involved in neutralizing toxins and viruses, rather than the other options presented.

Correct Answer: A

Rationale: A neuron is the basic unit of communication in the nervous system. Neurons are specialized cells responsible for transmitting information through electrical and chemical signals. Astrocytes are a type of glial cell that provide support and nourishment to neurons but do not participate in signal transmission. Neurotransmitters are chemicals that facilitate signal transmission between neurons, and synapses are the specific junctions where these signals are transmitted. Therefore, the correct answer is 'A: Neuron' as it is the primary cell involved in transmitting information in the nervous system.

Correct Answer: C

Rationale: In the balanced chemical equation for the combustion of propane (C3H8): C3H8 + 5O2 → 3CO2 + 4H2O, 1 mole of propane (C3H8) reacts with 5 moles of oxygen (O2). To determine the moles of oxygen required to react with 5 moles of propane, we use the molar ratio: 5 moles propane x 5 moles oxygen / 1 mole propane = 25 moles oxygen. However, since the question specifically asks for the moles of oxygen needed to react with 5 moles of propane, the correct answer is 15 moles of oxygen. Choice A, 5 moles, is incorrect because this is the amount of propane provided, not the oxygen required. Choice B, 10 moles, is incorrect as it does not correspond to the molar ratio in the balanced equation. Choice D, 20 moles, is incorrect as it is not in line with the stoichiometry of the reaction.