TEAS 7 science practice

Correct Answer: B

Rationale: Biological classification, also known as taxonomy, is the science of categorizing and organizing living organisms based on shared characteristics. The main purpose of biological classification is not to create a rigid and unchanging system (option A) or to simplify nature into neat and tidy categories (option C). Instead, it aims to help us understand the diversity of life on Earth and how different organisms are related to each other. By classifying organisms into groups based on their evolutionary relationships, we can gain insights into the interconnectedness of life and better appreciate the complexity and beauty of the natural world. Assigning organisms to specific ecological niches (option D) is more related to ecological studies rather than biological classification.

Correct Answer: A

Rationale: When a wave enters a different medium, its frequency remains constant. Frequency is an intrinsic property of the wave determined by its source, and it does not change when transitioning between different mediums. On the other hand, wavelength, amplitude, and speed of the wave can all be altered when the wave moves from one medium to another. Wavelength is dependent on the speed of the wave and can change when entering a different medium due to differences in propagation speed. Amplitude can also change as it is influenced by factors like energy loss or gain at the boundary of the mediums. Speed, determined by the medium's properties, typically changes when a wave transitions between different mediums due to variations in the medium's density and elasticity.

Correct Answer: B

Rationale: Deuterium, as an isotope of hydrogen, has an atomic number of 1 and a mass number of 2. The nucleus of deuterium contains one proton (as in all hydrogen atoms) and one neutron, totaling 2 nucleons in the nucleus. Therefore, the correct answer is that deuterium's nucleus contains a proton and a neutron. Choices A, C, and D are incorrect. Deuterium is not just a single proton (A), doesn't have two protons and an electron (C), and doesn't contain two neutrons (D). The correct composition of deuterium's nucleus is one proton and one neutron.

Correct Answer: A

Rationale: The diaphragm is the primary muscle responsible for inhalation. When it contracts, it moves downward, increasing the volume of the thoracic cavity and creating a pressure gradient that allows air to flow into the lungs. While the intercostal muscles also play a role in expanding the chest cavity during inhalation, the diaphragm is the main muscle involved in this process. Abdominal muscles and pectoral muscles are not directly involved in the process of inhalation.

Correct Answer: D

Rationale: The QRS complex on an ECG represents ventricular depolarization. This electrical activity is generated by the ventricular muscle cells. While the SA node generates the P wave, the AV node delays the impulse, and the Bundle of His and Purkinje fibers assist in rapidly conducting the impulse through the ventricles, it is the ventricular muscle cells that specifically create the QRS complex. Therefore, choice D, Ventricular muscle cells, is the correct answer. Choices A, B, and C are incorrect as they are primarily involved in initiating and coordinating the electrical impulses in the heart but do not directly generate the QRS complex on an ECG.