ati teas 7 science

Correct Answer: B

Rationale: The correct answer is B: One layer. Simple epithelium consists of a single layer of cells. This arrangement allows for efficient diffusion and absorption due to the short distance between cells and the underlying tissues. Option A is incorrect because epithelial tissue always has at least one layer. Option C is incorrect as it describes stratified epithelium, which has two or more layers. Option D is incorrect as it refers to stratified squamous epithelium, not simple epithelium.

Correct Answer: B

Rationale: The adrenal glands are responsible for secreting adrenaline and cortisol in response to stress, triggering the fight-or-flight response. Adrenaline increases heart rate and blood flow, while cortisol releases energy stores. The pancreas regulates blood sugar, the thyroid gland controls metabolism, and the pituitary gland regulates hormone production but are not directly involved in the fight-or-flight response.

Correct Answer: D

Rationale: The correct answer is D, the independent variable. This is the variable that is intentionally changed or manipulated by the researcher in a scientific investigation to observe its effect on the dependent variable. By varying the independent variable, the researcher can determine if changes in this variable cause changes in the dependent variable. The control (B) is used as a baseline for comparison, the hypothesis (C) is a proposed explanation, and the dependent variable (A) is the variable being measured as a result of changes in the independent variable.

Correct Answer: A

Rationale: The correct answer is A because the atomic number represents the number of protons in the nucleus of an atom, which determines the element's identity. The mass number is the total number of protons and neutrons in the nucleus, indicating the atom's mass. The number of electrons is not directly related to either the atomic or mass number, eliminating choices B and D. Choice C is incorrect because the atomic number specifically refers to the number of protons, not neutrons. Thus, choice A is the only accurate explanation of the difference between the atomic number and the mass number.

Correct Answer: A

Rationale: The correct answer is A: Neuron. Neurons are the fundamental unit of the nervous system because they are specialized cells that transmit information through electrical and chemical signals. Neurons have a unique structure with dendrites, cell body, and axon, allowing them to receive, process, and transmit signals. Nerves (B) are bundles of neurons, ganglia (C) are clusters of neuron cell bodies, and neuroglia (D) are support cells in the nervous system. Neurons are the primary functional unit responsible for communication in the nervous system.