ati teas 7 science

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.

Correct Answer: B

Rationale: The correct answer is B: Neuron. A neuron is the basic structural and functional unit of the nervous system because it is responsible for transmitting electrical and chemical signals within the nervous system. Neurons have three main parts: dendrites, cell body, and axon. Dendrites receive signals from other neurons, the cell body processes these signals, and the axon transmits signals to other neurons or to muscles and glands. The other choices, A: Axon, C: Dendrite, and D: Synapse, are all components of a neuron but do not individually represent the complete functional unit of the nervous system.

Correct Answer: A

Rationale: The correct answer is A: Perpendicular to the direction of wave travel. In a transverse wave, particles of the medium move up and down (or side to side) perpendicular to the direction of wave travel. This motion creates crests and troughs in the wave. This motion is what characterizes a transverse wave, where the disturbance is perpendicular to the direction of energy transfer. Choices B, C, and D are incorrect because in a transverse wave, the particles do not move parallel to the direction of wave travel (B), in a circular motion (C), or opposite to the direction of wave travel (D).

Correct Answer: B

Rationale: The correct answer is B: Humoral immunity. B-cells produce antibodies that circulate in bodily fluids to combat pathogens. This is a key aspect of humoral immunity. A: Cell-mediated immunity involves T-cells directly attacking infected cells, not antibody secretion by B-cells. C: Innate immunity is non-specific and does not involve B-cells producing antibodies. D: Phagocytic immunity involves phagocytes engulfing and destroying pathogens, not antibody secretion by B-cells.

Correct Answer: B

Rationale: The correct answer is B: Peptide bond. A peptide bond is a covalent bond that connects amino acids in a protein chain. During protein synthesis, the carboxyl group of one amino acid reacts with the amino group of another amino acid, forming a peptide bond. This bond is crucial for the structural integrity and function of proteins. A: Covalent bonds are generic chemical bonds that can occur between any atoms, not specifically between amino acids in proteins. C: Ionic bonds involve the transfer of electrons between atoms with opposite charges, which is not how amino acids are connected in proteins. D: Hydrogen bonds are weak interactions between hydrogen and electronegative atoms, not the primary bond connecting amino acids in proteins.