ATI TEAS 7 Science

Correct Answer: B

Rationale: The correct answer is B: 23. In humans, each normal cell contains 23 pairs of chromosomes, making a total of 46 chromosomes. The pairs consist of one chromosome from each parent, ensuring genetic diversity. Choices A, C, and D are incorrect because they do not reflect the accurate number of chromosome pairs in a human cell. Option A (46) is the total number of chromosomes, not pairs. Option C (64) and D (32) are not the correct numbers of chromosome pairs in a human cell.

Correct Answer: A

Rationale: The correct answer is A because polygenic inheritance refers to a trait that is influenced by multiple genes working together to produce a single phenotype. In contrast, pleiotropy occurs when a single gene has multiple effects on different traits. This distinction is crucial as it highlights the difference in the genetic basis of these phenomena. The other choices are incorrect because they either misinterpret the definitions of polygenic inheritance and pleiotropy (B and C) or provide vague statements without accurately distinguishing between the two concepts (D). The key to selecting the correct answer lies in understanding the fundamental genetic mechanisms underlying polygenic inheritance and pleiotropy.

Correct Answer: D

Rationale: The correct answer is D because chromosomal nondisjunction can lead to various genetic disorders such as Down syndrome (A), caused by an extra chromosome 21. Nondisjunction can also result in Turner syndrome (B) in females due to the absence of one X chromosome, and Klinefelter syndrome (C) in males with one or more extra X chromosomes. Therefore, all the options are potential consequences of chromosomal nondisjunction.

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: Iron (Fe). This is because an element with atomic number 26 corresponds to Iron on the periodic table. The mass number of 56 indicates the total number of protons and neutrons in the nucleus of the atom, which is consistent with the atomic mass of Iron. Choice B, Cobalt, has an atomic number of 27, not 26. Choice C, Nickel, has an atomic number of 28, not 26. Choice D, Manganese, has an atomic number of 25, not 26. Therefore, based on the given atomic number and mass number, Iron is the most likely element.