what is the basic structure of an atom

ATI TEAS 7

ATI TEAS Science Practice Test

1. What is the basic structure of an atom?

A. Protons, neutrons, electrons
B. Protons, electrons, ions
C. Neutrons, electrons, ions
D. Protons, ions, molecules

Correct answer: A

Rationale: The basic structure of an atom consists of protons and neutrons located in the nucleus, with electrons orbiting around the nucleus in specific energy levels or shells. Protons carry a positive charge, neutrons carry no charge, and electrons carry a negative charge. This arrangement maintains the overall neutrality of the atom, with the number of protons equaling the number of electrons. Therefore, the correct answer is 'Protons, neutrons, electrons.' Choices B, C, and D are incorrect as they do not accurately represent the fundamental components of an atom. Choice B includes 'ions,' which are charged particles, not fundamental components of an atom. Choice C includes 'ions' and lacks protons. Choice D includes 'ions' and 'molecules,' which are not part of the basic structure of an atom.

2. What are the components of the female external genitalia and their functions?

A. Ovaries: internal reproductive organs
B. Vulva: external structures of the female genitalia
C. Uterus: internal reproductive organ for fetal development
D. Vagina: birth canal

Correct answer: B

Rationale: The corrected answer is B: 'Vulva: external structures of the female genitalia.' The vulva includes external structures such as the labia, clitoris, and vaginal opening. These structures play roles in sexual arousal and protection of the internal genital organs. Choices A, C, and D are incorrect because they are internal reproductive organs. The ovaries produce eggs, the uterus houses the developing fetus, and the vagina serves as the birth canal. Hence, they are not components of the female external genitalia.

3. In the human skeleton, which of the following lists some of the vertebrae in descending order?

A. Atlas, axis, thoracic, lumbar, sacral, coccyx.
B. Axis, sacral, coccyx, atlas, lumbar, thoracic.
C. Thoracic, sacral, lumbar, axis, coccyx, atlas.
D. Coccyx, lumbar, axis, sacral, thoracic, atlas.

Correct answer: A

Rationale: The correct order of some of the vertebrae in the human skeleton in descending order is Atlas, Axis, Thoracic, Lumbar, Sacral, Coccyx. This sequence follows the typical arrangement from the top of the spine down towards the pelvis. Choice B is incorrect as it does not follow the descending order of vertebrae. Choice C is incorrect as it starts with Thoracic which is not the first vertebra in the descending order. Choice D is incorrect as it starts with Coccyx which is the last vertebra in the descending order.

4. Which of the following is a balanced chemical equation?

A. H2 + O2 â†’ H2O
B. 2H2 + O2 â†’ 2H2O
C. 3H2O â†’ 2H2 + O2
D. H2O â†’ H2 + O2

Correct answer: B

Rationale: A balanced chemical equation must have the same number of atoms of each element on both sides of the equation. In option B, 2H2 + O2 â†’ 2H2O, the equation is balanced as there are 2 hydrogen atoms and 2 oxygen atoms on both the reactant and product sides after balancing, satisfying the law of conservation of mass. Option A is unbalanced as there are 2 oxygen atoms on the reactant side but only 1 oxygen atom on the product side. Option C is unbalanced with 3 hydrogen atoms on the reactant side and 2 hydrogen atoms on the product side. Option D is unbalanced with 1 oxygen atom on the reactant side and 2 oxygen atoms on the product side.

5. What role does DNA play in evolution?

A. It stores genetic information that can be passed on to offspring.
B. It allows for mutations that can introduce new variations.
C. It regulates the expression of genes that influence traits.
D. All of the above

Correct answer: D

Rationale: A) DNA stores genetic information that is passed on from parents to offspring through the process of reproduction. This genetic information contains instructions for the development and functioning of an organism. It serves as the hereditary material that carries the blueprint for an organism's traits and characteristics, allowing for the transmission of genetic information from one generation to the next. B) DNA can undergo mutations, which are changes in the genetic sequence. These mutations can introduce new variations in the DNA, leading to genetic diversity within a population. These variations are essential for natural selection and adaptation to changing environments. C) DNA plays a crucial role in regulating the expression of genes. Gene expression determines which proteins are produced in an organism, influencing its traits and characteristics. By controlling gene expression, DNA contributes to the development and maintenance of an organism's traits. D) Therefore, DNA is involved in all of the above processes, making it a key factor in evolution by driving genetic variation, inheritance, and gene expression. The interplay of these functions allows for the diversity and adaptation of species over time, shaping the evolutionary process.