what is a mutation

ATI TEAS 7

TEAS 7 science practice questions

1. What is a mutation?

A. A change in the DNA sequence
B. A type of protein
C. A normal part of the DNA replication process
D. A harmless variation in DNA

Correct answer: A

Rationale: A mutation is defined as a change in the DNA sequence, which can occur due to various factors such as errors during DNA replication, exposure to mutagens (e.g., chemicals, radiation), or spontaneous changes. These alterations can lead to modifications in the genetic information carried by an organism, resulting in effects that can range from harmless variations to causing genetic disorders or diseases. Mutations play a crucial role in genetic diversity and evolution. Choices B, C, and D are incorrect as they do not accurately define what a mutation is. Option B is incorrect because mutations are not a type of protein but rather changes in DNA. Option C is incorrect because while mutations can occur during DNA replication, they are not considered a 'normal' part of the process as they can lead to genetic variations. Option D is incorrect because mutations can have a wide range of effects and are not always harmless variations.

2. What is the primary mode of CO2 transport in the body?

A. Bicarbonate
B. Carbamino compounds
C. None of these
D. Plasma

Correct answer: A

Rationale: The correct answer is A: Bicarbonate. In the body, the primary mode of CO2 transport is as bicarbonate. Carbon dioxide is converted to bicarbonate in red blood cells as part of the bicarbonate buffer system, which helps maintain the pH balance in the blood. Bicarbonate is then transported in the plasma to the lungs where it is converted back to carbon dioxide for exhalation. While carbamino compounds also play a role in CO2 transport by binding to amino groups on proteins, bicarbonate is the main mode of transport for carbon dioxide in the body. Options B, C, and D are incorrect as they do not represent the primary mechanism of CO2 transport in the body.

3. Where does the maturation of T-cells and the production of T-cell receptors occur?

A. Thymus
B. Spleen
C. Lymph nodes
D. Bone marrow

Correct answer: A

Rationale: The correct answer is the Thymus. T-cells mature and develop their receptors in the thymus gland, making it a vital organ for the immune system. The thymus provides the necessary environment for T-cells to differentiate and acquire their specific receptors and functions, which are essential for their role in the adaptive immune response. The spleen, lymph nodes, and bone marrow are all important components of the immune system, but they do not primarily serve as sites for T-cell maturation and T-cell receptor production.

4. What is the Aufbau principle?

A. The principle that electrons fill orbitals in order of increasing energy.
B. The principle that electrons cannot occupy the same orbital with the same spin.
C. The principle that the maximum number of electrons in an orbital is 2n^2, where n is the energy level of the orbital.
D. The principle that the attractive force between an electron and the nucleus is inversely proportional to the distance between them.

Correct answer: A

Rationale: The Aufbau principle states that electrons fill orbitals in order of increasing energy. This principle helps to explain the electron configuration of atoms and how electrons are distributed within the energy levels and sublevels of an atom. By following the Aufbau principle, one can determine the electron configuration of an atom by sequentially adding electrons to orbitals in order of their increasing energy levels, starting with the lowest energy level. Choice B is incorrect as it describes the Pauli Exclusion Principle, which states that no two electrons in an atom can have the same four quantum numbers. Choice C is incorrect as it refers to the formula for calculating the maximum number of electrons that can occupy an energy level. Choice D is incorrect as it relates to Coulomb's law, which describes the electrostatic interaction between charged particles.

5. What is the name of the regulatory region in a gene that controls its expression?

A. Exon
B. Intron
C. Promoter
D. Enhancer

Correct answer: C

Rationale: A) Exon: Exons are the coding regions of a gene that are transcribed into mRNA and eventually translated into proteins. Exons do not regulate gene expression. B) Intron: Introns are non-coding regions of a gene that are removed during RNA processing and do not play a direct role in controlling gene expression. C) Promoter: The promoter is a regulatory region located at the beginning of a gene that initiates the process of transcription by binding transcription factors and RNA polymerase. It plays a crucial role in controlling gene expression. D) Enhancer: Enhancers are regulatory regions that can be located far from the gene they regulate and can increase the transcription of a gene. While enhancers are important for gene expression, the specific region that controls gene expression is the promoter. Therefore, the correct answer is C) Promoter, as it is the regulatory region in a gene that controls its expression by initiating transcription.