what does monophyletic mean in the context of classification

ATI TEAS 7

Mometrix TEAS 7 science practice test

1. What does 'monophyletic' mean in the context of classification?

A. A group with a single representative organism
B. A group with diverse and unrelated members
C. A group with similar functions but different origins
D. A group descended from a common ancestor

Correct answer: D

Rationale: In the context of classification, 'monophyletic' refers to a group that includes a common ancestor and all of its descendants. This group shares a single evolutionary origin and forms a complete branch on a phylogenetic tree. Monophyletic groups are considered natural and valid taxonomic units because they reflect evolutionary relationships accurately. Option D is the correct choice as it accurately defines the term 'monophyletic' in the context of classification. Choices A, B, and C are incorrect. Choice A is incorrect because 'monophyletic' does not refer to a group with a single representative organism but rather a group descended from a common ancestor. Choice B is incorrect as a monophyletic group consists of related, not diverse and unrelated, members. Choice C is incorrect as a monophyletic group includes descendants from a common ancestor, not just organisms with similar functions but different origins.

2. 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.

3. During gas exchange in the alveoli, what happens to oxygen?

A. Oxygen is released from the alveoli into the bloodstream.
B. Oxygen is absorbed from the alveoli into the bloodstream.
C. Oxygen is converted into carbon dioxide.
D. Oxygen is stored in the alveoli for later use.

Correct answer: B

Rationale: During gas exchange in the alveoli, oxygen is absorbed from the alveoli into the bloodstream. This process occurs due to the difference in partial pressures of oxygen between the alveoli and the bloodstream, causing oxygen to move from an area of higher concentration (alveoli) to an area of lower concentration (bloodstream). Oxygen is then transported by red blood cells to tissues throughout the body for cellular respiration. Choice A is incorrect as oxygen moves from the alveoli into the bloodstream, not the other way around. Choice C is incorrect as oxygen is not converted into carbon dioxide during gas exchange. Choice D is incorrect as oxygen is not stored in the alveoli but rather continuously exchanged with carbon dioxide during respiration.

4. Isotopes are variants of a single element that differ in:

A. Having the same number of protons but varying numbers of neutrons
B. Having the same number of neutrons but varying numbers of protons
C. Having the same mass but different atomic numbers
D. None of the above

Correct answer: A

Rationale: Isotopes are variants of a single element that have the same number of protons, the defining characteristic of an element. They differ in the number of neutrons they possess, leading to isotopes having different atomic masses while retaining the same chemical properties. Choice B is incorrect because isotopes have the same number of neutrons and differ in the number of protons. Choice C is incorrect because isotopes have different masses due to varying numbers of neutrons, not different atomic numbers. Choice D is incorrect as isotopes do differ in the number of neutrons they possess.

5. Which of the following statements is true regarding the ventricles of the heart?

A. The left ventricle pumps blood into the aorta
B. The right ventricle pumps blood into the pulmonary trunk
C. Ventricles are the discharging chambers of the heart
D. All of the above

Correct answer: D

Rationale: All of these statements are true regarding the ventricles of the heart. The left ventricle does indeed pump oxygenated blood into the aorta, while the right ventricle pumps deoxygenated blood into the pulmonary trunk. Ventricles are indeed the discharging chambers of the heart, responsible for pumping blood out into the circulatory system. Therefore, as all the statements are accurate, the correct answer is 'All of the above.' Choices A, B, and C are all correct statements about the ventricles, making them incorrect answers in isolation.