what is the process by which rna molecules are modified after transcription but before translation

ATI TEAS 7

TEAS 7 science practice

1. What is the process by which RNA molecules are modified after transcription but before translation?

A. Replication
B. Splicing
C. Editing
D. Packaging

Correct answer: B

Rationale: B) Splicing is the correct answer. Splicing is the process by which non-coding regions (introns) are removed from pre-mRNA, and the remaining coding regions (exons) are joined together to form mature mRNA. This modification occurs after transcription but before translation. A) Replication is incorrect as replication is the process by which DNA is copied to produce a new DNA molecule, not RNA modifications. C) Editing may involve RNA editing, but it is not commonly used to describe the modification of RNA molecules after transcription. D) Packaging is not the correct term as it refers to the condensation and organization of DNA into chromatin in eukaryotic cells, not the modification of RNA molecules.

2. Vacuoles are large sacs for storage in plant cells. What is their main function in animal cells?

A. Protein synthesis
B. Waste storage and disposal
C. Photosynthesis
D. Cellular respiration

Correct answer: B

Rationale: Vacuoles in animal cells primarily function in waste storage and disposal, helping to maintain cellular homeostasis by storing waste products and aiding in their removal from the cell. Unlike plant cells, animal cells do not typically use vacuoles for storage purposes such as water, nutrients, or pigments. Instead, animal cells rely on other organelles like lysosomes for waste management and maintaining cellular balance. Choices A, C, and D are incorrect because protein synthesis occurs in ribosomes, photosynthesis takes place in chloroplasts (absent in animal cells), and cellular respiration mainly occurs in mitochondria, respectively. Vacuoles in animal cells serve a different purpose compared to plant cells.

3. How can a single gene mutation lead to multiple phenotypes depending on the organism?

A. Pleiotropy describes the effect of one gene influencing multiple seemingly unrelated traits.
B. Epigenetics involves environmental factors modifying gene expression without altering the DNA sequence.
C. Genetic drift refers to random changes in allele frequencies within a population.
D. Gene regulation controls the timing and level of gene expression within an organism.

Correct answer: A

Rationale: A single gene mutation can lead to multiple phenotypes through pleiotropy, where one gene influences diverse traits or functions in an organism. This phenomenon occurs when the mutated gene affects different biochemical pathways, developmental processes, or cellular functions, resulting in a cascade of downstream effects that manifest as a variety of phenotypic outcomes. Choice B, epigenetics, involves modifications in gene expression influenced by environmental factors without altering the DNA sequence, which is not directly related to the question about single gene mutations causing multiple phenotypes. Choice C, genetic drift, refers to random changes in allele frequencies within a population, which is unrelated to the impact of a single gene mutation on multiple phenotypes. Choice D, gene regulation, focuses on controlling the timing and level of gene expression within an organism, which is not directly addressing how a single gene mutation can lead to diverse phenotypes.

4. What is the function of the endocrine system?

A. To protect the body from infection
B. To release digestive enzymes
C. To break down food
D. To regulate the sleep-wake cycle

Correct answer: B

Rationale: The correct answer is B. The endocrine system releases hormones that regulate various functions, including metabolism and growth. It is responsible for producing and releasing hormones that control processes such as metabolism, growth, and development. The digestive enzymes are released by the digestive system, not the endocrine system. Choices A, C, and D are incorrect because protecting the body from infection is primarily the role of the immune system, breaking down food is the function of the digestive system, and regulating the sleep-wake cycle is controlled by the circadian rhythm which is mainly influenced by the brain's hypothalamus and not the endocrine system.

5. Which property of a wave determines its energy?

A. Wavelength
B. Amplitude
C. Frequency
D. Velocity

Correct answer: B

Rationale: The energy of a wave is determined by its amplitude, which is the measure of its maximum displacement from the equilibrium position. Waves with higher amplitudes carry more energy as energy is directly proportional to amplitude. Therefore, the correct answer is B) Amplitude. Choice A (Wavelength) does not determine the energy of a wave; it is related to the spatial length between wave crests. Choice C (Frequency) is not the property that determines a wave's energy; it refers to the number of complete oscillations a wave undergoes in a given time. Choice D (Velocity) is the speed at which a wave propagates through a medium and is not directly related to its energy.