what are the differences between rna and dna

ATI TEAS 7

TEAS 7 science practice

1. What are the differences between RNA and DNA?

A. Both have the same structure and function.
B. RNA is single-stranded, while DNA is double-stranded.
C. RNA contains ribose sugar, while DNA contains deoxyribose sugar.
D. RNA has adenine and guanine, while DNA has thymine and cytosine.

Correct answer: B

Rationale: A) This statement is incorrect. RNA and DNA have different structures and functions. RNA is involved in protein synthesis and other cellular processes, while DNA stores genetic information. B) This statement is correct. RNA is typically single-stranded, while DNA is double-stranded, forming a double helix structure. C) This statement is correct. RNA contains ribose sugar in its backbone, while DNA contains deoxyribose sugar. D) This statement is incorrect. RNA contains adenine, guanine, cytosine, and uracil, while DNA contains adenine, guanine, cytosine, and thymine. Choice B is the correct answer as it accurately describes one of the key differences between RNA and DNA, emphasizing their structural disparity in terms of single-strandedness for RNA and double-strandedness for DNA. Choices A, C, and D contain inaccuracies regarding the structural and compositional distinctions between RNA and DNA, making them incorrect choices.

2. What is the process by which a population gradually loses genetic variation?

A. Founder effect
B. Bottleneck effect
C. Gene flow
D. Speciation

Correct answer: B

Rationale: A) Founder effect: This occurs when a small group of individuals establishes a new population, leading to a loss of genetic variation compared to the original population. It does not necessarily result in a gradual loss of genetic variation in an existing population. B) Bottleneck effect: This process occurs when a population is drastically reduced in size, leading to a significant loss of genetic variation due to the limited number of individuals contributing to the gene pool. The reduced genetic diversity can have long-term effects on the population's ability to adapt to environmental changes. C) Gene flow: This refers to the movement of genes between populations, which can introduce new genetic variation and prevent populations from diverging. Gene flow does not lead to a gradual loss of genetic variation within a population. D) Speciation: This is the process by which new species evolve from existing species, often involving the accumulation of genetic differences that l

3. Which part of the brain is responsible for controlling involuntary functions like breathing and heart rate?

A. Cerebrum
B. Medulla oblongata
C. Cerebellum
D. Thalamus

Correct answer: B

Rationale: The medulla oblongata is located at the base of the brainstem and is responsible for controlling vital involuntary functions such as breathing, heart rate, and blood pressure. The cerebrum, although the largest part of the brain, is primarily responsible for higher brain functions like thinking and voluntary muscle movements. The cerebellum is involved in coordination, balance, and muscle control. The thalamus acts as a relay station for sensory information but is not directly responsible for regulating involuntary functions like breathing and heart rate. Therefore, the correct answer is the medulla oblongata.

4. Which of the following lobes of the brain is responsible for sensation, perception, and spatial reasoning?

A. Frontal
B. Occipital
C. Parietal
D. Temporal

Correct answer: C

Rationale: The parietal lobe is responsible for sensation, perception, and spatial reasoning. It plays a crucial role in processing sensory information, assisting in spatial orientation, and integrating various sensory inputs to create a comprehensive perception of the surrounding environment. The frontal lobe, although important for higher cognitive functions and motor skills, is not primarily responsible for sensation, perception, or spatial reasoning. The occipital lobe is mainly involved in visual processing, and the temporal lobe is primarily associated with auditory processing, memory, and emotions, making them incorrect choices for this question.

5. Which statement about white blood cells is true?

A. B cells are responsible for antibody production.
B. White blood cells are produced in the bone marrow before entering the bloodstream.
C. Platelets, a specialized class of blood cells, function to clot blood and stop bleeding.
D. The majority of white blood cells are active throughout life, providing immunity across all age groups.

Correct answer: A

Rationale: The correct answer is A: B cells, a type of white blood cell, are responsible for producing antibodies in response to pathogens. Antibodies play a crucial role in identifying and neutralizing foreign substances like bacteria and viruses in the body, aiding in the immune response and protecting against infections. This function is essential for maintaining a healthy immune system. White blood cells, including B cells, are produced in the bone marrow before entering the bloodstream. Platelets, not white blood cells, are a specialized class of blood cells that function to clot blood and stop bleeding. While white blood cells provide immunity, not all of them are active throughout life as some have specific lifespans and functions.