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. In the reaction 2Na + 2H2O â†’ 2NaOH + H2, what is the limiting reactant when 3 moles of sodium react with 2 moles of water?

A. Na
B. H2O
C. NaOH
D. H2

Correct answer: A

Rationale: The balanced chemical equation indicates that 2 moles of sodium react with 2 moles of water to yield 2 moles of sodium hydroxide and 1 mole of hydrogen gas. When 3 moles of sodium react with only 2 moles of water, sodium becomes the limiting reactant as it is present in excess compared to the available water molecules. This situation arises because not all sodium atoms can fully react with the limited amount of water, resulting in sodium being the limiting reactant in this specific case. Choice B (H2O), choice C (NaOH), and choice D (H2) are incorrect as they are not the limiting reactant in the given reaction scenario.

3. Neurons, the functional units of the nervous system, belong to which tissue type?

A. Epithelial tissue
B. Connective tissue
C. Muscle tissue
D. Nervous tissue

Correct answer: D

Rationale: Neurons are the functional units of the nervous system and are specialized cells that transmit nerve impulses. They belong to nervous tissue, which is the primary tissue type of the nervous system. Nervous tissue is composed of neurons and supporting cells called neuroglia. Choices A, B, and C are incorrect because epithelial tissue functions mainly in covering and lining body surfaces, connective tissue provides support and structure, and muscle tissue is responsible for movement. Neurons, being the basic functional units of the nervous system, are specifically classified under nervous tissue.

4. Which of the following is NOT a function of the endocrine system?

A. Regulating growth and development
B. Maintaining blood sugar levels
C. Controlling mood and emotions
D. Facilitating digestion through muscle contractions

Correct answer: D

Rationale: The endocrine system is responsible for producing hormones that regulate various bodily functions such as growth, metabolism, mood, and more. Facilitating digestion through muscle contractions is primarily the role of the muscular and nervous systems, not the endocrine system. Therefore, option D is the correct answer as it does not align with the functions typically attributed to the endocrine system. Choices A, B, and C are functions that are indeed associated with the endocrine system, making them incorrect answers in the context of this question.

5. What is the process by which damaged muscle tissue repairs and rebuilds itself?

A. Degeneration
B. Regeneration
C. Hyperplasia
D. Metaplasia

Correct answer: B

Rationale: Regeneration is the correct answer. It is the process by which damaged muscle tissue repairs and rebuilds itself. New muscle cells are formed during regeneration to replace the damaged ones, allowing the muscle to heal and regain its function. Degeneration refers to tissue breakdown, hyperplasia is the increase in the number of cells in an organ or tissue, and metaplasia is the transformation of one type of tissue into another.