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 primary difference between ionic and metallic bonding?

A. Ionic bonds involve electron transfer, while metallic bonds involve electron sharing.
B. Ionic bonds are weak and directional, while metallic bonds are strong and non-directional.
C. Ionic bonds exist between metals and non-metals, while metallic bonds exist only between metals.
D. Ionic bonds form discrete molecules, while metallic bonds form extended structures.

Correct answer: B

Rationale: Ionic bonds involve electron transfer, where one atom completely donates an electron to another, resulting in discrete molecules. On the other hand, metallic bonds are non-directional and strong, formed by a 'sea' of delocalized electrons shared among all metal atoms. This shared electron cloud allows for strong bonding throughout the entire material, making metallic bonds non-directional and strong compared to the directional and weaker nature of ionic bonds. Choice A is incorrect because metallic bonds do not involve electron sharing but rather the sharing of a sea of delocalized electrons. Choice C is incorrect as metallic bonds can also exist between metal atoms, not just between metals and non-metals. Choice D is incorrect because metallic bonds do not form discrete molecules but rather extended structures due to the sharing of electrons among all metal atoms.

3. How does the Pauli exclusion principle relate to the structure of the atom?

A. It defines the maximum number of electrons allowed in each energy level.
B. It explains why oppositely charged particles attract each other.
C. It describes the wave-particle duality of electrons.
D. It determines the arrangement of protons and neutrons in the nucleus.

Correct answer: A

Rationale: The Pauli exclusion principle states that no two electrons in an atom can have the same set of quantum numbers. This principle directly influences the structure of the atom by defining the maximum number of electrons allowed in each energy level. As a result, it helps determine the electron configuration and the arrangement of electrons in different orbitals within an atom. Choices B, C, and D are incorrect as they do not directly relate to the Pauli exclusion principle's specific impact on the electron distribution within an atom.

4. The acceleration of a falling object due to gravity has been proven to be 9.8 m/s². A scientist drops a cactus four times and measures the acceleration with an accelerometer and gets the following results: 9.79 m/s², 9.81 m/s², 9.80 m/s², and 9.78 m/s². Which of the following accurately describes the measurements?

A. They're both accurate and precise.
B. They're accurate but not precise.
C. They're precise but not accurate.
D. They're neither accurate nor precise.

Correct answer: A

Rationale: The measurements are both close to the actual value (accurate) and consistent with each other (precise). Accuracy refers to how close a measurement is to the true value, and precision refers to the reproducibility or consistency of the measurements. In this case, the measured values are all very close to the actual value of 9.8 m/s², indicating accuracy. Additionally, the measurements are clustered closely together, demonstrating precision. Therefore, the measurements are both accurate and precise, making choice A the correct answer. Choices B, C, and D are incorrect because the measurements exhibit both accuracy and precision, as they are close to the true value and also consistent with each other.

5. The kidneys are bean-shaped organs that perform several vital functions. Which of the following is NOT a primary function of the kidneys?

A. Filtering waste products from the blood
B. Regulating blood pressure
C. Producing red blood cells
D. Maintaining water balance in the body

Correct answer: C

Rationale: The correct answer is C. The kidneys do not produce red blood cells. This function is carried out by the bone marrow. The primary functions of the kidneys include filtering waste products from the blood, regulating blood pressure, and maintaining water balance in the body. Red blood cells are produced in the bone marrow, not in the kidneys. Choices A, B, and D are incorrect as they are primary functions of the kidneys, which involve filtering waste products, regulating blood pressure, and maintaining water balance in the body, respectively.