what is the mass number of an element

ATI TEAS 7

Mometrix TEAS 7 science practice test

1. What is the mass number of an element?

A. The number of protons in an atom's nucleus.
B. The number of neutrons in an atom's nucleus.
C. The number of electrons in an atom's valence shell.
D. The number of isotopes of an element.

Correct answer: B

Rationale: The mass number of an element represents the total number of protons and neutrons in an atom's nucleus. It specifically focuses on the number of neutrons in an atom's nucleus, which contributes to the overall mass of the atom. Therefore, the mass number is not solely determined by the number of protons, electrons, or isotopes. Choice A is incorrect because it refers to the atomic number, which is the number of protons in an atom's nucleus. Choice C is incorrect as the number of electrons in the valence shell is related to the atom's reactivity and bonding behavior, not the mass number. Choice D is incorrect because the mass number does not represent the number of isotopes of an element, but rather the sum of protons and neutrons in an atom's nucleus. Thus, option B, the number of neutrons in an atom's nucleus, is the correct choice.

2. Which of the following enzymes is responsible for adding a nucleotide to a growing DNA chain?

A. Helicase
B. Ligase
C. Nuclease
D. Polymerase

Correct answer: D

Rationale: The correct answer is Polymerase. Polymerase is the enzyme responsible for adding nucleotides to a growing DNA chain during DNA replication. Helicase unwinds the DNA double helix to separate the DNA strands for replication, Ligase joins DNA fragments together by catalyzing the formation of phosphodiester bonds between them, and Nuclease cuts or degrades DNA strands. Therefore, choices A, B, and C are incorrect in the context of adding nucleotides to a growing DNA chain.

3. What is the endoplasmic reticulum?

A. A network of tubules that transport proteins and lipids throughout the cell
B. A sac-like structure that stores water and nutrients
C. The site of protein synthesis
D. The site of cellular respiration

Correct answer: A

Rationale: A) The endoplasmic reticulum (ER) is a network of tubules that are involved in the transport of proteins and lipids throughout the cell. It plays a crucial role in protein synthesis, folding, and transport within the cell. The ER can be further divided into rough ER, which has ribosomes attached to its surface and is involved in protein synthesis, and smooth ER, which is involved in lipid metabolism and detoxification. Therefore, option A is the most accurate description of the endoplasmic reticulum compared to the other options provided. B) A sac-like structure that stores water and nutrients does not accurately describe the endoplasmic reticulum. While some organelles like vacuoles or vesicles may store water and nutrients, the ER's primary function is not storage. C) The site of protein synthesis is partially

4. What is the outermost protective layer of the kidney?

A. Renal cortex
B. Renal medulla
C. Renal capsule
D. Renal pelvis

Correct answer: C

Rationale: The correct answer is C, Renal capsule. The renal capsule is the outermost protective layer of the kidney. It is a tough fibrous layer that surrounds the kidney and helps protect it from injury and maintain its shape. Choice A, Renal cortex, is the outer region of the kidney where filtration occurs. Choice B, Renal medulla, is the inner region of the kidney where urine is formed. Choice D, Renal pelvis, is the funnel-shaped structure that collects urine from the kidney and funnels it into the ureter. Therefore, the renal capsule is specifically designated as the outermost protective layer of the kidney.

5. Which type of nuclear reaction releases a large amount of energy in a short time?

A. Radioactivity
B. Nuclear fission
C. Nuclear fusion
D. All of the above

Correct answer: C

Rationale: Nuclear fusion releases a large amount of energy in a short time by combining two light atomic nuclei to form a heavier nucleus. This process is the energy source of the sun and hydrogen bombs. Radioactivity involves the spontaneous emission of particles or energy from an unstable atomic nucleus, while nuclear fission is the splitting of a heavy atomic nucleus into two or more lighter nuclei, also releasing energy. While all the options are types of nuclear reactions, nuclear fusion is specifically known for releasing a large amount of energy rapidly, making it the correct choice in this context. Choices A and B are incorrect as they do not specifically describe the process of releasing a large amount of energy in a short time. Choice D is incorrect because not all the options listed release a large amount of energy in a short time, making it an inaccurate answer.