the defining characteristic of an element is determined by the number of

ATI TEAS 7

TEAS 7 science practice

1. What determines the defining characteristic of an element?

A. Neutrons in its nucleus
B. Electrons surrounding the nucleus
C. Protons in its nucleus
D. All of the above

Correct answer: C

Rationale: The defining characteristic of an element is determined by the number of protons in its nucleus, which is referred to as the atomic number. The number of protons uniquely identifies an element. The correct answer is choice C because the number of protons in the nucleus of an atom defines its elemental identity, as different elements have a unique number of protons. Neutrons and electrons do play essential roles in the atom, but they do not determine the defining characteristic of an element. Neutrons contribute to the stability of the nucleus and isotopes of an element, while electrons are involved in chemical bonding and the reactivity of an atom.

2. Which of the following substances is NOT typically found in healthy urine?

A. Urea
B. Glucose
C. Creatinine
D. Electrolytes

Correct answer: B

Rationale: Glucose is not typically found in healthy urine because the kidneys usually filter glucose from the blood and reabsorb it back into the bloodstream. The presence of glucose in urine, known as glucosuria, is usually indicative of diabetes or other medical conditions affecting glucose regulation. On the other hand, urea, creatinine, and electrolytes are commonly present in healthy urine as byproducts of metabolism and electrolyte balance. Urea is a waste product of protein metabolism, creatinine is a waste product of muscle metabolism, and electrolytes are essential for various physiological functions in the body. Therefore, choices A, C, and D are typically found in healthy urine, making them incorrect answers.

3. When a certain plant is introduced into an area, and the population of a certain insect species declines, what can be concluded from this?

A. The plant is toxic to the insect in question.
B. The plant competes with and drives out plants that the insect feeds on.
C. The insect population was declining anyway; the fact that it happened when the plant was introduced is a coincidence.
D. All of these explanations may be possible; further investigation is necessary to determine which is true.

Correct answer: D

Rationale: The given scenario presents multiple possible explanations for the decline in the insect population with the introduction of a particular plant. It could be due to the plant being toxic to the insect (Option A), competing with and driving out plants that the insect feeds on (Option B), or the decline could be coincidental with the plant introduction as the insect population was already decreasing (Option C). Without further investigation and evidence, it is not possible to definitively determine which explanation is correct. Therefore, all of these possibilities may be true, and thorough investigation is necessary to reach a conclusive conclusion.

4. What is the formula to calculate kinetic energy?

A. Kinetic Energy = Mass × Velocity
B. Kinetic Energy = Force × Distance
C. Kinetic Energy = Power × Time
D. Kinetic Energy = Potential Energy ÷ Time

Correct answer: A

Rationale: Kinetic energy is the energy an object possesses due to its motion. The formula to calculate kinetic energy is KE = 0.5 × mass × velocity^2, which can also be written as KE = mass × (velocity)^2. Therefore, the correct formula is Kinetic Energy = Mass × Velocity. Choice B is incorrect because it represents the work formula. Choice C is incorrect as it represents the formula for work done. Choice D is incorrect as it does not accurately represent the formula for calculating kinetic energy.

5. Which of the following antibodies can cross the placenta?

A. IgA
B. IgD
C. IgG
D. IgM

Correct answer: C

Rationale: The correct answer is IgG. IgG is the only antibody that can cross the placenta, providing passive immunity to the developing fetus. IgA, IgD, and IgM do not cross the placenta. IgA is mainly found in mucosal secretions, IgD is involved in the activation of B cells, and IgM is the first antibody produced in response to an infection, but it does not cross the placental barrier.