how do isotopes affect the atomic mass of an element

ATI TEAS 7

TEAS 7 science practice

1. How do isotopes affect the atomic mass of an element?

A. Isotopes have no effect on the atomic mass of an element.
B. Isotopes cause the atomic mass of an element to vary slightly.
C. Isotopes cause the atomic mass of an element to be exactly the same for all isotopes of that element.
D. Isotopes cause the atomic mass of an element to vary greatly.

Correct answer: B

Rationale: Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. Since the atomic mass of an element is the weighted average of the masses of its isotopes, the presence of isotopes causes the atomic mass of an element to vary slightly. This variation occurs because different isotopes have different masses due to their varying numbers of neutrons. The atomic mass is affected by the abundance of each isotope, leading to a slight fluctuation in the overall atomic mass of the element. Choice A is incorrect because isotopes do influence the atomic mass. Choice C is incorrect because isotopes have different masses, affecting the overall atomic mass. Choice D is incorrect as isotopes typically do not cause a significant variation in atomic mass, but rather a slight fluctuation.

2. Which of the following is a genetic condition that affects the respiratory system?

A. Asthma
B. Cystic fibrosis
C. Mycosis
D. Surfactant Deficiency

Correct answer: B

Rationale: The correct answer is B, Cystic fibrosis. Cystic fibrosis is a genetic disorder that primarily affects the respiratory and digestive systems. It leads to the production of thick mucus in the lungs, causing breathing difficulties and increasing the risk of respiratory infections. Choice A, Asthma, is a chronic respiratory condition characterized by inflammation and narrowing of the airways, but it is not a genetic condition. Choice C, Mycosis, refers to fungal infections and is not a genetic condition specifically affecting the respiratory system. Choice D, Surfactant Deficiency, is a condition related to respiratory distress syndrome in newborns and is not a genetic disorder affecting the respiratory system in general.

3. What is the main function of vacuoles in plant cells?

A. To provide structural support for the cell
B. To transport substances in and out of the cell
C. To synthesize proteins and lipids
D. To store water, enzymes, and waste products

Correct answer: D

Rationale: Vacuoles in plant cells primarily function as storage organelles. They store water, enzymes, pigments, and waste products, helping to maintain turgor pressure within the cell. This turgor pressure provides structural support for the plant cell. While vacuoles can also participate in transporting substances within the cell, their main role is storage. The synthesis of proteins and lipids is mainly handled by other organelles such as the endoplasmic reticulum and Golgi apparatus. Choice A is incorrect because while vacuoles indirectly contribute to structural support by maintaining turgor pressure, their primary function is storage. Choice B is incorrect as vacuoles are not primarily responsible for transporting substances in and out of the cell. Choice C is incorrect as vacuoles do not synthesize proteins and lipids; this function is carried out by other organelles.

4. Which of the following substances is typically a good conductor of electricity when dissolved in water?

A. Sugar
B. Sodium chloride
C. Olive oil
D. Oxygen gas

Correct answer: B

Rationale: Sodium chloride (table salt) is typically a good conductor of electricity when dissolved in water because it dissociates into ions (sodium cations and chloride anions) that can carry an electric current. Sugar (choice A), olive oil (choice C), and oxygen gas (choice D) do not dissociate into ions in water and therefore are not good conductors of electricity. Sugar does not dissociate into ions in water, so it cannot conduct electricity. Olive oil and oxygen gas are nonpolar substances and do not ionize in water, making them poor conductors of electricity.

5. Which of the following is a component of the immune system?

A. Red blood cells
B. White blood cells
C. Platelets
D. Plasma

Correct answer: B

Rationale: White blood cells are a crucial component of the immune system as they play a key role in fighting infections and foreign invaders. Red blood cells are primarily involved in oxygen transport, platelets are important for blood clotting, and plasma is the liquid component of blood that carries various substances but is not directly involved in the immune response.