isotopes are variants of a single element that differ in

ATI TEAS 7

TEAS Test 7 science quizlet

1. Isotopes are variants of a single element that differ in:

A. Having the same number of protons but varying numbers of neutrons
B. Having the same number of neutrons but varying numbers of protons
C. Having the same mass but different atomic numbers
D. None of the above

Correct answer: A

Rationale: Isotopes are variants of a single element that have the same number of protons, the defining characteristic of an element. They differ in the number of neutrons they possess, leading to isotopes having different atomic masses while retaining the same chemical properties. Choice B is incorrect because isotopes have the same number of neutrons and differ in the number of protons. Choice C is incorrect because isotopes have different masses due to varying numbers of neutrons, not different atomic numbers. Choice D is incorrect as isotopes do differ in the number of neutrons they possess.

2. What is the term for a group of organisms living in the same place and interacting with each other?

A. Ecosystem
B. Community
C. Population
D. Niche

Correct answer: B

Rationale: - A) Ecosystem refers to a biological community of interacting organisms and their physical environment. - B) Community specifically refers to a group of organisms of different species living in the same place and interacting with each other. - C) Population refers to a group of individuals of the same species living in the same area. - D) Niche refers to the role or function of an organism or species within an ecosystem. In this context, the term for a group of organisms living in the same place and interacting with each other is best described as a community because it involves multiple species interacting within a shared habitat.

3. Which valve prevents the backflow of blood into the left ventricle as it leaves through the aorta?

A. Pulmonary semilunar valve
B. Aortic semilunar valve
C. Tricuspid valve
D. Mitral valve

Correct answer: B

Rationale: The aortic semilunar valve is the correct answer as it prevents the backflow of blood into the left ventricle once it has been pumped into the aorta. The pulmonary semilunar valve prevents backflow into the right ventricle, the tricuspid valve controls blood flow between the right atrium and ventricle, and the mitral valve regulates blood flow between the left atrium and ventricle. Therefore, option B is the correct choice for this question.

4. Which statement about white blood cells is true?

A. B cells are responsible for antibody production.
B. White blood cells are produced in the bone marrow before entering the bloodstream.
C. Platelets, a specialized class of blood cells, function to clot blood and stop bleeding.
D. The majority of white blood cells are active throughout life, providing immunity across all age groups.

Correct answer: A

Rationale: The correct answer is A: B cells, a type of white blood cell, are responsible for producing antibodies in response to pathogens. Antibodies play a crucial role in identifying and neutralizing foreign substances like bacteria and viruses in the body, aiding in the immune response and protecting against infections. This function is essential for maintaining a healthy immune system. White blood cells, including B cells, are produced in the bone marrow before entering the bloodstream. Platelets, not white blood cells, are a specialized class of blood cells that function to clot blood and stop bleeding. While white blood cells provide immunity, not all of them are active throughout life as some have specific lifespans and functions.

5. What type of joint is found in the shoulder and hip, allowing for a wide range of motion?

A. Hinge joint
B. Ball-and-socket joint
C. Pivot joint
D. Saddle joint

Correct answer: B

Rationale: The correct answer is B: Ball-and-socket joint. A ball-and-socket joint, like those in the shoulder and hip, allows for a wide range of motion. In a ball-and-socket joint, the rounded end of one bone fits into the cup-like socket of another bone, enabling movement in multiple directions. Choice A, Hinge joint, is incorrect because hinge joints allow movement only in one plane, like a door hinge. Choice C, Pivot joint, is incorrect as it allows rotational movement around a single axis, not the wide range of motion seen in the shoulder and hip. Choice D, Saddle joint, is also incorrect as it allows movement in multiple directions but to a lesser extent compared to the ball-and-socket joint.