where is keratin

ATI TEAS 7

TEAS Practice Test Science

1. Where is keratin found?

A. It is a protein-digesting enzyme released by the stomach.
B. It is released in the neuromuscular junction.
C. It is a protein found in the hypodermis.
D. It is a protein found in hair.

Correct answer: D

Rationale: Keratin is a structural protein found in hair, skin, and nails, providing strength and protection. It forms the main structural component of hair, making choice D the correct answer. Choices A, B, and C are incorrect because keratin is not an enzyme released by the stomach, not released in the neuromuscular junction, and not found in the hypodermis. Remember that keratin is primarily associated with structural support in epithelial cells.

2. What are the components of the female external genitalia and their functions?

A. Ovaries: internal reproductive organs
B. Vulva: external structures of the female genitalia
C. Uterus: internal reproductive organ for fetal development
D. Vagina: birth canal

Correct answer: B

Rationale: The corrected answer is B: 'Vulva: external structures of the female genitalia.' The vulva includes external structures such as the labia, clitoris, and vaginal opening. These structures play roles in sexual arousal and protection of the internal genital organs. Choices A, C, and D are incorrect because they are internal reproductive organs. The ovaries produce eggs, the uterus houses the developing fetus, and the vagina serves as the birth canal. Hence, they are not components of the female external genitalia.

3. What information can be obtained from the mass number of an element?

A. The number of protons in the nucleus
B. The total number of protons and neutrons
C. The number of electrons in the valence shell
D. The element's chemical reactivity

Correct answer: B

Rationale: The mass number of an element represents the total number of protons and neutrons in the nucleus. This information is crucial for determining the atomic mass of the element and understanding its stability and isotopes. The number of protons in the nucleus (option A) is represented by the atomic number, not the mass number. The number of electrons in the valence shell (option C) is related to the element's position in the periodic table and its chemical properties, but it is not directly determined by the mass number. The element's chemical reactivity (option D) is influenced by the number and arrangement of electrons in the atom's energy levels, not by the mass number.

4. To which of the following bone types do the spine and hips belong?

A. Curved bones
B. Irregular bones
C. Flat bones
D. Long bones

Correct answer: B

Rationale: The correct answer is B: Irregular bones. The spine and hips belong to the category of irregular bones. Irregular bones have complex shapes that do not fit into other bone type categories. These bones serve functions such as support and protection, and their shapes vary depending on their specific roles in the body. Choice A, curved bones, is incorrect because bones like ribs are typically described as curved, not the spine and hips. Choice C, flat bones, is incorrect as flat bones include the skull and ribs, but not the spine and hips. Choice D, long bones, is also incorrect because long bones include bones like the femur and humerus, which are elongated with a shaft and distinct ends, unlike the spine and hips.

5. What property of a substance remains constant regardless of its location in the universe?

A. Mass
B. Weight
C. Density
D. Volume

Correct answer: A

Rationale: Mass is a measure of the amount of matter in an object and remains constant regardless of its location in the universe. Weight, on the other hand, is the force of gravity acting on an object and can vary depending on the gravitational pull at different locations. Density and volume can also change based on the environment in which an object is placed, making mass the property that remains constant universally. Therefore, the correct answer is mass. Weight changes with the gravitational force of a particular location, density varies with mass and volume, and volume can change depending on the shape or size of the object.