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. Which of the following terms refers to a muscle that lengthens while another muscle contracts to produce movement?

A. Synergist
B. Agonist
C. Antagonist
D. Flexor

Correct answer: C

Rationale: The correct answer is 'Antagonist.' An antagonist muscle is a muscle that lengthens while another muscle (agonist) contracts to produce movement. The antagonist muscle relaxes to allow the agonist muscle to contract effectively. In this scenario, the antagonist muscle works in opposition to the agonist muscle, providing control and precision to movement. The other choices are incorrect because a synergist muscle assists the agonist muscle in performing a movement, an agonist muscle is the primary muscle responsible for generating movement, and a flexor muscle is a muscle that decreases the angle at a joint.

3. Which statement correctly describes the concept of ionization energy?

A. The energy required to remove an electron from an outermost shell.
B. The energy released when an electron bonds with an atom.
C. The total energy possessed by all electrons in an atom.
D. The energy needed to change an atom's nucleus.

Correct answer: A

Rationale: Ionization energy is defined as the energy required to remove an electron from an atom in the gaseous state. This process typically involves removing an electron from the outermost shell of the atom. Therefore, option A accurately describes the concept of ionization energy. The other choices do not accurately describe ionization energy; option B refers to bond formation energy, option C is about the total energy of electrons in an atom, and option D relates to nuclear energy changes, not ionization energy.

4. Which hormone, produced by the adrenal glands, is essential for regulating electrolyte balance, particularly sodium and potassium, in the body?

A. Aldosterone
B. Epinephrine
C. Cortisol
D. Insulin

Correct answer: A

Rationale: Aldosterone is a hormone produced by the adrenal glands that plays a crucial role in maintaining electrolyte balance, specifically by regulating sodium and potassium levels in the body. Its primary function involves acting on the kidneys to increase the reabsorption of sodium and water while promoting the excretion of potassium. This process is essential for regulating blood pressure, fluid balance, and electrolyte concentrations in the body. Epinephrine is associated with the fight or flight response, cortisol is a stress hormone, and insulin is responsible for regulating blood sugar levels as produced by the pancreas. Therefore, the correct answer is Aldosterone as it directly targets electrolyte balance, particularly sodium and potassium, in the body.

5. What is the primary function of platelets in the blood?

A. To carry oxygen
B. To clot blood
C. To fight infection
D. To transport nutrients

Correct answer: B

Rationale: The correct answer is B: 'To clot blood.' Platelets play a crucial role in the clotting process, forming a plug at the site of blood vessel injury to prevent excessive bleeding. While red blood cells carry oxygen, white blood cells fight infection, and nutrients are transported by plasma, platelets are specifically responsible for blood clotting. Choice A is incorrect because red blood cells are responsible for carrying oxygen. Choice C is incorrect because white blood cells are primarily involved in fighting infection. Choice D is incorrect as the transport of nutrients is mainly carried out by plasma, not platelets.