which of the following is the primary physical barrier the body uses to prevent infection

ATI TEAS 7

TEAS 7 Science Practice Test

1. Which of the following is the primary physical barrier the body uses to prevent infection?

A. mucus membranes
B. stomach acid
C. skin
D. urine

Correct answer: C

Rationale: The correct answer is 'C: skin.' The skin is the primary physical barrier the body uses to prevent infection. It acts as a protective shield that prevents harmful microorganisms from entering the body. The outer layer of the skin, known as the epidermis, acts as a tough physical barrier that blocks the entry of pathogens. Additionally, the skin has special immune cells that can help fight off invaders that manage to breach the physical barrier. Choices A, B, and D are incorrect. While mucous membranes, stomach acid, and urine play important roles in the body's defense against pathogens, the primary physical barrier is the skin, which covers the entire body and provides a robust protective barrier.

2. What is the scientific unit used to measure the radioactivity of a substance?

A. Becquerel (Bq)
B. Joule (J)
C. Newton (N)
D. Kelvin (K)

Correct answer: A

Rationale: The correct answer is A: Becquerel (Bq). The Becquerel (Bq) is the scientific unit used to measure the radioactivity of a substance. It is named after Henri Becquerel, who discovered radioactivity. The Joule (J) is the unit of energy, Newton (N) is the unit of force, and Kelvin (K) is the unit of temperature. When measuring radioactivity, the Becquerel is used to quantify the rate of radioactive decay in a substance. Choices B, C, and D are incorrect as they represent units for energy, force, and temperature, respectively, not radioactivity.

3. Which hormone, produced by the pancreas, is involved in the regulation of blood sugar levels by inhibiting the release of insulin and promoting the release of glucose into the bloodstream?

A. Insulin
B. Glucagon
C. Cortisol
D. Somatostatin

Correct answer: D

Rationale: The correct answer is D, Somatostatin. Somatostatin is a hormone produced by the pancreas that plays a crucial role in regulating blood sugar levels by inhibiting the release of insulin and promoting the release of glucose into the bloodstream. It acts as a counterbalance to insulin, preventing excess insulin secretion and ensuring the availability of glucose when needed. Therefore, somatostatin helps maintain blood sugar balance in the body. Choices A, B, and C are incorrect. Insulin is responsible for lowering blood sugar levels, while glucagon and cortisol have roles that differ from the functions described in the question.

4. What is the oxidation state of carbon in CH4?

A. +1
B. -1
C. +2
D. -4

Correct answer: D

Rationale: In CH4 (methane), carbon is bonded to four hydrogen atoms. Hydrogen has an oxidation state of +1. Since the overall charge of CH4 is 0, the oxidation state of carbon must be -4 to balance the charges. Each hydrogen contributes an oxidation state of +1, resulting in a total of +4 from hydrogen atoms. To achieve a total oxidation state of 0 for the molecule, carbon must have an oxidation state of -4 to offset the contribution from hydrogen. Therefore, the correct answer is -4. Choices A, B, and C are incorrect: +1 is the oxidation state of hydrogen, -1 is not the oxidation state of carbon in methane, and +2 is not the correct oxidation state of carbon in CH4.

5. What type of tissue is found in the outermost layer of skin?

A. Muscle tissue
B. Connective tissue
C. Epithelial tissue
D. Nervous tissue

Correct answer: C

Rationale: The correct answer is C: Epithelial tissue. Epithelial tissue forms the outermost layer of the skin, providing protection against external factors. It serves as a barrier and helps in preventing water loss and entry of pathogens into the body. Choice A, Muscle tissue, is incorrect as muscle tissue is responsible for movement, not skin structure. Choice B, Connective tissue, is incorrect as it provides support and structure to the body but is not the main component of the outermost layer of the skin. Choice D, Nervous tissue, is incorrect as nervous tissue is responsible for transmitting signals within the body, not for the outermost layer of the skin.