what is the main component that gives bones their rigidity and hardness

ATI TEAS 7

Mometrix TEAS 7 science practice test

1. What is the main component that gives bones their rigidity and hardness?

A. Collagen
B. Calcium phosphate
C. Cartilage
D. Ligaments

Correct answer: B

Rationale: Calcium phosphate is the main component that gives bones their rigidity and hardness. It combines with calcium hydroxide to form hydroxyapatite crystals, which provide strength and structure to bones. Collagen, on the other hand, provides flexibility and tensile strength. Cartilage is a type of connective tissue found in joints, and ligaments are fibrous tissues that connect bones to other bones, but they do not contribute to the rigidity and hardness of bones.

2. Which of the following is a cluster of capillaries that functions as the main filter of the blood entering the kidney?

A. The Bowman's capsule
B. The Loop of Henle
C. The glomerulus
D. The nephron

Correct answer: C

Rationale: The correct answer is C, the glomerulus. The glomerulus is a cluster of capillaries in the kidney responsible for filtering blood as it enters the nephron. It plays a crucial role in the initial stages of urine formation by filtering waste products and excess substances from the blood. Choice A, the Bowman's capsule, is incorrect as it surrounds the glomerulus and captures the filtrate. Choice B, the Loop of Henle, is incorrect as it is part of the nephron responsible for water reabsorption. Choice D, the nephron, is incorrect as it comprises the functional unit of the kidney and includes the glomerulus, Bowman's capsule, and other structures.

3. In a balanced chemical equation, the coefficients represent the:

A. Number of elements
B. Ratio of reactants and products
C. Physical state of the substances
D. Rate of the reaction

Correct answer: A

Rationale: The correct answer is A: 'Number of elements.' In a balanced chemical equation, coefficients represent the ratio of moles of each species involved in the reaction. They indicate the relative number of molecules or formula units of each compound taking part in the reaction. Choice B, 'Ratio of reactants and products,' is incorrect because the coefficients in a balanced equation do not represent the ratio of reactants and products directly, but rather the stoichiometry of the reaction. Choice C, 'Physical state of the substances,' is incorrect because the physical states (solid, liquid, gas, or aqueous) are denoted with symbols next to the chemical formula, not the coefficients. Choice D, 'Rate of the reaction,' is incorrect as coefficients in a balanced equation do not provide information about the rate of the reaction, which is determined by factors like temperature, concentration, and catalysts.

4. Which of the following statements is true about an allergic reaction?

A. An allergic reaction, such as hives or wheezing, results from overactive body systems such as the integumentary and respiratory systems.
B. An allergic reaction is a result of overactive B-cells in the body that release various immunoglobulins.
C. An allergic reaction is caused by overactive mast cells in the body, which are stimulated by Immunoglobulin E.
D. An allergic reaction involves substances like histamine, keratin, and collagen.

Correct answer: C

Rationale: The correct answer is C. Mast cells are responsible for releasing histamine and other chemicals during an allergic response. Choice A is incorrect because hives and wheezing are symptoms of an allergic reaction, not the causes. Choice B is incorrect as B-cells are not directly involved in allergic reactions. Choice D is incorrect as keratin and collagen are not typically involved in allergic reactions, and histamine is released by mast cells.

5. What is the approximate composition of blood?

A. 45% plasma, 55% formed elements
B. 55% plasma, 45% formed elements
C. 55% water, 45% blood cells
D. 45% water, 55% plasma

Correct answer: B

Rationale: Blood is composed of approximately 55% plasma (mostly water with proteins, electrolytes, and nutrients) and 45% formed elements (red blood cells, white blood cells, and platelets). Choice B is the correct answer. Choice A is incorrect as it reverses the percentages. Choice C is incorrect because it incorrectly states that blood cells make up 45% of blood, while they are part of the formed elements along with platelets. Choice D is incorrect as it suggests that water makes up 45% of blood, which is not accurate.