the system maintains the bodys balance through the release of directly into the bloodstream

HESI A2

Biology HESI A2 Practice Test

1. Which system maintains the body's balance through the release of hormones directly into the bloodstream?

A. The gastrointestinal system
B. The endocrine system
C. The digestive system
D. The endocrine system

Correct answer: D

Rationale: The correct answer is D: The endocrine system. The endocrine system maintains the body's balance through the release of hormones directly into the bloodstream. Hormones produced by glands in the endocrine system regulate various bodily functions such as metabolism, growth, and reproduction. This system plays a crucial role in maintaining homeostasis by releasing hormones that help control and coordinate different processes in the body. Choices A, C, and B are incorrect. The gastrointestinal system is responsible for digestion, absorption of nutrients, and excretion of waste; the digestive system includes the gastrointestinal system and other accessory organs; and choice B is a duplicate of the correct answer.

2. Which component is not found in the nucleotide of DNA?

A. Simple sugar
B. Nitrogen base
C. Phosphate group
D. Citric acid

Correct answer: D

Rationale: Citric acid is not found in the nucleotide of DNA. A DNA nucleotide is composed of a simple sugar (deoxyribose), a nitrogen base (adenine, thymine, cytosine, or guanine), and a phosphate group. Citric acid is not part of DNA nucleotides; instead, it is involved in the citric acid cycle of cellular respiration. Choices A, B, and C are essential components of DNA nucleotides, making them incorrect answers.

3. Patient A, who weighs 68 kilograms, steps onto a scale 20 times. The scale consistently weighs Patient A as 75 kilograms. What is true of the measurement?

A. It is valid, but not reliable.
B. It is reliable, but not valid.
C. It is both valid and reliable.
D. It is neither reliable nor valid.

Correct answer: B

Rationale: The correct answer is B: 'It is reliable, but not valid.' The measurement is reliable because it consistently provides the same result (75 kg). However, it is not valid because it does not accurately reflect the true weight of Patient A (68 kg). Choice A is incorrect because if the scale consistently shows the same weight (75 kg), it is reliable. Choice C is incorrect because although the scale is consistent, the measurement does not reflect the true weight, making it not valid. Choice D is incorrect as the measurement is reliable but lacks validity.

4. Which of the following is true of optical microscopy?

A. Utilizes scanning electrons
B. Utilizes visible light
C. Utilizes dye for samples
D. More than one of the above is true

Correct answer: D

Rationale: The correct answer is D, 'More than one of the above is true.' Optical microscopy utilizes visible light (Choice B) and often involves the use of dyes for samples (Choice C). Using dyes helps enhance contrast, making it easier to visualize the structures being observed. Choice A is incorrect as optical microscopy does not utilize scanning electrons, but rather visible light.

5. What process involves the movement of water molecules through a selectively permeable membrane?

A. Diffusion
B. Osmosis
C. Active Transport
D. Facilitated Diffusion

Correct answer: B

Rationale: Osmosis is the process specifically involving the movement of water molecules through a selectively permeable membrane, from an area of higher water concentration to an area of lower water concentration. This process helps balance concentrations on both sides of the membrane. Choice A, Diffusion, refers to the movement of particles from an area of higher concentration to an area of lower concentration, not specific to water. Choice C, Active Transport, requires energy to move substances against their concentration gradient, unlike osmosis. Choice D, Facilitated Diffusion, involves the use of transport proteins to move specific substances across membranes, not limited to water molecules.