which statement confirms that the cell membrane is selectively permeable

ATI TEAS 7

ATI TEAS Practice Science Test

1. Which statement confirms that the cell membrane is selectively permeable?

A. Receptors are found on a cell's surface.
B. Cells communicate with each other using cell signals.
C. Environmental changes can cause a cell to expand or shrink.
D. Sodium ions must travel through ion channels to enter the cell.

Correct answer: D

Rationale: The correct answer is D because selective permeability is demonstrated by the fact that specific ions, such as sodium, require ion channels to cross the cell membrane. This process allows the cell to control what substances can enter or exit, highlighting the selective nature of the cell membrane. Choices A, B, and C do not directly relate to the concept of selective permeability of the cell membrane. Receptors on a cell's surface (Choice A) are involved in cell signaling rather than selective permeability. Cell communication through signals (Choice B) and environmental changes affecting cell size (Choice C) are not directly related to the selective permeability of the cell membrane, which specifically refers to the regulation of substances passing through the membrane.

2. What is the primary function of the circulatory system?

A. To regulate body temperature
B. To transport oxygen and nutrients
C. To fight infection
D. To break down waste

Correct answer: B

Rationale: The correct answer is B: To transport oxygen and nutrients. The primary function of the circulatory system is to deliver oxygen and essential nutrients to cells throughout the body and remove waste products like carbon dioxide. Choice A is incorrect as regulating body temperature is primarily the function of the body's thermoregulatory system. Choice C is incorrect as fighting infection is mainly the role of the immune system. Choice D is incorrect as breaking down waste is primarily handled by the digestive system.

3. What enzymes do lysosomes contain, leading to their nickname as the cell's 'suicide bags'?

A. Hydrolytic enzymes
B. Ligases (bonding enzymes)
C. Transferases (molecule transfer)
D. Oxidoreductases (redox reactions)

Correct answer: A

Rationale: Lysosomes are organelles filled with hydrolytic enzymes that break down proteins, nucleic acids, lipids, and carbohydrates. These enzymes aid in digesting cellular waste and foreign substances, hence the term 'suicide bags' due to their involvement in cell degradation and recycling. Ligases are enzymes that catalyze the joining of two large molecules by forming a new chemical bond, not present in lysosomes. Transferases are enzymes that catalyze the transfer of functional groups from one molecule to another, not found in lysosomes. Oxidoreductases are enzymes involved in oxidation-reduction reactions, which are not the primary function of lysosomes.

4. Which of the following cations is found at the center of a heme?

A. Cr (III)
B. Cu (II)
C. Iron (II)
D. Iron (III)

Correct answer: C

Rationale: The correct answer is Iron (II) (Fe2+), which is the cation found at the center of a heme group. Heme contains an iron (II) ion that is coordinated within the porphyrin ring structure. This iron ion is crucial for the function of heme in binding and transporting oxygen in hemoglobin and myoglobin. Choice A (Cr (III)) is incorrect as chromium is not typically found at the center of a heme group. Choice B (Cu (II)) is incorrect as copper is not the cation typically present in heme. Choice D (Iron (III)) is also incorrect as heme predominantly contains iron (II) at its center, not iron (III).

5. Which structure in the eye is responsible for detecting light?

A. Cornea
B. Retina
C. Lens
D. Iris

Correct answer: B

Rationale: The retina is the correct answer as it is the light-sensitive structure in the eye that detects light and converts it into signals for the brain to process visual information. The cornea is the transparent outer covering of the eye that helps to focus incoming light onto the lens. The lens further focuses the light onto the retina, which is where the actual light detection and signal conversion occur. The iris, on the other hand, controls the amount of light entering the eye by adjusting the size of the pupil but is not directly responsible for detecting light.