Transport of materials across a cell membrane
A)is selective.
B)always takes place from a region of greater concentration to a region of lesser concentration.
C)is an energy-requiring process regardless of the chemical properties of the substance being transported.
D)requires a carrier molecule in the membrane regardless of the chemical properties of the substance being transported.

Question

Quizplus · Accepted Answer

Transport across a cell membrane is selective, meaning that only certain substances can pass through the membrane. This selectivity is due to the presence of specific transport proteins or channels within the membrane that allow only particular substances to pass.

Option B is incorrect as transport can be both from an area of greater to lesser concentration (passive transport) and from an area of lesser to greater concentration (active transport).

Option C is incorrect because some transport processes can occur without energy input (passive transport), while others require energy expenditure (active transport).

Option D is incorrect because not all substances require carrier molecules to move across the membrane. Some can diffuse freely through the membrane due to their chemical properties. Carrier molecules are required only for substances that cannot cross the membrane on their own.

Transport of Materials Across a Cell Membrane