UCT - Active vs Passive Transport

The movement of substances from low concentration region to high concentration region across a plama membrane is known as

• simple diffusion

• active transport

• facilitated diffusion

• osmosis

Answer explanation

Active transport is the process that moves substances from a low concentration to a high concentration region across a plasma membrane, requiring energy, unlike simple diffusion and facilitated diffusion which occur passively.

The following statements are true about passive transport EXCEPT

• Energy is not required

• Occurs against the concentration of the gradient

• Occurs until a dynamic equilibrium is achieved

• Occurs following the concentration of the gradient

Answer explanation

Passive transport does not require energy and occurs along the concentration gradient, not against it. It continues until dynamic equilibrium is reached, making 'occurs against the concentration of the gradient' the false statement.

What does semi-permeable mean?

• Some molecules can move through the membrane

• Nothing can move through the membrane

• All molecules can pass through the membrane.

Answer explanation

Semi-permeable means that some molecules can pass through the membrane while others cannot. This selective permeability allows certain substances to enter or exit, making the correct choice "Some molecules can move through the membrane."

Molecules will tend to spread out from an area of greater concentration to an area of lesser concentration.

• True

• False

Answer explanation

True. This statement describes the process of diffusion, where molecules naturally move from areas of higher concentration to areas of lower concentration to achieve equilibrium.

The picture below is an example of _________________.

• osmosis

• isotonic

• diffusion

• active transport

Answer explanation

The picture illustrates diffusion, which is the movement of particles from an area of higher concentration to an area of lower concentration. This process occurs naturally and does not require energy, distinguishing it from active transport.

Use the diagram to answer the following question. What process is occurring and what is missing from this diagram?

• The diagram is showing active transport because the molecules are moving from low concentration to high concentration, but energy should be included in the diagram.

• The diagram is showing passive transport because the molecules are moving from high concentration to low concentration, but energy should be included in the diagram.

• The diagram is showing active transport because the molecules are moving from high concentration to low concentration, but energy should be included in the diagram.

• The diagram is showing passive transport because the molecules are moving from low concentration to high concentration, but energy should be included in the diagram.

Answer explanation

The correct choice states that the diagram shows active transport, as molecules move from low to high concentration, which requires energy. This is why energy should be included in the diagram.

Endocytosis is a process of a cell bringing things into the cell. This is a(n) ____________ process.

• active

• passive

• hypotonic

• isotonic

Answer explanation

Endocytosis requires energy to transport substances into the cell, making it an active process. In contrast, passive processes do not require energy. Therefore, the correct answer is 'active'.

Which is an accurate description of the diagram below?

• Na+ and Amino Acids are both transporting passively.

• Na+ and Amino Acids are both transporting actively.

• Na+ is diffusing passively, and Amino Acids are transporting actively.

• Na+ is transporting actively, and Amino Acids are diffusing passively.

Answer explanation

The correct choice states that Na+ is diffusing passively, which means it moves along its concentration gradient without energy. Amino acids, however, are actively transported, requiring energy to move against their gradient.

Passive transport moves material __________ its concentration gradient. While active transport moves substances ___________ its concentration gradient.

• down, against

• against, down

• down, down

• up, up

Answer explanation

Passive transport moves material down its concentration gradient, meaning substances move from areas of higher concentration to lower concentration. In contrast, active transport moves substances against their concentration gradient, requiring energy.

Tap on all the pictures of ACTIVE transport.