Biology SOL Unit 2.3 - Cell Membrane Transport Mechanisms

Which of the following best describes passive transport?

• It is the movement of substances across a cell membrane without the need for cellular energy.

• It is the movement of substances across a cell membrane using ATP.

• It is the movement of water only across a membrane.

• It is the movement of substances against their concentration gradient.

Answer explanation

Passive transport refers to the movement of substances across a cell membrane without the use of cellular energy, allowing molecules to move along their concentration gradient.

What is the main difference between primary and secondary active transport?

• Primary active transport uses ATP directly, while secondary active transport uses the electrochemical gradient created by primary active transport.

• Primary active transport moves water, while secondary active transport moves ions.

• Primary active transport does not require energy, while secondary active transport does.

• Primary active transport only occurs in plant cells, while secondary active transport occurs in animal cells.

Answer explanation

The correct choice highlights that primary active transport directly uses ATP for energy, while secondary active transport relies on the electrochemical gradient established by primary transport, making it distinct in energy usage.

Which of the following is NOT an example of passive transport?

• Endocytosis

• Diffusion

• Facilitated Diffusion

• Osmosis

Answer explanation

Endocytosis is NOT passive transport; it requires energy to engulf substances into the cell. In contrast, diffusion, facilitated diffusion, and osmosis occur without energy input, relying on concentration gradients.

Explain how facilitated diffusion differs from simple diffusion, and provide an example of when a cell might use facilitated diffusion instead of simple diffusion.

• Facilitated diffusion uses transport proteins to move molecules across the membrane, while simple diffusion does not; for example, glucose entering a cell uses facilitated diffusion.

• Facilitated diffusion requires ATP, while simple diffusion does not; for example, oxygen entering a cell uses facilitated diffusion.

• Facilitated diffusion moves water, while simple diffusion moves ions; for example, sodium entering a cell uses facilitated diffusion.

• Facilitated diffusion only occurs in plant cells, while simple diffusion occurs in animal cells; for example, carbon dioxide leaving a cell uses facilitated diffusion.

Answer explanation

Facilitated diffusion involves transport proteins to help move specific molecules like glucose across the membrane, unlike simple diffusion which does not use proteins. This is crucial for cells that need to uptake glucose efficiently.

Why does active transport require cellular energy, and what form does this energy usually take?

• It is because substances are moved against their concentration gradient; the energy is usually in the form of ATP.

• It is because substances are moved with their concentration gradient; the energy is usually in the form of glucose.

• It is because substances are moved by osmosis; the energy is usually in the form of water.

• It is because substances are moved by diffusion; the energy is usually in the form of proteins.

Answer explanation

Active transport requires energy because it moves substances against their concentration gradient, which is energetically unfavorable. This energy is typically provided in the form of ATP.

Tags

NGSS.HS-LS1-7

The process that involves a cell capturing a substance or particle from outside the cell by engulfing it with the cell membrane is called (a)   .

• Exocytosis

• Endocytosis

• Diffusion

• Osmosis

Answer explanation

The correct answer is Endocytosis, which is the process where a cell engulfs substances from outside by wrapping them in its membrane, allowing for the intake of materials necessary for cellular functions.

What is the main function of exocytosis in a cell?

• To engulf particles from outside the cell

• To transport water across the membrane

• To export substances such as proteins or remove waste products

• To break down toxins inside the cell

Answer explanation

The main function of exocytosis is to export substances like proteins and remove waste products from the cell, making it essential for maintaining cellular function and homeostasis.

Both endocytosis and exocytosis are mechanisms for transporting which of the following?

• Small ions only

• Large molecules or particles

• Only water molecules

• Only gases

Answer explanation

Both endocytosis and exocytosis are processes that transport large molecules or particles across the cell membrane, making 'Large molecules or particles' the correct choice.

Match each cellular process with its correct description.

• Process that moves substances from high to low concentration

• Diffusion, because it moves substances from high to low concentration.

• Process that involves movement of water across a membrane

• Exocytosis, because it exports substances out of the cell.

• Process that exports substances out of the cell

• Osmosis, because it involves water movement.

• Process that brings substances into the cell

• Endocytosis, because it brings substances into the cell.

Answer explanation

Refer to your notes.

Match each process or description with what happens to the particle or how it interacts with the cell membrane.

• Endocytosis: The particle enters the cell from the outside

• The particle is transported by osmosis.

• Extracellular digestion: The particle is degraded outside the cell

• The particle is engulfed from outside the cell into the cytoplasm.

• Exocytosis: The particle leaves the cell

• The particle exits the cell through the internal membrane.

• Osmosis: The particle moves across the membrane with water

• The particle is broken down outside the cell.

Answer explanation

Reer to your notes.