Cell Transport: Passive and Active Transport

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Questions and Answers

What is the primary driving force behind the process of diffusion?

Thermal energy causing collisions of molecules

ATP energy molecules

Contractile vacuoles expelling fluids

Concentration gradient between regions (correct)

In which direction do molecules move during diffusion?

Towards an area of higher concentration

In a circular motion

Towards an area of lower concentration (correct)

Randomly with no particular direction

Which of the following is a necessary condition for diffusion to occur?

A semi-permeable membrane

A concentration gradient (correct)

An area with zero concentration

The presence of ATP

What would likely happen to diffusion if the concentration gradient between two areas decreases?

Diffusion rate would decrease Signup and view all the answers

Which statement best characterizes diffusion?

Movement of molecules from higher to lower concentration areas Signup and view all the answers

Which term describes the process by which water molecules move across a semipermeable membrane?

Osmosis Signup and view all the answers

Which type of solution has a higher concentration of solutes outside the cell than inside?

Hypertonic Signup and view all the answers

What is a characteristic feature of active transport?

It requires energy in the form of ATP Signup and view all the answers

Which of the following best describes facilitated diffusion?

Movement of molecules through a cell membrane without the use of energy, aided by proteins Signup and view all the answers

What is a key difference between passive and active transport?

Passive transport does not require energy, whereas active transport does. Signup and view all the answers

Which process involves the cell membrane engulfing materials to bring them into the cell?

Endocytosis Signup and view all the answers

What is the primary function of aquaporins in the cell membrane?

To allow water molecules to move freely across the cell membrane Signup and view all the answers

Why is facilitated diffusion important for cellular processes?

It allows the movement of molecules like water without using cellular energy Signup and view all the answers

In an osmotic system, the side with higher concentration of sugar will have what kind of solution?

Hypertonic solution Signup and view all the answers

What happens to the water movement when the concentration of water becomes equal on both sides of the membrane?

Water will continue to move equally in both directions Signup and view all the answers

Which of the following statements best describes the direction of net water movement in osmosis?

Water moves from hypotonic to hypertonic solution Signup and view all the answers

What does 'selectively permeable' mean in the context of cell membranes?

Only allows some molecules to pass through while blocking others Signup and view all the answers

How does the concept of osmosis explain the movement of water in Figure 8.18?

Water moves from the area with less sugar to the area with more sugar Signup and view all the answers

What term describes a solution with lower solute concentration compared to another solution?

Hypotonic Signup and view all the answers

What is the movement of water when a cell is placed in a hypertonic solution?

Water moves out of the cell Signup and view all the answers

How does a hypotonic solution affect an animal cell?

The cell expands Signup and view all the answers

What happens to a plant cell in an isotonic solution?

The concentration of solutes is the same inside and outside the cell, leading to equal movement of water. Signup and view all the answers

What causes water to move into a cell in a hypotonic solution?

Higher solute concentration inside the cell Signup and view all the answers

Which effect does a hypertonic solution have on a plant cell?

The cell membrane pulls away from the cell wall Signup and view all the answers

How does the net movement of water occur in isotonic solutions for animal cells?

Water moves equally in both directions Signup and view all the answers

Why does osmotic pressure develop across a cell membrane?

Due to differences in solute concentrations across the membrane Signup and view all the answers

What does the semipermeable membrane control in cells?

What enters and leaves the cell Signup and view all the answers

Which type of cell membrane transport mechanism is primarily responsible for maintaining cell volume?

Sodium pump Signup and view all the answers

What is the primary difference between active transport and diffusion?

Active transport moves materials against a concentration gradient; diffusion does not. Signup and view all the answers

Which cell structure is directly involved in the active transport of large molecules?

Endoplasmic reticulum Signup and view all the answers

How does bulk transport differ from other forms of cell membrane transport?

It involves the transport of very solid clumps of material. Signup and view all the answers

Which transport mechanism involves the cell membrane folding inward to enclose molecules?

Endocytosis Signup and view all the answers

Why is active transport critical for cells?

It maintains cell volume and homeostasis by moving materials against a concentration gradient. Signup and view all the answers

How does the sodium pump contribute to molecular transport?

By using ATP to create ion gradients. Signup and view all the answers

What role do synthesizers play in cell membrane transport?

They bind molecules to transport across the membrane. Signup and view all the answers

What occurs immediately after the pocket that results from endocytosis breaks loose from the cell membrane?

It forms a vesicle or vacuole within the cytoplasm Signup and view all the answers

Which process involves the extensions of cytoplasm surrounding and packaging a particle within a food vacuole?

Phagocytosis Signup and view all the answers

What is one specific function of phagocytosis in white blood cells?

Removing damaged or foreign cells Signup and view all the answers

In exocytosis, what occurs when the membrane of a vesicle fuses with the cell membrane?

The contents are released outside the cell Signup and view all the answers

Which type of endocytosis do amoebas use to take in food?

Phagocytosis Signup and view all the answers

How do aquaporins assist in the process of osmosis?

They form channels that allow water molecules to diffuse through the cell membrane Signup and view all the answers

What is one example of exocytosis mentioned in the text?

Removing water by means of a contractile vacuole Signup and view all the answers

What does the process of endocytosis enable cells to take up?

Large molecules, clumps of food, and whole cells Signup and view all the answers

Study Notes

Cell Transport

Cells have internal systems that distribute and deliver support, and boundaries that separate the cell from its surroundings.

Passive Transport

Diffusion: the movement of molecules from an area of higher concentration to an area of lower concentration.
Osmosis: the movement of water molecules through a selectively permeable membrane from an area of higher concentration to an area of lower concentration.
Facilitated Diffusion: a type of passive transport that uses specialized channels called aquaporins to move molecules through the cell membrane without using energy.

Osmosis

Osmosis is a type of facilitated diffusion that occurs through specialized channels called aquaporins.
Osmosis is the movement of water molecules through a selectively permeable membrane from an area of higher concentration to an area of lower concentration.
Osmotic pressure is controlled by the net movement of water across the cell's semipermeable membrane, affected by the concentration of solutes.

Effects of Osmosis on Cells

Hypertonic solution: a solution with a higher concentration of solutes than the cell, causing water to leave the cell.
Hypotonic solution: a solution with a lower concentration of solutes than the cell, causing water to enter the cell.
Isotonic solution: a solution with the same concentration of solutes as the cell, causing no net movement of water.

Active Transport

Active Transport: a semi-permeable membrane transport process that moves material against a concentration difference, requiring energy.
Used to maintain cell volume and create gradients for other substances.
Example: Sodium Pump, which uses ATP to pump sodium and potassium ions across the cell membrane.

Cell Membrane Transport

Synthesizers: proteins that bind molecules to transport across the cell membrane.
Endocytosis: a method of cell transport where the cell membrane folds inward and encloses molecules to form a transport vesicle.

Bulk Transport

Bulk Transport: the movement of very solid clumps of material across the cell membrane.
Used to remove large amounts of waste or produce a larger cell.

Endocytosis and Exocytosis

Endocytosis: the process of taking material into the cell by means of infoldings or pockets of the cell membrane.
Phagocytosis: a type of endocytosis in which extensions of cytoplasm surround a particle and package it within a food vacuole.
Exocytosis: the release of large amounts of material from the cell, where the membrane of a vesicle surrounding the material fuses with the cell membrane, forcing the contents out of the cell.

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Description

Understand the different types of cell transport, including passive and active transport, and how they work. Learn about diffusion, osmosis, and bulk transport.