Cell Membranes and Transport Quiz

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Questions and Answers

What occurs to a cell placed in a hypertonic solution?

The cell swells and bursts.

The cell maintains its size.

The cell shrinks due to water moving out. (correct)

Water moves into the cell.

What is the main characteristic of an isotonic solution?

Lower concentration of water compared to the cell.

Leaves the cell in a state of plasmolysis.

Higher concentration of solutes inside the cell.

The concentration of solutes is equal inside and outside the cell. (correct)

How do bacteria and plants cope with osmotic pressure?

They use specialized gills to expel excess salt.

They excrete excess water through contractile vacuoles.

They absorb water through their membranes at all times.

They have cell walls that reduce expansion. (correct)

What mechanism do saltwater fish use to maintain osmotic balance?

They use their gills to pump out excess salt. Signup and view all the answers

What is turgor pressure in plants?

The pressure exerted by the cell wall against the cell membrane. Signup and view all the answers

What is one of the primary functions of the cell membrane?

Controls what enters and exits the cell Signup and view all the answers

What characteristic of phospholipids in the cell membrane makes it selectively permeable?

Fatty acid tails are non-polar Signup and view all the answers

Which of the following transport processes does not require energy?

Facilitated Diffusion Signup and view all the answers

Which statement accurately describes the lipid bilayer of the cell membrane?

It is composed of two layers of phospholipids. Signup and view all the answers

In the context of cellular transport, what is osmosis?

The passive transport of water molecules. Signup and view all the answers

Which component of the cell membrane serves as markers for cell recognition?

Carbohydrate chains Signup and view all the answers

What term is used to describe the model that explains the structure of the cell membrane?

Fluid Mosaic Model Signup and view all the answers

What occurs during active transport?

Cells use energy to move substances against their concentration gradient. Signup and view all the answers

What is the primary characteristic of facilitated diffusion?

It occurs through transport proteins. Signup and view all the answers

Which process describes the movement of water across a selectively permeable membrane?

Osmosis Signup and view all the answers

What is the outcome of a hypotonic solution on a cell?

The cell swells and may burst. Signup and view all the answers

In what direction do sodium ions move during the operation of the sodium-potassium pump?

Out of the cell Signup and view all the answers

What is one primary distinction between passive and active transport?

Active transport can move substances against their concentration gradient. Signup and view all the answers

Which type of active transport involves the cell membrane in-folding around food particles?

Endocytosis Signup and view all the answers

What would likely happen to a cell placed in a hypertonic solution?

Water exits the cell causing it to shrivel. Signup and view all the answers

Which type of molecules are typically transported by ion channels?

Ions such as Na+, K+, and Cl- Signup and view all the answers

Which pump is vital for nerve impulse transmission?

Sodium-potassium pump Signup and view all the answers

What happens during exocytosis?

Particles are transported out of a cell in bulk. Signup and view all the answers

Which statement best describes diffusion?

It is the random movement from high to low concentration until equilibrium is reached. Signup and view all the answers

What role do carrier proteins play in facilitated diffusion?

They change the shape to transport specific molecules across the membrane. Signup and view all the answers

Which type of solution has a higher solute concentration relative to the cell's interior?

Hypertonic solution Signup and view all the answers

What type of diffusion specifically involves the movement of water?

Osmosis Signup and view all the answers

Study Notes

Cell Membranes

All cells possess a cell membrane.
Functions include controlling what enters and exits the cell, maintaining homeostasis, and providing protection and support.

Structure of the Cell Membrane

Composed of a lipid bilayer (two layers of phospholipids).
Phospholipids have polar phosphate heads (water-loving) and non-polar fatty acid tails (water-fearing).
Proteins are embedded within the membrane.
Carbohydrate cell markers are present.
The fluid mosaic model describes the membrane's structure.

Cell Membrane Permeability

The membrane is selectively permeable, allowing some molecules to pass and blocking others.
Pores (holes) in the membrane contribute to its selectivity.

Cellular Transport

Passive Transport

Requires no energy input from the cell.
Molecules move from high concentration to low concentration.
- Diffusion: random movement of particles from high to low concentration until equilibrium is reached.
- Facilitated Diffusion: diffusion aided by transport proteins, specifically designed proteins for particular molecules.
- Osmosis: diffusion of water across a selectively permeable membrane.

Active Transport

Requires energy input from the cell.
Molecules move against their concentration gradient (low to high).
- Protein Pumps: transport proteins that use energy to move molecules. An example is the Sodium-Potassium pump which has an important role in nerve responses.
- Endocytosis: taking bulky materials into the cell. The cell membrane folds around the material, forming a vacuole, which is then used to digest the substances.
- Exocytosis: forcing materials out of the cell.

Sodium-Potassium Pump

A vital active transport protein.
Moves three sodium ions out of the cell and two potassium ions into the cell per cycle, against their concentration gradients. This action helps transmit nerve impulses.
The pump changes shape during the process, using energy from ATP breakdown.

Osmosis and Solutions

Hypotonic Solution: Water moves into the cell, causing the cell to swell and possibly burst (cytolysis).
Hypertonic Solution: Water moves out of the cell, causing the cell to shrink (plasmolysis).
Isotonic Solution: Equal water movement in and out of the cell, maintaining cell size.

How Organisms Deal with Osmotic Pressure

Cell walls prevent overexpansion in plants and bacteria.
Contractile vacuoles aid protists in water regulation.
Some organisms, like saltwater fish, actively regulate internal salt concentration and water balance.
Animal kidneys maintain blood isotonicity.

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Description

Test your knowledge on cell membranes, their structures, and functions. This quiz covers topics such as selective permeability, passive transport, and the fluid mosaic model. Perfect for students studying cellular biology.