Biology Chapter 3.3 and 3.5 Flashcards

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Questions and Answers

What is passive transport?

Moving molecules into/out of the cell without energy input.

What is diffusion?

Spontaneous movement of fluid (gas or liquid) particles from an area of high concentration to an area of low concentration.

Does diffusion require energy?

False

What does diffusion occur by?

Random kinetic movement. Signup and view all the answers

When does net diffusion stop?

When concentration on both sides is equal. Signup and view all the answers

What happens when net diffusion stops?

Equilibrium is reached and diffusion of one compound is independent of diffusion of other compounds. Signup and view all the answers

What factors affect diffusion across a plasma membrane?

Diffusion directly through lipid bilayer and diffusion of hydrophilic molecules across a plasma membrane. Signup and view all the answers

What is osmosis?

The passive transport of water across a semi-permeable membrane. Signup and view all the answers

What is the plasma membrane permeable to?

It is permeable to water but not to solute. Signup and view all the answers

What are the three solution types relative to the cell?

Hypertonic solution, hypotonic solution, and isotonic solution. Signup and view all the answers

What is a hypertonic solution?

More dissolved particles outside the cell than inside of the cell. Signup and view all the answers

What is a hypotonic solution?

Less dissolved particles outside the cell than inside of the cell. Signup and view all the answers

What is an isotonic solution?

Solute concentration of solution equal to that of cell. Signup and view all the answers

What can movement of water into a cell do to the plasma membrane?

It can put pressure on the plasma membrane. Signup and view all the answers

What happens to animal cells in osmosis?

Animal cells will expand and may burst. Signup and view all the answers

What kind of organisms do not burst in osmosis?

Organisms with a cell wall, such as plants. Signup and view all the answers

Why do organisms with cell walls not burst during osmosis?

Cell membrane pushes against cell wall, which resists due to its own structural integrity. Signup and view all the answers

What happens if you don't water a plant?

It wilts, this is called plasmolysis. Signup and view all the answers

What does facilitated diffusion allow to diffuse?

It allows diffusion of large, membrane-insoluble compounds such as sugars and amino acids. Signup and view all the answers

Does facilitated diffusion require energy?

False Signup and view all the answers

What is a property of facilitated diffusion?

It is highly selective. Signup and view all the answers

What happens in facilitated diffusion?

Substance binds to membrane-spanning transport protein; binding alters protein conformation, exposing the other surface. Signup and view all the answers

Is facilitated diffusion reversible?

True Signup and view all the answers

What is an example of something that takes place in facilitated diffusion?

Glucose. Signup and view all the answers

What is active transport?

Movement across membrane with an energy cost, usually against concentration gradient. Signup and view all the answers

Does active transport require energy?

True Signup and view all the answers

Study Notes

Passive Transport

Passive transport is the movement of molecules across cell membranes without the need for energy input.

Diffusion

Diffusion is the spontaneous movement of fluid particles from high to low concentration, moving down a concentration gradient.
No energy is required for diffusion, occurring through random kinetic movement.
Net diffusion ceases when concentrations on both sides are equal, reaching equilibrium where diffusion of one compound is independent of others.

Factors Affecting Diffusion

Factors influencing diffusion include the direct passage through the lipid bilayer and the diffusion of hydrophilic molecules across the plasma membrane.

Osmosis

Osmosis refers to the passive transport of water, specifically the diffusion of water across a semi-permeable membrane from high to low concentration.
Plasma membranes are permeable to water but not to solute; water moves from dilute to concentrated solutions.

Solution Types

Solutions are classified into three types relative to cells: hypertonic, hypotonic, and isotonic.
- Hypertonic Solution: Higher concentration of dissolved particles outside the cell, causing water to move out, resulting in cell shrinkage.
- Hypotonic Solution: Lower concentration of dissolved particles outside the cell, causing water to move in and potentially making the cell expand or burst.
- Isotonic Solution: Solute concentration is equal inside and outside the cell, resulting in no net water movement.

Effects of Osmosis on Cells

Water movement into a cell can exert pressure on the plasma membrane, and in animal cells, it may lead to expansion and bursting.
Organisms with cell walls, like plants, do not burst due to osmosis as the rigid wall resists the pressure from the cell membrane pushing against it.

Plant Responses to Water Availability

A lack of water causes plants to wilt, referred to as plasmolysis. Rehydration restores turgidity, raising the leaves back up.

Facilitated Diffusion

Facilitated diffusion allows larger, membrane-insoluble compounds (e.g., sugars, amino acids) to diffuse down a concentration gradient without energy use.
It is highly selective and involves the binding of the substance to membrane proteins, changing the protein's shape to facilitate transport.

Characteristics of Facilitated Diffusion

It is reversible; molecules can enter and exit the cell via the transport protein.
An example includes glucose transport, where glucose binds to the protein, alters its shape, and is released into the cell.

Active Transport

Active transport moves substances across membranes with an energy cost, typically against their concentration gradient.
Energy is required to overcome both concentration and electrochemical gradients or to allow the passage of larger or charged particles through the membrane.

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Description

Test your knowledge of diffusion, osmosis, active transport, and endocytosis with these flashcards. Each card features key terms and definitions to help you understand passive transport mechanisms in cells. Perfect for students aiming to master these concepts in biology.