Diffusion,Osmosis and active transport igcse

Basic revision on this topic

What is diffusion in biology?

Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration.

Why does diffusion occur?

Molecules move down a concentration gradient as a result of their random movement.

What role does the cell membrane play in diffusion?

The cell membrane is a partially permeable membrane that allows some molecules to cross easily, while restricting others.

What helps living organisms obtain requirements and get rid of waste?

Diffusion helps obtain requirements and eliminate waste products.

What is Brownian motion?

Brownian motion is the random movement of particles that provides the energy for diffusion.

What factors influence the rate of diffusion?

Factors include surface area to volume ratio, distance, temperature, and concentration gradient.

How does the surface area to volume ratio affect diffusion?

The larger a cell, the smaller its surface area to volume ratio, slowing down diffusion.

What happens to cells that are adapted for diffusion?

They have increased surface area, like root hair cells in plants and cells lining the ileum in animals.

How does distance affect the rate of diffusion?

The smaller the distance molecules have to travel, the faster transport occurs.

What is the effect of temperature on diffusion?

Higher temperatures increase molecular movement and result in a faster rate of diffusion.

What is the concentration gradient?

The difference in concentration on either side of a membrane that affects the rate of diffusion.

What is osmosis?

Osmosis is the diffusion of water molecules from a dilute solution to a more concentrated solution across a partially permeable membrane.

How does water move during osmosis?

Water moves from a region of higher water concentration to a region of lower water concentration.

What happens to plant cells in different concentration solutions?

Plant cells can gain or lose mass depending on the concentration of the surrounding solution.

What role does water play in living organisms?

Water is a solvent that helps transport substances, remove toxic waste, and participate in metabolic reactions.

What happens to plant cells when they absorb water through osmosis?

The vacuole becomes larger, pushing the cell membrane against the cell wall, making the cell turgid.

What does it mean when a plant cell is turgid?

It means the cell is firm and rigid due to water entering by osmosis.

What is a plasmolysed cell?

A plasmolysed cell is one where the cell membrane has pulled away from the cell wall due to water loss.

What happens to animal cells in hypotonic and hypertonic solutions?

In hypotonic solutions, they may swell and burst; in hypertonic solutions, they may shrink and crenate.

What is active transport?

Active transport is the movement of particles from a region of lower concentration to a region of higher concentration using energy.

What energy source do cells use for active transport?

Cells use energy from respiration for active transport.

Why is active transport important?

It allows for the uptake of essential molecules and ions against their concentration gradients.

What are carrier proteins?

Carrier proteins are proteins embedded in the cell membrane that transport substances across the membrane.

What happens to substances during active transport?

They combine with carrier proteins and are transported through the cell membrane using energy.

How does the concentration gradient affect diffusion?

A greater difference in concentration on either side of the membrane results in faster movement.

What is the effect of temperature on molecular motion?

Higher temperature increases kinetic energy and the speed of molecular motion.

What is the role of water as a solvent within organisms?

It allows for the easy transport of dissolved substances in organisms.

How does the size of molecules affect their movement through the cell membrane?

Smaller molecules can pass through more easily than larger molecules.

What is the importance of the cell membrane's selective permeability?

It regulates the movement of substances in and out of the cell.

What happens to water potential in a concentrated solution?

The water potential is lower in a concentrated solution compared to a dilute solution.

How is diffusion important for gas exchange in organisms?

It allows gases like oxygen and carbon dioxide to move in and out of cells.

What is an example of diffusion in plants?

Plants use diffusion to take in oxygen for respiration and carbon dioxide for photosynthesis.

What is the result of osmosis in plant cells when placed in distilled water?

Water enters the cells, making them turgid and firm.

What are the consequences of a plant cell losing water?

The cell becomes flaccid, and the plant may start to wilt.

What is the significance of root hair cells in plants?

They increase surface area for better absorption of water and minerals.

What does the term 'kinetic energy' refer to in the context of diffusion?

It refers to the energy of motion that causes molecules to move randomly.

How do ions move into root hair cells?

They move against their concentration gradient via active transport.

What technique can demonstrate osmosis using dialysis tubing?

Filling dialysis tubing with a solute and observing water movement across its membrane.

How does dehydration affect animal cells?

Animal cells may shrivel and crenate if placed in a hypertonic solution.

What is the relationship between diffusion rate and surface area?

Higher surface area typically increases the rate of diffusion across a membrane.

Why do organisms rely on osmosis?

Osmosis regulates water balance, which is crucial for maintaining cell function.

What determines the movement of water through a partially permeable membrane?

The concentration gradient of water on either side of the membrane.

In relation to osmosis, what does 'net movement' refer to?

The overall direction and volume of water movement across a membrane.

What role do environmental conditions play in the rate of diffusion?

Conditions like temperature, surface area, and concentration affect how quickly diffusion occurs.

What is the importance of understanding water potential in plant cells?

It helps explain turgor pressure and the conditions under which cells will gain or lose water.

What is brownnan motion

Is when particles move randomly