MOVEMENT INTO AND OUT OF CELLS. Why does the colour of concentrated fruit drink change when it is added to water? Why can you smell cooked food from a.

MOVEMENT INTO AND OUT

OFCELLS

Why does the colour of concentrated fruit drink change when it is added to water?

Why can you smell cooked food from a distance?

Smells and liquids spreading out

Why can you smell perfume or aftershave when someone walks past you?

These processes are all examples of diffusion.

Smelling cooked food or perfume and diluting juice in water all involve things moving around and spreading out.

Smells and liquids spreading out

Diffusion involves the movement of molecules.What type of molecules are moving in these examples?

The molecules in every substance are always moving.

Moving molecules

In which state are molecules able to spread out?

water (liquid) water vapour (gas)

Diffusion involves the movement of gas and dissolved molecules. Why don’t solid molecules diffuse?

ice (solid)

When smelling body spray where is the smell strongest and where is the smell weakest?

Diffusion and changing concentrations

Smell is strongest at source.

Diffusion means the smell spreads out and gets weaker further away from the source.

How does the concentration of smell molecules change during diffusion?

Smell molecules move from an area of high concentration to an area of lower concentration. This is called a concentration gradient.

Where will the molecules be after diffusion?Diffusion can be represented on a simple diagram.

Changing concentrations

before diffusion

Diffusion is the movement of gas or dissolved molecules from higher to lower concentration.

Molecules diffuse down a concentration gradient.What does this mean?

after diffusion

What has happened to the concentration of the molecules?

Diffusion animation 1

Diffusion animation 2

Diffusion animation 3

Why is diffusion so important?

Diffusion occurs in the organ systems that control your breathing, circulation, digestion and other life processes.

Diffusion explains why you can smell smelly smells and what happens when you dilute a concentrated fruit drink.

More importantly, diffusion is an essential process that is going on inside your body right now and keeping you alive!

Diffusion is the movement of gas or dissolved molecules.

What gas and dissolved molecules do body cells need?

Your body’s survival depends on oxygen and dissolved food molecules getting into your cells.

Diffusion and life processes

How do these vital substances cross boundaries within the body to get to where they are needed?

Oxygen and dissolved food molecules must diffuse into and out of the blood for transportation around the body.

Where does diffusion take place within the body?

Diffusion in and out of cellsOxygen and dissolved food molecules are transported to the body’s cells in the bloodstream.

How does the concentration of these useful substances in the blood compare with the concentration inside the cells?

The concentration of oxygen and dissolved

food molecules is higher in the blood

arriving at the cells than inside the cells.

Diffusion in and out of cellsHow do oxygen and dissolved food molecules pass from the blood into the cells?

Oxygen and dissolved food molecules diffuse into the body cells, moving from higher to lower concentration.

The concentration of oxygen and dissolved

food molecules is higher in the blood

arriving at the cells than inside the cells.

What process involving these useful substances takes place inside the cell?

diffusion

Diffusion in and out of cellsThe cells use the food and oxygen for respiration.

Carbon dioxide is the waste product of respiration and will poison a cell if it is not removed. How is it removed?

Carbon dioxide molecules diffuse from the cells into the bloodstream, moving from higher to lower concentration.

How is this waste carbon dioxide removed from the body?

diffusion

What is active transport?Movement of substances in and out of cells by diffusion involves molecules moving down a concentration gradient from high to low concentration.

Sometimes substances move into cells from low to high concentration. This is called active transport.

Active transport needs energy to make it happen.

How do molecules move along the concentration gradient during active transport?

high concentration

low concentration

diffusion active transport

Active transport and plantsPlants need mineral elements from the soil for healthy growth. Minerals enter a plant though its roots.

The concentration of minerals in the soil is lower than that inside a root hair cell, so how do minerals enter the root cell?

soil

mineralelement

root hair cell

Active transport and plantsMinerals enter a root cell by active transport.

The plant uses energy to move minerals up the concentration gradient from the soil into its root cells.

Why is it important for plants to use energy in this way?

soil

mineralelement

root hair cell

active transport

What is osmosis?Osmosis is a special type of diffusion.

Diffusion involves gas or dissolved molecules, but osmosis only involves the movement of water molecules.

Osmosis occurs across a semipermeable membrane which has tiny holes in it.

These holes are small enough for water molecules to pass through but larger molecules cannot pass through.

watermolecule

What happens during osmosis?

Osmosis is the movement of water molecules from a region of high water concentration to a region of low water concentration across a semipermeable membrane.

Osmosis is a type of diffusion, so what do you think happens to water molecules during this process?

watermolecule

semipermeable membrane

osmosis

Osmosis animation 1

Osmosis animation 2