Diffusion, Osmosis and active transport

Diffusion

Is a net movement of particles from a region of higher concentration to a lower concentration down the concentration gradient

Factors Effect Diffusion

1.The higher the the temperature the higher the rate of diffusion because heat energy is converted to kinetic energy so molecule will move faster

2.Concentration gradient: the higher the difference between the two regions the higher the rate of diffusion.

3.The thicker the wall the slower the rate of diffusion

4.The larger the surface area the higher the rate of diffusion

5.The smaller the molecules the faster they move.

Osmosis

It is the net diffusion of water molecules from area of higher water potential to area of lower water potential through partially permeable membrane down the concentration gradient

Hypotonic solution

Turgid Putting plant cells in a solution of higher water potential than the inside of the cell

Hypertonic solution

Plasmolysed Putting plant cell in a solution with lower water potential than the inside of the cells

Isotonic solution

Flaccid plant is put in a solution with same water potential as the inside of the cell

Hypotonic solution in animal cell

Lysed burst

Hypertonic in animal cell

Shrink

Isotonic in animal cell

Normal

Percentage change in mass

End mass - start mass / start mass×100

Active Transport

Is the movement of ions from a region of low concentration toa higher concentration across a membrane using energy released during respiration against the concentration gradient via a protein pump

What Active transport needs for transporting substances across the membrane

Protein carriers

An example of active transport

The absorption of mineral ions from the soil

Root hair cell

Its main function is to absorb water from the soil by osmosis and mineral and ions by active transport

Root hair cell Structure

Increase the surface area for absorption.

The cell sap is concentrated to create water potential gradient for more water absorption

It has many mitochondria for more aerobic respiration and release of energy for active uptake

Preparing a slide and use a microscope

Cut a thin section using a scalpel.

Apply the section on a glass slide.

Add stain for contrast

Wash off excess stain
Apply coverslip, carefully avoiding trapped

air bubbles
Start with lowest power objective lens for focusing. Then observe under high power

Focus by moving the objective lens away from the specimen to avoid damage of the objective lens when touching the specimen

Magnification

Measured length \ Actual length