BW1

BW1: Students should be able to investigate the structures of animal and plant cells and relate them to their functions

All living things, animals, plants, fungi etc. are composed of small units called cells.

Animal cells have 3 main parts

1. Nucleus – contains chromosomes and controls the cell.

2. Cell membrane – controls what enters and leaves the cell.

3. Cytoplasm – a watery liquid which supports smaller structures in the cell.

Plants cells also have 3 more parts

4. Cell wall – made from cellulose which gives strength to the cell.

5. Vacuole – contains a liquid which pushes outwards making the cell strong.

6. Chloroplasts – makes food for the plant.

A microscope is used to magnify cells to make them bigger.

Specimens must be thin enough to allow light to pass through to be seen with a microscope.

Total magnification = power of eyepiece X power of objective lens.

A stain is used to make cells easier to see.

Methylene blue is used to stain cheek cells.

Iodine is used to stain onion cells.

A cover slip holds the cells in place on a microscope slide and keeps them wet.

When using a microscope, place the slide on the stage, start with the low power lens and look through the eyepiece.

Turn on the lamp and adjust the focus knob to see a clear image