Biology - Cells

Secondary 1

Microscope

Magnification = Image Size / Actual Size Magnification = Eyepiece x Objective Lens

1 meter (m) = 100 centimeters (cm)• 1 cm = 10 millimeters (mm)• 1 mm = 1000 micrometers (μm)• 1 μm = 1000 nanometers (nm)

What are Cells

Life’s Building Blocks

A cell is a basic building block of life

Unicellular Organism: Living thing made up of just one cell.

E.g. Amoeba, E.Coli

Multicellular Organism: Living thing made up of many cells.

E.g. Dog, Fish

Animal Cell

Plant Cell

Cytoplasm

Nucleus Chromosomes

Drawing Cells

•Title• Use sharp pencil• Draw LARGE diagram (at least 2/3 of space available)• Clean, clear, sharp lines• Label on side, no arrows, use ruler

Note: Lines should not cut across a big partof the picture.

Functions of Cell Organelles

1. Cell/Plasma Membrane - Allow some substances to move in and out of the cell but not others i.e. Partially Permeable - Separates a cell from adjacent cells - Control & regulate passage of substances in and out of the cell e.g. Uptake of nutrients and release of metabolic waste

2. Cytoplasm - Jelly-like substance where chemical reactions (e.g. metabolic reactions) take place

3. Nucleus - Controls activities in the cell - Required for cell division

4. Chromosomes Controls instructions which controls how the cell functions

5. Vacuoles Enclosed compartments filled with water and other substances

such as enzymes, food molecules, air etc. Central Vacuole in plant cells makes it firm by taking in water

6. Mitochondria Powerhouse of the celli.e. Produces energy for the cell to use

7. Cell Wall Supports plant cell and gives it a regular shape

8. Chloroplasts Found only in green plants Contains chlorophyll which trap sunlight for photosynthesis

Animal Cell vs Plant Cell

Levels of Organisation

1. Cells2. Tissue cells of the same type, working together, having thesame function. Animal Tissue1. Connective Tissue2. Muscle Tissue3. Epithelial Tissue4. Nerve Tissue Plant Tissue1. Epidermal Tissue2. Vascular Tissue3. Supporting Tissue

3. Organs Different tissues working together to perform a particular

function

Animal Organs1. Brain2. Stomach3. Heart4. Lungs

Plant Organs1. Leaves2. Roots3. Flowers

4. Systems Different organs working together to

perform a particular function

Animal Systems1. Nervous2. Reproductive

Plant Systems Transport1. Reproductive

Division of Labour

Dividing the work of the organism among cells Each type of cell does a particular function well More efficient Cells may have special adaptive features to do these jobs more effectively