Summary Grade 9: NS: Revision

Cells as the basic unit of life:
Plant and animal cells
Animal and plant cells consist of the following:
1. Membrane
2. Cytoplasm
3. Nucleus
4. Organelles

Plants Cells Animal Cell Nucleus




Basic structure
Membrane
 Outer boundary/ surrounds the cell
 Selectively permeable – allows certain substances in and out
Cytoplasm
 Jelly like substance
 Acts as a solvent for complex substances and materials
 A medium for chemical reactions to take place
Nucleus
 Contains DNA (deoxyribonucleic acid)
 DNA carries genetic code for cell reproduction
 DNA carries inherited characteristics: eye colour, freckles, hair colour etc.
 DNA is unique to each person and allows for variation in species
 Controls functions and processes of the cell

Organelles
Mitochondria
• Cellular respiration occurs here and releases energy
• The Powerhouse of the cell
• Animal and plant cells
Vacuoles
• Fluid filled sac
• Surrounded by a membrane
• Stores sugars, salts and water
• Larger in plants and very few small ones or none in animal cells
Chloroplast
• Plant cells ONLY
• Chlorophyll (green pigment) – allows photosynthesis to happen