- every cell is surrounded by a cell membrane that controls what goes in and out if the cell.
- organelles such as nucleus controls the cell's activity and chemical reactions occuring in the cytoplasm.
- mitochondria use glucose to release energy.
- ribosomes synthesis (make) protein.
- all ells in the body differ from one another. These specialise cells have features that help them to do their jobs successfully.
=> sperm cell: has a tail and lots of mitochondria because they move continuously looking for and egg.
=> epithelial cell: has cilia moving constantly to move particles along.
=> muscle cell: have fibrils that can shorten.
=> nerve cell: has fibers to carry electrical impulses.
- plant cells are the only cells that have cell walls giving them support and strenght.
- in the cytoplasm is found an organelle called chloroplast and it contains the green pigment chlorophyll.
- chlorophyll is a chemical used in photosynthesis to produce glucose.
- the vacuole contains cell sap which is salt, sugar and water.
- plant cells are specialised for specific jobs
=> palisade cells: are found in the leaf and packed with chloroplast.
they help in absorbing the maximised amount of sunlight during photosynthesis.
=> root hair cells: have extentions to absorb water and dissolved mineral ions.
=> xylem vessels: are dead cells arranged in tubes with no end walls between them. They transport water from roots through the stem to the leaves.
::: each root hair is only 0.1 mm long.
Cells make tissues make organs
- some organisms are uni-cellular and others are multi-cellular.
- specialised cells group together to form tissues.
=> epithelial tissues: cover the surface of organs as skin and lines all tubes.
- groups of tissues group together to make the complex organs.
=> arteries: are aogans lined with epithelial tissues and surrounded by muscle tissues and fibrous tissues.
- plant cells group together to make tissues like epidermal, photosynthetic and vascular.
- plant organs are root, stem and leaves.
=> vascular tissue: transport water and sugar.
=> epidermal tisse: protects the tissue.
=> photosythetic tissue: produce glucose.
- smelly particles spread through the air. It can spread many meters.
- diffusion is the movement of particles from area of high concentration to area of low concentration. As particles diffuse their concentration decrease.
- diffusion happens also in liquid. The difference in concetration is the " concentration gradient ".
- the greater the concentration gradient the faster the rate of diffusion.
- particles in liquid diffuse through a partially permeable membrane.
- a dilute solution contains more water particles than a concentrated one.
- osmosis is the diffusion of water across a partially permeable membrane.
- in osmosis there is always a net movement from dilute to concentrated solutions.
::: water moves from soil to root hair cells to stem cells then to leaves by osmosis. From the dilute solution to the concentrated step by step.
- if too…