- A nucleus controls everything that happens inside the cell and contains the imformation to make new cells.
- Cytoplasm, a jelly like substance in which the chemical reactions of the call take place. These chemical reactions are controlled by enzymes.
- A Cell membrane, which gives the cell its shape and controls which substances enter and leave the cell.
-Ribosomes, which are where proteins are made.
- A cell wall is found outside the cell membrane. This is made of Cellulose and strengthens the cell.
- Chloroplasts are found in the cytoplasm of many plant cells. They absorb light energy to make food by photoynthesis.
- A vacuole is a large sac in the centre of the cytoplasm. It contains a watery fluid called cell sap. Also keeps the cell firm.
Differences between plant and animal cells
Plant cell Animal cell
Have tough cell walls No cell walls
Many have chloroplasts No chloroplasts
Have a large permanent vacuole Some have small vacuoles but no cell sap
Many have a box like shape The shape varies
Mitochondria are small sausage-shaped structures that can only be seen clearly under an electron microscope. They are found in the cytoplasm of cells and realise energy from respiration for the cell to use.
Tissues and Organs
- Tissues are groups of identical cells that all do the same job. For example, heart muscle cells from the heart muscle tissue that beats throughout your life.
- Organs are made up of tissues. For example, your heart is made up of muscle tissue, blood tissue and nerve tissue. These tissues all do different jobs, but work together to pump blood around your body. They work together to do a particular job.
- A number of organs working together makes up a system. Your heart and blood vessels make up your ciculatory system. This tranports blood to all the cells of your body.
Put all of the body's systems together and you get an organism.
Diffusion and Osmosis
Dissoled substances can move in to and out of our cells by diffusion and osmosis.
- Diffusion is the movement of particles from the region of high concentration to a region of lower concentration until they are evenly spread out.
- Osmosis is the diffusion of water molecules from a dilute solution to a more concentrated solution through a partially permeable membrane.
Photosynthesis is the process by which plants make their own food. To do this they need a source of energy to build food molecules. Sunlight is absorbed by the green substance called chlorophyll. Chrolophyll is found inside the chloroplasts of some plant cells. Light energy is found inside the chloroplasts of some plant cells.
Carbon Dioxide + Water--> Glucose + Oxygen
Carbon dioxide enters the leaf of a plant by diffusion through the stomata. Water is absorbed from the soil by the roots and carried up the stem to the leaves in the xylem vessels. Plants use some of the glucose in respiration to get their own energy. Excess glucose can be stored in the leaf as insoluble . When we test a leaf for starch with iodine, it will turn blue/blck.
Oxygen is released as a byoproduct of photosynthesis.