cells

• magnification = image size / real size
• light microscopes use light and lenses to form and image of a specimen and magnify it
• electron microscope uses electrons instead of light, so can see much smaller objects than light microscopes
• differentiation is the process by which a cell changes to become specialised for its job
• sperm cells are specialise for reproduction
• nerve cells are specialise for rapid signalling
• muscle cells are specialised for contraction
• root hair cells are specialise for absorbing water and minerals
• phloem and xylem are specialised for transporting substances
• the function of the sperm cell is to get the male DNA to the female DNA
• the function of muscle cells is to contract when stimulated by nerves, producing movement or force
• the function of nerve cells is to transmit electrical impulses rapidly along their length
• the function of root hair cells is to absorb water and mineral salts from soil into plant roots
• the sperm cell has a long tail and a streamlined head to help it swim
• the muscle cells are long and contain lots of mitochondria to generate energy
• diffusion is the spreading out of particles from an area of high concentration to an area of low concentration
• osmosis is the movement of water molecules from a region of high water concentration to a region of low water concentration
• active transport is used in the gut when there is a lower concentration of nutrients in the gut but a higher concentration of nutrients in the blood
• mitochondria is where most of the aerobic respiration takes place
• the nucleus contains genetic material that controls the activities of the cell
• chemical reactions take place at the cytoplasm
• photosynthesis happens at the chloroplasts
• proteins are made at the ribosomes in the cell
• the cell membrane holds the cell together and controls what goes in and out of the cell