B1

• an electron microscope has a higher resolution than a light microscope
• the equation for magnification is

  image size / real size
• a bacteria cell is an example of a prokaryotic cell
• an animal or plant cell is an example of a eukaryotic cell
• sperm cells are adapted to have a streamlined head and long tail for swimming, lots of mitochondria for energy, and enzymes to break down the egg cell membrane
• muscle cells are adapted to their function as they have lots of mitochondria to provide energy to contract
• how many divisions occur in mitosis?

  1
• how many daughter cells are created by mitosis?

  2
• how many divisions occur in meiosis?

  2
• how many daughter cells are created by meiosis?

  4
• stem cells can be used to repair damaged tissue, replace faulty blood cells and treat diseases
• in diffusion, particles move from a high concentration to a low concentration
• does diffusion require energy?

  no
• osmosis is a passive process that goes with the concentration gradient.
• osmosis is movement from a high concentration to a low concentration of water
• active transport is an active process
• active transport goes against the concentration gradient
• does active transport require energy?

  yes
• does osmosis require energy?

  no
• how do root hair cells use active transport?

  minerals are absorbed from the soil to the plant from a very dilute solution
• how do humans use active transport?

  when there is a lower concentration of nutrients in the gut than the blood, active transport is used to absorb them into the blood anyway
• how are alveoli specialised to maximise diffusion of oxygen and carbon dioxid?

  Thin walls, large surface area, good blood supply
• how is the small intestine adapted as an exchange surface?

  they’re covered in villi which increase the surface area for absorption
• how are villi adapted for absorption?

  -single layer of surface cells

  -very good blood supply