biology

• what are two types of eukaryotic cell?

  animal and plant
• What type of cell is bacteria?

  Prokaryotic
• Where is DNA found in an animal and plant cell?

  nucleus
• what is the function of the cell membrain

  controls the movement of substance in and out of the cell
• what is the function of the mitochondria

  stie of respiration to transfer energy to the cell
• what is the function of the chloroplasts?

  Photosynthesis
• what is the function of the ribosomes?


  Protein synthesis
• what is the function of the cell wall?

  Protection and support for the cell
• what is the structure of the main genetic material in a prokaryotic cell?

  Circular DNA (one loop)
• how are electron microscopes different to light microscopes?

  electron microscopes beam rays of electrons instead of light, cannot be used to view living samples, are mucvh more expesive, muchg hight magnification and resolution.
• what is the function of the red blood cell?

  Oxygen transport
• give three adaptations of the red blood cell:

  large surface area, thin walls, haemoglobin
• what is the function of the nerve cell?


  carries impulses around the body
• give two adaptations of the nerve cell:

  long axon so it can carry electrical impulses over long distances
• what is diffusion?


  The movement of particles from an area of high concentration to an area of low concentration.
• name three factors that effect the rate of diffusion:

  concentration gradient, surface area, temperature, pressure
• how are the villi adapted for exchanging substances?

  long and thin

  one-cell-thick membrane

  good blood supply
• how are the lungs adapted for efficient gas exchange?

  Alveoli

  moist membrane

  one-cell-thick membrain
• how are fish gills adapted for efficient gas exchange?

  large surface area for gasses to diffuse across thin layers of cells
• what is osmosis?


  The movement of water molecules from an area of high concentration to an area of low concentration across a semi-permeable membrane.
• give one example of osmosis in a plant:

  water moves from the soil to the root hair cell.
• what is active transport?

  movement of particles against a concentration gradient
• why is active transport needed in plant roots?

  concentration of mineral ions in the soil is lower than inside the root hair cells
• what is the purpous of active transport in the small intestine?

  sugars can be absorbed when the concentration of sugar in the small intestine is lower than the concentration of sugar in the blood
• what is a stem cell?


  an undifferentiated cell that can differentiate into one or more specialised cell types
• what are adult stem cells?

  Undifferentiated cells found in adult tissues that can differentiate into various cell types.
• where can adult stem cells be found?

  Bone marrow
• what are embryonic stem cells?

  stem cells from the embryo that have the potential to develop into any type of cell in the body
• where can embryonic stem cells be found?

  early human embryos
• what is therapeutic cloning?

  Creating genetically identical cells or tissues for medical purposes.
• give one advantage of using therapeutic cloning?

  stem cells from the embryo have not been rejected as they have the same genes as the patient.
• give one advantage of using adult stem cells:

  fewer ethical issues, as obtained by adults who can consent to their use.
• give two disadvantages of using adult stem cells:

  take a long period of time to find a donor, stem cells may not be able to differentiate into the type of cell needed
• what are plant meristems?


  area where rapid division occurs in the tips of roots and shoots
• give two advantages of using plant meristems to clone plants:

  rare species can be cloned to prevent extinction and pants with special features can be cloned and made more of
• give one disadvantage of using meristems to clone plants:

  no genetic variation, an entire cloned crop could die of disease
• what is cell division by mitosis?

  body cells divide to form two identical daughter cells.
• what is the purpose of mitosis?


  growth and repair of cells, asexual reproduction
• what happens during mitosis?


  one set of chromosomes is pulled to each end of the cell and the nucleas divides