biology Paper 1

• Eukaryotic Cell


  Cell that has a nucleus and other membrane-bound organelles
• Prokaryotic Cells


  Genetic material is not enclosed in a nucleus. They are much smaller
• An Animal cell contains...

  Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes

  
• A plant cell contains...

  Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes, chloroplasts, cell wall, vacuole

  
• Function of Nucleus


  Enclose genetic material
• Function of Cytoplasm


  Liquid where chemical reactions occur
• Function of cell Membrane


  Control what enters and leaves the cell
• Function of Mitochondria


  Where aerobic respiration takes place
• Function of Ribosomes


  Site of protein synthesis
• Function of chloroplasts


  Contain chlorophyll and are the site of photosynthesis
• Function of cell wall

  Strengthen the cell; made of cellulose
• Function of Vacuole


  Full of cell sap; keeps the plant cells shape
• Differentiation


  The process of a cell becoming specialised; having a specific function
• Sperm cells adaptations


  Half the genetic material, long tail for swimming, lots of mitochondria for energy, contain egg-digesting enzymes
• Nerve cell adaptations


  Long axons carry impulses, connections to create a network, synapse allow impulses to move,
• Muscle cell adaptations


  Can contract, lots of mitochondria, wok together
• Root hair cell adaptations

  Large surface area to volume ratio, no chloroplasts
• Xylem adaptations


  No end walls, made from dead lignin cells
• Phloem adatations


  Have a companion cell to provide energy
• Microscopes Practical


  Use a slide and place it in microscopes on the lowest magnification. Focus the microscope while increasing the magnification.
• Magnification =


  size of image/size of real object
• Electron Microscopes


  Have a higher resolution and magnification. Can see in greater detail. they are more heavy, less portable and more expensive.
• Bacteria


  Multiply by Binary fission. About once every 20 minutes.
• Practical: Antibiotics and bacteria

  1. Sterilise area

  2.Sterilise inoculation loop using fire

  3. Open agar plate near flame

  4. Spread Bacteria over plate

  5. Place antibiotic paper in plate

  6. Incubate for a few days at 25 degrees
• Gametes


  Sex cells that contain half the number of chromosomes
• Chromosomes


  Humans have 23 pairs of chromosomes. They carry genes
• Cell Cycle


  1. DNA replicates, the cell grows and copies internal structures

  2. Mitosis takes place, cell splits

  3. Two identical cells are formed
• Stem cell


  An undifferentiated cell which can give rise to more cells of the same type and can differentiate to form other types of cells
• Stem cells Location


  They are found in plant meristems, embryos and in bone marrows
• Bone Marrow Transplant


  Treat patients with leukaemia. The implanted stem cells divide to form new blood cells.
• Therapeutic Cloning


  A donor embryo is conceived to provide stem cells with the same genes for a patient.
• Diffusion


  The spreading out of particles resulting in a net movement from an area with a high concentration to an area of low concentration
• Factors affecting the rate of diffusion

  ↑ concentration gradient ↑ diffusion

  ↑ temperature ↑ diffusion

  ↑ SA:V ↑ diffusion

  ↓ diffusion pathway ↑ diffusion
• Osmosis


  Diffusion of water from a dilute solution through a partially permeable membrane
• Active Transport


  Moves substances from a more dilute solution to a more concentrated solution against the concentration gradient.
• Practical: effects of osmosis

  1. Cut potato into equal-sized cubes

  2. Measure mass and size of the cube

  3. Put potato into 10cm3 of 0.5 molar sugar solution

  4. Put potato into 10cm3 of 0.25 molar sugar solution

  5. Put potato into 10cm3 of Water

  6. Leave overnight

  7. Measure mass and sizw again
• Tissue


  A group of cells with a similar structure and function
• Organ


  Group of tissues working together for a specific function
• Digestion


  Is the breaking down large insoluble molecules into small soluble molecules by enzymes
• The digestive system contains

  Mouth, oesophagus, stomach,small intestine, large intestine, liver, panaceas, rectum, duodenum