Biology Y7 B1.1

• Cells


  • The building blocks of life
  • The smallest unit capable of performing life functions
• Microscope


  Used to observe cells
• To Use A Microscope

  1. Lower the stage using the coarse adjustment knob

  2. Switch to the lowest magnification objective (shortest lens)

  3. Put the slide on the stage and secure with clips

  4. Look through the eyepiece and slowly turn the coarse adjustment knob until you see the object. Repeat with the fine adjustment knob

  5. Switch to the medium objective and refocus using the coarse then the fine adjustment knobs

  6. Switch to the highest objective (longest lens) and refocus using the coarse then the fine adjustment knobs
• Total magnification of a microscope

  Eyepiece magnification x Objective magnification
• Animal cells


  • Round and irregular

  
• Plant cells


  • Rectangular
• Nucleus


  • Controls the cell
  • Stores genetic information
  • Not the brain of the cell
• Cytoplasm


  Jelly-like substance where chemical reactions take place
• Cell membrane


  Controls what substances go into and out of the cell
• Mitochondria


  Use respiration to convert glucose (sugar) into energy
• Cell wall


  • Provides support to plants
  • Does not protect the cell or prevent substances from entering or leaving the cell
• Chloroplasts


  • Use photosynthesis to convert light energy into glucose (food)
  • Root cells of plants do not have chloroplasts since they don't receive sunlight
• Vacuole


  Large storage space filled with cell sap to keep the cell firm (turgid)
• Cell parts that plant cells have but animal cells don't

  • Cell wall
  • Vacuole
  • Chloroplasts
• Specialized cells


  Have a different shape and structure so they are suited for a particular job
• Specialized animal cells


  • Sperm cell: Digestive enzymes to get inside egg, lots of mitochondria for energy for swimming, nucleus with genetic material to fertilise egg, long tail for swimming to reach egg
• Specialized plant cells


  • Leaf cell or palisade cell: Lots of chloroplasts to do photosynthesis, found near top of leaf to absorb sunlight easily, long and thin with large surface area to absorb more sunlight
• Cellular respiration


  Releases energy
• The word equation for cellular respiration is: glucose + oxygen → carbon dioxide + water + energy
• Photosynthesis uses sunlight energy to make glucose


  Cellular Respiration uses glucose to release ATP energy

  
• Photosynthesis and Cellular Respiration are opposites!

  
• Substances that move out of the blood into cells during cellular respiration

  • Glucose
  • Oxygen
• Substances that move out of cells and into the blood during cellular respiration

  • Carbon Dioxide
  • Water
• Diffusion


  The movement of particles from a place where they are in high concentration to a place where they are in low concentration
• Concentration


  The number of particles in a given volume
• How substances move into and out of cells

  By diffusion
• How water enters and moves through a plant

  By diffusion
• Wilting


  Occurs because the vacuole shrinks and the cell becomes less rigid
• Unicellular organism


  A single-celled organism, an organism that has just one cell
• Unicellular organisms


  • Protoctists
  • Yeast
  • Bacteria
• Plants, animals, and some fungi are multicellular organisms
• Microscopic unicellular organisms


  • Amoeba: Nucleus, food vacuole, contractile vacuole, cytoplasm, cell membrane, pseudopods
  • Euglena: Nucleus, flagellum, chloroplasts, eye spot, nucleus, cytoplasm, contractile vacuole

  
• How amoeba move


  By flowing in water using pseudopods
• How amoeba get nutrition

  By engulfing tiny food particles with pseudopods and digesting them in food vacuoles
• How amoeba reproduce


  By binary fission, which is splitting in half to form two unicellular organisms
• How euglena move


  By moving their flagella to swim through water
• How euglena get nutrition

  If there is no light, they can absorb nutrients from water. If there is light, they use their eye spot to detect and move towards light so their chloroplasts can photosynthesize their own food.
• How euglena reproduce


  By binary fission, which is splitting in half to form two unicellular organisms
• Nerve cell (neurone)

  • long
  • can carry electrical signals
  • job is to carry nerve impulses to different parts of the body
• Red blood cell

  • Contains haemoglobin (pigment that combines with oxygen)
  • No nucleus = more space for haemoglobin = more oxygen
  • Disc-shaped and dent on each side creates large surface area
  • Large surface area compared to volume so oxygen always close to surface