Science

• Cell


  The smallest unit found in an organism that is capable of carrying out the basic functions of life
• Cells are the building blocks of life
• Organisms such as bacteria can be formed from a single cell
• Millions of cells can join together to form a person
• Observation


  Carefully and in detail looking at an object
• Microscope


  An instrument that magnifies small objects so they can be seen in detail
• Using a microscope


  1. Move stage to lowest position

  2. Place object on stage

  3. Select lowest magnification objective lens

  4. Look through eyepiece and turn coarse focus knob

  5. Turn fine focus knob until object is in focus

  6. Repeat with higher magnification objective lens
• Magnification


  The degree to which an object is enlarged when viewed through a microscope
• Eyepiece lens magnification


  Multiplied by objective lens magnification = total magnification
• Robert Hooke first observed plant cells using a microscope
• Components of an animal cell

  • Nucleus
  • Cell membrane
  • Cytoplasm
  • Mitochondria
• Additional components found in plant cells

  • Cell wall
  • Vacuole
  • Chloroplasts
• Cytoplasm


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


  Barrier around the cell that controls what can come in and out
• Nucleus


  Controls the cell and contains genetic material
• Mitochondria


  Where respiration happens to transfer energy
• Cell wall


  Strengthens and supports the cell, made of cellulose
• Vacuole


  Contains cell sap to keep the cell firm
• Chloroplasts


  Where photosynthesis happens, contain chlorophyll
• Specialised cell


  A cell that has changed its shape and structure to carry out a particular job
• Examples of specialised animal cells

  • Nerve cell
  • Red blood cell
  • Sperm cell
• Nerve cell


  Carries electrical impulses around the body
• Red blood cell


  Transports oxygen around the body, has no nucleus
• Sperm cell


  Carries male genetic material, has streamlined head and tail
• Examples of specialised plant cells

  • Leaf cell
  • Root hair cell
• Leaf cell


  Packed with chloroplasts to carry out photosynthesis
• Root hair cell


  Absorbs water and nutrients from the soil
• Diffusion


  The movement of particles from a high concentration to a low concentration
• Substances like glucose, oxygen, and carbon dioxide move in and out of cells by diffusion
• Water diffuses into plant root hair cells from the soil
• If a plant does not have enough water


  The cells become floppy and the plant wilts
• Unicellular organism


  An organism that is made up of a single cell
• Multicellular organism


  An organism made up of many cells
• Levels of organisation in a multicellular organism

  • Cells
  • Tissues
  • Organs
  • Organ systems
  • Organism
• Tissue


  A group of similar cells that work together to perform a certain function
• Animal tissues


  • Muscle tissue
  • Nervous tissue
• Plant tissues


  • Xylem
• Organ


  A group of different tissues that work together to perform a certain function
• Organ system


  A group of different organs that work together to perform a certain function
• Flowers are an organ system as they contain both male and female sex organs