Unit 2

• Microscope


  Used to study the structure of cells
• Eukaryotic cells


  Plant and animal cells that contain a nucleus and membrane-bound organelles such as ribosomes and mitochondria
• Prokaryotes


  Bacteria that do not contain a nucleus or membrane-bound organelles
• Prokaryotes do not contain a rough endoplasmic reticulum
• Calculating the size of a specimen under a microscope

  Image size = Actual size / Magnification
• Cytoplasm


  Jelly-like material within the cell where reactions occur, containing structures like ribosomes and vesicles
• Cell membrane


  Thin membrane that surrounds the cell, controls entry and exit of substances
• Nucleus and DNA


  The nucleus contains genetic material in the form of DNA which codes for proteins, and is where DNA replication occurs
• Ribosomes and rough endoplasmic reticulum (RER)


  The RER surrounds the nucleus, and ribosomes are attached to it, being the site of protein synthesis
• Mitochondria


  Site of respiration, provides energy for the cell to function
• Vesicles


  Used to transport materials in the cell
• Additional structures in plant cells

  • Vacuole
  • Chloroplasts
  • Cell wall
• Vacuole


  Fluid-filled sac containing mineral salts, sugars, amino acids, waste substances and pigments which colour the cell and attract pollinating insects
• Chloroplasts


  Site of photosynthesis, allowing plants to convert light energy to glucose
• Cell wall


  Gives the cell structure and prevents bursting, controls what enters and exits the cell
• Tissue


  A group of similar cells working together to carry out a particular process
• Organ


  A group of tissues working together to carry out a specific function
• Organ system


  A group of related organs working together to carry out functions in the body
• Ciliated cells


  • Found lining the trachea, have hair-like projections called cilia which move together to transport mucus, dust and bacteria upwards to the throat
• Root hair cells


  • Adapted to have a large surface area, which speeds up the rate of osmosis and mineral ion uptake in plants
• Xylem vessels


  • Used to transport water through plants in transpiration, made from hollowed-out dead cells with the ends removed to make a tube for water to pass through, have a thick cell wall to provide structural strength and are thin to allow capillary action
• Palisade mesophyll cells


  • Where photosynthesis occurs, are tall and closely packed to efficiently absorb light and contain lots of chloroplasts for photosynthesis, placed at the top of the leaf where most light hits
• Nerve cells


  • Adapted to rapidly transmit electrical impulses, are myelinated to insulate the cell and prevent the impulse weakening and slowing down, contain lots of mitochondria to provide energy, have dendrites with a large surface area and are branched to receive impulses from many other neurons
• Red blood cells


  • Contain haemoglobin to carry oxygen around the body, have a biconcave shape to increase their surface area for rapid diffusion, have thin cell membranes to decrease the diffusion distance, do not contain a nucleus to have more space for oxygen
• Sperm cells


  • Contain lots of mitochondria to provide energy to reach the egg cell, have a tail to allow movement, and contain digestive enzymes to help penetrate the egg cell membrane