Cells

• Whats the function of the nucleus

  Stores DNA & controls most of cells processes
• Whats the function of cytoplasm

  Where chemical reactions take place
• Whats the function of ribosomes?


  Protein synthesis
• Whats the function of cell membran?


  Controls what enters and leaves the cell
• Whats the function of chloroplast?

  Contains chlorophyll (absorbs light needed for photosynthesis)

  Where photosynthesis occurs
• Whats the function of cell wall?

  Made from cellulose & strengthens the cell
• What organelles do bacterial cells not have?

  No chloroplasts, nucleus or mitochondria
• Where is DNA stored in bacteria?

  Long strands of DNA (nucleoid)

  small circular strands of DNA (plasmid)
• Advantages and disadvantages of light microscope

  Advantages- cheap & easy to use

  disadvantage- depend on light, have a lower resolution and lower magnification
• What can be seen with a light microscope?

  Individual cells & large subcellular structures e.g nuclei
• Advantages and disadvantages of electron microscope

  Advantage- higher resolution & higher magnification

  Disadvantage- expensive and hard to use
• What is cel differentiation?

  Process where cells become specialised
• What are undifferentiated cells?

  Stem cells
• Whats the function of muscle cells?

  Contraction to allow body parts to move
• How are muscle cells specialised for contraction?

  Being long- Protein fibres have space to contract

  contain protei fibres- can change their length

  Full of mitochondri- provide energy needed for contraction
• What is the fuction of nerve cellsr?

  Rapid signalling

  Transmitting electrical signals from one part of the body to another
• How are nerve cells specialised for rapid signalling?

  Long axons- allows electrical signals to travel more distance

  Have dendrites- connects to other nerve cells, form a network

  Mylein sneath- surrounds axon, speeds up the transmission of nerve impulses
• Whats the function if root hair cells?

  Absorb water and mineral ions from the soil
• How are root hair cells specialised?

  Large surface afea due to projection into soil

  Contains lots of mitochondria for process of active transport

  No chloroplasts, it’s underground
• Whats the function of sperm cells?


  Reproduction
• How are sperm cells specialised for reproduction?

  Long tail & streamlined head - helps it swim to the egg

  Contain lots of mitochondri- provide energy

  Contains enzymes- allows them to digest their way through egg cell
• What is the cell cycle?


  Regular sequence of growth & division that cells undergo
• Stage 2 of the cell cycle?

  Mitosis

  1 set of chromosomes is pulled to each end of the cell and the nucleus divides
• Stage 3 of the cell cycle?

  Cytoplasm & cell membrane divide to form 2 identical cells
• Whats the functions of mitosis?

  Essential for growth & development of multicellular organisms (plants& animals)
• What is osmosis?


  diffusion of water from a dilute concentration to a concentrated solution through a partially permeable membrane.
• What do partially permeable membranes do?


  Allow some molecules to pass through, not all molecules
• Osmosis in plant cells with concentrated solution


  Place plant cell into concentrated solutio, water moves out of plant through osmosis

  Causes cell to shrink, become flaccid
• Osmosis in plant cells with water


  Place plant cell in water, water will move into cell through osmosis

  Cell will expand

  Cell wall prevents plant cell from burstin- keeps it turgid
• What is active transport?

  moves substances from a more dilute concentration to a more concentrated solution

  (against concentration gradient)
• compare diffusion and active transport

  diffusion— particles move down the concentration gradient

  -doesnt require energy from respiration

  active transport— particles move against the concentration gradient

  -requires energy from respiration