Paper 1

• Name the main organelles in an animal cell:


  > nucleus > cytoplasm > cell membrane > ribosomes > mitochondria
• What organelles does a plant cell have but animal cell doesn't?

  > chloroplast > cell wall> vacuole
• What organelles does a Bacteria cell have?

  > no nucleus > circular strand of DNA > rings of plasmid> cell wall> cell membrane
• What is a eukaryotic cell?


  A cell that contains a nucleus
• Give an example of a eukaryotic cell:

  > Animal cell> Plant cell
• What is a prokaryotic cell?

  Single cells of bacteria that has its DNA in a loop not inclosed in a nucleus
• Give an example of a prokaryotic cell:

  > Bacteria> Archaeans
• What is the function of a chloroplast? (plant cell only)

  > photosynthesis > contain chlorophyll which absorbs light needed for photosynthesis
• What is the function of cell wall? (plant cell only)

  supports the cell - strengthens it
• What us the function of a vacuole? (plant cell only)

  > contains cell sap - helps to make the cell RIGID> weak solution of sugars and salts
• What is the function of a nucleus?


  > contains DNA > controls the cell
• What is the function of mitochondria?

  > aerobic respiration respiration transfers energy that the cell needs to work
• What is the function of ribosomes?

  > proteins are made here
• What is the function of cell membrane?

  > controls what goes in and out> holds the cell together
• What is the function of cytoplasm?

  > chemical reaction take place here> contains enzymes
• What is the function of a plasmid?


  They are involved in the genetic exchange
• What is cell differentiation?


  The process in which cells change to become specialised to its job.
• What are the types of specialised cells? (6)


  > sperm cell> nerve cell> muscle cell> root hair cell > xylem cell > phloem cell
• What is the function of the sperm cell? and what is it specialised for?

  To get male DNA to the female DNA > specialised for reproduction
• How is sperm cell specialised for its job?

  > long tail + streamlined head for swimming to the egg> lots of mitochondria = energy > enzymes in its head to digest through the egg cell membrane
• What is the function of a nerve cell? And what is specialised for?

  To carry electric signals from one part of the body to another> specialised for rapid signalling
• How is the nerve cell specialised for its job?

  > long to cover more distance > have branched connections to connect with other nerve cells
• What is Axon?

  the EXTENSION of a NERVE CELL along which electrical impulses travel
• What is the function of a muscle cell?

  To contract quickly
• How is a muscle cell specialised for its job?

  > long = space to contract > lots of mitochondria = energy needed for contraction
• What is the function of a root hair cell?

  To adsorb water, nutrients and minerals from the soil
• How is a root hair cell specialised to do its job?

  > LARGE SURFACE AREA to absorb more water form the soil> THIN MEMBRANE so nutrients cross easily into the cell
• What is the function of xylem and phloem cells?

  To transport substances ( water + food) around the plant
• How are xylem and phloem specialised for their job?

  > long and join end to end = large volume
• What are the advantages of a LIGHT microscope?

  > color images > easier to carry
• What are the disadvantages of a LIGHT microscope?

  > limited magnification (not power enough)> limited resolution (blurred image)
• What are the advantages of an ELECTRON microscope?

  > much greater magnification > higher resolution
• What are the disadvantages of a ELECTRON microscope?

  > Black and white images> heavy to carry
• How do we work out magnification?

  magnification = image size / real size (in mm)
• What is BINARY FISSION?

  The process by which prokaryotic cells (bacteria) replicates (approx. every 20 mins)
• What are the stages of BINARY FISSION?

  1. Circular DNA and Plasmids REPLICATE 2. Circular DNA strands MOVE to opposite 'poles' (ends) of the cell3. CYTOPLASM DIVIDES and new cell walls begin to form4. 2 new DAUGHTER cells are formed
• The daughter cells after binary fission have........

  > ONE copy of circular DNA > VARIABLE numbers of PLASMIDS
• What conditions are needed for bacteria to divide more quickly? (2 things)

  > warm environment > lots of nutrients
• What are chromosomes?

  Chromosomes are COILED UP MOLECULES of DNA, which contain GENES and are found in the NUCLEUS
• In body cells chromosomes are found in........

  pairs, with one chromosome from each parent.