Cell Biology

• How many pairs of chromosomes are found in the nucleus of a human cell?

  23 pairs
• What structure do chromosomes contain?

  A double helix of DNA
• What do chromosomes have a large number of?

  Genes
• What is the purpose of the cell cycle?

  To make new cells
• What must happen to cell DNA before mitosis occurs?

  It must be copied or replicated
• What are the key vocabulary terms related to cell biology?

  • Active transport
  • Alveoli
  • Chromosome
  • Diffusion
  • Eukaryotic
  • Gas exchange
  • Multicellular
  • Prokaryotic
  • Undifferentiated
  • Replicated
  • Specialised
  • Villi
• What are embryonic stem cells?

  Undifferentiated cells with the potential to turn into any kind of cell
• Where are adult stem cells found?

  In the bone marrow
• What types of cells can adult stem cells turn into?

  Some types of cells, e.g., blood cells
• What are some uses of stem cells?

  • Replacing faulty blood cells
  • Making insulin-producing cells
  • Making nerve cells
• Why are some people against stem cell research?

  They believe it compromises the rights of embryos
• What are the arguments for and against stem cell research?

  For:

  • Curing patients is more important than embryo rights
  • Using unwanted embryos from fertility clinics

  
  

  Against:

  • Compromises the rights of embryos
• Where are stem cells found in plants?

  In the meristem of the plant
• What can plant stem cells produce?

  Clones of the plant
• How can plant stem cells be used in agriculture?

  To grow crops with specific features, e.g., disease resistance
• How do multicellular organisms exchange substances?

  • They have a large surface area to volume ratio
  • This allows efficient exchange of substances
• Where does gas exchange take place in humans?

  In the alveoli
• What features of alveoli facilitate gas exchange?

  Large surface area, moist lining, thin walls, and good blood supply
• What increases the surface area in the small intestine?

  Millions of villi
• What is the function of villi in the small intestine?

  To absorb more digested food
• How does the leaf structure aid in gas exchange?

  The flattened surface increases the surface area for gas exchange
• What do guard cells control in plants?

  The opening and closing of stomata
• What is diffusion?

  The spreading out of particles from higher to lower concentration
• What is osmosis?

  The movement of water molecules across a partially permeable membrane
• What is active transport?

  The movement of substances against the concentration gradient requiring energy
• What do fish use for gas exchange?

  Gills
• How does oxygen move from water to blood in fish?

  By diffusion
• What structures increase the surface area of gills?

  Gill filaments and lamellae
• What is the purpose of capillaries in gills?

  To provide a good blood supply for diffusion
• What are the steps in the microscopy required practical?

  1. Prepare a slide
  2. Use a light microscope
  3. Draw observations with a pencil
  4. Label important observations
• What are the variables in the osmosis and potato practical?

  • Independent variable: Concentration
  • Dependent variable: Change in mass
  • Control variables: Volume of solution, temperature, time, surface area of the potato
• What happens to a potato in a sugar solution?

  It will lose water and have less mass
• What is differentiation?

  The process by which a cell becomes specialised
• What are the adaptations of specialised cells?

  • Sperm: Streamlined head, long tail, lots of mitochondria
  • Nerve: Long with branched connections
  • Muscle: Long with lots of mitochondria
  • Root hair: Large surface area
  • Phloem: Pores for sap flow
  • Xylem: Hollow tubes joined end-to-end
• What is the difference between prokaryotic and eukaryotic cells?

  Prokaryotic cells do not have a true nucleus
• What do bacterial cells contain instead of a true nucleus?

  A single strand of DNA that floats in the cytoplasm
• What additional structure do bacterial cells contain?

  A plasmid