Cell biology

• What is inside the small intestine?

  Tiny projections (villi)
• What do Villi do? What characteristics do they have?

  Increase the SA so digested food is absorbed quicker into the blood, Single layer of surface cells, good blood supply to assist in good absorption
• What does the nucleus do?

  Controls activities of cell
• What does the cell membrane do?

  Holds together the cell, decides what goes in and out
• What does the cytoplasm do?

  Where chemical reactions occur, contain enzymes that control reactions
• What does the mitochondria do?

  Where aerobic reactions take place
• What do chloroplasts do (plant)?

  Where photosynthesis occur, contains lots of chlorophyll which absorb light needed for photosynthesis
• What are plasmids?


  Small rings of DNA
• What's active transport?


  Moves substances from a more dilute solution to a more concentrated solution
• What does active transport require?

  Energy from respiration
• What does active transport allow mineral ions to do?

  Be absorbed from plant rot hairs from very dilute solutions in the soil
• What do plants require for healthy growth?

  Ions
• What does active transport allow sugar molecules to do?

  To be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration
• What are sugar molecules used for ?

  Cell respiration
• What is cell differentiation?

  Process cell changes to be specilaised for a specific function
• What does cell differentiation allow a cell to do?

  To carry out a specific function
• When does differentiation occur in plant cells?

  At any stage
• When does differentiation occur in animal cells?

  At an early stage
• When does differentiation occur in mature animals?

  Used for repair and replacement
• What are undifferentiated cells called?

  Stem cells
• Why might cells be specialised?


  To become specialised for a specific function
• What process changes a cell to be specialised for its job?

  Differentiation
• What are sperm cells specilaised for? How?

  Reproduction. Long tail, streamlined head
• What are Nerve cells specialised for? How?

  Rapid Nerve signaling. Long branched connections at end to connect to other cells
• What are muscle cells specialised for? How?

  Contraction. Long for space to contract, lots of mitochondria for energy needed to contract
• What are Root Hair Cells specialised for? How?

  Absorb water/minerals. Long hairs stick out of the soil
• What are Phloem/Xylem specialised for? How?

  Xylem=Transporting substance. Hollow

  Phloem=Have structure. Substances can flow through them
• What are some of the substances transported in and out of the cell by diffusion?

  Oxygen and caron dioxide in gas exchange & waste product urea from cells into the blood plasma for excretion in kidneys
• What does a single-celled organism have?

  Large SA to volume ratio
• What increases the effectiveness of an exchange surface?

  Large SA

  Thin membrane, short diffusion path

  Efficient blood supply
• What part of the cell cycle is mitosis?


  When cell divides
• What's the cell cycle?

  Where cell is divided in series of stages
• What do multicellular organsims use mitosis for?

  Growth/repair of damaged cells
• What happens at the end of the cell cycle?

  2 identical cells produced, same number of chromosomes and identical to the original cell
• What are the 2 main stages of the cell cycle?

  1.Cell increases number of subcellular structures

  2.DNA replicates to form 2 copies of each chromosome

  3.Once DNA is copied, cell is ready for mitosis

  4.One set of chromosomes is pulled to each end of the cell and the nucleus divides

  5.Cytoplasm and cell divide to form 2 identical daughter cells
• What happens in therapeutic cloning?

  Embryos produced with same genes as patient
• What might therapeutic cloning be used for and why?

  Medical treatment, not rejected by patients body
• What are the risks of therapeutic cloning?

  Risk of infection, Religious objections
• How can stem cells from meristems be used to produce clones of plants quickly & economically?


  Rare species cloned to protect from extinction

  crop plants with special features->Disease resistant can be cloned to produce more of them
• What is osmosis?


  Diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane