B2.1 SUPPLYING CELL

• where does exchange of substances occur?

  cell membrane
• what are the 3 transport processes?

  diffusion, osmosis and active transport
• what is diffusion?

  the movement of particles from higher to lower concentration
• is diffusion a passive process and why?

  yes because the movement of particles in a fluid is dependant on how much kinetic energy they have.
• why is the cell membrane partially permeable?

  because some substances are able to leave/enter the cell while others aren't
• fill in the blanks!

  A) cant

  B) can

  C) cytoplasm

  D) higher

  E) lower

  
• why cant starch diffuse across the cell membrane?

  its too big
• plant root cell for diffusion

  A) root hair cell

  B) root

  C) soil

  D) water

  
• what is osmosis?

  the movement of water molecules into and out of cells
• what type of membrane does osmosis occur at?

  a partially-permeable membrane
• TRUE OR FALSE: osmosis occurs from lower water conc to high water conc.

  false
• • Like, diffusion, osmosis is a form of passive transport (does not require energy) but it only applies to water
• fill in the blanks!

  A) sucrose

  B) cant

  C) partially permeable

  
• • Water potential is the potential (likelihood) of water molecules to diffuse out of or into a solution.
  • Water potential indicates how concentrated a solution is
• does active transport require energy?

  yes
• • Active transport moves substances from a more dilute solution to a more concentrated solution
• Active transport across the cell membrane involves protein carrier molecules embedded in the cell membrane.

  A) higher

  B) lower

  C) carrier

  D) concentration gradient

  
• which body cell is not produced by mitosis?

  gametes
• what is the 1st part of the cell cycle?

  interphase

  • consists of phases of cell growth and synthesis of DNA
  • DNA copies itself exactly in the nucleus
• what is the 2nd part of the cell cycle?

  mitosis

  • chromosomes line up along the centre of the cell and are pulled apart
• what is the 3rd part of the cell cycle?

  cytokinesis

  • the cell cytoplasm and membrane divides to product 2 daughter cells
• steps of mitosis:

  1. DNA is replicated
  2. each chromosome is duplicated
  3. the nuclear membrane breaks down
  4. chromosomes line up along the centre of the cell
  5. once the chromatids have been divided the cell begins to divide (cytokinesis)
  6. 2 genetically identical daughter cells are produced
• • Specialised cells are cells that have a particular structure and composition of sub-cellular structures
  • The structural differences between different types of cells enables them to perform specific functions
  • This allows organisms to operate more efficiently
• what process do cells specialise by?

  differentiation
• how is a red blood cell adapted?

  biconcave disk --> increases surface area --> more efficient diffusion of oxygen

  haemoglobin --> joins with oxygen to transport it

  no nucleus --> increase space available for haemoglobin inside cell
• how is the nerve cell adapted?

  axon covered with fatty sheath --> insulation --> speeds up the nerve impulse

  extensions/branches --> can communicate with other nerve cells, muscles and glands

  long --> can run to and from different parts of the body to the CNS
• how is the sperm cell adapted?

  tail --> enables sperm to swim

  lots of mitochondria --> release energy needed to swim

  acrosome in head contains digestive enzymes --> penetrates an egg
• how is the egg cell adapted?

  lots of cytoplasm --> contains nutrients for embryo

  haploid nucleus --> genetic mnaterial for fertilisation

  cell membrane changes after fertilisation --> no more sperm can enter
• how is the root hair cell adapted?

  root hair --> increase surface area of cell --> max absorption of water/mineral ions

  thin walls --> water move through quickly
• how is the xylem vessel adapted?

  no bottom/top walls --> continous column of water running through

  cells are dead --> free passage of water

  lignin lined walls --> thick walls help support plant
• what are stem cells?

  undifferentiated cells that have the potential to become specialised
• where are embryonic stem cells found?

  on the inside layer of an embryo
• where are adult stem cells found?

  certain places such as bone marrow
• TRUE OR FALSE: embryonic stem cells can turn into any kind of cell type

  true