B1

• what are the 2 types of cells

  Eukaryotic (plant and animal)

  prokaryotic (bacteria)
• what are plasmids 


  small circular loops of dna found free in the cytoplasm

  carry genes
• function of permanent vacuole and what does it contain

  supports the cell

  contains cell sap
• how often do bacteria multiply

  once every 20 mins if enough nutrients available and temp is suitable
• 3 main stages of cell cycle

  replication of dna and syntheseis of organelles

  mitosis

  division of cell
• 3 main factors affecting rate of diffusion

  concentration gradient

  temp

  surface area
• function of stem cells in adult bone marrow

  differentiate into several cell types to replicate dead or damaged tissue.
• how are chromosomes arranged in nucleus of a body cell

  in pairs, 46 chromosomes in 23 pairs
• how is genetic info stored in a prokaryotic cell

  free in cytoplasm as chromosomal dna and plasmid dna
• what may happen when an animal cell is placed in a very hypotonic solution

  water moves into cell causing it to burst
• when may happen when animal cell is placed in very hypertonic solution

  water moves out the cell causing it to shrivel
• what is meant when a solution is hypertonic to a cell

  concentration of external solution is higher than internal solution
• what is meant by a solution being isotonic to a cell

  concentrations of external and internal solutions are the same
• function of stem cells in plant meristem

  differentiate into any type of cell throughout their lifespan
• what may happen to a plant in a very hypertonic solution

  water moves out the cell by osmosis around the vacuole and cytoplasm decrease in size. Cell membrane may pull away from cell wall causing cell to become plasmolysed
• what are chromosomes made up of

  dna molecules combined with proteins

  contains genes which provide instructions for protein synthesis
• factors increasing effectiveness of a gas exchange surface

  large surface area

  thin membrane

  efficient blood supply (animals)

  ventilation (animals)
• describe how xylem cells in plants are adapted for their function

  no upper or lower margins between cells, continuous root for water to flow

  thick woody walls, strengthens structure and prevents collapse
• list the component only found in plant cells

  chloroplasts

  permanent vacuole

  cell wall
• function of stem cells in embryos

  can replicate and differentiate into many other type of cell

  treat conditions such as diabetes and paralysis by dividing to replicate damaged cells
• how is active transport used to absorb products of digestion

  used to transport glucose from a lower concentration in gut to higher concentration in blood. Glucose is then transported to tissues where it can be used in respiration
• what is a stem cell


  an unspecialised cell which is capable of differentiating into other types of cells
• how are single celled organisms adapted for diffusion

  large surface area to volume ratio which maximises rate of diffusion of molecules to meet organisms needs
• why is mitosis important

  produce identical cells which all have some genetic info

  produces additional cells for growth and repair
• what is a gene

  a section of dna which codes for a protein
• what is osmosis

  movement of water from dilute solution to a concentrated solution through a partially permeable membrane. High to low concentration
• what’s meant when a solution is hypotonic to a cell

  concentration of external solution is lower than internal solution
• describe how phloem cells in plants are adapted to their function

  sieve plates, let dissolved amino acids and sugars be transported up and down the stem.

  companion cells provide energy needed for active transport of substances across phloem
• what’s the function of cell wall and what’s it made up of

  provides strength

  prevents cell bursting when water enters through osmosis

  made of cellulose
• what is active transport

  movement of molecules from more dilute solution to more concentrated solution against concentration gradient using energy from respiration.

  Low to high concentration
• examples of substances transported by diffusion in lungs and kidney

  In lungs oxygen diffuses into blood from lungs and carbon dioxide diffuses into lungs from blood. both down their concentration gradient.

  In kidney urea diffuses from cells inot blood plasma so it can be excreted in urine
• what is diffusion

  movement of particles from high to low concentration
• what is cell differentiation

  when cells become specialised

  allows production of different tissues and organs that perform vital functions in body
• function of chloroplast

  site if photosynthesis
• define resolution

  smallest distance between 2 objects that can be distinguished
• how do bacteria multiply

  binary fission (cell division)
• list component of both animal and plant cells

  nucleus

  cytoplasm

  cell membrane

  mitochondria

  ribosomes
• describe how root hair cells in plants are adapted to their function

  large surface area to absorb nutrients and water from surrounding soil

  Thin walls that dont restrict water absorbed
• describe how nerve cells in animals are adapted to their function

  Long axon allows electrical impulses to be transmitted all over body from cns

  Dendrites from cell body connect to receive impulses from other nerve cells muscles and glands

  Myelin sheath insulates axon and speeds up transmission of impulses along nerve cell