Paper 1

• Compare and contrast the structures of eukaryotic and prokaryotic cells.

  Include reference to the relative sizes of cellular structures in your answer. (6 marks) - BACK CONTAINTS ONLY STRUCTUAL COMPARISIONS 


  Structural comparisons:

  -both have membranes, cytoplasm and ribosomes

  -sperm cells and some prokaryotes have a flagellum

  -only eukaryotes have mitochondria and chloroplasts

  -prokaryotes have loose DNA in the cytoplasm

  -EUKARYOTIC PLANT CELLS HAVE A CELLULOSE CELL WALL, WHERAS A PROKARYOTIC CELL WALL IS MADE FROM PEPTIDOGLYCAN
• Compare and contrast the structures of eukaryotic and prokaryotic cells.

  Include reference to the relative sizes of cellular structures in your answer. (6 marks)- SIZE COMPARISONS ONLY ON BACK

  -prokaryotic cells are much smaller (around 1 µm compared to 10-100 µm in eukaryotic cells)

  -some organelles like chloroplasts and mitochondria are actually bigger than prokaryotic cells
• Suggest how the cell in Figure 1 is adapted for its function: (4 marks)

  Contains many ribosomes (uses protein synthesis to make enzymes) -2

  Contains many mitochondria (provides energy from aerobic respiration) used to build proteins/ enzymes

  
• How are xylem adapted for carrying water and mineral ions around a plant

  1)Cells are dead, form hollow tubes and have no organelles

  2) Walls are strengthened with (lignin) and thickened
• Why can't antibiotics be used to treat dieases caused by viruses?

  Antibiotics target bacterial infections, not viral infections

  Viruses live inside cells
• What are two examples of active transport?

  1)uptake of glucose by epithelial cells in the villi of the small intestine

  2)uptake of mineral ions by root hair cells in plants
• Why are scatter graphs used?

  -show the relationship of two dependent variables

  -there is no dependent variable
• How would you prepare a specimen to be viewn under a micoscope? e.g an onion cell

  1)Get sample, e.g with a swab/ using a pair of tweezers to peel back a layer of epidermal tissue

  2) add a drop of water to a clean slide

  3) spread sample on the slide

  4) add a drop of dye (iodine) so structures are clear

  5) place a cover slip over the top

  6) tap gently to remove air bubbles
• for a biological drawing:

  -there should be no shading --> use clean lines

  -draw structures in proportion

  -label features with clear lines
• Binary fission --> two genetically identical daughter cells
• on a petri dish, the area around the antibiotic is called the "zone of inhibition"
• bacterium don't contain mitochondria as it's too small/ wouldn't fit in the cell

  -aerobic respiration occurs in cytoplasm/ cell membrane
• Prokaryotic cells evolved long before eukaryotic cells and are much simpler in form and function. Consequently, they have a much smaller chromosome which is circular. Separating this chromosome from the rest of the cytoplasm offers no advantage to the bacterial cell so they never evolved a nucleus
• permanent vacuole —> filled with cell sap to keep the cell turgid
• xylem —> transport water from the roots to the leaves

  
  

  specialisation: cells have no ends and are hollow

  Lignin in cell wall to waterproof cells

  
  

  involved in transpiration
• phloem —> transportation for sugars

  
  

  specialisation: small holes in the end plates allow sugars to move through the cells

  
  

  involved in translocation
• transpiration —> process in which plants loose water (absorption of water through roots, stomata opening to loose water)
• translocation —> involved in transporting substances from leaves to rest of the plant
• zones of inhibition —> clear areas around bacteria colonies (antibiotic areas)
• What is the pH in:

  -saliva: (amylase at pH7)

  -stomach: (pepsin at pH2)

  -lipase: (small intestine at pH8)
• What does a plant with a nitrate deficiency look like?

  stunted growth
• What does a plant with a magnesium deficiency look like?

  Yellow leaves
• arteries --> thin lumen = increased pressure
• viens --> wide lumen = low pressure

  have valves to prevent backflow
• CHD symptoms:

  -Angina (chest pains)

  -Heart failure

  -Heart atack
• stents --> hold arteries open, are not a permanent solution
• statins --> reduce blood cholesterol levels, reduce rate of fatty material deposit

  are not a permanent solution
• sieve tubes in phloem --> have no nuclei, are more specialised for transport
• aspirin: comes from willow bark

  digitalis: comes from foxgloves

  penicillin: comes from penicillium mould
• Monoclonal antibodies:

  1. mouse is injected with an antigen
  2. mouse lymphocytes are formed
  3. complementary antibodies (to antigen) are formed
  4. antibodies extracted
  5. fused with myeloma (tumour) cells to make a hybridoma cell
• rose black spots --> spots on leaves

  TMV --> discolouration

  aphid infection --> presence of pests
• plant défenses:

  -cellulose cell walls

  -bark

  -waxy cuticle (prévente pathogens entering through leaf)