Okay guys I thought it might be a good idea to start to piece together an unofficial mark scheme, as I believe this paper was stupid, and if you guys are anything like me, you would like to feel prepared for whats coming on results day by knowing where you went wrong.
These are only the questions I can remember and I do believe that some of this will probably be wrong so feel free to correct as you see fit. Anything with a ? by it means I am not to sure.
1)a)i) Tissue type: cuboidal epithelial tissue (1mark) location in the body: any glands such as saliva glands etc. (1 mark)
a)ii) Tissue type: columnar epithelial tissue (possibly a mark for villus epithelial cells yet highly unlikely) (1 mark) Location in the body: lining of the trachea/ileum/fallopian tubes (1 mark)
1)b) Definition of an organ: A structure that contains two or more different types of tissue (1 mark) functioning together for a common purpose (1 mark)
?) B – nucleus – function: contains genetic material in the form of chromatin to provide the protein code for dna replication???? (not sure on that one) (1 mark)
C- Nuclear pores – function: to allow messenger RNA and nucleotides to exit the nucleus and enter the cytoplasm. (1 mark)
D – nucleolus (1 mark) – function: produces ribosomal RNA (1 mark)
?) Difference between the nuclear membrane and the mitochondrial membrane: Any 1 from: mitochondrial membrane is infolded to form cristae, nuclear membrane is not: Mitchondrial membrane has a fluid filled inter membrane space, the nuclear membrane does not.
?) 2 differences between prokaryotic and animal cell ribosomes: any two from: in animal cells ribosomes are much larger than in prokaryotic cells (1 mark) : in animal cells ribosomes can be in the cytoplasm or attached to the rough endoplasmic reticulum, in prokaryotic cells they are only found in the cytoplasm (1 marks)
?) 3 differences between mitotic daughter cells and meiotic daughter cells:
Mitotic daughter cells: diploid, genetically identical/clones, go on to become regular bodily cells???
Meiotic daughter cells: haploid, genetically varied/different/not clones, go on to become gametes???
(3 marks awarded for three comparisons)
?)Drawn DNA nucleotide.
A – phosphate group
B – deoxyribose sugar
C – organic nitrogenous base
?) differences between DNA and RNA polymers: any two from:
DNA has deoxyribose sugar wheras RNA has ribose sugar: DNA contains the bases, adenine, thymine, cytosine and guanine wheras in RNA thymine is replaced by uracil (4 marks?)
?) Chitin question:
a) Group it belonged to: carbohydrates (might accept polysaccharides but that wasn’t the group) (1 mark)
b) Difference in its structure: Every other molecule was rotated 180 degrees allowing hydrogen bonds to form between the layers, as these hydrogen bonds are very strong it creates a strong exoskeleton. (chitin is pretty much just cellulose with an amino groups on it) (2 marks)
c) Group amino group belonged too: protein (again may allow amino acid but might be picky as it isn’t really its group) (1 mark)
?)Vitamin A and glucose, cell membranes:
Vitamin A: as it was lipid soluble it moved by diffusion through the phospholipid bilayer (1 mark) it moved from an area of high to low concentration over a concentration gradient (1 mark??)
Glucose: as it was water soluble it could not move through the phospholipid bilayer and thus moved by facilitated diffusion (1 mark) from an area of high to low concentration via intrinsic/channel/carrier proteins in the membrane (1 mark)
?)diffusion and active transport graphs:
?) width of the cell membrane: 7nm (need units for one mark) (in the teachers guide it says between 7 and 8 so they may have that range)
a) Graph A – describe the type of movement across the cell membrane: diffusion (1 mark) as there was no limiting factor/as concentration of oxygen increased, the rate of uptake also increased at the same rate (1 mark)
b) Graph B – describe between A and B the why this occurred for nitrogen Ions: as the concentration of nitrogen ions was much less than the amount of carrier/ channel protiens/ no limiting factor (1 mark)
c) What was the method of transport in graph B: (it said cyanide poison meaning that it had to be an active process) active transport (1 mark)
?) water potential = -300KPA (need both answer, correct sign and units for two marks) (if units are not present only one mark)
?) inorganic ion in the haem group: iron (1 mark)
?) why is it a Quaternary protein:they are made up of four subunits/tertiary protiens joined together/ polpeptide chains joined toegther (1 mark) which are joined by bonds between the variable/R groups of the amino acids (1 mark)
?)immobilised enzymes:
a) two advantages about immobilized enzymes: (any 2 from) more than one enzyme differeing in optimum can be used at the same time: the reaction can be easily controlled by the adding or removed of the immobilised enzymes: The enzymes can be reused which lowers the overall costs (2 marks)
b) effect of slowing down the flow: it would mean that more substrate would react as previously the active sites would have been occupied/the substrate would have been moving too fast. (1 mark) Thus if it is a slower flow there will be more chance of successful collisions and more juice will be made as product. (1 mark)
c)test for protiens: adding buiret solution to the sample (1 mark) after shaking the blue rung on the surface will dissapear and the solution will become purple if protein is present (1 mark)
d)test for a specific protien: biosensor which is specific to that particular protien(1 mark)
?) b) essay on golgi body, rough endoplasmic reticulum and lysosomes (10 marks)
Rough endoplasmic reticulum:
· (internal) system of flattened sacs/cisternae/membrane compartments (any two for one mark)
· Ribosomes attached
· Used to transport products of protein synthesis
· Continuous with the nuclear membrane
Golgi Body
· Consist of (interconnected) flattened (membranous) sacs
· Proteins from RER are transported here in vesicles
· Vesicles fuse with the golgi membrane and the contents are shed into the golgi sacs (at the cis face)
· They are built into more complex molecules such as enzymes/glycoproteins
· One other golgi function is carbohydrate secretion/transporting and storing lipids
· At the other end vesicles containing products/lysosomes bud off
· These can fuse with the plasma membrane cause exocytosis of contents
Lysosomes
· Are membrane bound vesicles/sacs which contain digestive enzymes
· They fuse with the membrane of the cell vacuole and enzymes digest contents
· These contents would have previously been enclosed by phagocytosis
· They break down worn out organelles/cause autolysis
A maximum of 10 marks can be awarded from the fifteen available