Topic Test Flashcards
1.b. Elastase only catalyses the breakdown of the structural protein in the elastic tissue.
Explain why elastase doesn’t break down other molecules. (2)
(1) its active site shape is specific to its substrates shape…
(2) so E-S complexes are only formed between these 2 molecules
2.a. Describe how you would test a piece of food for the presence of lipid. (2)
(1) dissolve in alcohol, then add water
(2) white emulsion shows presence of lipid
2.f. Suggest one advantage of the percentage of cholesterol being higher in RBCs compared to ileum cells. (1)
(1) RBCs are not supported by other cells so cholesterol helps it maintain shape
2.g. E.coli has no cholesterol in its cell-surface membrane. Despite this, the cell maintains a constant shape. Explain why. (2)
(1) because it has a cell wall
(2) which is rigid / made of peptidoglycan/murein
3.b. In the osmosis exp, why did the student blot dry the potato cylinders before weighing them? (1)
(1) water/solution on the outside increases the mass of the potatoes
4.b.i. Describe how the RER is involved in the production of enzymes. (2)
(1) has ribosomes
(2) to make proteins, including enzymes
4.b.ii. Describe how the golgi apparatus is involved in the secretion of enzymes. (1)
(1) packages / puts enzymes into vesicles
5.a. Describe the part played by the diaphragm in causing air to enter the lungs during breathing. (3)
(1) diaphragm contracts
(2) and flattens / increases volume of chest
(3) reduced pressure = allows air to enter
5.d.i. There’s a greater percentage reduction in blood flow to the diaphragm than to the lungs during a dive.
Explain the advantage to a diving seal of blood continuing to flow to the lungs. (1)
(1) some oxygen is left in the lungs / removal of CO2
5.d.ii. There’s a greater percentage reduction in blood flow to the diaphragm than to the lungs during a dive. Explain the advantage to a diving seal of a large reduction in blood flow to the diaphragm. (2)
(1) diaphragm muscles aren’t contracting
(2) so it will not require as much oxygen / glucose
6.c. RBCs contain haemoglobin. Haemoglobin has a high affinity for oxygen. This causes a high rate of diffusion of oxygen from the alveoli into the blood. Why? (1)
(1) Increases / maintains concentration gradient
8.a. Define the term genome. (1)
(1) the complete set of DNA in an organism/species/cell/etc.
8.b. ‘At least 75% of the DNA in our genome is useless junk after all.’
Use your knowledge of DNA to suggest what the author of the article meant by ‘useless junk’. And describe where this junk DNA is located within the human genome. (2)
(1) DNA that’s non-coding
(2) introns WITHIN a gene
