Jun 2016 Paper 2 Flashcards
Endopeptidases and exopeptidases are involved in the hydrolysis of proteins.
Name the other type of enzyme required for the complete hydrolysis of proteins to amino acids.
Dipeptidases
Suggest and explain why the combined actions of endopeptidases and exopeptidases are more efficient than exopeptidases on their own.
Endopeptidases hydrolyse internal (peptide bonds)
increase in surface area (for exopeptidases)
The addition of a respiratory inhibitor stops the absorption of amino acids.
Explain why.
No respiration means no ATP produced so no active transport
Sodium ions build up in the cell
so no diffusion gradient for sodium (to move into cell with amino acid)
In addition to the information provided in Figures 4 and 5, what other measurement is required to calculate an index of diversity for dung beetles?
Number (of individuals) in each species
Explain what the standard deviations suggest about the difference in mean total number of dung beetles between the different types of farm.
No overlap in standard deviations
(Difference in mean total) significant/is not due to chance/is real;
Explain the importance of the sites being chosen at random.
No bias
Explain why the removal of hedges caused a decrease in the diversity of birds.
Decrease in plant/insect diversity
Fewer food sources available
destruction/ of a habitat
Name the type of reaction used to break down phospholipids to release phosphate.
Hydrolysis
Suggest two reasons why an increase in phosphate can be linked to growth of the embryo.
(Phosphate required) to make RNA;
(Phosphate required) to make DNA
The chilling requirement of seeds of certain plant species is considered to be an adaptation for survival in countries with seasonal changes in environmental conditions.
Suggest how this adaptation may enable these plant species to survive and respond to seasonal changes.
seed is dormant and survives winter/cold
seed germinates when during spring when the temp starts to increase
Plant photosynthesise (in spring/when warm);
Produce (more) seeds
HIV attaches to a specific protein receptor on helper T cells. A low percentage of people have a mutation of the CCR5 gene which codes for this protein receptor. This mutation results in a non-functional protein receptor.
Explain how this mutation can result in the production of a non-functional protein
receptor
Change in DNA base/nucleotide (sequence);
Change in amino acid (sequence)/primary structure;
Changes position of the hydrogen/ionic/disulfide bonds;
Change in tertiary structure (of receptor)
People with the CCR5 mutation show a greater resistance to developing AIDS.
Explain why.
(Receptor) is not complementary so (HIV) cannot infect (helper) T cell;
No replication of HIV takes place
Using these data, scientists have concluded that the high frequency of the CCR5 mutation is not due to natural selection in response to HIV.
Suggest two reasons why scientists reached this conclusion.
There is a low number of HIV/AIDS (infections/cases)
HIV) has only been present for a short time period
Some people produce a much higher ventricular blood pressure than normal.
This can cause tissue fluid to build up outside the blood capillaries of these people.
Explain why.
More fluid forced out of capillary (due to high pressure)
Lymph(atic) (system) cannot drain away all excess fluid
Some drugs used to reduce high ventricular blood pressure cause widening of blood vessels.
Suggest how widening of blood vessels can reduce ventricular blood pressure.
Blood vessel has larger volume so reduces (blood) pressure
