Biology Exam notes As Flashcards
What is the purpose of a double-blind trial?
Reduces bias from the scientists and means the participants have no way of knowing and so they cannot show psychological expectations.
What are enzymes treated as in practicals?
Acids/
How do you calculate rate from a table?
Difference / unit of time
How would you measure the SA of an irregular shape?
Draw around it on graph paper and count the squares.
Why may results not support the hypothesis?
Restricted time limit, small sample size or insignificant changes in the dependent variable.
Why are animals used ins scientific studies?
Large number of them, cannot test on humans and are likely to have the same reactions.
How would you control the pH of a solution for an enzyme controlled reaction?
Use a buffer at the enzymes optimum pH.
What is hydrolysis of ATP used for in a cell?
Phosphorylation substances (making them more reactive) and to provide the cell with energy.
How can a protein be the substrate of two different reactions?
If the enzymes are complementary to different parts of the substrate.
What would the hydrolysis of a lipid do to the pH?
Decrease it, forms fatty acids.
What do hydrogen bonds form between in collagen’s structure?
The R groups of adjacent amino acids.
Why are peptidases secreted in an inactive form?
Proteins are found in cell membranes and may be digested if the peptidase was active.
Give two properties of water in the cytoplasm?
Polar, it acts as a solvent.
Reactive, it involves hydrolysis and condensation reactions.
Why does DNA polymerase act in opposite directions?
Strands are anti-parallel and have differently aligned nucleotides. its an enzyme so has a specific active site so can only bind in a specific direction to the complementary substrate.
Give five key features of aseptic technique.
All equipment and surfaces must be sterilized with disinfectant or alcohol.
Minimise the agar’s exposure to air.
Inoculate all equipment using fame-technique.
Don’t sellotape all the way around the plate to allow the bacteria to respire anaerobically.
Incubate upside down so water formed doesn’t condense and drip down.
Why would an inactive virus produce no symptoms?
It is not replicating.
What equipment would you use to measure the size of a cell?
Eye piece graticule with is calibrated with a micrometer, one is transposed over the other to get a reading.
Why are there no organelles in the cytoplasm of a red blood cell?
It is full of haemoglobin.
What do repeats allow?
Anomalous results to be identified so the mean is more reliable.
Why would it be impossible to have antibodies in the blood without being currently infected by the pathogen?
Antibodies die quickly.
Why should studies of the immune system include participants of similar ages?
Age affects the immune system.
How do you calculate pulmonary ventilation rate?
Breathing rate x tidal volume.
What does a blockage of the coronary artery cause?
Prevents blood reaching heart muscles so they receive no oxygen and die causing a myocardial infarction.
Why does hydrostatic pressure in the capillaries fall between the atrial and venule ends?
Loss of water.
Why does high blood pressure cause build up of tissue fluid?
Increased outward pressure in capillaries.
Which direction would the oxygen dissociation curve shift in a high partial pressure of CO2?
Right.
Why may a vein be described as an organ?
It is made up of different specialised tissues.
How does elastic tissue even out the pressure of blood flowing through the artery?
It allows the artery to expand with pressure and then recoil.
