Biology paper 2 Flashcards
What happens to a DNA probe at the region of interest?
They hybridise to the DNA
How is genetic fingerprinting carried out?
Obtain DNA, use PCR to clone the VNTRs using primers which bind to either side of the repeats or using restriction endonucleases to cut up the VNTRs after cloning DNA.
Add tag (fluorescence)
Gel electrophoresis
Fragments are viewed as bands
What does reverse transcriptase do?
Converts mRNA back into cDNA which can then be inserted into another organism.
What do restriction endonucleases do?
Cut the DNA at specific complementary palindromic sequences, producing sticky ends.
What is required in the solution before PCR?
DNA, complementary primers, free nucleotides and DNA polymerase.
What is the enzyme used to anneal the vector to the cut out sequence?
DNA ligase.
What do promoter and terminator regions do?
Tell RNA polymerase when to start and stop transcribing DNA. Must be present in a vector if you want the organism to create a protein.
What is an example of a unipotent cell?
Cardiomyocytes.
what do RNAi’s do?
Degrade mRNA before it is transcribed into a protein.
What is the difference between siRNA and miRNA?
miRNAs are less specific, they aren’t fully complementary.
What can metastatic tumours do?
Invade multiples do?
How does pyruvate enter the mitochondrial matrix?
active transport
What is nitrogen fixation?
N2 becomes nitrogen containing compounds.
What is ammonification?
Nitogen containing compounds become ammonia and then ammonium ions in the soil.
What is nitrification?
Ammonium ions become nitrites and then nitrates.
What is denitrification?
Nitrates become N2.
What are the two main features of receptors?
They only respond to specific stimuli and the stimulation of a receptor leads to the establishment of a generator potential.
Give an example of a myogenic muscle.
heart muscle.
What are the two centres in the medulla oblongata that control heart rate?
cardioacceleratory centre and cardioinhibitory centre.
What 3 things does the refractory period ensure?
- Impulses are discrete,
- Impulses are unidirectional,
- There is a limit to the frequency of transmission.
What does acetylcholinesterase do?
breaks down acetylcholine, its reformed in the pre-synapse
Give 4 features of a neuromuscular junction?
Excitatory,
only links neurones to muscles,
only has motor neurones involved,
acetyl choline binds to membranes of muscle fibres.
What is the genotype?
genetic constitution
What is the phenotype?
Expression of the genetic constitution and its interaction with the environment
What is allopatric speciation?
Geographical isolation
What is sympatric speciation?
reproductive isolation
What is the glomerulus?
A ball of vessles at the start of a nephron.
What happens to the sarcomere during contraction?
z-lines get closer, H zones get smaller and isotropic bands get smaller.
What is the ratio of 2 heterozygous plants in a dihybrid inheritance?
9:3:3:1
What happens to electrons from photolysis?
They replace those lost in chlorophyll.
What happens if the threshold has been reached?
A maximal response will occur no matter what the pressure.
Give two causes of variation produced from mitosis.
Crossing over and continuous variation
what happens to biodiversity in a climax community?
Remains constant and community remains stable.
Why should samples be large?
So findings can be generalised, reduce the significance of anomylous results.
Why is the fovea the area of the best vision?
Where the light is focused by the lens
What does myogenic mean?
Contracts independantly, without nerves.
What muscles are used for whole body movement?
Skeletal.
How does selective reabsoption occur?
Diffusion, facilitated diffusion and active transport.
