june 2017- paper 2 Flashcards
1
Q
why heart rate increases during exercise (4)
A
- chemoreceptors detect drop in pH
- send impulses to cardiac centre
- more impulses to SAN
- via sympathetic NS
2
Q
mark release recapture equation
A
no in first x no in second sample / no recaptured
3
Q
why is an increase in shoot biomass a measure of NPP? (2)
A
- measures dry mass
- represents gross production - respiratory losses
4
Q
why are pancreas transplants not used in treatment of type 2 diabetes? (3)
A
- type 2 usually produce insulin
- cells are less responsive to insulin
- can be treated with diet/exercise
5
Q
what is phenotype? (2)
A
physical characteristics due to genotype and environment
6
Q
why does DNA not replicate during PCR? (1)
A
limited number of nucleotides
7
Q
sympatric speciation (6)
A
- same habitat
- mutation causes reproductive isolation
- change in frequency of different alleles
- disruptive selection
- eventually species cannot interbreed to produce fertile offspring
