june 2017- paper 3 Flashcards
1
Q
how does a nerve impulse cause the release of a neurotransmitter? (3)
A
- nerve impulse causes Ca2+ channels to open
- Ca2+ enter by facilitated diffusion
- causes synaptic vesicles to fuse with the synaptic cleft
2
Q
movement of myosin up actin (2)
A
- myosin head binds to actin and bends
- whatever is attached to the myosin is pulled along actin
- next myosin head binds to actin
3
Q
method of determining species richness (3)
A
- select sampling sites at random
- use a quadrat
- identify which species are present in each quadrat
4
Q
why does phosphorylation cause enzyme catalysed reactions to happen
A
raises the energy level of substrates