What might cause a cold spell in the northern united states?
a the doldrums move south
b the subtropical high moves north
c the subtropical jet stream moves north
d the polar jet stream moves south

a

explanation:

many plants naturally reproduce this way, but it can also be induced artificially. horticulturalists have developed asexual propagation techniques that use vegetative plant parts to replicate plants. success rates and difficulty of propagation vary greatly. monocotyledons typically lack a vascular cambium and therefore are harder to propagate.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.