Answer:
Explanation: i don't know
You breathe in oxygen, you exhale carbon dioxide.
It is safe but you shouldn't breathe in carbon dioxide all the time.
Mutation are two types somatic and germ cell mutation...as there is mutation in germ cell it will alter the normal behavior and produce variation !
random fertilization also causes variation as different setup of genes meets with another different...so chances of variation increases !
and third crossing over is in meiosis when chiasmata forms....so in this two homologous chromosome attach to each other and on separation ... some part exchange so leads to variation !
Answer:1 : substratum. 2 : the base on which an organism lives the soil is the substrate of most seed plants. 3 : a substance acted upon (as by an enzyme)