Which atmospheric gas would influence the rate of photosynthesis and this is the most oxygen and carbon dioxide?

Can someone i have no idea of how to do this.

In sweet pea, gene c is responsible for color production and gene p is responsible for the purple color pigment. both of them are located on two different loci on different chromosomes. the flowers will be purple only when the plant has the genotypes as c_p_. no color will be produced with genotypes: ccpp, ccpp, ccpp, ccpp. thus, gene c controls the expression of gene p. what pattern of inheritance is exhibited here? a. pleiotropy b. epistasis c. multiple alleles

What do we call an individual that has inherited two identical alleles for the same trait? a.homozygous b.heterozygous c.monozzygous