Apurebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds. the seeds of all of the offspring are yellow. why?

Because the yellow trait is dominant and the parent with this trait is homozygous for it.

Explanation:

Gregor Mendel performed experiments on pea plants, where he studied varying traits. In his experiments, he discovered that, for each trait, an organism (pea, in this case) receives two forms of gene called ALLELES, one from each parent. He stated in his law of segregation that these alleles randomly separate into gametes, with each gamete receiving only one allele from each parent. This alleles combine via the gamete to produce the genotype that determines the phenotype of the organism.

In a pair of allele, one allele is capable of masking the expression of another in a heterozygous state i.e. covering it up. The allele that masks or is expressed is called DOMINANT allele while the allele that is masked is called RECESSIVE allele.

Therefore, in this case, the allele for Yellow seed (Y) is dominant over the allele for green seeds (y). In a cross between two purebreds (homozygous) i.e identical alleles (YY and yy), all the F1 offsprings will possess a heterozygous genotype (Yy), which means they will all be phenotypically yellow-seeded because the allele for yellow will mask the expression of its green pair.

the answers are as following:

1. c. double helix, nucleosome, coil, supercoil, chromosome

2. b. g2 phase, preparation for mitosis

3. d. interphase consists of the g1, s, and g2 phases

4. c. metaphase

5. a. chromosomes are duplicated before cell division so that each new daughter cell has a complete set