Question

 (a) Consider a somatic cell taken from a sexually-reproducing organism. If this cell is resting, or performing the normal functions of the cell, but not going through cell division, how many versions of each type of chromosome would it contain? (BOLD the correct answer)

 ONE or TWO or THREE or twenty three or forty six

 (b) Explain why sexually reproducing organisms have the number chromosome copies you indicated in part a.

 (c) Consider a gamete taken from a sexually-reproducing organism. How many versions of cach chromosome does it contain?

 (d) If you were to look inside the nucleus of a zygote. How many versions of each

 chromosome would it contain?

 (c) Explain why zygotes have the number of chromosome copies you indicated in part

 d. Relate your answer to how zygotes are formed.

 (f) After a zygote is formed, it undergoes many cell divisions to eventually form an embryo. Are these cell divisions mitotic or meiotic? Explain your answer.

 (g) What is the word to describe the different "versions" of a chromosome that diploid cells contain?

 (h) What does "S phase" stand for during the cell cycle?

Answer 1

1a.Sexually reproducing organisms undergo meiosis to produce gametes. Gametes fuse and produce the zygote. Meiotic division requires chromosome pairs in the gamete mother cells. So, the somatic cells contain two sets of chromosomes (Assuming that the somatic body is the sporophyte).

1b. Two sets of chromosomes are separated and transmitted to haploid gametes. Gametes fuse and produce the zygote. Hence the chromosome number remains constant in a species.

1c. A gamete contains a single set of chromosomes (haploid)

1d. A zygote is the product of the fusion of two gametes. It contains two sets of chromosomes.

1e. A zygote is the product of the fusion of two gametes. It contains two sets of chromosomes.

1f. The zygote generally undergoes mitotic divisions to produce the adult somatic cells (If the dominant generation is sporophyte). In most algae, zygote immediately undergoes and produces haploid spores. These haploid spores germinate and produce haploid gametophyte.

1g. Chromosome sets

1h. Synthesis phase = Characterized by DNA replication