Question

1. Which of the statements are true about the cellular processes that occur during specific phases of the cell cycle in somatic cells? Select all that apply.
   1. During S phase, there is synthesis of cell components required for mitosis.
   2. During S phase, there is expression of proteins and enzymes required for DNA replication.
   3. During cytokinesis, separation of the cytoplasm forms two genetically identical daughter cells.
   4. During the second gap phase, there is separation of replicated chromosomes so that each daughter cell gets the same complement of chromosomes.
   5. During the first gap phase, there is increasing expression of cyclin genes if conditions favor cell division.
      

31. Why does meiosis result in more genetic variation than can be explained by mutation alone?

35. A chemical is added to cells growing in a culture dish. This chemical blocks the completion of DNA replication. In what stage of the cell cycle will the cells be stuck?

36. In diploid organisms, having two homologues of each chromosome can be beneficial if one allele of a gene encodes a nonfunctional protein. Can haploid organisms survive having nonfunctional alleles? Explain your answer.

37. What would be the result if a cell completed interphase and mitosis but failed to complete cytokinesis—how many cells would there be at that point, and how many chromosomes would those cells have in comparison to the parent cell?

38. Describe at least two major differences between mitosis and meiosis.

Answer 1

1. Answer: Options B, C, and E are correct
Explanation:
G1 = Synthesis of cell components required for mitosis
S = DNA replication
G2 = Synthesis of cell components required for mitosis
Karyokinesis = Nuclear division
Cytokinesis = Cytoplasmic division

31. Meiosis is essential for the generation of variability in sexually reproducing organisms. it generates variability by two mechanisms.
a. Crossing over
b. Independent assortment of chromosomes

35. If an inhibitor of DNA replication is added to the cell culture, cells will be arrested at S-phase (Specifically (G2-S transition)

36. Diploid organisms contain two alleles for each gene. So, they can survive even in the heterozygous condition for a recessive deleterious allele.
However, haploid organisms contain only one allele for each gene. So, they cannot survive if there is a deleterious mutation.

37. If Karyokinesis is not followed by cytokinesis, the coenocytic condition is generated = Multinucleated condition
Each cell contains two nuclei. Each nucleus contains two sets of chromosomes.

38. Mitosis:
a. Equational division
b. Two daughter cells are produced
c. No genetic variation

Meiosis:
a. Reductional division
b. Four daughter cells are produced
c. Genetic variation is generated