General Biology I
BIO 103-33
Exam III – Review Questions (Chs. 8, 9)

1. What is sexual reproduction? When does it occur?

2. What is asexual reproduction? When does this process occur in eukaryotic cells?

3. What is mitosis? What does it produce?
 The goal of mitosis is to increase genetic variation when your producing gamies.

4. What is meiosis? What does it produce?
• Meiosis- produces 4 daughter cells that are not genetically apparent
5. What is chromatin? What are chromosomes?
• Chromosomes exist as a diffuse mass of long, thin fibers, this material is called chromatin.
• Chromosomes contain an organism’s DNA. Chromosomes are homologous pairs; where genes are located. Chromosomes determine sex in many species.

6. What are homologous chromosomes?
• Chromosomes are homologous pairs—“think of two x’s sitting next to eachother”. In these chromosomes, genes are located in same location. “you get one from mom and one from dad”. -

7. What are sister chromatids?
• They contain identical copies of the DNA molecule, they are created during the S (DNA replication) phase.
8. What are chiasmata? What is the centromere?
• Chiasmata is The point of contact between paired chromatids during meiosis, resulting in a cross-shaped configuration and representing the cytological manifestation of crossing over.
• Chiasmata=The X-shaped, microscopically visible region representing homologous chromatids that have exchanged genetic material through crossing over during meiosis
• The centromere is the center (“narrow waist”) of the “X” shape of a chromosome. -

9. How do prokaryotic and eukaryotic chromosomes differ?


10. How does the DNA differ between identical twins? Between siblings with the same parents?

11. What are the two major phases of the cell cycle?

12. What occurs during mitosis? What are the major events associated with each phase of the mitotic phase (mitosis)?
o A process of nuclear division in eukaryotic cells conventionally divided into four stages: prophase, metaphase, anaphase, and telophase. Mitosis conserves chromosome number by equally allocating replicated chromosomes to each of the daughter nuclei
o The mitotic phase is divided into two stages: one is mitosis and one is cytokinesis. In mitosis, the nucleus and its contents divide and are evenly distributed to form 2 daughter nuclei. During cytokinesis, the cytoplasm is divided in 2. The combination of mitosis and cytokinesis produces 2 genetically identical daughter cells.

13. What occurs during interphase? What are the major events associated with each phase of interphase?
o The period in the cell cycle when the cell is not dividing. During interphase, cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. Interphase accounts for 90% of the cell cycle

14. What is cytokinesis?
o The division of the cytoplasm to form two separate daughter cells immediately after mitosis

15. How does cytokinesis differ in plant and animal cells?

16. Eukaryotic cells spend most of their time in which phase of the cell cycle?

17. What is the law of segregation?

18. What is the law of independent assortment?

19. What is density-dependent inhibition?
o The phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another

20. What is a “cancer” cell? How do cancer cells form?
o Do not have a properly functioning cell-cycle system; instead, they divide excessively and can invade other tissues of the body
o Cancer cells form when the genetic material (DNA) of a cell is changed, or mutated. A tumor is the result of multiple gene mutations within a single cell.


21. What is a tumor?
o A mass of abnormal cells within otherwise normal tissue, caused by the uncontrolled growth of a transformed (mutated) cell

22. How do benign and malignant tumors form?
A benign tumor is localized, meaning it stays at the site of organ. Grow slowly & tend not to spread. IE= moles, warts, etc.
Malignant= A cancerous tumor that is invasive enough to impair functions of one or more organs

23. What is a gamete? How are they produced?
Gametes are the male and female sex cells (sperm, egg).
Gametes from each parent have a single set of chromosomes: 22 autosomes plus a single sex chromosome, either X or Y.
Produced through sexual intercourse

24. What is a zygote? How are they produced?
Zygote= the result of a FERTILIZED egg. It is diploid, which means that the mother and the father gave the fertilized egg their chromosomes, each contributing 23 chromosomes. (Remember N=23. 2N=46). So now the fertilized egg has 46 chromosomes total.
Produced from the mother’s haploid sets (n=23) and the father’s haploid sets (n=23).Remember that the mother and father’s haploid sets combined= a diploid; (2n=46), or 46 chromosomes to their offspring.

25. How do gametes differ from somatic cells?

26. What is crossing over? When does crossing over occur?
 Crossing over= an exchange of corresponding segments between 2 homologous chromosomes.-->
 The reciprocal exchange of genetic material between nonsister chromatids during synapsis of meiosis I
27. What are “true-breeders”?

28. What are P-generation plants?

29. What are F1 plants? What are F2 plants?

30. What is a monohybrid cross? What is a dihybrid cross?

31. What are genes? What are alleles?

32. What is the difference between genotype and phenotype?

33. What phenotypic ratio is seen in the F1 generation produced from a monohybrid cross?

34. What phenotypic ratio is seen in the F2 generation producedfrom a monohybrid cross?

35. What phenotypic ratio is seen in the F1 generation produced from a dihybrid cross?

36. What phenotypic ratio is seen in the F2 generation produced from a dihybrid cross?

37. What fraction of the F2 generation offspring are parental phenotypes? What fraction are recombinant phenotypes?

38. What are homozygous alleles? What are heterozygous alleles?

39. What is complete dominance? (Be able to draw out Punnett squares to predict phenotypic and genotypic frequencies in offspring)

40. What is incomplete dominance? (Be able to draw out Punnett squares to predict phenotypic and genotypic frequencies in offspring)

41. What is codominance? How does this pattern of inheritance differ from incomplete dominance?
 Codominance= A phenotypic situation in which the two alleles affect the phenotype in separate, distinguishable ways


42. What is pleiotropy?
o The ability of a single gene to have multiple effects

43. What is polygenic inheritance?
o An additive effect of two or more gene loci on a single phenotypic character

44. What are linked genes?
 Genes that are located on the same chromosome
45. How does gene linkage affect recombination frequency?

46. What does recombination frequency reveal about the relative positions of alleles on a chromosome?

47. How many alleles for a gene are carried in a gamete?

48. How many chromosomes are found in a diploid cell? A haploid cell?

49. What is an autosomal dominant trait? How and when are these traits inherited?

50. What is an autosomal recessive trait? How and when are these traits inherited?

51. For which of these traits does a heterozygote “carry” the trait?

52. What are autosomes? What are sex chromosomes?
o Autosome= A chromosome that is not directly involved in determining sex, as opposed to a sex chromosome. 22 of the 23 chromosome pairs in each parent’s gametes are called autosomes.
o Sex chromosome= One of the (23) pair of chromosomes responsible for determining the sex of an individual. The “X”and “Y” chromosomes.

53. What is a karyotype?
o “Think of it as Laying DNA out on a table and looking at it”
o Isolating the DNA from white blood cells
o A method of organizing the chromosomes of a cell in relation to number, size, and type

54. What is a “carrier”?
Carrier= People who have one copy of the allele for a recessive disorder and do not exhibit symptoms are called carriers of the disorder.

55. What is an X-linked trait? How do these traits differ in males and females?

56. Who can “carry” X-linked traits?

57. What is a Y-linked trait? How do these traits differ in males and females?