Unit 4 Practice Exam Key

1. Mitotic cell division occurs during:

A. Growth

B. Repair injured tissues

C. Renew tissues

D. Sexual reproduction

E. A, B and C


2. DNA is replicated during

A. Interphase

B. Prophase

C. Prometaphase

D. Metaphase

E. Anaphase


3. Checkpoints in mitosis occur prior to

A. Synthesis of DNA, Metaphase and Cytokinesis

B. G1 of interphase, G2 of interphase, Mitosis

C. Synthesis of DNA (G1 checkpoint), Mitosis (G2 checkpoint), Anaphase of Mitosis (M checkpoint)

D. G1 of interphase, Prophase, Telophase

E. Interphase, metaphase and anaphase


4. Cancer cells keep growing indefinitely due to a lack of

A. Anchorage-dependence (allows cancer to spread)

B. Density-dependence

C. Metastasis (the method of cancer spreading)

D. Cyclin

E. None of the above


5. Homologous chromosomes

A. Are the same length

B. Code for the same genes

C. Code for the same traits

D. A and B

E. A and C


6. A chromosome containing 92 chromatids at metaphase would produce daughter cells with

A. 92 chromosomes

B. 184 chromosomes

C. 46 chromosomes

D. 23 chromosomes

E. None of the above


7. Microtubules of the spindle fibers originate from

A. Centromeres

B. Centrosomes

C. Centrioles

D. Chromatids

E. Chromosomes


8. A cell plate is beginning to form in the middle of a cell and nuclei are reforming at opposite ends of the cell. What kind of cell is this?

A. An animal cell in metaphase

B. An animal cell in telophase

C. An animal cell in cytokinesis

D. A plant cell in metaphase

E. A plant cell undergoing cytokinesis


9. Proteins that are involved in the regulation of the cell cycle and show fluctuations in concentration during the cycle are called

A. ATPases

B. Kinetechores

C. Centrioles

D. Proton pumps

E. Cyclin


10. How do cells at the completion of meiosis compare with cells that have replicated their DNA and are about to begin meiosis?

A. They have half the number of chromosomes, and half the DNA

B. They have half the number of chromosomes, but the same amount of DNA

C. They have the same number of chromosomes, but half the DNA

D. They have half the number of chromosomes, but 1/4th the amount of DNA

E. They have the 1/4th the number of chromosomes and 1/4th the amount of DNA


11. Major differences between Meiosis and Mitosis include (mark all that apply)

A. The type of cells produced

B. The chromosome number

C. The mechanism of separating chromosomes

D. The number of steps

E. The number of times DNA is replicated

F. Crossing over occurs in Meiosis

G. The number of cell divisions


12. Crossing over occurs between _________ during ___________

A. Sister chromatids, Prophase II

B. Homologous chromosomes, Prophase I

C. Sister chromatids, Prophase I

D. Homologous chromosomes, Prophase II

E. Sister chromatids, Interphase


13. Offspring are not genetically identical to parents due to

A. Independent assortment of chromosomes

B. Crossing over of chromosomes

C. Random fertilization

D. A, B and C

E. Two of the above


14. One difference between of Anaphase I of meiosis and Anaphase of mitosis is that

A. Anaphase I of meiosis reduces the cell from diploid to haploid

B. Anaphase I separates homologous chromosomes, Anaphase of mitosis separates chromatids

C. Kinetechores are only important in anaphase of mitosis

D. Telophase does not follow Anaphase I of meiosis

E. A and B


15. After meiosis I

A. 4 daughter cells exist, each identical

B. 2 daughter cells exist, each identical

C. 2 daughter cells exist, but they contain different chromosomes

D. 2 daughter cells exist, but they each contain half the number of chromosomes

E. C and D


Use the following answers for 16-21

A. Mitosis only

B. Meiosis I only

C. Meiosis II only

D. Mitosis and Meiosis I

E. Mitosis and Meiosis II


16. A cell divides to form 2 identical nuclei


17. Homologous chromosomes synapse and crossing over occurs


18. Centromeres pull sister chromatids apart


19. Independent assortment of chromosomes occurs


20. Causes the majority of genetic recombination


21. Process preceded by copying of DNA



22. A cross between homozygous purple flowers and homozygous white flowers produces offspring with purple flowers. This shows

A. That purple flowers are recessive

B. That purple flowers are sex-linked

C. That white flowers are dominant

D. That purple flowers are dominant

E. That incomplete dominance is occurring


23. What was the most significant result of Mendel's work?

A. There is considerable variation in garden peas

B. Traits are inherited in discrete units and are not a result of blending

C. Genes are composed of DNA

D. All genes exhibit dominance

E. Chromosomes are the basis of inheritance


24. Mendel's Law of Segregation was nearly impossible for biologists to understand until their was an understanding of

A. Dominance

B. Meiosis

C. Mitosis

D. DNA shape

E. DNA replication


25. A couple who are both carriers of the gene for cystic fibrosis have two children who have cystic fibrosis. What are the odds the 3rd child will have the disease?

A. 0%

B. 25%

C. 50%

D. 75%

E. 100%


26. Two flies, both MmNn, mate and have thousands of offspring. What percentage of their offspring will exhibit the dominant phenotype for both characters?

A. 1/16

B. 3/16

C. 1/4

D. 9/16

E. ½


27. In snapdragons heterozygotes have pink flowers, while homozygotes with the dominant trait have red flowers, and homozygotes with the recessive trait have white flowers. When red flowers are crossed with pink flowers, what percentage of the offspring will have red flowers?

A. 1/16

B. ¼

C. ½

D. ¾

E. 100%


28. A mother's genotype is AABbCC. What are possible genotypes for her eggs?



C. abc


E. Abc


31. In a dihybrid cross, the odds of ending up recessive in both traits is

A. 1/16

B. ¼

C. ½

D. ¾

E. 0%


32. In a cross between AaBbCc and AaBbCc what are the odds of ending up AABBCC?

A. 1/16

B. 1/32

C. 1/64

D. 9/64

E. 3/64


33. Blood types are an example of

A. Incomplete dominance

B. Codominance

C. Multiple alleles

D. Dominance

E. B and C


34. Huntington's Disease is

A. Recessive, Sex-linked

B. Dominant, Sex-linked

C. Recessive, Autosomal

D. Dominant, Autosomal

E. Multifactorial


35. People who have red hair usually have freckles. This could best be explained by

A. Independent assortment

B. Law of Segregation

C. Linkage

D. Crossing over

E. Sex-linked


36. Vermillion eyes is a sex-linked recessive characteristic in fruit flies. If a female with vermillion eyes is mated with a wild type male, what percentage of the F1 males will have vermillion eyes?

A. 0%

B. 25%

C. 50%

D. 75%

E. 100%


37. The greater the distance between two alleles on a chromosome

A. The more likely they are to be inherited together

B. The more likely crossing over will occur at some segment between them

C. The higher the recombinant frequency

D. A and C

E. B and C


38. A 0.1% frequency of recombination can only be found between two alleles

A. On different chromosomes

B. Far apart on one chromosome

C. Very close together on the same chromosome

D. On homologous chromosomes

E. On sister chromatids


39. New combinations of linked genes still occurs due to

A. Independent assortment of chromosomes

B. Separation of sister chromatids during Meiosis

C. Crossing over during Mitosis

D. Crossing over during Meiosis

E. Random fertilization


40. In females

A. Both X chromosomes are expressed

B. Only 1 X chromosome is expressed, but it's the same chromosome every time

C. Only 1 X chromosome is expressed, but about half the cells express each chromosome

D. X chromosomes are only expressed during puberty

E. X chromosomes only code for female traits, and are only expressed during development


41. The Recombinant frequency between A and B is 35%, between A and C is 25 % and between B and C is 45%. The most likely order genes on the chromosome is







42. A man who carries an X-linked allele will pass it on to

A. All of his daughters

B. Half of his daughters

C. All of his sons

D. Half of his sons

E. Half of all children