STATEUNIVERSITYCOLLEGE AT BUFFALO

Department of Biology

Biology 100Spring 2004

Principles of BiologyDr.Wadsworth

Mid-Term Exam 3a

Genes and Biotechnology

Cover Sheet

Name: ______

(Print)

Instructions.

1.Print your name in the space designated on this cover sheet.

2.Be sure that your exam has 9 pages including this cover sheet.

3.Read each question carefully and answer in the space provide

4.At the end of the exam there are 6 short answer questions. Answer only 5 of these 6 questions. Answering all six questions may reduce your grade. Under the question you choose not to answer, please write the word "Skip". Failure to write "SKIP" under the one question you choose not to answer will reduce your grade.

Multiple Choice

Choose the best answer for the question or the best ending for each statement. Write the letter (A-E) which corresponds to the best answer on the line before the question. (2 pts each)

____1. Which of the following sentences best describes the relationship between histones and chromosomes?

  1. Histones are the amino acids that compose the DNA of chromosomes.
  2. Histones make up the centromere of chromosomes.
  3. DNA is wrapped around histones to make up chromosomes.
  4. DNA gets its dcolor from darkly pigmented histones.
  5. Histones replicate the DNA during S-Phase of the cell cycle.

_____ 2. Suppose that anucleus ofa frog liver cell contained 50 chromosomes. How many chromosomes would you expect in the nuclei after M-phase of the cell cycle?

  1. 100
  2. 50
  3. 25
  4. 100 sister chromatids
  5. 200 sister chromatids

_____ 3. How many autosomes would you expect to find in a human skin cell?

  1. 44
  2. 48
  3. 46
  4. 2
  5. 4

_____ 4. Mitosis is important in cell division because it:

  1. produces both somatic cells and gametes in humans.
  2. generates aneuploids, providing variation in the offspring.
  3. ensures proper gene expression in offspring.
  4. replicates the DNA before cell division .
  5. ensures that daughter cells receive a complete set of chromosomes.

_____ 5. A man and woman with type B blood get married. The woman has a son with type O blood. Which of the following would a genetic consular likely tell the husband.

  1. Both the man and the woman are heterozygous for the ABO blood type gene.
  2. Because the O allele is sex linked it is expressed in the son.
  3. The man isn’t the father of the child since its blood type didn’t match either of the parents.
  4. There had to be a mixup at the hospital, because this child blood type doesn’t match either parents.
  5. The child is an extraterrestrial being with green blood.

_____ 6.In dogs, a single gene controls ear floppiness. The allele for erect ears is dominant and the allele for floppy ears is recessive. If I breed a true-bred german shepherd (erect ears) with a true-bred Labrador retriever (floppy ears) what is the probability that the first pup will have erect ears?

  1. 0%
  2. 25%
  3. 50%
  4. 75%
  5. 100%

_____ 7. In peas, the allele for round seeds (R) is dominant to the allele for wrinkled seeds (r). If a heterozygous plant were bred with a homozygous recessive plant, what proportion of the offspring would have round seeds.

  1. 0%
  2. 25%
  3. 50%
  4. 75%
  5. 100%

_____8. In chickens there is a gene called “frizzled”. The gene gets this name because the recessive allele causes abnormal feathers. However, the frizzled gene also affects the body temperature of the bird as well as the structure of some internal organs. This characteristic of frizzle affecting several different traits is an example of which of the following.

  1. Codominance
  2. Polygenic
  3. Pleiotropy
  4. Partial Dominance
  5. Segregation

_____9. A healthy couple has a child with cystic fibrosis. Remember that cystic fibrosis is a recessive human trait. What is the probability that their next child will have cystic fibrosis?

  1. 0%
  2. 25%
  3. 50%
  4. 75%
  5. 100%

_____10. Hemophilia is an example of a sex-linked trait. A hemophiliac man will pass the alleles for this trait to:

  1. only his sons
  2. only his daughters
  3. all of his children
  4. none of his children
  5. every other son

_____11. In Mendel’s time, most people believed that:

  1. all genetic traits bred true.
  2. only certain forms of domesticated plants and animals bred true.
  3. the characteristics of parents were blended in the offspring.
  4. genes were always dominant
  5. the inheritance of traits was controlled by blood.

_____ 12. All the offspring of a white hen and black rooster are grey. This is probably an example of which of the following?

  1. Codominance
  2. Lethality
  3. Pleiotropy
  4. Incomplete Dominance
  5. Segregation

_____ 13. In class we discussed the inheritance of hypercholesterolemia as an example of a gene with incomplete dominance. If two people with hypercholesterolemia have children, what is the probability that their children will also have hypercholesterolemia?

  1. 0%
  2. 25%
  3. 50%
  4. 75%
  5. 100%

_____ 14. Which of the following best describes the role of the sex reversal Y (sry) gene in humans.

  1. It reverses the sex of any individual that carries it.
  2. It causes hermaphrodism in humans
  3. There are two copies of it in females and one copy in males
  4. It is found in all sperm
  5. Individuals with sry develop a male phenotype.

_____ 15. A woman heterozygous for color blindness (an X-linked recessive allele) marries a man with normal color vision. What is the probability that their first child will be color blind?

  1. 0%
  2. 25%
  3. 50%
  4. 75%
  5. 100%

_____ 16. If a segment of DNA is 5’ – CATTAC – 3’, then the complementary strand would be:

  1. 3’ – CATTAC – 5’
  2. 5’ – CATTAC – 3’
  3. 3’ – GTAATG – 5’
  4. 5’ – GTAATG – 3’
  5. 5’ – CATTAC – 5’

_____17. Rank the following nucleic acid structures from largest to smallest.

  1. Chromosome, Gene, Open Reading Frame, Codon
  2. Genes, Chromosome, Open Reading Frame, Codon
  3. Codon, Genes, Chromosome, Open Reading Frame
  4. Chromosome, Codon , Gene, Open Reading Frame
  5. Codon, Chromosome, Open Reading Frame, Genes

_____ 18. If two nitrogenous bases from DNA are described as complementary, then they:

  1. would hydrogen bond with each other
  2. would be involved in protein synthesis
  3. would be found in the cytosol
  4. would be attached to ribosomes
  5. would be found in mRNA

_____ 19.The enzyme, RNA polymerase, binds to which of the following components of a gene?

  1. Start Codon
  2. Stop Codon
  3. Promoter
  4. The first slot of the ribosome
  5. The dominant allele

_____20. Which of the following is not a difference between RNA and DNA

  1. RNA is single stranded and DNA is double stranded
  2. RNA uses Uracil (U) and DNA uses Thymine (T)
  3. RNA is in prokaryotes and DNA is in eukaryotes
  4. RNA has ribose and DNA has deoxyribose

_____21. Which of the following carries amino acids to ribosomes, and is considered the "adaptor" molecule between codons and amino acids?

  1. mRNA
  2. tRNA
  3. hnRNA
  4. rRNA
  5. all of these

_____22. Which of the following is not considered to be a significant risk of BT corn?

  1. It is killing Monarch Butterflies
  2. Some people may be allergic to it
  3. The cry1a gene may spread to other species
  4. It promotes the use of monocultures
  5. None of these are significant risk

_____ 23. Which of the following explains why golden rice is being introduced to developing nations.

  1. It is resistant to rice fungus which destroys rice crops in tropical regions.
  2. It will generate a rice product that can be exported and provide a cash crop for farmers.
  3. It provides a source of vitamin A to the diet in developing countries
  4. It is resistant to insects, so farmers in developing nations do not need to use pesticides
  5. It can be cultivated with other crops, providing farmers with more food per acre.

_____ 24. Which of the following is not part of translational elongation?

  1. The ribosome rachets over one codon
  2. The ribosome accepts a new tRNA
  3. The ribosome expels the used tRNA
  4. The ribosome catalyzes the synthesis of a new peptide bond
  5. The ribosome releases the new polypeptide chain

_____ 25. Which of the following best describes why DNA replication is called semi-conservative?

  1. Replication of DNA in the nucleus is catalyzed by two different enzymes, RNA polymerase and DNA polymerase
  2. Only deoxynucleotides are used during DNA replication
  3. A equal mixture of deoxynucleotides and ribonucleotides are used during replication of DNA.
  4. After replication the DNA molecules are composed of one new strand and one old strand.
  5. The DNA is only replicated between start and stop codons.

Short Answer Questions

Answer only five of the following six questions in the space below each question. Under the one question you choose not to answer, write the word "SKIP".

26. Pseudohypertorphic muschular dystrophy is a disorder that causes gradual deterioration of the muscles. It is only seen in boys born to apparently normal parents and usually results in premature death in the early teens. Is this disorder caused by a dominant or recessive allele. Explain your reasoning.

27. Explain the difference between reproductive cloning and therapeutic cloning.

28. Explain why a non-sense mutation will usually have a bigger impact on phenotype than a mis-sense mutation.

29. Studies of human aneuploids have demonstrated that it is not the number of X chromosomes that is important for sex determination but it is the presence or absence of a Y chromosome. Describe how Klinefelter's Syndrome demonstrates this principle. How would the phenotype of this type of aneuploid been different if the Y chromosome was irrelevant to sex determination but instead the number of X chromosomes was important.

30. Explain why the substrate specificity of enzymes were important in Avery’s experiment that proved genes were made of DNA.

31. The sequence of a very short mRNA is written below. How many amino acids will the polypeptide encoded by this mRNA have and what is the sequence of amino acids in the polypeptide?

GUAGGACCUAGAUGACUGUAUUUGGCUAACCUGUAGUAGU