BIOLOGY 1400
Spring 2004
Lecture Exam 2

This exam consists of 50 multiple-choice questions. Each one has only one right answer. Read each question and all possible answers carefully before answering. If you have any difficulty understanding a question, raise your hand and I will answer as best I can.

Please mark your answers on the Scantron form provided, using only #2 lead pencil. If you erase an answer, make sure you erase it fully, or the machine may mark it incorrect. Check carefully to ensure that your answers are on the correct rows on the Scantron form.

Turn in both the Scantron form and the test paper when you are finished. Make sure your name is on both. You may write on the test paper if you wish, but anything you write on the test paper will not be graded.

Good luck.

Here's a problem straight out of the practice problems: In rabbits, mono-colored fur (F) is dominant over spotted fur (f). Your son is entering the 4-H county fair for rabbits. He has a male white rabbit without spots and crosses it with a female white rabbit without spots. Some of the baby rabbits have spots.

1. What is the genotype of the male rabbit in this cross?
Ff.

2. What is the genotype of the female rabbit in this cross?
Ff.

3. You could solve this problem by using
Punnett squares.

4. I recently got an e-mail from a lady who runs a professional rabbit breeding outfit called Usagi no Tsukiyo Rabbitry (http://www.tsukiyo.org/). The e-mail reads, in part:

I am not sure if you are the correct one to contact about this, but the spotting gene in rabbits is NOT recessive to mono-colour (known in the rabbit world as "solid"). . . . It is actually an incomplete dominance.

If this is true-and I assume it is, since this person is an experienced rabbit breeder-if you compared a rabbit with the Ff genotype and one with the ff genotype, what would you see?
Both would be spotted, but the ff would be spotted more.

5. If you crossed two Ff rabbits, what would you NOT expect to find in the offspring?
25% of the rabbits would be lightly spotted.

6. The rabbit-breeder also wrote that

Oh, also, lopped ears are not caused by a certain gene, per se, but rather by modifiers.

This ability of some genes to modify the effects of other genes is
epistasis.

7. Horses have 64 chromosomes in most of their cells. A horse's egg cell would have ___ chromosomes.
32.

8. When a horse sperm unites with a horse egg cell, the resulting fertilized egg has ___ chromosomes.
64.

9. The fertilized egg cell is technically called a
zygote.

The next questions deal with a rare genetic disease in humans called trichothiodystrophy.

10. Patients with trichothiodystrophy show unusually thin fingernails, brittle hair, coarse scaly skin, mental retardation, and cataracts. These symptoms would be the
phenotype.

11. The fact that this one gene has many different effects is an example of
pleiotropy.

12. Children with trichothiodystrophy are almost always born to normal parents. This implies that the gene for trichothiodystrophy is ___ with respect to the normal gene.
recessive

13. Trichothiodystrophy is found equally in boys and girls. This suggests that the gene for trichothiodystrophy is carried
on an autosome (a non-sex chromosome).

14. Two normal parents have a child with trichothiodystrophy. What are the odds that their second child will also have the disease?
25%.

15. The monomers that make up proteins can themselves be divided up into
amino, carboxyl, and R groups.

16. The scientists who developed the theory that all living things are made up of cells were
Schlieden and Schwann.

17. Which of the following statements about the stages of mitosis is FALSE?
anaphase ends when the chromosomes reach the midline of the cell.

18. How many different kinds of gametes can an individual with genotype AABbccDdEEff form?
four.
Boy, was this one eee-vil! The trick is to notice that the individual is only heterozygous for the genes B and D. All of his gametes will carry A, c, E, and f, so those genes don't count in determining the number of different gene combinations he can pass on in his gametes. The only possibilities are: ABcDEf, ABcdEf, AbcDEf, AbcdEf.

19. A cell that has one of each type of chromosome is said to be
haploid.

20. Many drugs have the effects that they do because they mimic a naturally occurring compound within cells. (These drugs are called analogs.) A drug called ddI (sold under the trade name Videx®), shown at right, is a nucleotide analog-it resembles a nucleotide, but it doesn't work in the same way that the body's nucleotides do. Dosing a cell with ddI would impair the cell's ability to make DNA.

21. In the above diagram, the arrow is pointing towards
the base.

22. Which of the following statements about the information molecule DNA is FALSE?
DNA is held together by bonds between amino and carboxyl groups.
It's proteins that are held together by amino-carboxyl bonds. . .

23. At the start of cell division, the two chromatids that make up a chromosome (the "sister chromatids") are held together at a point called the
centromere.

24. Each sister chromatid is formed when
DNA "unzips" and each half is the basis for assembling a new strand.

25. During meiosis, sister chromatids are held together until:
anaphase II.

26. The human disease called Asperger's syndrome is one type of autism. Affected children do not respond normaly to the world around them and often show repetitive actions (such as rocking) or other unusual behaviors. Asperger syndrome is far more common in boys than in girls. This suggests that
the Asperger gene is carried on the X chromosome.

27. A boy with Asperger's syndrome must have inherited it
from his mother.

28. Expression of a genetic trait such as smooth or wrinkled seeds is an example of:
a phenotype.

29. Which of the following is NOT a component of DNA?
twenty amino acids.

Fruit flies may have alleles for vestigial wings (v), which causes the wings to be small and useless for flight; and brown eyes (b), which makes the eyes look reddish brown. These are both recessive to the wild-type alleles (V and B-normal wings and red eyes).

30. Suppose you cross a brown-eyed, vestigial-winged female with a wild-type male. You get hundreds of offspring, and every one of them is wild-type. The genotype of the male parent would be
VVBB.

31. The genotype of the offspring in this cross (the F1 generation) would be
VvBb.

32. These genes are located close to each other on chromosome 2. This is
genetic linkage.

33. Suppose you crossed a fly from the F1 generation with a brown-eyed, vestigial-winged fly. If the genes involved are close together on the same chromosome, you would expect that the F2 generation would have
only wild-type flies AND brown-eyed, vestigial-winged flies (but no red-eyed vestigial-winged flies and no brown-eyed normal-winged flies).

34. What you actually find in the F2 generation is both male and female flies with all possible combinations of traits: red-eyed normal-winged, red-eyed vestigial-winged, brown-eyed normal-winged, and brown-eyed vestigial-winged. What makes this result possible?
Crossing over in meiosis.

35. You could use data from counting the flies in the F2 generation to construct a
linkage map.

36. James Watson was one of the scientists who worked out the double-helix structure of DNA. His partner was
Francis Crick.

37. The stage of the cell cycle in which a cell's chromosomes duplicate, going from one chromatid to two, is
S phase.

38. The rules of Mendelian genetics were worked out by
Gregor Mendel, a monk in what's now the Czech Republic.

39. Which of the following are NOT made through the process of meiosis?
None of these four cell types [brain, muscle, liver, or kidney] are made by meiosis.

Suzi Q. Ditzburger was a fifth-year freshman at a small Arkansas university. Nine months after an unusually successful fraternity-sorority mixer during Rush Week, Miss Ditzburger gave birth to a bouncing baby boy, much to her surprise. She couldn't quite remember how everything happened, but she was able to name several possible fathers.

40. Miss Ditzburger had type A blood, and the baby had type B blood. Which of the following three could be the father?
The rowdy Pike with type AB blood.

41. A charming Sig Tau who was also at the mixer had type B blood. His mother had type B blood and his father had type O blood. What must his genotype be?
BO

42. Miss Ditzburger actually got along so well with the Sig Tau guy that they ended up getting married, and they lived happily ever after. What are the chances that their next child will have type AB blood?
25%.

43. What are the chances that their next child could have type O blood?
25%.

44. Why can't you see chromosomes in the nucleus of a cell that's not dividing?
Because they're uncoiled.

45. You could recognize a cell in metaphase of mitosis because at that stage the chromosomes
are lined up in the center of the cell.

46. A rare condition called Patau's syndrome, which is uaually fatal in infancy, results when infants are born with three copies of chromosome 14 in each cell. (It's also called trisomy-14.) This probably results from
an error in meiosis when the father's sperm or mother's egg was forming.

47. Who used X-ray crystallography to show that DNA was a helix?
Rosalind Franklin.

48. When it's liquid, SuperGlue^TM is composed of a lot of small molecules called cyanoacrylate. As it dries, the cyanoacrylate molecules link together to form chains and networks that hold together whatever it is that's being glued. Dried SuperGlue^TM is a/an
polymer.

49. The spindle fibers are responsible for
moving the chromosomes during division.

50. The President of this university is
Lu Hardin.