Download ANSWER KEY FOR PROBLEM SET #2

ANSWER KEY FOR PROBLEM SET #2
1. Genotype: The actual genetic makeup of the cells of an individual with respect to a
given trait. Phenotype: The observable properties of an organism with regard to a specific
trait.
2a. 9/16 F-P-, 3/16 F-pp, 3/16 ffP-, 1/16 ffpp 2b. 1/4 BbTt, 1/4 Bbtt, 1/4 bbTt, 1/4 bbtt
3a. 2x2x2x2=16 3b. 1x2x1x2=4 3c. 2x3x2x4=48 3d. 2x2x1x3=12 3e. 1/2 x 1/4 x 1/2 x
1/4 = 1/64 3f. 1/2 x 3/4 x 1 x 3/4 = 9/32
4. II-6, 2/3; IV-1, 1
5. Primary Sex Ratio: ratio of males to females at conception. Secondary Sex Ratio: ratio
of males to females at birth. Tertiary Sex Ratio: ratio of males to females at any time after
birth.
6. Female cats have two chromosomes and male cats have one X chromosome. Since the
gene/locus for coat color in cats is on the X chromosome, male cats have only one coat
color gene and thus are one solid color. Since female cats have two X chromosomes they
can be heterozygous for coat color. Depending on which X is active in a given cell (the
other X being an inactive Barr body) coat color patches are possible. A male with a calico
coat color pattern would have to be XXY, and would be sterile.
7. Difference: Spermatogenesis yields four functional sperm produced from one primary
spermatocyte; Oogenesis produces only one egg from one primary Oocyte along with
three non-functional polar bodies.
8. 1 - Meiosis produces gametes containing the haploid numbers of chromosomes. 2 Meiosis makes genetic recombination possible through crossing over and independent
segregation.
9. Meiosis I is where crossing over between homologous chromosomes occurs, as well as
reduction in chromosomes # from 46 to 23. Meiosis II is similar to Mitosis in that sister
chromatids separate and move to opposite poles of the cell.
10. An antigen is a substance that is capable of stimulating the production of a specific
antibody. An antibody is a specific complex protein made in response to the entry and
recognition of a "foreign" antigen.
ANSWER KEY FOR TEST #2 – October 20, 2004
1.a. –Japanese cities bombed in World War II
-20 fold increase in leukemia among survivors (somatic mutations)
-Increase in chromosome aberrations
-Increase in birth defects for babies who were in utero at time of bombing
b. –XY chromosomes but more so female than male
-Abdominally located testes, but testosterone produced in their testes fails to be
activated
-X-linked recessive
-Female physical features but psychosexual orientation
c. –Spermatagonia multiply by mitosis
-Involves 2 meiotic divisions over 64-78 days to form sperm cells
-4 functional sperm produced from one primary spermatocyte
-One or more billion sperm produced weekly
d. –Dr. McKenzie’s female cat with mosaic coat color due to a heterozygous genotype for
X-linked coat color gene and inactivation of one X in some cells; the other X in
others
-Due to Barr body inactivation
e. –Genes on the same chromosome are said to be linked
-Due to linkage, many genes are transmitted as a single unit
-Crossing over can occur in between linked genes
f. –The ratio of males to females at birth – 105:100 worldwide
2.a. T
b. F – sex-limited
c. F – ovaries or testes
d. T
e. T
f. T
3. 2 x 1 x 1 x 2 = 4
1x2x2x2=8
2 x 2 x 2 x 4 = 32
1 x 2 x 2 x 4 = 16
1 x ½ x ½ x ¼ = 1/16
½ x ½ x ½ x ¼ = 1/32
4. a. A
b. I
c. J
d. G
e. E
f. C
5. a. No
b. Yes
c. any that contain “BD” or “bd” along with either A or a and either C or c
d. 2 x 2 x 2 x 2 = 16
6. a. B
b. B
c. C
d. D
e. F
f. D
7. a. influenced
b. Non-bald
c. Bb
d. ¼
e. 3/8
8. a. aa
b. Non-Achondroplastic
c. Aa
d. ½
e. ¼
9. 4 points each for a well-thought out, thorough explanation of any of the given choices
ANSWER KEY FOR TEST #2 – March 18, 2004
1.a. –The proportion of individuals which show the phenotype expected from a given
genotype
-An all or none effect. Ex. If a gene always produces its characteristic phenotype it is
said to be 100% penetrant
b. –Process of sperm production
-Germ cells -> spermatagonium -> 1º spermatocyte -> 2º spermatocyte -> 4 spermatids
-> 4 sperm cells
c. –Gene in the Y chromosome which activates other genes
-Ex. Sets in motion sex development…male when present, female when absent
-Causes ovotestes to become testes
d. –Dr. McKenzie’s presentation to the Watauga Club on genetic mutations -> due to
environmental/mutagen/carcinogen/teratogen conditions or exposure
e. –Type of point mutation – submicroscopic change in DNA
-When one base pair is replaced by another
f. –“Penis at age 12”
-Sex ambiguity at birth
-46 chromosomes – XY
-X-linked or autosomal recessive
2. 2 x 1 x 1 x 2 = 4
1x2x2x2=8
2 x 2 x 2 x 4 = 32
1 x 2 x 2 x 4 = 16
1 x ½ x ½ x ¼ = 1/16
½ x ½ x ½ x ¼ = 1/32
3.a. F - 32
b. F – locus
c. F – 1/900
d. F – sex-limited
e. T
f. T
4.a. Hh
b. HY
c. ½ = 50%
d. 100%
5. Testicular Feminization - Example of intersexual or pseudohermaphrodite individual.
Although they appear to be female, they have XY sex chromosomes, and testes located in
their abdomen. Faulty gene is in the X chromosome, resulting in sex developmental
confusion.
Klinefelter Syndrome – (XXY) – 47 chromosomes total (an extra sex chromosome)
results in a sterile make with some female features.
Turner Syndrome – (XO) – 45 chromosomes total (missing a sex chromosome) results
in a sterile female
6.a. A
b. A
c. B
d. A
e. A
f. D
7.a. B
b. C
c. D
d. F
e. A
f. G
8.a. sex-influenced (or sex-conditioned)
b. Not bald
c. Bb
d. ¼ = 25%
9. a Draw diagram
b. FfLl
c. freckles, free ear lobes
d. ½ or 50%
10. Specific and detailed examples from the video.