Download Genetics CH 6 Test 2011

SBI 3U Chapter 6 Test
Name: ____________________________________
Knowledge/Understanding
Communication
Thinking & Inquiry
Application
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/6
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PART A: MULTIPLE CHOICE [K/U: 1 mark each = 5 marks]
Circle the choice that best answers the question.
1. A test cross is one in which the organism with the unknown genotype is mated with an organism that
is
a. heterozygous for the trait
b. homozygous dominant for the trait
c. homozygous recessive for the trait
d. of the same genotype as the organism being tested
e. of the opposite genotype to the organism being tested
2. When two alleles for a given gene are both equally and fully expressed, the alleles are said to be
a. Incompletely dominant
b. Codominant
c. Linked
d. Homozygous dominant
e. Dominant
3. Which of the following is/are true for alleles?
a. They can be identical or different for any given gene
b. They can be dominant or recessive
c. They can represent alternative forms of a gene
d. Only A and B are correct
e. A, B, and C are correct
4. What is the probability that a PpQQRrSs parent will produce a gamete that is PQRS?
a. 1/2
b. 1/4
c. 1/8
d. 1/16
e. 1/32
5. If 3/4 of the offspring from any experimental crosses showed only the dominant characteristics, the
parents of those particular offspring are
a. one homozygous dominant, one recessive
b. one heterozygous, one homozygous dominant
c. both heterozygous
d. both homozygous dominant
e. both homozygous recessive
PART B: MATCHING [K/U: 1 mark each = 10 marks]
Match the following terms with the correct definition or example. Note: there will be 4 choices left over.
DO NOT use a number/word more than once!
1. Heredity
_____ produced by the process of crossing over
2. Mendel
_____ the process of passing traits from one generation to the next
3. Recombinants
_____ when a blending occurs in heterozygotes
4. 9:3:3:1
_____ the allele expressed in a heterozygote
5. Pure-breed
_____ a trait that is only visible when it is homozygous
6. Monohybrid cross
_____ when there are more than two possible alleles for a given gene
7. Recessive
_____ organism that produces an offspring identical to the parent
8. Multiple Allelism
_____ requires 2 individuals heterozygous for one gene
9. Dominant
_____ requires 2 individuals heterozygous for two genes
10. Incomplete dominance
_____ ratio observed in a dihybrid cross
_____ ratio observed in a monohybrid cross
_____ observed a 1:2:1 phenotypic ratio in a monohybrid cross
_____ observed a 1:2:1 genotypic ratio in a monohybrid cross
PART C: SHORT ANSWER
1. Describe the difference between incomplete dominance and co-dominance. Provide an example of
each. Use only the space provided [Comm – 4 marks]
Incomplete dominance
Co-dominance
2. A man has six fingers on each hand and six toes on each foot. His wife and their daughter have a
normal number of digits. Having extra digits is a dominant trait and the man has a heterozygous
genotype. What fraction of this couple’s children would be expected to have extra digits? (Show all
work for full marks) [TI - 5 marks]
3. In dogs, barking (B) is dominant to non-barking (b), and pointy ears (E) are dominant to drooping ears
(e). What fraction of non-barking, droopy eared pups can you expect from a cross between a female
barking, pointy eared dog, and a male non-barking, droopy eared dog? The female dog had a nonbarking and droopy eared father. (Show all work for full marks) [TI – 9 marks]
a. Write the cross of the parents, include possible gametes of the parents [TI – 2 marks]
b. Draw the Punnett square for the cross. Be sure to show your phenotypic and genotypic ratios.
[TI – 5 marks]
c. What percentage of the offspring would display the same phenotype as the mother?
_________________ [TI – 1 mark]
d. What fraction of the offspring would be appropriate to use in a test cross?
_________________ [TI – 1 mark]
4. Explain how the phenotypic expression of height (a multifactorial trait) demonstrates a continuous
distribution. Provide an example of a graph, with possible genotypes, illustrating this type of
distribution. [App - 3 marks, Comm – 1 marks]
5. In sesame plants, the one-pod (T) condition is dominant to the three-pod (t) condition, and normal leaf
(N) is dominant to wrinkled leaf (n). A one-pod, normal leaf plant (TTNN) is crossed with a threepod, wrinkled leaf plant (ttnn). Breeding two of the F1 offspring results in the following F2 generation:
280 one-pod/normal leaf plants, 44 one-pod/wrinkled leaf plants, 49 three-pod/normal leaf plants, and
273 three-pod/wrinkled leaf plants.
Are the genes for pod type and leaf type linked (located on the same chromosome)? Explain. [App - 3
marks]
6. A, B, C, D and E are genes that are known to be linked. Use the following experimental results to
determine the sequence of the genes on the chromosome. [TI – 2 marks, Comm – 1 mark]
◦
◦
◦
◦
◦
◦
◦
B is at one extreme of the chromosome
D crosses over with A 5% of the time
D crosses over with B 10% of the time
C crosses over with D 15% of the time
E crosses over with C 10% of the time
A crosses over with E 30% of the time
A crosses over with C 20% of the time