Genetics – 3.1, 3.4, 3.5
SL
Practice problems
1. What technique is used in DNA profiling?
a.
b.
c.
d.
Gene transfer
Gene therapy
Gel electrophoresis
Electron microscopy
2. Huntington’s chlorea is a rare degenerative disease which usually
develops when a person is between 30 and 45 years of age and leads to
death within a few years. It is caused by a dominant allele. If one parent of
two children develops Huntington’s clorea, but the other parent does not,
what is the probability that both of the children will develop the disease?
a.
b.
c.
d.
1/16
1/4
9/16
3/4
3. The pattern of inheritance of sex linked genes is the same in Drosphila as
in humans. Eye colour in Drosphila is controlled by a sex linked gene. The
allele for red eye is dominant over the allele for white eye. A red eyed
male mates with a white eyed female. Which eye colours are found in the
offspring?
A
B
C
D
Male offspring
All red
All red
All white
50% red and 50% white
Female offspring
All red
All white
All red
50% red and 50% white
4. What could be achieved by DNA profiling using gel electrophoresis?
a. The chromosome number of an organism could be counted
b. It could be proved that human tissue found at the site of a crime
did not come from a person suspected of having committed the
crime.
c. The quality of a new breed of farm animal or a new variety of crop
plant could be assessed
d. Extinct species of living organism could be brought back to life.
5. There are ethical arguments for and against the cloning of human
embryos. Which is the strongest argument for cloning?
a. Cloning was needed to complete the Human Genome Project
b. Mothers would be able to have children and return to work more
quickly, if their embryos were cloned
c. Cloning allows parents to choose the characteristics of their
children
d. Cloning happened naturally when identical twins are formed.
6. A healthy couple have a daughter who has a rare disease caused by a
recessive mutation of a gene. They then have two healthy children. What
is the probability that a fourth child will have the same rare disease?
a.
b.
c.
d.
0.00
0.25
0.50
0.75
7. What is a clone?
a. A group of organisms which could interbreed and produce fertile
offspring
b. A group of cells descended from two parent cells
c. A group of organisms of the same species living together and
interbreeding
d. A group of organisms with identical genotype.
8. Which enzymes are needed to produce recombinant plasmids that are
used in gene transfer?
a.
b.
c.
d.
DNA polymerase and ligase
DNA polymerase and restriction enzymes
Restriction enzymes and ligase
Helicase and restriction enzymes
9. The pedigree chart below shows the inheritance of Daltonism in a family.
Daltonism (red-green colour blindness) is sex linked. The allele for
Daltonism is recessive to normal colour vision.
Persons I and II have a child. What is the chance that the child will be
colour blind?
a. 0%
b. 25%
c. 75%
d. 100%
10. What is copied by the polymerase chain reaction (PCR)?
a.
b.
c.
d.
Polypeptides
Polysaccharides
Poly nucleotides
Polyunsaturated fats
11. When red and whilte flowered Mirabilis jalapa plants are crossed
together, all the offspring have pink flowers. The symbols for the two
alleles involved are Cr (red) and CW (white).
a. State the genotypes of the red and white-flowered parents and the
pink flowered offspring (1)
Red genotype:
White genotype:
Pink genotype:
b. When Mendel crossed red and white flowered pea plants together,
all of the offspring had red flowers. Suggest a reason for the
difference in results between pea plants and Mirabilis jalapa
plants. (1)
c. Predict the outcome of a cross between two pink flowered
Mirabilis jalapa plants, using the Punnett grid given below. (3)
12.
a. Define sex linkage (1)
b. State one example of sex linkage (1)
c. Draw a simple pedigree chart that clearly shows sex linkage in
humans. Use conventional symbols. Start with an affected woman
and an unaffected man. (4)
13. The diagram below shows the pedigree of a family with red-green colourblindness, a sex linked condition.
a. Define the term sex linkage. (1)
b. Deduce with a reason, whether the allele producing the condition
is dominant or recessive (2)
c.
i. Determine all the possible genotypes of the individual
(second generation-1) using appropriate symbols (1)
ii. Determine all the possible genotypes of the individual
(third generation -4) using appropriate symbols (1)