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GRADE 12 LIFE SCIENCES GENETICS TEST
LIFE SCIENCE
GRADE 12
TEST: GENETICS
Examiner: L. Seymour
Time Allocated: 55 minutes
Moderator: K.L Dewar
Marks Allocated: 55
Date: 24 August 2021
NAME: ______________________________
INSTRUCTIONS
1.
2.
3.
4.
This paper consists of 8 pages. Please ensure you have them all
Answer question 1 on the question paper
Answer the rest of the paper on metscap paper
Use the mark allocation as an indication of the amount of detail required
in your answers
5. Only draw diagrams/ flow charts when requested to do so
QUESTION 1
1.1.
Match the columns- write the LETTER (from column C) that corresponds
to the description in Column B. Write the answer in Column A, next to
the corresponding description in Column B.
COLUMN A
COLUMN B
Recessive Allele
Locus
Continuous Variation
Phenotype
Mendel
COLUMN C
A. Polygenic Inheritance
B. Only shows in heterozygous form
C. Physical manifestation of alleles
D. Only shows in homozygous form
E. The position of a gene on a chromosome
F. Complete Dominance
G. Father of Genetics
H. Meiosis
[5]
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GRADE 12 LIFE SCIENCES GENETICS TEST
1.2.
Multiple Choice- for each of the following questions, choose the most
correct option and write the correct LETTER in the table below.
1.2.1
1.2.2
1.2.3
1.2.4
1.2.5
1.2.1. The pedigree diagram below shows the inheritance of a genetically inherited
disorder. What is the most likely way in which this disorder is inherited?
Please note: the shaded individuals are NOT affected by the disorder.
A.
B.
C.
D.
Parent A and Parent B are homozygous dominant
Parent A and Parent B are heterozygous
Parent A and Parent B are homozygous recessive
Only males pass on the gene for the disorder
1.2.2. Which of the following descriptions show the genotype AND phenotype of an
individual?
A. A brown-eyed female
B. A tall pea plant
C. A colour-blind female
D. A non-albino male
1.2.3. Which of the following best describes polygenic inheritance?
A. One allele can have many different outcomes in the phenotype
B. There are many alleles that could produce one phenotypic trait
C. There are many genes that contribute to the outcome of one phenotypic trait
D. There are many phenotypes that could result from one gene with two alleles
1.2.4. An organism that has been engineered to contain a gene from another
species, in order to have a specific characteristic:
A. Cloning
B. Gene Therapy
C. GMO
D. Stem Cell
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GRADE 12 LIFE SCIENCES GENETICS TEST
1.2.5. Curly hair is dominant over straight hair. A curly-haired man has a child with a
straight haired woman. They have two children with curly hair and one child
with straight hair. The father’s genotype is:
A. HH
B. Hh
C. hh
D. Can be either Hh or HH
[5]
1.3.
The following pedigree chart shows the inheritance of colour-blindness
in a family. Answer the questions that follow:
1.3.1. On the actual diagram above, circle THREE carriers of colour blindness.
(2)
1.3.2. Complete the following sentence:
Colour-blindness is a sex-linked disorder because ___________________________
_______________________________________________________________ (2)
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GRADE 12 LIFE SCIENCES GENETICS TEST
1.3.3. In the space below, calculate the possible genotypes and phenotypes of
the offspring of a carrier female and affected male.
(3)
1.3.4. Name another genetic disorder that is sex-linked. ________________ (1)
[8]
TOTAL QUESTION 1 [18]
QUESTION 2
1.1.
Cystic fibrosis is a disorder caused by a faulty gene on chromosome
number 7, which in turn produces a faulty protein. This results in
mucous secreting glands (specifically in the lungs and pancreas)
producing abnormally thick mucous. The cystic fibrosis gene can be
present in a heterozygous individual and the individual will not be
affected by the disorder. If an individual is homozygous for the cystic
fibrosis gene, then he/she will be affected by the disorder.
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GRADE 12 LIFE SCIENCES GENETICS TEST
The image below illustrates some of the physical symptoms of Cystic Fibrosis.
2.1.1. Is cystic fibrosis gender-linked? Provide a reason for your answer.
(2)
2.1.2. State the term given to an individual as explained by the underlined sentence
in the text.
(1)
2.1.3. Using a punnett diagram, calculate the chances of two heterozygous
individuals having a child with cystic fibrosis.
(3)
2.1.4. If there is a chance of having a child with cystic fibrosis, a couple may be
advised to see a genetic counsellor. Explain the role that a genetic counsellor
would have in such a scenario.
(2)
The life expectancy of an individual with Cystic Fibrosis has increased
substantially. About 30 years ago, a Cystic Fibrosis patient would be expected
to only survive a few years. Now, patients are surviving well into their 40s.
Although there is no cure for Cystic Fibrosis, the experimental technology of
lung transplants has shown some success in further prolonging a patient’s
life. Lung transplants are a risky option, as some Cystic Fibrosis patients may
not be strong enough to recover fully from the surgery.
2.1.5. Seeing as though the life expectancy has improved and lung transplants are
risky, if you were faced with making the decision to have the surgery would
you do it? Substantiate your answer.
(3)
[11]
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GRADE 12 LIFE SCIENCES GENETICS TEST
2.2.
Huntington’s Disease is a disease that causes a breakdown of the brain
cells and progressive dementia. It usually only starts to develop
symptoms between the ages of 40 and 50 years of age. It is hereditary.
The pedigree chart below shows the inheritance pattern of Huntington’s
Disease.
KEY: shaded individuals affected by Huntington’s Disease
Non-shaded individuals  not affected by Huntington’s Disease
2.2.1. Define the term ‘hereditary’.
(2)
2.2.2. In response to the each of the following statements, write ‘true’ or ‘false’:
a. Huntington’s is a sex-linked disorder
b. The disorder is present in every generation
c. If two individuals who are unaffected have a child, there is a 50% chance
that the child will be affected
(3)
2.2.3. Provide the genotypes of the following:
a. Individual 1
b. Individual 2
c. Individual 9
(3)
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GRADE 12 LIFE SCIENCES GENETICS TEST
2.2.4. Individual number 11 marries a man who does not have Huntington’s. They
have four children, all of which develop Huntington’s. What is the most likely
genotype of individual 11? Explain your answer.
(2)
2.2.5. Most harmful mutations that occur frequently are ‘bred out’ of familiesmeaning that if a person is affected by a genetic disorder they either die
before reproducing or choose not to have children and pass on the allele.
Huntington’s is an exception to this rule. Explain why Huntington’s is still so
common in many families.
(2)
[12]
TOTAL QUESTION 2 [23]
QUESTION 3
3.1. Read the text below and answer the questions that follow.
One of the exciting applications of DNA analysis is that it can be used to combat wildlife
crime. It works by targeting areas of DNA that are highly variable within species, making
them show a difference between individual animals.
By separating out these markers from physical samples (such as rhino horn) forensic
scientists are often able to determine where the animal or plant came from, what it’s
ancestry might be, the age of the sample, and how this relates to other seized shipments.
Occasionally, it’s possible to uncover more information about the criminal networks behind
the trade by detailing where the animals were killed and ports were used to transport them.
The University of Pretoria has created ‘rhODIS’- a genetic database of DNA samples from
black and white rhinos throughout South Africa. This database will be used to help match
recovered rhino horn to individual and poached rhinos by comparing the genetics of the
seized horn to those in the database.
Taken from IEB Life Science Paper 1, 2017
3.1.1. Would the “highly variable” sections of DNA be found within the genes
(coding DNA) or within the non-coding DNA? Explain.
(3)
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GRADE 12 LIFE SCIENCES GENETICS TEST
3.1.2. Using the information provided in the text, create a flow chart to explain the
procedure that would take place from the point at which the SA police find
smuggled Rhino horn in the boot of a vehicle stopped at a road block, through
to the point of conviction of the criminals in possession of the rhino horn. (5)
3.1.3. Do you think that the database of Rhino genetics (‘rhODIS’) should be
protected to the same extent as the actuals Rhinos? Provide a reason for your
answer.
(2)
[10]
3.2.
Rabbits are popular pets, whose fur colour can have a few different
phenotypes.
The table below shows the alleles involved in Rabbit fur colour inheritance.
3.2.1. What is/are the possible genotype(s) that a Himalayan rabbit can have?
(2)
3.2.2. A chinchilla and a white rabbit produce offspring. What genotype(s) is/are
impossible in the offspring? Explain your answer.
(2)
[4]
TOTAL QUESTION 3 [14]
GRAND TOTAL [55]
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