Genetic Inheritance
CHAPTER 2: GENETIC INHERITANCE
MULTIPLE CHOICE QUESTIONS
1. The pea plant was an excellent choice for Mendel’s experiments because
A. the plant can self-fertilize.
B. true-breeding varieties were available.
C. true-breeding varieties were available and it can be cross-fertilized.
D. true-breeding varieties were available, the plant can self-fertilize and it can
be cross-fertilized.
2. If tall (D) is dominant to dwarf (d), and two homozygous varieties DD and dd are
crossed, then what kind of progeny will be produced?
A. All tall.
B. All dwarf.
C. All intermediate forms.
D. ½ tall, ½ dwarf.
3. A testcross consists of a cross
A. of two pure-breeding forms to find out which form of a gene is dominant.
B. between two unknown forms to determine their genotypes.
C. between an offspring and its parent.
D. of an F1 hybrid to an individual that is homologous recessive.
4. Short hair (L) is dominant to long hair (l).If a short-haired animal of unknown
origin is crossed with a long-haired animal and they produce one long-haired and
one short-haired offspring, this would indicate that
A. The short-haired animal was pure-breeding.
B. The short-haired animal was not pure-breeding.
C. The long-haired animal was not pure-breeding.
D. The long-haired animal was pure-breeding.
5. The diagram illustrates the arrangement of two pairs of homologous chromosomes
at metaphase of the first meiotic division. R and r, Q and q are two allelic pairs.
Crossing over occurs at the chiasmata. What will be the genetic constitution of the
gametes produced?
A.
B.
C.
D.
Rr
RR
Rq
R
qq
qq
rq
q
Rr
rr
RQ
Q
QQ
QQ
rQ
r
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Genetic Inheritance
6. What is the phenotype ratio for the crossing of F1 individuals which are produced
from the crossing of AABB x aabb.
A.
B.
C.
D.
3: 1
1 : 2 : 1
1 : 1 : 1 : 1
9 : 3 : 3 : 1
7. If gene A and gene B are located in a different chromosome, which of the
following crossing will produce the progeny with genotype AaBb?
I. Aabb X aaBb
II. AaBB X Aabb
III. aaBB X AABb
IV. aabb X AaBb
A.
B.
C.
D.
I, II and III.
I, II and IV.
I, III and IV
I, II, III and IV
8. In aubergine plant, the gene for brown stem is dominant over its allele for green
stem, and the gene for purple fruit is dominant over its allele for white fruit. If
two aubergine plants which are heterozygous for both characteristics are crossed,
what is the ratio of the expected progeny to have brown stem and white fruit?
A. 1/16
B. 3/16
C. 4/16
D. 6/16
9. In Drosophila, the ebony colored body is caused by the recessive gene e and grey
colored body is caused by the dominant gene e+, while the vestigial wing is caused
by the recessive gene vg and normal wing is caused by the dominant gene vg+. If
the crossing between two heterozygote Drosophila of grey and normal wings
produce 128 offspring, how many offspring in F1 generation will be grey and
vestigial winged?
A. 8
B. 24
C. 32
D. 72
10. In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous
(Rr) offspring of red (RR) and white (rr) homozygotes. When two roan cattle are
crossed, the phenotypes of the progeny are found to be in the ratio of 1 red : 2
roan : 1 white. Which of the following crosses could produce the highest
percentage of roan cattle?
A.
B.
C.
D.
red x white
roan x roan
white x roan
red x roan
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Genetic Inheritance
11. In radish, the long shape has the genotype LL, the sphere shape genotype ll, and
the oblong shape genotype Ll. The red reddish has the genotype RR, the white
genotype rr, and the purple genotype Rr. What is the phenotype ratio if a cross
breeding was done onto a white oblong radish plant and a red oblong radish plant?
A.
B.
C.
D.
Purple
long
1
1
Red
long
1
1
-
Purple
oblong
1
2
2
Red
Oblong
2
-
Purple
sphere
2
1
Red
Sphere
1
1
-
12. Puan Aishah has type B blood group and Puan Siti has type A. Both of them give
birth on the same day at the same hospital. Puan Aishah named her child Ahmad
while Puan Siti named her child Zain.
After being discharged from the hospital, Puan Siti suspected that her child had
been changed with that of Puan Aishah’s. A blood test found that Ahmad has type
O blood group while Zain has type B blood group
Which of the following statements is/are true about the above case if their
husbands have type A blood group?
I. Puan Siti’s assumption is not correct
II. Zain is Puan Aishah’s child
III. Their children have been changed at the hospital
IV. Zain can have type B blood group
A.
B.
C.
D.
II only.
I and II.
I and III.
II, III and IV.
13. Polygenes are:A. Both alleles in a heterozygote are dominant and fully expressed in
phenotype.
B. Both alleles that give partial influence in heterozygous condition.
C. More than two alternative forms of a particular gene that occupy the same
locus
D. More than two genes occupy different locus but control the same
characteristic.
14. When two yellow mice are mated, they produce offspring which are in the ratio of
2 yellow to 1 grey. What are the possible suggestions for the above phenotype
ratio?
I. allele for yellow is dominant to allele for grey.
II. both the yellow mice are heterozygous.
III. all homozygotes yellow are dead fetus or not conceived.
IV. allele for yellow color is dominant and recessive for lethal characteristic.
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Genetic Inheritance
A.
B.
C.
D.
I only.
I and II only.
I, II and III only.
All of the above.
15. The family tree was assembled by a genetic counselor for Mr and Mrs X who
suffer from heart disease due to hypercholesterolemia. Children who inherit the
dominant mutant allele from both parents rarely survive beyond puberty.
What is the probability that Mr and Mrs X’s third child will be affected?
A. 0.75
B. 0.50
C. 0.25
D. 0.00
16. In a study of grasshopper in which long wings (W) are dominant over short wings
(w) and a spotted body (S) is dominant over spotless body (s). Crosses between
long wings, spotted body with short wings spotless body result in the following
offspring.
Phenotype
Long wings, spotted body
Long wings, spotless body
Short wings, spotted body
Short wings, spotless body
Male
498
8
8
502
Female
489
8
8
495
Which is best illustrated by this mating?
A. Autosomal linkage
B. Sex linkage
C. Crossing over
D. Independent assortment
17. In domestic cats, the genes for yellow and black fur are an allelic pair which are
sex-linked and codominant, the heterozygote being tortoise-shell, a mixture of
yellow and black fur. When black males are mated with tortoise-shell females,
what are the expected ratios of phenotypes and sexes in the offspring?
A.
B.
C.
D.
Males
1 black : 1 tortoise-shell
1 black : 1 yellow
1 black : 1 yellow
1 black
Females
1 black : 1 tortoise-shell
1 black : 1 tortoise-shell
1 black : 1 yellow
1 black : 1 yellow : 1 tortoise-shell
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Genetic Inheritance
18. In Drosophila, the male is the heterogametic sex. The allele for white eyes is
recessive and sex-linked. A female which is heterozygous at this gene locus was
mated with a normal male. White eyes will be present in
A. all the offspring.
B. all the male offspring but none of the female offspring.
C. none of the female offspring and 50% of the male offspring.
D. none of the male offspring and 50% of the female offspring.
19. The diagram below shows the inheritance of hemophilia in a family.
What is the genotype of person 7?
A. XHXH
B. XHY
C. XHXh
D. XhXh
20. Genes P, Q, R and S are on the same chromosome. Cross over value for gene
pairs are:P and R - 24%
R and S - 2%
P and Q - 49%
S and Q - 27%
The sequence of genes on the chromosome is
A. PRSQ
C. QSRP
B. PSRQ
D. RQSP
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Genetic Inheritance
SRUCTURED QUESTIONS
1. In the garden pea, yellow seeds are dominant to green seeds and round seeds are
dominant to wrinkled seeds. A cross was made between pure breeding pea plants
with yellow and round seeds with green and wrinkled seeds. The F1 offspring
were then allowed to self-pollinate and the seeds produced were grown. Mendel
selected 556 peas from F2 generation and the following results are obtained:315 round and yellow
101 wrinkled and yellow
108 round and green
32 wrinkle and green
a) Explain by using diagram for the above result.
[6 marks]
b) Mendel gave TWO conclusions from this experiment. State these conclusions.
_______________________________________________________________
_______________________________________________________________
[2 marks]
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Genetic Inheritance
c) From this result, Mendel had created a Law. State and explain the Law.
_______________________________________________________________
_______________________________________________________________
[2 marks]
2. The ABO blood group system in human being is an example of interactions of
alleles that are illustrated by multiple alleles.
a) What is meant by multiple alleles?
_______________________________________________________________
_______________________________________________________________
[2 marks]
b) State THREE possible alleles combinations in ABO blood group system.
_______________________________________________________________
[3 marks]
c) The table below shows three couples of husband and wives with their
respective
blood groups and the percentage of the number of children
produced in accordance with blood group.
Couple
Parent’s
blood
First
Second
Third
O x A
B x A
A x AB
% number of children in accordance with Parent’s
blood group
genotype
A
B
AB
O
50
50
….x….
25
25
25
25
….x….
50
25
25
….x….
State the parents’ genotype for each of the crossed couple in the table above.
_______________________________________________________________
[3 marks]
d) ABO blood group system shows the phenomenon of codominant alleles
i.
Define the term codominant alleles.
____________________________________________________________
[1 mark]
ii.
Name the codominant alleles in this blood group system
____________________________________________________________
[1 mark]
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Genetic Inheritance
3. Corn (Zea mays) seed may have various colors and shapes. Red (R) and nonshrunken (S) are dominant over white (r) and shrunken (s) respectively. A cross
was done between a homozygous red shrunken line and a homozygous white nonshrunken line. The F1 generation was then crossed with a homozygous white
shrunken line, and the following progeny were produced.
Phenotype
Red, shrunken
White, non-shrunken
Red, non-shrunken
White, shrunken
Number of plants
48
46
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12
a) Draw a genetic diagram to show the genotype and phenotype in F1 generation.
[3 marks]
b) State the type of cross between the F1 generation and the homozygous white
shrunken line above.
_______________________________________________________________
[1mark]
b) Does the above cross in accordance to the Mendelian ratio? Give reasons for
your answer.
_______________________________________________________________
_______________________________________________________________
[2 marks]
c) Explain how the situation in (b) can occur.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
[2 marks]
d) List TWO genotypes of the F2 progeny
_______________________________________________________________
[2 marks]
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Genetic Inheritance
4. Black coloured body and vestigial wing in Drosophila is controlled by two
recessive allele b and vg respectively. Dominant alleles, b+ and vg+ produce wild
type fly (grey-coloured body, normal wing). A homozygous wild type is crossed
to a homozygous fly with black-coloured body and vestigial wing. The F1
progeny produced (all of wild type) is test crossed. The F2 generations are as
follows:
Phenotype
Wild type
Black, vestigial
Black, normal
Grey, vestigial
Number of plants
1930
1888
412
370
a) i. What is the proof to show that the genes controlling the colour and the
wing type are linked?
____________________________________________________________
____________________________________________________________
[2 marks]
ii. Calculate the distance between the genes controlling the body colour and
the type of wing.
[2 marks]
iii. If the genes are not linked, what is the expected number of individuals of
each phenotype in the F2 generation?
____________________________________________________________
[1 mark]
b) In Drosophila, the locus for eye-colour is located on the X chromosome. The
allele for red eye colour (in wild flies) is dominant to the mutant allele for
white eyes. A white-eyed female fly mates with a normal male fly.
i. State the genotype of the female and male flies.
Female: _____________________
Male: ______________________
[2 marks]
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Genetic Inheritance
ii. What is the genotype of the female offspring from this cross?
____________________________________________________________
[1 mark]
iii. What is the chance of the female and male offspring to have white eye?
Female: ______________________
Male: ______________________
[2 marks]
ESSAY QUESTIONS
1. With examples, explain what is meant by the genetic terms in each pair below:a) Allele and gene
b) Phenotype and genotype
c) Test cross and back cross
d) Multiple alleles and polygenic inheritance
e) Linkage and sex linkage
[20 marks]
2. a) Explain the characteristic of the pea plant Pisum sativum used by Gregor
Mendel in carrying out crossbreeding experiments.
[8 marks]
b) Describe the principles of genetics formulated by Mendel
[6 marks]
c) A married couple both has normal color vision, but their daughter has redgreen color blindness. The husband sues the wife for divorce on grounds of
infidelity. Can genetics provide evidence supporting his case? Explain, with
the help of genetic diagrams.
[6 marks]
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