Sickle cell anaemia has not been eliminated from the African population because :
it is controlled by recessive genes
(b) it is not a fatal disease
it provides immunity against malaria
it is controlled by a dominant genes
Which of the following shows linkage group in coupling phase?
A Ba b
A b a B
A ba b
a Ba b
Which pair is incorrect?
Haemophilia - X linked recessive
baldness - X- linked dominance
colour blindness- X linked recessive
antler in deer - sex limited.
A pure breeding pea plant with the dominant phenotype of character A and recessive phenotype of character B was crossed with another pure breeding plant with the recessive phenotype of character A and dominant phenotype character B. Offspring of this cross was crossed with a homozygous recessive for both the characters A and B. The following results were obtained.
22 were phenotypically dominant of A and recessive of B
22 were phenotypically recessive for both A and B
22 were phenotypically recessive for A and dominant for B
22 were phenotypically dominant for both A and B
The results show that
genes A and B are linked
independent segregation of genes A and B
Mendelian dihybrid inheritance
polygenic inheritance.
Which of the following is not a X-linked recessive disease?
Haemophilia
Colour blindness
β thalassemia
Glucose-6-phosphate dehydrogenase deficiency.
A pure tall red plant is crossed with a pure dwarf white plant. The progenies thus produced in F1 generations are selfed. The different types of gametes that will be produed in F2 generaion will be
2
4
8
16
Which of the following chromosomal disorders is the commonest in the new borns?
Edward's syndrome
Patau's syndrome
Down's syndrome
None of these.
An inherited character and its detectable variant is termed as
unit factor
trait
genetic profile
genotypic charcter
A diagramatic representation of karyotype of a species is referred to as its
idiogram
hologram
karyogram
Both 1 and 3
Which of the following is not an autosomal genetic disorder ?
Sickle-cell anaemia
Cystic fibrosis
Huntington's disease
Study the pedigree chart of a family showing the inheritance of myotonic dystrophy.
The trait under study is
dominant X-linked
recessive X-linked
autosomal dominant
recessive Y-linked.
The ratio in a dihybrid test cross between two individuals is given by
2:1
1:2:1
3:1
1:1:1:1
A point mutation comprising the substitution of a purine by pyrimidine is called
transition
translocation
deletion
transversion
Pure line breed refers to
heterozygosity only
heterogyzosity and linkage
homozygosity only
homozygosity and self assortment.
If a homozygous red flowered plant is crossed with a homozygous white flowered plant and red colour allele is completely dominat over white colour allele, the offspring would be
half red-flowered
all red-flowred
half white-flowered
half pink- flowered.
One of the genes present exclusively on the X-chromosome in humans is concerned with
(d) night blindness
baldness
red-green colour blindness
facial hair/moustaches in males
Given below is a pedigree chart of a family with five children. It shows the inheritance of attached ear-lobes as opposed to the free ones. The squares represent the male individuals and circles the females individuals. Which one of the foloowing conclusions drawn is correct?
The parents are homozygous recessive.
The trait is Y-linked.
The parents are homozygous dominant.
The parents are heterozygous.
How many different types of gametes can be formed by F1 progeny, resulting from the following cross:
AA BB CC X aa bb cc
3
27
64
Given below is a pedigree chart showing the inheritance of a certain sex-liniked trait in humans.
The Trait traced in the above pedigree chart is
dominant Y-linked
recessive Y-linked
The "cri-du-chat" syndrome is caused by change in chromosome structure invloving
duplication
inversion
Grain colour in wheat is determined by three pairs of polygenes. Following the cross AABBCC (dark colour) X aabbcc (light colour), in F2 generation what proportion of the progeny is likely to resemble either parent?
None
Less than 5 percent
One third
Half
Primary source of allelic variation is
independent assorment
recombination
mutation
polyploidy
Which one of the following pairs of features is a good example of polygenic inheritance?
Human height and skin colour
ABO blood group in humans and flower colour of Mirabilis jalapa
Hair pigment of mouse and tongue rolling in humans
Human eye colour and sickle cell anaemia
Mating of an organism to a double recessive in order to determine whether it is homozygous or heterozygous for a character under consideration is called
reciprocal cross
test cross
dihybrid cross
back cross
Given below is a highly simplified representation of the human sex chromosomes from a karyotype.
The gene a and b could be of
colour blindness and body height
attached ear lobe and Rhesus blood group
haemophilia and red-green colour blindness
phenylketonuria and haemophilia
Which of the following statements are correct with respect to Law of dominance :
i. Tall and dwarf traits were identical to their parental type and didn’t show any blending
ii. Only one of the parental traits was expressed in F1 generation.
iii. Both traits were expressed in the F2 generation.
iv. The contrasting trait showed blending at F2 generation.
ii, iii and iv
i, ii and iii
ii and iii
i, ii, iii and iv
Mendel was born in
19th century.
18th century.
17th century.
20th century.
Gregor Mendel is known for
Species concept
Hybridisation experiments
Discovery of chromosomes
Experiments on maize plant
Myotonic dystrophy is
Autosomal recessive trait
Autosomal dominant trait
X- linkeddominant trait
X- linked recessive trait
In which one of the following combinations (a-d) of the number of chromosomes is the present day hexaploid wheat correctly represented?
Combination
Monosomic
Haploid
Nullisomic
Trisomic
(1)
21
28
42
43
(2)
7
40
(3)
(4)
41
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