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Q.1
Children have A and B types of blood. What are the blood types of parents ... .. [ KCET 2002]
0%
a) A and O
0%
b) AB and A
0%
c) AB and O
0%
d) A and B
Explanation
I
O
I
O
I
A
I
A
I
O
(A blood group)
I
A
I
O
(A blood group)
I
B
I
B
I
O
(B blood group)
I
B
I
O
(B blood group)
Genotypes of blood group A are IAIA or IAIA and B are IBIB or IBIO. Answer : (c)
Q.2
Genetically identical progeny is produced when the individual ... .. [ AFMC 1994 ]
0%
a) Performs self fertilization
0%
b) Produces identical gametes
0%
c) Practices inbreeding without meiosis
0%
d) Practices reproduction
Explanation
Genetically identical progeny can be produced if genes which carry same character property. This can happens when individual produces identical gametes. Answer : (b)
Q.3
Variations appear during meiosis due to .... [BHU 2008] (i) Independent assortment (ii) Crossing over (iii) Linkage (iv) Glycolysis Select the correct code
0%
a) 1, 2, 3 correct
0%
b) 1,2 correct
0%
c) 2, 4 correct
0%
d) 1, 3 correct
Explanation
Variation are differences in morphological, physiological, cytological and behavioristic trait of individuals belonging to same species. They appear in offsprings due to:- (i) Reshuffling of genes/chromosomes by chance separation of chromosomes. They occurs during independent assortment. (ii) Crossing over: Chromosomal crossover, or crossing over, is the exchange of genetic material during sexual reproduction between two homologous chromosomes' non-sister chromatids that results in recombinant chromosomes. (iii) Chance combination of chromosomes during meiosis and fertilization. Answer : (b)
Q.4
In Mirabilis jalapa, RR, Rr and rr determine red, pink and white colours respectively. When F1 hybrid of RR and rr was crossed with dominant parent, the ratio produced is ... .. [ RPMT 2002 ]
0%
a) All red
0%
b) 2 red : 2 pink
0%
c) all white
0%
d) 2 pink : 2 white
Explanation
Gametes
R
r
R
RR (red flower)
Rr (pink colour)
R
RR (red flower)
Rr (pink colour)
In Mirabilis jalapa, Red flower (RR) is crossed with white flower (rr) which produces hybrid Pink colour flower (Rr). Pink colour flower (Rr) × Red colour flower (RR) Red flower : pink flower = 2 : 2 Answer : (b)
Q.5
If two Pea plants having red ( dominant) coloured flowers with unknown genotypes are crossed, 75% of the flowers are red and 25% are white. the genotype constitution of the two parents would be
0%
a) Both homozygous
0%
b) Both heterozygous
0%
c) Both heizygous
0%
d) One homozygous and other heterozygous
Explanation
Gametes
R
r
R
RR (red)
Rr (red)
r
Rr (red)
Rr (white)
Offspring obtained has ratio red flower : white flower = 3 : 1. This implies that recessive trait i.e. white has appeared in the progeny. This occurs when both the parent are heterozygous with dominant character. Thus genotype of both parent is Rr ( heterozygous) . Rr (red flower) × Rr (red flower) Answer : (b)
Q.6
First geneticist/ father of genetics was ... ... [ CBSE 1991 ]
0%
a) De Vries
0%
b) Mendel
0%
c) Darwin
0%
d) Morgan
Explanation
Gregor Johann Mendel appropriately known as father of genetics, proposed the theory of inheritance. Hugo de Vries is Father of Mutation theory of evolution. Darwin is known as father of evolution. Morgan and his colleagues confirmed the chromosomal theory of inheritance. Answer : (b)
Q.7
B-blood group man marries A blood group woman. the first child has B-blood group. Genotype of the child is .... [ CPMT 2004 ]
0%
a) IAIO
0%
b) IBIO
0%
c) IAIB
0%
d) IBIB
Explanation
I
B
I
O
I
A
I
A
I
B
(AB blood group)
I
A
I
O
(A blood group)
I
O
I
B
I
O
(B blood group)
I
O
I
O
(O blood group)
Answer : (b)
Q.8
Phenotypic ratio of monohybrid F2 progeny of incomplete dominance is ... .. [ RPMT 1998 ]
0%
a) 1:1:1:1
0%
b) 2:1:1
0%
c) 1:2:1
0%
d) 3:1
Explanation
Phenotypic ratio in F2 progeny of incomplete dominance is same as genotypic ratio Ratio= 1 : 2 : 1 Answer : (c)
Q.9
In lathyrus odoratus, cross between two purple flowered plants gives a pink/white progeny. it is due to ... ... [ BHU 1998 ]
0%
a) Codominance
0%
b) incomplete dominance
0%
c) Epistasis
0%
d) Segregation
Explanation
Gametes
CP
Cp
cP
cp
CP
CCPP (purple)
CCPp (purple)
CcPP (purple)
CcPp (purple)
Cp
CCPp (purple)
CCpp (white)
CcPp (purple)
Ccpp (white)
cP
CcPP (purple)
CcPp (purple)
ccPP (white)
ccPp (white)
cp
CcPp (purple)
Ccpp (white)
ccPp (white)
Ccpp (white)
Sweet pea (Lathyrus odoratus) is an example of complementary genes. Here, the flower colour is purple if dominant alleles of two genes C and P are present together. The colour is white if the double dominant condition is absent. CcPp × CcPp → Purple : white = 9 : 7 So, White colour not appear in the previous generation, reappears in the next generation. It is called Law of segregation. Answer : (d)
Q.10
The term genetics was proposed by ... .. [ MPPMT 2007 ]
0%
a) Johannsen
0%
b) Morgan
0%
c) Mendel
0%
d) Bateson
Explanation
Word genetics comes from the word gene. The term was coined and used for the first time by W. Bateson(1905). Answer : (d)
Q.11
If both parents are albino, all the offspring shall be ... .. [ BHU 1999 ]
0%
a) Albino
0%
b) Some albino, some normal
0%
c) Homozygous normal
0%
d) Heterozygous normal
Explanation
Albinism is an autosomal genetic recessive disorder. The gene for albinism is a. It does not produce the enzyme tyrosinase but is produced by normal allele A . Thus only homozygous individuals (aa) are affected. Both the parents are albino, it means their alleleic pair is aa. Then all the progeny will also have genotype aa i.e., they will be albino. Answer : (a)
Q.12
Heterozygous tall ( Tt) is crossed with homozygous tall (TT). Percentage of heterozygous tall in the progeny would be ... .. [ AMU 2001]
0%
a) 25%
0%
b) 50%
0%
c) 75%
0%
d) 100%
Explanation
Gametes
T
T
T
TT
TT
t
Tt
Tt
Tt (heterozygous tall plant) × TT ( homozygous tall plant) F2 generation All the offsprings are tall plants with 50% homozygous and 50% heterozygous Answer : (b)
Q.13
A brown eyed couple has a blue-eyed child. The trait of brown eye (B) is dominant over blue-eye (b). What is the genotype of the couple?
0%
a) Bb × Bb
0%
b) BB × BB
0%
c) BB × Bb
0%
d) BB × bb
Explanation
Recessive trait (blue eye) is expressed in progeny. This occurs when parents has heterozygous allele expressing dominant trait. Thus genotype of parents are Bb. Answer : (a)
Q.14
A child of O-group has B-group father. the genotype of father will be ... ... [ CBSE 1992 ]
0%
a) IOIO
0%
b) II
0%
c) IAIB
0%
d) IBIO
Explanation
Blood group O has genotype IOIO. One allele is obtained from mother and one from father. That means one of the IO is obtained from father. Father has B blood group. So phenotype can be IBIB or IBIO. So correct genotype of this case will be IBIO Answer : (d)
Q.15
Incomplete dominance was discovered by ... .. [ RPMT 2005]
0%
a) Correns
0%
b) Mendel
0%
c) Johannsen
0%
d) Bateson
Explanation
While Mendel's work laid the foundation, it was German botanist Carl Correns (1864–1933) who is credited with the actual discovery of incomplete dominance. Answer : (a)
Q.16
tt mates with Tt. What will be characteristic of offspring? .... ... [ CBSE 1990 ]
0%
a) 75% recessive
0%
b) 50% recessive
0%
c) 25% recessive
0%
d) All dominant
Explanation
Gametes
T
t
t
Tt
tt
t
Tt
tt
Tt (heterozygous tall plant) × tt ( homozygous dwarf plant) F2 generation 50% are heterozygous tall plant and 50% are recessive dwarf plant. Answer : (b)
Q.17
on Q328) How many different gametes will be produced by a plant having the genotype AABbCC?
0%
a) Two
0%
b) Three
0%
c) Four
0%
d) Nine
Explanation
Number of gametes = (2)n where n= number of heterozygous allele. Here n=1. No. of gametes = 2 Answer:(a)
Q.18
Self fertilizing trihybrid plants form ... .. [ CBSE 2004 ]
0%
a) Eight different gametes and 64 different zygotes
0%
b) Four different gametes and sixteen different zygotes
0%
c) Eight different gametes and sixteen different zygotes
0%
d) Eight different gametes and thirty two different zygotes
Explanation
No. of traits (n)
Experiment
Types of gametes (2
n
)
No. of offsprings (gametes)
2
No. of phenotype (2
n
)
No. of genotype (3
n
)
Phenotypic ratio
Genotypic ratio
3
Trihybrid cross
8
64
8
27
(3:1)
3
(1:2:1)
3
Answer : (a)
Q.19
Allelomorphic pair implies ... .. [ MPPMT 1997 ]
0%
a) A pair of contrasting characters
0%
b) A pair of non-contrasting characters
0%
c) Any two characters
0%
d) Sex-linked characters
Explanation
A pair of contrasting characters is called allelomorph or allele. Answer : (a)
Q.20
A homozygous red flowered Pea plant is crossed with homozygous white flowered Pea plant. The offspring would be ... ... [ AIIMS 2002 ]
0%
a) 50% red flowered
0%
b) 50% pink flowered
0%
c) All red flowered
0%
d) All pink flowered
Explanation
One allele is dominant over other. In F1 generation the dominant phenotype appears, the recessive reappears in F2 generation. Since red is dominant over white, all offspring produced will be plants having red flower. Answer : (c)
Q.21
A cross between pure tall Pea plant with green pods and dwarf Pea plant with yellow pods will produce tall F2 plants, out of 16 ... .. [ CPMT 2000 ]
0%
a) 15
0%
b) 13
0%
c) 12
0%
d) 7
Explanation
Gametes
TY
Ty
tY
ty
TY
TTYY
TTYy
TtYY
TtYy
Ty
TTYy
TTyy
TtYy
Ttyy
tY
TtYY
TtYy
ttYY
ttYy
ty
TtYy
Ttyy
ttYy
ttyy
Tall F2 progeny = 12/16 Answer : (c)
Q.22
In Pisum sativum there are 14 chromosomes. how many pairs with different chromosomal composition can be prepared? ... .. [ BHU 2005 ]
0%
a) 214
0%
b) 27
0%
c) 7
0%
d) 14
Explanation
No. of chromosomal composition that can be prepared is derived by formula 2n where n is number of homologous pair of chromosomes. In Pisum sativum, there are 14 chromosomes. Number of homologous pair will be 7. No. of composition is 27. Answer : (b)
Q.23
Assertion : The linked genes tend to get inherited together. Reason : The bond between them fails to break
0%
a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion
0%
b) The Assertion and Reason are true but Reason is not correct explanation of Assertion
0%
c) Assertion is true but, Reason is false
0%
d) Assertion is false but, Reason is true
Explanation
When two genes are close together on the same chromosome, they do not assort independently and are said to be linked. Whereas genes located on different chromosomes assort independently and have a recombination frequency of 50%, linked genes have a recombination frequency that is less than 50%. The linked genes tend to get inherited together. The link between them fails to break. Genes whose loci are nearer to each other are less likely to be separated onto different chromatids during chromosomal crossover, and are therefore said to be genetically linked. In other words, the nearer two genes are on a chromosome, the lower is the chance of a swap occurring between them, and the more likely they are to be inherited together. Answer : (a)
Q.24
Theory of pangenesis was given by ... .. [ Pb PMT 2007 ]
0%
a) Weismann
0%
b) De Vries
0%
c) Darwin
0%
d) Lanmarck
Explanation
In 1868 Charles Darwin proposed Pangenesis, a developmental theory of heredity. He suggested that all cells in an organism are capable of shedding minute particles he called gemmules, which are able to circulate throughout the body and finally congregate in the gonads. Answer : (c)
Q.25
Which blood group can safely be transfused in emergency when there is no time to analyse the blood group of recipient? ... .. [ MPPMT 2009 ]
0%
a) O and Rh-
0%
b) O and Rh+
0%
c) B and Rh-
0%
d) AB and Rh+
Explanation
Blood group is determined by antigen. An antigen is any substance that causes your immune system to produce antibodies against it. Blood group O does not have antigen A and antigen B. Thus they can carry both anitbodies Anti-A and Anti-B in their serum. Rh- does not carry Rh antigen and thus can carry anitbodies. So, correct answer O and Rh-. Answer : (a)
Q.26
A cross between F1 hybrid and recessive parent give a ratio of ... ... [ manipur 2009]
0%
a) 3:1
0%
b) 1:1
0%
c) 2:1
0%
d) 4:1
Explanation
Crossing of F1 individual having dominant phenotype with its homozygous recessive parents is called test cross. The test cross is used to determine whether the individuals exhibiting dominant characters are homozygous or heterozygous. Answer : (b)
Q.27
All are dominant traits studied by Mendel ... .. [ AMU 2012 ]
0%
a) Axial flower, green pod, green seed
0%
b) Green pod, inflated pod, axial flower
0%
c) Yellow seed, violet flower, yellow pod
0%
d) Rounded seed, constricted pod, axial flower
Explanation
Traits
Dominant
Recessive
Plant height
Tall (1.2 – 2.0m)(T)
Dwarf (0.25 – 0.5m) (t)
Flower position
Axillary (A)
Terminal (a)
Pod colour
Green (G) or (Y)
Yellow (g) or (y)
Pod shape
Full or inflated (I) or (C)
Constricted (i) or (c)
Flower colour
Violet (V) or (W)
White (v) or (w)
Seed shape
Round (R) or (W)
Wrinkled (r) or (w)
Seed colour
Yellow (Y) or (G)
Green (y) or (g)
Answer : (b)
Q.28
Which amino acid is substituted in sickle cell anaemia? .... [ AFMC 1997 ]
0%
a) Glutamic acid by valine in α-chain
0%
b) Glutamic acid by valine in β-chain
0%
c) Valine by glutamic acid in β-chain
0%
d) Valine by glutamic acid in α-chain
Explanation
Sickle cell anemia is caused by the substitution of Glutamic acid (Glu) by Valine (Val) at the sixth position of the beta globin chain of the haemoglobin molecule. The substitution of amino acid in the globin protein results due to the single base substitution at the sixth codon of the beta globin gene from GAG to GUG. The mutant haemoglobin molecule undergoes polymerisation under low oxygen tension causing the change in the shape of the RBC from biconcave disc to elongated sickle like structure. Answer : (b)
Q.29
An allele is dominant if it is expressed in ... ... [ CBSE 1992 ]
0%
a) Both homozygous and heterozygous states
0%
b) Second generation
0%
c) Heterozygous combination
0%
d) Homozygous combination
Explanation
Law of dominance: When a pair of alleles are bought together in F1 hybrid, then only one of them expresses itself, masking the expression of other completely. Allele is dominant if it is expressed in both homozygous and heterozygous condition. Answer : (a)
Q.30
Variation found in offspring are important component of ... ... [ DPMT 2011]
0%
a) Genetics
0%
b) Speciation
0%
c) Species fixation
0%
d) Heredity
Explanation
Variation are differences in morphological, physiological, cytological and behavioristic trait of individuals belonging to same species. They appear in offsprings due to:- (i) Reshuffling of genes/chromosomes by chance separation of chromosomes. They occurs during independent assortment. (ii) Crossing over: Chromosomal crossover, or crossing over, is the exchange of genetic material during sexual reproduction between two homologous chromosomes' non-sister chromatids that results in recombinant chromosomes. (iii) Chance combination of chromosomes during meiosis and fertilization. Answer : (a)
Q.31
An allele contributed by one parent is IA and allele contributed by the other parent is i the bloodgroup of off spring will be .... ... [ DPMT2011]
0%
a) A
0%
b) AB
0%
c) B
0%
d) O
Explanation
The offspring has blood group genotype IAi. IA is dominant over i. the blood group is A. Answer : (a)
Q.32
Mendel's law of independent assortment is based on F2 ratio of ... ... [ RPMT 1996 ]
0%
a) 1:2:1
0%
b) 9:3:3:1
0%
c) 2:1
0%
d) 3:1
Explanation
No. of traits (n)
Experiment
Types of gametes (2
n
)
No. of offsprings (gametes)
2
No. of phenotype (2
n
)
No. of genotype (3
n
)
Phenotypic ratio
Genotypic ratio
2
Dihybrid cross
4
16
4
9
9:3:3:1
2:4:2:1:2:1:1:2:1
Answer : (b)
Q.33
Biometric genetics is connected with ... .. [ AMU 2002 ]
0%
a) Effect of radiations on living organisms
0%
b) Biochemical explanation of genetic phenomena
0%
c) Effect of environment on genetic set up of organisms
0%
d) Inheritance of quantitative traits
Explanation
Biometrical genetics is the science concerned with the inheritance of quantitative traits. Answer : (d)
Q.34
Mendel's last law is ... ... [ CBSE 1991 ]
0%
a) Segregation
0%
b) Dominance
0%
c) Independent assortment
0%
d) Polygenic inheritance
Explanation
Mendel has three laws: (i) Law of dominance (ii) Law of segregation and last (iii) Law of independent assortment. Answer : (c)
Q.35
What should be the composition of gametes? [Manipal 2003 ]
0%
a) GgLl
0%
b)Ggl
0%
c) Gg
0%
d) Gl
Explanation
gamete, is a cell containing only one set of dissimilar chromosomes, or half the genetic material necessary to form a complete organism (i.e., haploid). There are two set of allele G and g, L and l. Gametes can have only half of the allele. So correct option is Gl Answer : (d)
Q.36
Hybrid vigour is due to ... .. [ DPMT 1999 ]
0%
a) Mixing of traits of male and female
0%
b) Homozygosity in gamete state
0%
c) Superiority of genes
0%
d) Heterozygosity
Explanation
Hybrid vigour or heterosis is the superiority of hybrid over either of its parents in one or more traits. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions of its parents. Hybrid vigour is directly proportional to the strength of heterozygosity. Answer : (d)
Q.37
A gamete normally contains ... .. [ KCET 2002 ]
0%
a) Many alleles of gene
0%
b) All alleles of gene
0%
c) Two alleles of gene
0%
d) One allele of gene
Explanation
At the time of formation of gametes, these two factors obviously separate or segregate. A gamete may either carry either the dominant or the recessive factor but not both. Answer : (d)
Q.38
A genetic disorder in African which reduces oxygen uptake is ... .. [ BHU 1998 ]
0%
a) Haemophilia
0%
b) Pernicious anaemia
0%
c) Anaemia
0%
d) Sickle cell anaemia
Explanation
Sickle cell anemia is an inherited genetic condition in which afflicated individuals contain red blood cells that under low oxygen tension become elongated and curved. Because of the shape, sickled cells clump together, and blood becomes more viscous. The result is slowing of flow, even greater loss of oxygen from the haemoglobin. Answer : (d)
Q.39
Which mutation / variation is not hereditary .... .. [ MPPMT 2012]
0%
a) Genetic
0%
b) Gametic
0%
c) Somatic
0%
d) Germinal
Explanation
Non-inherited variants occur at some time during a person's life and are present only in certain cells, not in every cell in the body. Because non-inherited variants typically occur in somatic cells (cells other than sperm and egg cells), they are often referred to as somatic variants. Answer : (c)
Q.40
Which is dominant trait? [ MPPMT 2007 ]
0%
a) Colour blindness
0%
b) Albinism
0%
c) Haemophilia
0%
d) Rh+ factor
Explanation
Color blindness is determined by a sex-linked recessive allele found on the X chromosome. Oculocutaneous albinism is inherited in an autosomal recessive pattern , which means both copies of a gene in each cell have mutations. Hemophilia A and hemophilia B are inherited in an X-linked recessive pattern. The Rh-positive gene is the dominant gene when paired with an Rh-negative gene. Answer : (d)
Q.41
Which of the following is correct for dihybrid cross? ... ... [ RPMT 2006]
0%
a) 1YYRR, 2 YyRR, 2yyRr, 4YyRr
0%
b) 1YYRR, 3YyRR, 2yyRr, 3YyRr
0%
c) 3YYRR, 3YyRR, 2yyRr,4YyRr
0%
d) 1YYRR, 1YyRR, 2yyRr, 3YyRr
Explanation
Gametes
RY
Ry
rY
ry
RY
RRYY
RRYy
RrYY
RrYy
Ry
RRYy
RRyy
RrYy
Rryy
rY
RrYY
RrYy
rrYY
rrYy
ry
RrYy
Rryy
rrYy
rryy
F2 generation 1RRYY, 2RRYy, 2Rryy, 4RrYy Answer : (a)
Q.42
O group mother with O group child sues AB group man for fathership of child. What is true? [ MPPMT 1994 ]
0%
a) The claim is correct
0%
b) Father is true but mother is not
0%
c) Both parents are false
0%
d) Mother is true but father claimed is wrong
Explanation
I
O
I
O
I
A
I
A
I
O
(A blood group)
I
A
I
O
(A blood group)
I
B
I
B
I
O
(B blood group)
I
B
I
O
(B blood group)
Mother has O blood group. Genotype is IOIO. Father blood group is AB. Genotype is IAIB. The child will have either A blood group or B blood group. Mother is true but father claimed is wrong. She cannot sue the wrong person. Answer : (d)
Q.43
Which one is a dominant trait out of characters chosen by Mendel ? [ Manipal 2000 ]
0%
a) Pod colour - Yellow
0%
b) Seed colour - White
0%
c) Flower Position - Axillary
0%
d) Plant height - Dwarf
Explanation
Traits
Dominant
Recessive
Plant height
Tall (1.2 – 2.0m)(T)
Dwarf (0.25 – 0.5m) (t)
Flower position
Axillary (A)
Terminal (a)
Pod colour
Green (G) or (Y)
Yellow (g) or (y)
Pod shape
Full or inflated (I) or (C)
Constricted (i) or (c)
Flower colour
Violet (V) or (W)
White (v) or (w)
Seed shape
Round (R) or (W)
Wrinkled (r) or (w)
Seed colour
Yellow (Y) or (G)
Green (y) or (g)
Answer : (c)
Q.44
Blood group A person can ... ...
0%
a) Be parent of child with B blood group
0%
b) Possess only B-antigen
0%
c) safely receives blood from donor of B-group
0%
d) Possess both antigens A and B
Explanation
Blood group A has genotype IAIO and IAIA. Antigen produced is A and it produces antibodies Anti- A also known as (b) antibodies. Due to its genotype, it can donate to blood group A and blood group AB person. Blood group A person can be a parent to Child with blood group if the other parent has Blood group of B or AB. In the above options, option (a) is correct. Answer : (a)
Q.45
factors present on the surface of RBCs which are related to heredity are .. .. [ AFMC 2003 ]
0%
a) Blood groups
0%
b) Haemoglobin
0%
c) Antigens
0%
d) Antibodies
Explanation
The proteins present on the surface of Red blood cells are called Antigens. They induce a specific immune response and induce the formation of specific antibodies against it. Answer : (c)
Q.46
Non-allelic genes having similar phenotypic effect, interact to produce a different trait and a ratio of 9:7 in F2 generation are ... ... [ CBSE 2001 ]
0%
a) Epistatic genes
0%
b) Hypostatic genes
0%
c) Supplementary genes
0%
d) Complementary genes
Explanation
Gametes
CP
Cp
cP
cp
CP
CCPP (purple)
CCPp (purple)
CcPP (purple)
CcPp (purple)
Cp
CCPp (purple)
CCpp (white)
CcPp (purple)
Ccpp (white)
cP
CcPP (purple)
CcPp (purple)
ccPP (white)
ccPp (white)
cp
CcPp (purple)
Ccpp (white)
ccPp (white)
Ccpp (white)
Sweet pea (Lathyrus odoratus) is an example of complementary genes. Here, the flower colour is purple if dominant alleles of two genes C and P are present together. The colour is white if the double dominant condition is absent. CcPp × CcPp → Purple : white = 9 : 7 Answer : (d)
Q.47
Number of phenotypes possible from AaBbCc × AaBbCc is .... [ RPMT 1998 ]
0%
a) 16
0%
b) 12
0%
c) 8
0%
d) 4
Explanation
No. of traits (n)
Experiment
Types of gametes (2
n
)
No. of offsprings (gametes)
2
No. of phenotype (2
n
)
No. of genotype (3
n
)
Phenotypic ratio
Genotypic ratio
3
Trihybrid cross
8
64
8
27
(3:1)
3
(1:2:1)
3
There are 3 traits involved. Thus, this is a trihybrid cross. Answer : (c)
Q.48
Which is true? [ BHU 1997 ]
0%
a) Etiolation is genetic while albinism is physiological
0%
b) Etiolation is not reversible
0%
c) Etiolation is physiological but albinism is genetic
0%
d) Etiolation and alinism are synonyms
Explanation
Etiolation is a process in flowering plants grown in partial or complete absence of light. It is characterized by long, weak stems; smaller leaves due to longer internodes; and a pale yellow color. The development of seedlings in the dark is known as "skotomorphogenesis" and leads to etiolated seedlings. An albinism is a group of inherited disorders characterised by little or no melanin production. Answer : (c)
Q.49
Number of genotypes found in F2 progeny of a dihybrid cross is ... .. [ MPPMT 2001 ]
0%
a) 9
0%
b) 6
0%
c) 3
0%
d) 1
Explanation
No. of traits (n)
Experiment
Types of gametes (2
n
)
No. of offsprings (gametes)
2
No. of phenotype (2
n
)
No. of genotype (3
n
)
Phenotypic ratio
Genotypic ratio
2
Dihybrid cross
4
16
4
9
9:3:3:1
2:4:2:1:2:1:1:2:1
Answer : (a)
Q.50
In the cross YYRRxyyrr, the number of green coloured seeds in F2 generation is ... .. [ AMU 2012 ]
0%
a) 8/16
0%
b) 6/16
0%
c) 4/16
0%
d) 2/16
Explanation
Gametes
RY
Ry
rY
ry
RY
RRYY
RRYy
RrYY
RrYy
Ry
RRYy
RRyy (green)
RrYy
Rryy (green)
rY
RrYY
RrYy
rrYY
rrYy
ry
RrYy
Rryy (green)
rrYy
Rryy (green)
RRYY (Round, yellow seed) and × rryy(wrinkled, green seed) Green F2 progeny = 4/16 Answer : (c)
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