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Inheritance And Variation Mcq
Quiz 7
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Q.1
If F1 generation has all tall plants and ratio of F2 generation is 3 tall : 1 dwarf, it proves ... .. [ Odisha 2011 ]
0%
a) law of independent assortment
0%
b) law of segregation
0%
c) law of dominance
0%
d) incomplete dominance
Explanation
3:1 ratio in F2 generation of a monohybrid cross suggested that segregation of alleles does take place and it can be confirmed by test cross. Answer : (c)
Q.2
Female AaBb is crossed to male AAbb. The gamete shall be ..... [CPMT 1991 ]
0%
a) Female AB and ab, male AA and bb
0%
b) Female Aa and Bb, male AA and bb
0%
c) Female AB, Ab, aB and male Ab
0%
d) Female AA, bb, AB and male Ab
Explanation
Number of gametes = 2n where n = no. of heterozygous allele pair. Female has two heterozygous allele pair. Thus number of gamete = 22 = 4. Gametes are AB, Ab, aB and ab. Male has no heterozygous allele pair. Thus number of gamete = 2. Gamete is Ab. Answer : (c)
Q.3
Total number of progeny of a dihybrid cross is 1280 in F2 generation. How many recombinants? ... .. [ EAMCET 2005]
0%
a) 240
0%
b) 360
0%
c) 480
0%
d) 720
Explanation
Gametes
RY
Ry
rY
ry
RY
RRYY (round, yellow)
RRYy (round,yellow)
RrYY (round, yellow)
RrYy (round, yellow)
Ry
RRYy (round, yellow)
RRyy (round, green)
RrYy (round, yellow)
Rryy (round, green)
rY
RrYY (round, yellow)
RrYy (round, yellow)
rrYY ( wrinkled, yellow)
rrYy (wrinkled, yellow)
ry
RrYy (round, yellow)
Rryy ( round, green)
rrYy ( wrinkled, yellow)
Rryy (wrinkled, green)
Recombinant offspring are children that have a different allele combination to their parents i.e., have different phenotype. Example RRYY × rryy → F1 generation RrYy In a dihybrid cross, during F2 generation 16 progeny are formed, in this, 10 progeny shows parental phenotypes, remaining 6 progeny shows new phenotypes. These are called recombinants. So, in the F2 generation 1280 progeny are formed, in this 800 progeny shows parental phenotypes and 480 progenies are recombinants. Answer : (c)
Q.4
Law of Mendel which is not completely applicable .... [ Pb PMT 200 7]
0%
a) Law of dominance
0%
b) Law of segregation
0%
c) Law of independent assortment
0%
d) Co-dominance
Explanation
Law of Mendel is not completely applicable for co-dominance. Answer : (c)
Q.5
TT Pea plant is crossed to tt plant F2 generation will have ... .. [ kerala 2003 ]
0%
a) All tall plants
0%
b) Tall and dwarf in the ratio of 3:1
0%
c) Tall and dwarf in the ratio of 1:2
0%
d) Tall and dwarf in the ratio of 1:1
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
1
Monohybrid cross
2
4
2
3
3:1
1:2:1
Answer : (b)
Q.6
How many types of gametes will be produced by individuals of AABcc genotype? ... ..[ CBSE 1998 ]
0%
a) Two
0%
b) Four
0%
c) Six
0%
d) Nine
Explanation
Gametes produced by individuals = 2n where n = no. of heterozygous allele pair. No. of gametes having produced from one heterozygous pair = 21 = 2 Answer : (a)
Q.7
Dihybrid cross is related to ... .. [ RPMT 1995 ]
0%
a) Principle of dominance
0%
b) Principle of independent assortment
0%
c) Principle of segregation
0%
d) Principle of purity of gametes
Explanation
Law of independent assortment is demonstrated by dihybrid cross. Law of segregation or purity of gamete and law of dominance is demonstrated by monohybrid cross Answer : (b)
Q.8
In humans blue eye colour is recessive to brown eye colour. if a boy has brown eyes and mother blue eyed, what would be phenotype of father? .. .... [ KCET 200 7]
0%
a) Green eye
0%
b) Blue eye
0%
c) Black eye
0%
d) Brown eye
Explanation
Brown eye colour is dominant and blue eye colour is recessive. The progeny has brown eyes. This implies that progeny has character of dominant individual. Since mother has blue eyes, phenotype of father should be brown eyes in order for progeny to have brown eyes. Answer : (d)
Q.9
Dihybrid test cross ratio is ... .. [ AIIMS 2000 ]
0%
a) 9:3:3:1
0%
b) 1:1:1:1
0%
c) 3:1
0%
d) 1:1
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.10
Mendel formulated the law of purity of gametes on the basis of ... .. [ RPMT 1990 ]
0%
a) Test cross
0%
b) Back cross
0%
c) Monohybrid cross
0%
d) Dihybrid cross
Explanation
Mendelian principles are the rules of inheritance first discovered by Mendel. Law of dominance and law of segregation also called law of purity are based on monohybrid cross. Law of independent assortment are based on dihybrid cross. Answer : (c)
Q.11
Cross between AaBB and aaBB will form .... ...[ CBSE 1990 ]
0%
a) 1 AaBB : 1aaBB
0%
b) All AaBB
0%
c) 3 AaBB : 1 aaBB
0%
d) 1 AaBB : 3 aaBB
Explanation
Gametes
AB
aB
aB
AaBB
aaBB
aB
AaBB
aaBB
AaBB × aaBB AaBB : aaBB 1 : 1 Answer : (a)
Q.12
Children of father with 'O' blood group and mother with 'AB' blood group would be ... ..
0%
a) O
0%
b) AB
0%
c) O or AB
0%
d) A or B
Explanation
Answer : (d)
Q.13
Two dominant independently assorting genes react with each other. They are... .. [ BHU 1997]
0%
a) Complementary
0%
b) Supplementary
0%
c) Duplicate
0%
d) Collaborative
Explanation
Complementary gene may be defined as two or more dominant genes present on separate gene loci which interact to produce a particular phenotypic trait, but neither of them produces phenotypic trait in absence of other. Supplementary gene are two independent genes (nonallelic pair) present on different gene loci, each producing its own trait. These genes interact when present in dominant state to produce a new trait. Answer : (a)
Q.14
In a cross between AABB × aabb, the ratio of F2 genotypes between AABB, AaBB, Aabb and aabb would be ... .. [ CBSE 1992 ]
0%
a) 9 : 3 : 3 : 1
0%
b) 2 : 1 : 1:2
0%
c) 1 : 2 : 2 :1
0%
d) 7 : 5 : 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 : (c)
Q.15
How many types of gametes will be produced by an organism with AaBBCc / AABcCc genotype ... .. [ AMU 2011 ]
0%
a) 3
0%
b) 4
0%
c) 9
0%
d) 6
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 : (b)
Q.16
1:2:1 phenotypic and genotypic ratios occur in case of ... .. [ DPMT 2001 ]
0%
a) blending/ intermediate inheritance
0%
b) pseudoalleles
0%
c) Multiple alleles
0%
d) Complementary genes
Explanation
Gametes
R
r
R
RR (red)
Rr (pink)
r
Rr (pink)
Rr (white)
Blending inheritance is the phenomenon where none of two contrasting alleles or factors is dominant . Example: In a cross between true-breeding red-flowered (RR) and truebreeding white-flowered plants (rr), the F1 (Rr) was pink . When the F1 was self-pollinated the F2 resulted in the following ratio 1 (RR) Red: 2 (Rr) Pink: 1 (rr) White. The genotype ratios is exactly as monohybrid cross. Red flower (RR) × White flower (rr) → Pink flower (Rr) Pink flower (Rr) × Pink flower (Rr) → Genotypic ratio RR : Rr : rr = 1 : 2 : 1 Phenotypic ratio Red : pink : white = 1 : 2 : 1 Answer : (a)
Q.17
The term eugenics was first applied by ... .. [ CPMT 1994 ]
0%
a) Urey
0%
b) Lederberg
0%
c) Galton
0%
d) Morgan
Explanation
"Eugenics is the study of the agencies under social control that may improve or impair the racial qualities of future generations either physically or mentally." Eugenics, meaning "well born," was introduced in the 1880s by Sir Francis Galton, a cousin of Charles Darwin and the father of modern statistics. Answer : (c)
Q.18
Mendel did not propose ... .. [ BHU 1991 ]
0%
a) Dominance
0%
b) Incomplete dominance
0%
c) Segregation
0%
d) Independent assortment
Explanation
Mendel choose characters which shows complete independent assortment. He took only those traits for his studies which did not show linkage, interaction or incomplete interaction. Answer : (b)
Q.19
position of gene on chromosome is called ... ..
0%
a) Locus
0%
b) Factor
0%
c) Cistron
0%
d) Nucleosome
Explanation
The portion or region on chromosomes representing a single gene is called gene locus. Answer : (a)
Q.20
Mendel is called father of .... ... [ MPPMT 2000 ]
0%
a) Taxonomy
0%
b) Genetics
0%
c) Palaeobotany
0%
d) Modern physiology
Explanation
Gregor Johann Mendel appropriately known as father of genetics, proposed the theory of inheritance. Answer : (b)
Q.21
Phenotype of an organism is the result of .... .. [ CBSE 2006 ]
0%
a) mutations and linkages
0%
b) Genotype and environment interactions
0%
c) Cytoplasmic effects and nutrition
0%
d) Environmental changes and sexual dimorphism
Explanation
phenotype, all the observable characteristics of an organism that result from the interaction of its genotype (total genetic inheritance) with the environment. Answer : (b)
Q.22
Mendel conducted hybridization experiments on ... ... [ CPMT 1990 ]
0%
a) Pigeon Pea
0%
b) Garden Pea
0%
c) Wild Pea
0%
d) Sweet Pea
Explanation
Mendel conducted breeding experiments on garden peas (Pisum sativum) in the garden of his monastery and was luckily the first to formulate clear cut principles or laws of heredity. Answer : (b)
Q.23
Find out the correct statement ... .. [ manipur 2005 ]
0%
a) There are several pairs of contrasting characters of allotropic traits
0%
b) Hybrids remains infertile
0%
c) Plants can be self fertilized
0%
d) Small herbaceous plant can be easily cultivated
Explanation
Organisms have various traits and they have contrasting characters. Example height is trait which have contrast character like tall and dwarf. Option (a) is correct statement. Hybrids are fertilized and produces progeny. Option (b) is incorrect statement. Plants can undergo self fertilization. Example sunflowers. Option (c) is correct statement. Small herbaceous requires small area and thus can be easily cultivated. Option (d) is correct statement. Answer : (b)
Q.24
Carl Correns, a rediscovered of Mendel's work was from .... ...
0%
a) Austria
0%
b) Germany
0%
c) Holland
0%
d) Denmark
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 : (b)
Q.25
Genome represents total number of genes in .... ... [ MHTCET 2009]
0%
a) A chromosome
0%
b) Homologous chromosome pair
0%
c) Haploid set of chromosomes
0%
d) Diploid set of chromosomes
Explanation
A genome is a complete set of chromosomes where every gene chromosome is represented singly as in gamete. Thus, genome represents total number of genes in haploid set of chromosomes. Answer : (c)
Q.26
Mendel studied inheritance of seven pairs traits in Pea which can have 21 possible combinations. If you are told that in one of these combinations, independent, your reaction will be ... ... [ CBSE 1993 ]
0%
a)Independent assortment principle may wrong
0%
b) Mendel might not have studied all the combinations
0%
c) It is impossible
0%
d) Later studies may be wrong
Explanation
Mendel luckily studied only those characters which showed complete independent assortment. If one of the combination does not show independent assortment, that implies Mendel might not have studied all the combinations. Answer : (b)
Q.27
Which one shows complementary gene interaction ratio of 9:7? ... [ kerala 2009
0%
a) Four O'clock plant
0%
b) Feather colour in Fowl
0%
c) Flower colour in Sweat Pea
0%
d) Fruit shape in Shephered's purse
Explanation
Characters
Expected ratios
Example
Monohybrid cross
Phenotypic = 3 : 1
Genotypic = 1 :2 : 1
Pisum sativum
Dihybrid cross
Phenotypic = 9:3:3:1
Pisum sativum
Incomplete dominance
1 : 2 : 1
Mirabilis jalapa
Complementary genes
9 : 7
Lathyrus odoratus
Supplementary genes
9 : 3 : 4
Coat colour of mice
Collaborative supplementary genes
9 : 3 : 3 : 1
Poultry birds – comb pattern
Dominant epistasis
12 : 3 : 1
Fruit colour in
Curcurbita
Recessive epistasis
9 : 3 : 4
Coat colour in mice/pigmentation in onion bulb
Duplicate genes
15 : 1
Fruit shape in
Capsella bursapastoris
Polymeric gene
9 : 6 : 1
Cucurbita pepo
Suppresor gene
13:3
Leaf colour of rice
Answer : (c)
Q.28
Mendel’s work was rediscovered in ... .. [ RPMT 1995]
0%
a) 1756
0%
b) 1865
0%
c) 1900
0%
d) 1910
Explanation
It was in 1900, three workers independently rediscovered the principles of heredity already worked out the mendel. They were Hugo de Vries of Holland, Carl Correns of Germany and Erich von Tschermak of Austria. Answer : (c)
Q.29
By cross pollinating certain tobacco species, some fertile hybrides were obtained by ... .. [ HPPMT 2001 ]
0%
a) Mendel
0%
b) Morgan
0%
c) Kolreuter
0%
d) Khorana
Explanation
Kolreuter, a German botanist obtained fertile interspecific hybrids in tobacco. The hybrid did not resemble either of the parents. Hybrids were self pollinated. Some offspring resembled the hybrids while remaining resembled one of the other grandparents in different characters. This proved that the traits have particulate nature and remain discrete. Answer : (c)
Q.30
Monohybrid test cross is ... .. [ JKCMEE 2010 ]
0%
a) 1:1:1:1
0%
b) 1:1
0%
c) 9:3:4
0%
d) 9:3:3:1
Explanation
Answer : (b)
Q.31
Gregor Johann Mendal, the father of genetics was ... ... [ MHTCET -2000 ]
0%
a) Austrian monk
0%
b) British monk
0%
c) Italian monk
0%
d) German scientist
Explanation
Gregor Johann Mendel was a meteorologist, mathematician, biologist, Augustinian friar and abbot of St. Thomas' Abbey in Brno, Margraviate of Moravia. He was an Austrian monk. Answer : (a)
Q.32
Which pair of features represents polygenic inheritance? ... ... [ AIIMS 2006 ]
0%
a) Human eye colour and sickle anaemia
0%
b) Hair pigments of mouse and tongue rolling in humans
0%
c) ABO blood groups in humans and flower colour of Mirabilis jalapa
0%
d) Human height and skin colour
Explanation
Human eye colour, skin colour and height shows polygenic inheritance. ABO blood group is an example of co-dominance, multiple alleles and dominance. Mirabilis jalapa is an incomplete dominance. Sickle cell aneamia is an example of pleiotropy. Answer : (d)
Q.33
A woman with blood group 'O' has a child with blood group 'O'. Father with blood group 'A' must have the genotype ... .. [ HPPMT 2012 ]
0%
a) IOIO
0%
b) IAIB
0%
c) IAIO
0%
d) IBIO
Explanation
Progeny has blood group O is IOIO. Each allele is obtained from each parent. That implies one IO is from mother and IO is from father. Thus genotype of father blood group should have IO. Since the father’s blood group is A, thus genotype will be IAIO Answer : (c)
Q.34
The procedure adopted by Mendel which was different from his predecessors is ... ... [ CPMT 1991 ]
0%
a) Keeping breeding records
0%
b) Employing many traits at one time
0%
c) Differentiating inherited traits
0%
d) Quantitative analysis of data
Explanation
Unlike his predecessors who worked on large number of characters simultaneously, Mendel worked with one or few pairs of trait at one trait. He kept record of every cross and subsequent generations produced through self-breeding. Thus he maintained the statistical records of all experiments and analyzed them carefully. Answer : (d)
Q.35
Sickle cell anaemia is an example of ... ... [ AFMC 1999 ]
0%
a) Epistasis
0%
b) Codominance
0%
c) Pleiotropy
0%
d) Incomplete dominance
Explanation
The disease is controlled by a single pair of allele, HbA and HbS . HbS has ability to produce multiple phenotypic effect. In homozygous state, it is diseased phenotype. In heterozygous state, it is carrier phenotype. This ability is called pleiotropy. Answer : (c)
Q.36
An exception to Mendel's principles / Mendel did not include in his discoveries ... ... [ RPMT 1990 ]
0%
a) Dominance
0%
b) Purity of gametes / segregation
0%
c) Linkage
0%
d) Independent assortment
Explanation
Though Mendel did not know about chromosomes, all the traits he studied were on different pairs of homologous chromosomes. That is why he concluded that gene pairs segregate independently of one another. Mendel’s gene pair did not show linkage. Answer : (c)
Q.37
Which is mismatched ... .. [ Chd. CET 2012 ]
0%
a) Tt × Tt - 3:1
0%
b) Tt × tt - 2:1
0%
c) TtYy × tt yy - 1:1:1:1:1
0%
d) TtYy × TtYy - 9:3:3:1
Explanation
No. of traits (n)
Experiment
Types of gametes (2n)
No. of offsprings (gametes)
2
No. of phenotype (2
n
)
No. of genotype (3
n
)
Phenotypic ratio
Genotypic ratio
1
Monohybrid cross
2
4
2
3
3:1
1:2:1
2
Dihybrid cross
4
16
4
9
9:3:3:1
2:4:2:1:2:1:1:2:1
3
Trihybrid cross
8
64
8
27
(3:1)
3
(1:2:1)
3
Answer : (b)
Q.38
In a dihybrid cross AABB &time aabb, F2 progeny of AABB, AABb, AaBB and AaBb occurs in the ratio of .... [ CBSE 1994 ]
0%
a) 1:1:1:1
0%
b) 9:3:3:1
0%
c) 1:2:2:1
0%
d) 1:2:2:4
Explanation
Gametes
AB
Ab
aB
ab
AB
AABB
AABb
AaBB
AaBb
Ab
AABb
AAbb
AaBb
Aabb
aB
AaBB
AaBb
aaBB
aaBb
ab
AaBb
Aabb
aaBb
aabb
AABB × aabb → F1 generation AaBb AaBb × AaBb AABB : AABb : AaBB : AaBb 1 : 2 : 2 : 4 Answer : (d)
Q.39
Which one is exception to Mendel's principle of dominance? .... ... [ RPMT 1995 ]
0%
a) Wild Pea
0%
b) Mirabilis
0%
c) Garden Pea
0%
d) Maize
Explanation
Mirabilis jalapa expresses incomplete dominance. Answer : (b)
Q.40
Mendel's principle of segregation is based on separation of alleles during .. ... [ MPPMT 1993]
0%
a) Gamete formation
0%
b) Seed formation
0%
c) Pollination
0%
d) Embryonic development
Explanation
Mendel’s principle of segregation is based on segregation of allele during gamete formation. At the formation of gamete, allele separate and gametes carry either dominant or recessive of alleleic pair but not both. The gametes which are formed are always pure for a particular character. Answer : (a)
Q.41
In Antirrhinum two plants with pink flowers were hybridized. the F1 plants produced red, pink and white flowers in ratio 1:2:What could be genotype of the parent plants, RR is red , rr is white ... ... [ CBSE Mains 2010 ]
0%
a) rr
0%
b) Rr
0%
c) RR
0%
d) rrrr
Explanation
The ratio suggests that incomplete dominance occur. In this phenomenon there is no dominant-recessive relationship, and the hybrid i.e., F1 generation is intermediate. In this case, pink flower is intermediate and its genotype is herterozygous allelic pair. Genotype of F1 is Rr. Answer : (b)
Q.42
If a cross between two individuals produces off spring with 50% dominant character A and 50% recessive character a, the genotypes of the parents are ... ... [ W.B 2011]
0%
a) Aa × Aa
0%
b) AA × aa
0%
c) Aa × aa
0%
d) AA × Aa
Explanation
Gametes
A
a
a
Aa (dominant)
aa (recessive)
a
Aa (dominant)
aa (recessive)
Given result is obtained when one parent is heterozygous dominant and another is recessive. Aa × aa Answer : (c)
Q.43
In mendelian crosses the genes responsible for different characters separate through ... .. [ AMU 2000 ]
0%
a) Fusion
0%
b) Aggregation
0%
c) Segregation
0%
d) Distribution
Explanation
Mendel’s principle of segregation is based on segregation of allele during gamete formation. At the formation of gamete, allele separate and gametes carry either dominant or recessive of alleleic pair but not both. The gametes which are formed are always pure for a particular character. Answer : (c)
Q.44
When two hybrids rrTt and Rrtt are crossed the phenotypic ratio of offspring shall be ... ... [ CPMT 1990 ]
0%
a) 3 : 1
0%
b) 1 : 1 : 1 : 1
0%
c) 1 : 1
0%
d) 9 : 3 : 3 : 1
Explanation
Gamete
RT
Rt
rT
rt
rt
RrTt;
Rrtt
rrTt
rrtt
rt
RrTt
Rrtt
rrTt
rrtt
RrTt × rrtt → F2 generation Round, tall : Round, dwarf : wrinkled, tall : wrinkled, dwarf 1 : 1 : 1 : 1 Answer : (b)
Q.45
In his classic experiments on pea plants, Mendel did not use : [ ReAIPMT 2015]
0%
a) Flower position
0%
b) Seed colour
0%
c) Pod length
0%
d) Seed shape
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)
Mendel studied the following Pod length was not studied by Mendel. Ans:(c)
Q.46
In plant, red fruit (R) is doinant over yellow fruit (r) and tallness (T) dominant over shortness (t). A plant with RRTt genotype is crossed with plant of rrtt genotype. the progeny is ... .. [ CBSE 2004 ]
0%
a) All red fruit, tall25%
0%
b) All red fruit, tall 50%
0%
c) All red fruit, tall 75%
0%
d) All red fruit and tall
Explanation
Gametes
RT
Rt
rt
RrTt (red fruit, tall)
Rrtt (red fruit, dwarf)
RRTt × rrtt All the progeny is red fruit and 50% progeny is tall and 50% dwarf. Answer : (b)
Q.47
the offspring of AA bb × aa BB is crossed with, aabb. the genotypic ratio of progeny will be ... .. [CPMT 2007]
0%
a) 9:3:3:1
0%
b) 1:2:1
0%
c) 1:1:1:1
0%
d) 4:1
Explanation
Gametes
AB
Ab
aB
ab
ab
AaBb
Aabb
aaBb
aabb
Progeny of AAbb and aaBB will be AaBb. AaBb × aabb → AaBb : Aabb : aaBb : aabb 1 : 1 : 1 : 1 Answer : (c)
Q.48
Lethal genes are ... ... [ CPMT 1991 ]
0%
a) Causative for appearance of ancestral traits
0%
b) Always recessive
0%
c) Genes present on different chromosomes but influencing single trait
0%
d) Killer in homozygous state
Explanation
Lethal alleles (also referred to as lethal genes or lethals) are alleles that cause the death of the organism that carries them. They are usually a result of mutations in genes that are essential for growth or development. Lethal genes are those genes which cause the death of organisms but only when they are present in the homozygous state. Answer : (d)
Q.49
In humans, height shows a lot of variation. it is an example of ... ... [ DPMT 1996 ]
0%
a) Multiple alleles
0%
b) Pleiotropic inheritance
0%
c) Polygenic inheritance
0%
d) Pseudoallele
Explanation
Inheritance of skin color, eye colour and height is an example of polygenic inheritance Answer : (c)
Q.50
Tall plant with round seed (TTRR) is crossed with dwarf plant having wrinkled seed ( ttr). F1 plants are tall with rounded seeds. Types of gametes produced by them would be ... ... [ AMU 2005 ]
0%
a) One
0%
b) Two
0%
c) Three
0%
d) Four
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 : (d)
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