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Genetic Basis of Inheritance

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A cross between yellow round and green wrinkled seed pea plants gave the following four types of progeny in equal proportions: yellow round, yellow wrinkled, green round and green wrinkled. The genotypes of the parents in this case must be

  1. YYRR X yyrr

  2. YyRr X yyrr

  3. YYRR X YYRR

  4. YyRr X YYRR

  5. yyrr X yyrr


Correct Option: B
Explanation:

YyRr X yyrr produces yellow round, yellow wrinkled, green round and green wrinkled progeny.

Sickle cell anemia is caused by the presence of mutant alleles in the

  1. 10th chromosome

  2. 11th chromosome

  3. 12th chromosome

  4. 13th chromosome


Correct Option: B
Explanation:

Sickle cell anaemia is caused by the presence of mutant alleles in the 11th chromosome.

Mendal conducted experiments in pea plant pisum sativum. The total number of chromosomes in pea plant is

  1. 4 pairs

  2. 5 pairs

  3. 7 pairs

  4. 14 pairs


Correct Option: C
Explanation:

Total number of chromosomes in pea plant is 7 pairs (14).

Mendel's findings were rediscoverd in the year 1900 by

  1. Jacob and Monad

  2. De Vries, Corren and Tscherm

  3. Avery, MacLeod and McCarty

  4. Watson and Crick


Correct Option: B
Explanation:

Mendel's findings were rediscoverd in 1900 by De Vries, Corren and Tschermk.

Genetic constitution of an organism is called

  1. phenotype

  2. genotype

  3. dominant character

  4. co-dominance


Correct Option: B
Explanation:

Internal genetic constitution of an organism is genotype.

In F2 generation of Mendel's monohybrid cross, recessive character appears in which of the following proportions?

  1. 1/2

  2. 1/4

  3. 2/4

  4. 3/4


Correct Option: B
Explanation:

Monohybrid F2 ratio is 3:1. Therefore, F2 generation's recessive character appears in 1/4 proportion.

Which of the following traits is a recessive feature studied by Mendel?

  1. Round seed

  2. Axial flower

  3. Violet flower

  4. Green seed


Correct Option: D
Explanation:

Green seed is recessive character studied by Mendel.

After a cross of round seeded plant with wrinkled seed plant, F1 produced 50 per cent round seed plants and 50 per cent wrinkled seed plants. What is the genotype of parental plants?

  1. RR X rr

  2. RR X RR

  3. Rr X RR

  4. Rr X rr


Correct Option: D
Explanation:

After a cross of round seeded plant with wrinkled seeded plant, F1 produced 50 per cent round seed and 50 per cent wrinkled seeded plant. The cross is test cross, i.e. Rr X rr.

Which of the following is a sex-linked mendelian disorder?

  1. Sickle cell anemia

  2. Haemophilia

  3. Phenylketonuria

  4. Muscular dystrophy


Correct Option: B
Explanation:

Haemophilia is a sex-linked Mendelian disorder

Which of the following shows an incomplete dominance?

  1. Flower colour in Pisum sativum

  2. Flower colour in Mirabilis jalapa

  3. Flower colour in Lathyrus odoratus

  4. Eye colour in Drosophila melanogaster


Correct Option: B
Explanation:

Flower colour in Mirabilis jalapa shows incomplete dominance

The blood group of father is A and mother is AB. What is/are the possible blood group(s) of their children?

  1. A and AB

  2. A and B

  3. A,B and AB

  4. AB only


Correct Option: C
Explanation:

When the blood group of father is A and mother is AB, the possible blood groups of their children are A, B and AB.

Gene mapping was first developed by

  1. T.H Morgan

  2. Alfred Staurtevant

  3. Alec Jeffrey

  4. De Vries


Correct Option: B
Explanation:

Gene mapping was first developed by Alfred Staurtevant.

Which of the following characters is controlled by multiple allele?

  1. Flower colour in pea plant

  2. Flower colour in mirabilis

  3. Flower colour in snapdragon

  4. Blood group in man


Correct Option: D
Explanation:

Blood group in man is controlled by multiple alleles.

A chromosomal abnormality in male due to trisomy of sex chromosome is

  1. Turner's syndrome

  2. Down's syndrome

  3. Klinefelter's syndrome

  4. Edward's syndrome


Correct Option: C
Explanation:

A chromosomal abnormality in male due to trisomy of sex chromosome is Klinefelter's syndrome.

AB blood group in man is an example of

  1. complete dominance

  2. incomplete dominance

  3. codominance

  4. polygenic inheritance


Correct Option: C
Explanation:

AB blood group in man is an example of codominance.

ZW-ZZ type of sex determination is found in

  1. drosophila

  2. grasshopper

  3. humans

  4. birds


Correct Option: D
Explanation:

ZW-ZZ type of sex determination is found in birds.

What will be the genotype(s) of F1 upon crossing 'TtRr' with 'ttrr'?

  1. TtRr

  2. TtRr and ttrr

  3. TtRr,Ttrr, ttRr, ttrr

  4. TTRR, ttRR, TTrr and ttrr


Correct Option: C
Explanation:

A cross 'TtRr' with 'ttrr' is test cross and produces TtRr, Ttrr, ttRr, ttrr genotypes in F1.

In epistatic type of inheritance

  1. the behaviour of two genes is entirely independent

  2. one gene alters the effect of the other

  3. a portion of a chromosome is deleted

  4. a portion of a chromosome is inverted


Correct Option: B
Explanation:

In epistatic type of inheritance, one gene alters the effect of the other.

In the F2 generation of a dihybrid cross

  1. four phenotypes appear in the ratio 9 : 3 : 3 : 1, if the loci are linked

  2. four phenotypes appear in the ratio 9 : 3 : 3 : 1, if the loci are unlinked

  3. two phenotypes appear in the ratio 3 : 1, if the loci are unlinked

  4. 3 phenotypes appear in the ratio 1 : 2 : 1, if the loci are unlinked


Correct Option: B
Explanation:

In the F2 generation of a dihybrid cross, four phenotypes appear in the ratio 9:3:3:1, if the loci are unlinked.

If there is a lot of distance between two genes, the chance of crossing over

  1. is more

  2. is less

  3. is zero

  4. will remain unaffected


Correct Option: A
Explanation:

If there is a lot of distance between two genes, the chance of crossing over is more.

The experimental material of TH Morgan was

  1. pisum sativum

  2. drosophila melanogaster

  3. oenothera lamarckiana

  4. mirabilis jalapa


Correct Option: B
Explanation:

Drosophila melanogaster was the experimental material of TH Morgan.

A cross between F1 and homozygous recessive parental combination is called

  1. back cross

  2. test cross

  3. reverse cross

  4. reciprocal cross


Correct Option: B
Explanation:

A cross between F1 and homozygous recessive parental combination is called test cross.

The percentage of 'ab' gametes produced by AaBb parent will be

  1. 25

  2. 50

  3. 75

  4. 80


Correct Option: A
Explanation:

AaBb parents produce 25% AB, 25% Ab , 25% aB and 25% ab gametes. Therefore, this is the right option.

If a haemophilic man marries a woman with haemophilia, what would be the possibility of their daughter being haemophilic?

  1. 100%

  2. 75%

  3. 50%

  4. 0%


Correct Option: C
Explanation:

If a haemophilic man marries a woman carrier for haemophilia, the possibility that their daughter would be haemophilic is 50%.

In sickle cell anaemia due to point mutation, the sixth amino acid, glutamic acid in beta chain of haemoglobin is replaced by

  1. alanine

  2. tyrosine

  3. valine

  4. serine

  5. lysine


Correct Option: C
Explanation:

In sickle cell anaemia due to point mutation, the sixth amino acid, glutamic acid in beta chain of haemoglobin is replaced by valine.

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