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Free download in PDF CBSE Class 12 Biology MCQs with Answers. Here Gkseries provide Biology Solve Questions and Answers for CBSE Class 12 Students.
101
ZIFT is transfer of
[A]
zygote into fallopian tube.
[B]
a mixture of sperms and ova into the fallopian tube.
[C]
a mixture of sperms and ova into the uterus.
[D]
embryo into the uterus.
Answer: zygote into fallopian tube.
102
Diaphragms are the contraceptive devices used by females. Choose the correct option about them.
[A]
They are placed to cover the cervix.
[B]
They block the entry of sperms.
[C]
They are reusable.
[D]
All of these.
103
When ‘Aa’ is crossed with ‘aa’, (A is dominant over a)
[A]
all the offspring will have dominant phenotype.
[B]
all the offspring will have recessive phenotype.
[C]
50% of offspring will have dominant phenotype and 50% will have recessive phenotype.
[D]
75% of offspring will have dominant phenotype and 50% will have recessive phenotype.
Answer: 50% of offspring will have dominant phenotype and 50% will have recessive phenotype.
104
The possibility of all genotypes of offspring in a genetic cross is calculated by a graphical representation which was developed by
[A]
Gregor Mendel
[B]
Reginald Punnett
[C]
Komberg
[D]
T.H. Morgan
105
Study the pedigree chart given
Select the correct option about the conclusion.
[A]
It is a sex-linked recessive trait.
[B]
It is an autosomal recessive trait.
[C]
It is an autosomal dominant trait.
[D]
It is a sex-linked dominant trait.
Answer: It is an autosomal recessive trait.
106
Mother and father of a person with ‘O’ blood group have ‘A’ and ‘B’ blood group respectively. What would be the genotype of both mother and father? [NCERT Exemplar]
[A]
Mother is homozygous for ‘A’ blood group and father is heterozygous for ‘B’.
[B]
Mother is heterozygous for ‘A’ blood group and father is homozygous for ‘B’.
[C]
Both mother and father are heterozygous for ‘A’ and ‘B’ blood group, respectively.
[D]
Both mother and father are homozygous for ‘A’ and ‘B’ blood group, respectively.
Answer: Both mother and father are heterozygous for ‘A’ and ‘B’ blood group, respectively.
107
If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is: [NCERT Exemplar]
[A]
Sex-linked recessive.
[B]
Sex-linked dominant
[C]
Autosomal dominant
[D]
Autosomal recessive
Answer: Sex-linked recessive.
108
In a dihybrid cross, if you get 9:3:3:1 ratio it denotes that: [NCERT Exemplar]
[A]
It is a case of multiple allelism.
[B]
The alleles of two genes are segregating independently.
[C]
The alleles of two genes are interacting with each other.
[D]
It is a multigenic inheritance.
Answer: The alleles of two genes are segregating independently.
109
Which of the following traits studied by Mendel in garden pea is a dominant trait?
[A]
Inflated pod.
[B]
Yellow colour of pod.
[C]
Green colour of seed.
[D]
Terminal flowers.
110
If a haemophilic woman marries a normal man,
[A]
all their children will be normal.
[B]
all their sons will be haemophilic.
[C]
all their daughters will be haemophilic.
[D]
50% sons and 50% daughters will be haemophilic.
Answer: all their sons will be haemophilic.
111
Operon model for regulation of transcription was proposed by
[A]
Meselson and Stahl
[B]
Jacob and Monod
[C]
Watson and Crick
[D]
Hershey and Chase
112
Eukaryotic RNA polymerase III catalyses the synthesis of
[A]
tRNA
[B]
hnRNA
[C]
mRNA
[D]
rRNA
113
The sequence of nitrogen bases in a # segment of a coding strand of DNA is ’ AATGCTTAGGCA. What will be the sequence of nitrogen bases in the wRNA transcribed by it?
[A]
UUA CGA AUC CGU
[B]
AAU GCU UAG GCA
[C]
AAU GCU AAC CGA
[D]
AAU GCA AUC CGU
114
Which of the following sets of codons contains only termination codons?
[A]
UAA, UGA, UAG
[B]
UUU, UCC, UGG
[C]
UAA, UUU, UGG
[D]
UAA, UAG, UAC
115
The central dogma of molecular biology (genetic information flow) was modified by the discovery of
[A]
RNA polymerase
[B]
DNA ligase
[C]
Reverse transcriptase
[D]
DNA polymerase
Answer: Reverse transcriptase
116
The human chromosome with the highest and least number of genes in them are respectively
[A]
Chromosome 21 and Y
[B]
Chromosome 1 and Y
[C]
Chromosome X and Y
[D]
Chromosome 1 and X
Answer: Chromosome 1 and Y
117
The net electric charge on DNA and histone, is
[A]
positive, negative
[B]
negative, positive
[C]
positive, positive.
[D]
negative, negative
Answer: negative, positive
118
In E.coli, the lac operon gets switched on when [NCERT Exemplar]
[A]
lactose is present and it binds to the », repressor.
[B]
repressor binds to operator.
[C]
RNA polymerase binds to the operator.
[D]
lactose is present and it binds to RNA polymerase.
Answer: lactose is present and it binds to the », repressor.
119
Which of the following are the functions of RNA?
[A]
It is a constituent component of ribosomes
[B]
It carries amino acids to ribosomes
[C]
It is a carrier of genetic information from DNA to ribosomes synthesising polypeptides.
[D]
All of the above.
Answer: All of the above.
120
In the lac operon of E.coli, the i gene codes for
[A]
inducer
[B]
repressor
[C]
lactase
[D]
β-galactosidase
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