CBSE 12 Biology Question Paper-2021 Term-1 by Pavan | Practice Test to Test Your Knowledge
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  3. CBSE 12 Biology Question Paper-2021 Term-1
CBSE 12 Biology Question Paper-2021 Term-1

CBSE 12 Biology Question Paper-2021 Term-1

This mock test includes actual CBSE Class 12 Biology board exam questions from the year 2021 Term-1, helping students understand exam trends and practice real paper format

2025-08-12
Pavan Pavan
CBSE Class 12 Biology 2021 Grade 12

Duration

30 min

Questions

28

Marking

Negative

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Questions Preview

The structure of bilobed anther consists of

A
2 thecae, 2 sporangia
B
4 thecae, 4 sporangia
C
4 thecae, 2 sporangia
D
2 thecae, 4 sporangia

In the figure of anatropous ovule given below, choose the correct option for the characteristic distribution of cells within the typical embryo sac

A
3 2 3
B
3 3 2
C
2 3 3
D
2 2 4

The coconut water from tender coconut is

A
cellular endosperm
B
free nuclear endosperm
C
both cellular and nuclear endosperm
D
free nuclear embryo

Pollen grains are well preserved as fossils because of presence of

A
sporopollenin
B
cellulose
C
lignocellulose
D
pectocellulose

Which of the following statements are true related to Seed X and Y?

A
(i), (iii)
B
(ii), (iii)
C
(i), (iv)
D
(ii), (iv)

Which of the following statements are correct with respect to hormones secreted by placenta?

A
(i) and (iv)
B
(i), (ii) and (iv)
C
(iii) and (iv)
D
(ii), (iii) and (iv)

Identify the correct stage of development of human embryo that takes place at site X, Y, and Z respectively in the human female reproductive system.

A
Morula, Fertilized egg, Blastocyst
B
Unfertilized egg, Fertilized egg, Morula
C
Blastocyst, Fertilized egg, Unfertilized egg
D
Fertilized egg, Morula, Blastocyst

Penetration of the sperm in the ovum is followed by

A
formation of first polar body
B
completion of meiosis II
C
first meiosis
D
dissolution of zona pellucida

The correct sequence of hormone secretion from the beginning of menstruation is

A
FSH, progesterone, estrogen
B
estrogen, FSH, progesterone
C
FSH, estrogen, progesterone
D
estrogen, progesterone, FSH

In the dioecious aquatic plant shown, identify the characteristics of the male flowers that reach the female flowers for pollination:

A
small brightly coloured, light weight and non-sticky
B
large colourless, large and sticky
C
small white, small, covered with mucilage
D
large colourless, non sticky

The thalamus contributes to the fruit formation in

A
banana
B
orange
C
strawberry
D
guava

How many types of gametes would be produced if the genotype of a parent is AaBB?

A
1
B
2
C
3
D
4

Which of the following statements indicates parallelism in genes and chromosomes?

A
(i) and (iii)
B
(ii) and (iii)
C
(i), (ii) and (iii)
D
(i), (ii) and (iv)

Which of the following amino acid substitution is responsible for causing sickle cell anemia?

A
Valine is substituted by Glutamic acid in the α globin chain at the sixth position
B
Valine is substituted by Glutamic acid in the β globin chain at seventh position
C
Glutamic acid is substituted by Valine in the α globin chain at the sixth position
D
Glutamic acid is substituted by Valine in the β globin chain at the sixth position

In human beings, where genotype AABBCC represents dark skin colour, aabbcc represents light skin colour and AaBbCc represents intermediate skin colour; the pattern of genetic inheritance can be termed as:

A
Pleiotropy and codominance
B
Pleiotropy and incomplete dominance
C
Polygenic and qualitative inheritance
D
Polygenic and quantitative inheritance

Which of the following combination of chromosome numbers represents the correct sex determination pattern in honey bees?

A
Male 32, Female 16
B
Male 16, Female 32
C
Male 31, Female 32
D
Female 32, Male 31

Rajesh and Mahesh have defective haemoglobin due to genetic disorders. Rajesh has too few globin molecules while Mahesh has incorrectly functioning globin molecules. Identify the disorder they are suffering from.

A
Thalassemia
B
Sickle cell anemia
C
Hemophilia
D
Huntington's disease

Which of the following criteria must a molecule fulfill to act as a genetic material?

A
(i) and (ii)
B
(ii) and (iii)
C
(iii) and (iv)
D
(ii) and (iv)

The promoter site and the terminator site for transcription are located at

A
3′ (downstream) end and 5′ (upstream) end, respectively of the transcription unit
B
5′ (upstream) end and 3′ (downstream) end, respectively of the transcription unit
C
the 5′ (upstream) end of the transcription unit
D
the 3′ (downstream) end of the transcription unit

Which of the following is correct about mature RNA in eukaryotes?

A
Exons and introns do not appear in the mature RNA.
B
Exons appear, but introns do not appear in the mature RNA.
C
Introns appear, but exons do not appear in the mature RNA.
D
Both exons and introns appear in the mature RNA.

In E.coli, the lac operon gets switched on when

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.

Oswald Avery, Colin MacLeod and Maclyn McCarty used enzymes to purify biochemicals such as proteins, DNA, and RNA from the heat-killed S cells to see which ones could transform live R cells into S cells in Griffith's experiment. They observed that

A
Proteases and RNases affected transformation.
B
DNase inhibited transformation.
C
Proteases and Lipases affected transformation.
D
RNases inhibited transformation.

AUG on the mRNA will result in the activation of which of the following RNA having correct combination of amino acids:

A
UAC Methionine
B
Methionine UAC
C
Methionine AUG
D
AUG Methionine

Short stretches of DNA used to identify complementary sequence in a sample are called

A
probes
B
markers
C
VNTRs
D
primers

Lactational amenorrhea is the natural method of contraception. It increases the phagocytosis of sperm.

A
Both A and R are true and R is the correct explanation of A
B
Both A and R are true and R is not the correct explanation of A
C
A is true but R is false
D
A is False but R is true

Saheli, an oral contraceptive for females, contains a steroidal preparation. It is a 'once a week' pill with very few side effects.

A
Both A and R are true and R is the correct explanation of A
B
Both A and R are true and R is not the correct explanation of A
C
A is true but R is false
D
A is False but R is true

Parturition is induced by a complex neuro endocrine mechanism. At the end of gestation period, the maternal pituitary releases prolactin which causes uterine contractions.

A
Both A and R are true and R is the correct explanation of A
B
Both A and R are true and R is not the correct explanation of A
C
A is true but R is false
D
A is False but R is true

When the two genes in a dihybrid cross are situated on the same chromosome, the proportion of parental gene combinations is much higher than non-parental type. Higher parental gene combinations can be attributed to crossing over between two genes.

A
Both A and R are true and R is the correct explanation of A
B
Both A and R are true and R is not the correct explanation of A
C
A is true but R is false
D
A is False but R is true