ST. XAVIER’S SENIOR SECONDARY SCHOOL, DELHI – 110 054
Class 12
28-9-2021
PERIODIC TEST – 2 - BIOLOGY
Time : 1½ hrs.
Name : ________________________________________________ Section : _____ Roll No: _____
General Instructions:
i)
The Question Paper contains three sections.
ii)
Section A has 24 questions. Attempt any 20 questions.
iii)
Section B has 24 questions. Attempt any 20 questions.
iv)
Section C has 12 questions. Attempt any 10 questions.
v)
Attempt TOTAL 50 questions.
vi)
All questions carry equal marks.
vii)
There is no negative marking.
SECTION – A
Section – A consists of 24 questions. Attempt any 20 questions from this section.
The first attempted 20 questions would be evaluated.
1.
In a typical angiosperm embryo sac, 7-cells are as following:
Egg Cell
Synergid Central cell Antipodal
A.
2
2
1
2
B.
1
3
2
1
C.
1
3
1
2
D.
1
2
1
3
2.
Complete the following statement:
(I) in sporogenous mass undergo (II) to form a tetrad that on separation gives rise to
(III) functional microspore/s.
(I)
(II)
(III)
A.
Pollen mother cell
Meiosis
1
B.
Pollen mother cell
Meiosis
4
C.
Megaspore mother cell
Meiosis
4
D.
Megaspore mother cell
Mitosis
1
3.
Artificial hybridization does not include or cause
A)
crop improvement
C)
emasculation
4.
In case of polyembryony, an embryo I develops from the synergids and an embryo II develops
from the nucellus. State the ploidy of embryo I and II.
A)
I-Haploid, II-Diploid
B)
I-Diploid, II-Diploid
C)
I-Haploid, II-Haploid
D)
I-Diploid, II-Haploid
5.
Usually pollen grains in angiosperms are shed at 2-celled stage. In few members, pollen grains
are shed at 3-celled stage. These cells are:
A)
1 vegetative cell + 2 generative cells
B)
1 vegetative cell + 2 male gametes
C)
2 vegetative cell + 1 male gamete
D)
1 vegetative cell + 1 generative cells + 1 male gamete
6.
Androgens are synthesized by
A)
Sertoli Cells
C)
Seminal vesicles
B)
D)
Leydig cells
Bulbourethral gland
7.
Result of meiosis-ll in secondary oocyte is
A)
1 Ootid
C)
1 Ootid + 2 polar bodies
B)
D)
1 Ootid + 3 polar body
1 Ootid + 1 polar body
B)
D)
inbreeding depression
bagging
Std. 12
8.
-2-
BIOLOGY
This diagram shows a part of the human female reproductive system.
Name the gamete cells that would be
present in ‘X’ if taken from a new born baby.
A)
Primary follicle
B)
Primary oocyte
C)
Secondary oocyte
D)
Graafian follicle
9.
Signals for foetal ejection reflex originate from
A)
fully developed foetus only
C)
fully developed foetus and maternal adrenal gland
10.
Diagram of a plant is given with two types of flowers (A and B).
Select the correct option.
11.
B)
D)
A)
A is chasmogamous flower and it promotes autogamy
B)
A is cleistogamous flower and it promotes autogamy
C)
B is chasmogamous flower and it promotes autogamy
D)
B is cleistogamous flower and it promotes autogamy
placenta
Both A and B
Diagrammatic view of a typical ovule is given.
Select the option with incorrect identification.
A)
4-Outer integument, 8-Chalazal end
B)
2-Funicle, 6-Nucellus
C)
7-Embryo sac, 3- Placenta
D)
1 -Hilum, 5-lnner integument
12.
Monosomy and trisomy are represented respectively as
A)
n- 1, n+ 2
B)
C)
2n - 1, 2n + 1
D)
13.
Select
A)
B)
C)
D)
14.
2n + 2, 2n+ 1
2n - 2, 2n + 1
the correct statement from the ones given below with respect to dihybrid cross.
Tightly linked genes on the same chromosome show higher recombination.
Genes far apart on the same chromosome show very few recombination.
Genes loosely linked on the same chromosome show similar recombination as the
tightly linked ones.
Tightly linked genes on the same chromosome show very few recombination.
Gamete mother cells of the chromosome 44+XY suffers from non-disjunction at first
meiotic division. Identify the set of gametes which will be formed.
A)
22 + XX, 22 + YY and 22, 22
B)
22 + XY, 22 + XY and 22, 22
C)
22 + X, 22 + Y and 22+Y, 22
D)
22 + X, 22 +X and 22+Y, 22+Y
Std. 12
15.
-3-
BIOLOGY
Read the following steps and arrange them in correct sequence of occurrence.
P — Entry of an allele in gamete.
Q — Fertilization.
R — Segregation of alleles.
S — Formation of recombinants.
A)
P→Q→S→R
B)
P→R→Q→S
C) R→P→Q→S
D)
R→P→S→Q
16.
Which of the following characteristics represents 'Inheritance of blood groups' in humans?
I.
Dominance
II.
Codominance
III.
Multiple allele
IV.
Incomplete dominance
V.
Polygenic inheritance
A)
I, IV and V
B)
I, II and III
C)
II, III and V
D)
I, III and V
17.
Anish has colour blindness and married to Sheela, who is not colourblind. What is the chance
that their son will have the disease?
A)
100%
B)
50%
C)
25%
D)
0%
18.
The packaging of chromatin at higher level requires an additional set of proteins that are
collectively referred to as
A)
histone proteins
B)
non - histone proteins
C)
basic proteins
D)
histone octamer
19.
How many of the following statements are incorrect?
(i) Nitrogenous base in a nucleotide is attached to pentose sugar by phosphoester linkage.
(ii) Adenosine is a nucleoside.
(iii) Genome of E. coli possess 4.6 × 109 bp.
(iv) Pitch of DNA helix is 3.4 nm.
(v) Euchromatin stains light.
(vi) RNA is more stable than DNA.
(vii) RNA can mutate at faster rate than DNA.
A)
Two
B)
Three
C)
Four
D)
Five
20.
During transforming experiments, what inference can be extracted from the following step:
"Heat killed S-strain + R-strain + RNases".
A)
Protein is not the genetic material
B)
RNA is not the genetic material
C)
DNA is the genetic material
D)
DNA is not the genetic material
21.
A free phosphate moiety can be observed at one end of a polynucleotide chain attached to
A)
3'—end of pentose sugar
B)
5’— end of pentose sugar
C)
3'—end of nitrogenous base
D)
5'—end of nitrogenous base
22.
Fertile
A)
C)
D)
23.
In sea urchin DNA, which is double stranded, 17% of the
The percentages of the other three bases expected to be
A)
G 17%, A 16.5%, T 32.5%
B)
C)
G 34%, A 24.5%, T 24.5%
D)
24.
Read the following steps involved in DNA replication and answer the question following them:
(1)
Action of ligase enzyme
(2)
Polymerisation
(3)
Origin of replication
(4)
Formation of replication fork
If we arrange the above steps in sequence of occurrence, then which step will be the third
step in sequence to occur?
A)
1
B)
2
C)
3
D)
4
couples should be made aware of all of following except
birth control measures.
B)
sex determination by tests like amniocentesis.
prevention of STDs.
importance of breast feeding and care of pregnant mother.
bases were shown to be cytosine.
present in this DNA are
G 8.5%, A 50%, T 24.5%
G 17%, A 33%, T 33%
Std. 12
-4-
BIOLOGY
SECTION – B
Section - B consists of 24 questions. Attempt any 20 questions from this section.
The first attempted 20 questions would be evaluated.
Question Nos. 25 to 28 consist of two statements – Assertion (A) and Reason (R).
Answer these questions selecting the appropriate option given below:
A)
B)
C)
D)
Both A and R are true and R is the correct explanation of A.
Both A and R are true and R is not the correct explanation of A.
A is true but R is false.
A is false but R is true.
25.
Assertion (A): Periodic abstinence is a method in which couples avoid from coitus
from day 17 to 27 of menstrual cycle.
Reason (R): It is not an effective method because chances of failure are high.
26.
Assertion (A) : Diaphragms, cervical caps and vaults are barriers made of rubber.
Reason (R) : They are inserted into the male reproductive tract during coitus.
27.
Assertion (A): The endometrium undergoes cyclic changes during the menstrual cycle.
Reason (R): Perimetrium contracts strongly during delivery of the baby.
28.
Assertion (A): At F2-generation in monohybrid cross, both parental traits are expressed
in the proportion of 3:1.
Reason (R) : The contrasting parental traits show blending at F2 -generation.
29.
Which of the following transformation indicates spermiogenesis?
A)
Secondary spermatocyte → Spermatid
B)
Spermatid → Spermatozoa
C)
Spermatogonia →Primary spermatocyte
D)
Primary spermatocyte → Spermatozoa
30.
Read the statements from a to e and answer the question following them.
a — Exine is a discontinuous layer.
b — Typical microsporangium appears nearly circular in transverse section.
c — Endothecium is a nutritive layer.
d — Pollen mother cell is diploid in nature.
e — Pectinase degrades sporopollenin.
How many of the above statements are correct?
A)
One
B)
Two
C)
Three
D)
Four
31.
P is the removal of anthers and is done in Q flowers.
P
Q
A
Emasculation
Unisexual
B
Emasculation
Bisexual
C
Bagging
Unisexual
D
Bagging
Bisexual
32.
Regarding determination of sex in human, which of the following statement is correct?
A)
Sex of baby is determined by mother.
B)
Female produces two types of ovum.
C)
50% of sperms carry XX chromosomes while another 50% carry XY chromosomes.
D)
None of the above.
33.
During IVF-ET (In vitro fertilization embryo transfer), after fertilization if embryo is having 8
or less number of blastomeres, than it is transferred to (I) while if the number is more than 8,
it is transferred to (II).
A)
I = fallopian tube, II = fallopian tube
B)
I = fallopian tube, II = uterus
C)
I = uterus, II = fallopian tube
D)
I = uterus, II = uterus
Std. 12
-5-
BIOLOGY
34.
Select
A)
B)
C)
D)
the incorrect statement.
MTP in second trimester is much riskier than first trimester.
Genital herpes is curable STD.
In Intracytoplasmic sperm injection (ICSI), sperm is directly injected in ovum.
Pelvic inflammatory diseases, still birth and infertility are some of the complications
of STDs.
35.
Which of the following are not the comparable terms?
A)
Embryo sac — Female gametophyte
B)
C)
Pollen grain — Male gametophyte
D)
36.
In Antirrhinum, two plants with pink flowers were hybridised. The F1 plants produced red, pink
and white flowers in the proportion of 1 red, 2 pink and 1 white. What could be the genotype
of the two plants used for hybridisation? Red flower colour is determined by RR and white by rr .
A)
rr
B)
RR
C)
Rr
D)
rr
37.
According to Mendel, what was the ratio of gametes formed by YyRr?
A)
YR : yr = 1 :1
B)
YR : yr = 3 :1
C)
RY: yr: yR : Yr = 9 :3 : 3 :1
D)
RY: yr: yR : Yr = 1 :1 :1 :1
38.
The genotypes of a husband and wife are IAIB and IAi. Among the blood types of their children,
how many different genotypes and phenotypes are possible?
A)
3 genotypes; 4 phenotypes
B)
4 genotypes; 3 phenotypes
C)
4 genotypes; 4 phenotypes
D)
3 genotypes; 3 phenotypes
39.
A and B are pedigree charts of 2 diseases.
Megasporangium — Ovule
Microsporangium — Anther
Select the correct statement:
A)
A represents Y-linked trait while B
represents X-linked trait
B)
A represents autosomal recessive
trait while B represents X-linked
dominant trait.
C)
A represents autosomal dominant
trait while B represents autosomal
recessive trait.
D)
A represents autosomal recessive trait while B represents autosomal dominant trait.
40.
In human beings, multiple genes are involved in the inheritance of
A)
sickle-cell anaemia
B)
skin colour
C)
colour blindness
D)
phenylketonuria
41.
Haemophilic man marries a normal woman. Their offspring will be
A)
all haemophilic
B)
all boys haemophilic
C)
all girls haemophilic
D)
all normal
42.
Phenotype of an organism is the result of
A)
genotype and environment interactions.
B)
C)
cytoplasmic effects and nutrition.
D)
environmental changes and sexual dimorphism.
43.
Select the correct matching from the four options .
A.
B.
C.
D.
Method
The pill
Condom
Vasectomy
Copper T
Mode of Action
Prevents sperms reaching cervix
Prevents implantation
Semen contains no sperms
Prevents ovulation
mutations and linkages.
Std. 12
-6-
BIOLOGY
44.
In the
A)
B)
C)
D)
DNA molecule,
the proportion of adenine in relation to thymine varies with the organism.
there are two strands which run antiparallel, one in 5′ → 3′ direction and other in 3′ → 5′.
the total amount of purine nucleotides and pyrimidine nucleotides is not always equal.
there are two strands which run parallel in the 5′ → 3′ direction.
45.
Artificial Insemination means
A)
artificial introduction of sperms of a healthy donor into the vagina.
B)
introduction of sperms of a healthy donor directly into the ovary.
C)
transfer of sperms of a healthy donor to a test tube containing ova.
D)
transfer of sperms of husband to a test tube containing ova.
46.
A molecule that can act as a genetic material must fulfil the traits given below, except
A)
it should be able to express itself in the form of ‘Mendelian characters’.
B)
it should be able to generate its replica.
C)
it should be unstable structurally and chemically.
D)
it should provide the scope for slow changes that are required for evolution.
47.
The technique called Gamete Intra Fallopian Transfer (GIFT) is recommended for those females
A)
who cannot provide suitable environment for fertilisation.
B)
who cannot retain the foetus inside uterus.
C)
whose cervical canal is too narrow to allow passage for the sperms.
D)
who cannot produce an ovum.
48.
Escherichia coli when fully labelled with 15N, is allowed to grow in 14N medium. The two strands
of DNA molecule of the first-generation bacteria have
A)
different density and do not resemble parent DNA.
B)
different density but resemble parent DNA.
C)
same density and resemble parent DNA.
D)
same density but do not resemble parent DNA.
SECTION – C
Section-C consists of one case followed by 6 questions linked to this case (Q. Nos. 49 to 54). Besides this,
6 more questions are given. Attempt any 10 questions in this section. The first attempted 10 questions
would be evaluated.
Case:
The graph given below shows the variation in the levels of ovarian hormones during various
phases of menstrual cycle:
49.
Identify ‘A’ and ‘B’.
A)
A – Estrogen, B – Progesterone
C)
A- Progesterone, B- Estrogen
50.
Specify the source of the hormone marked in the diagram.
A)
A – Corpus luteum, B – Corpus luteum
B)
A- Corpus luteum, B – Graafian follicle
C)
A- Uterus lining, B – Developing egg
D)
A - Graafian follicle, B - Corpus luteum
B)
D)
A- FSH, B- LH
A- LH, B-FSH
Std. 12
51.
-7What
A)
B)
C)
D)
BIOLOGY
is the role of hormone A?
Maintenance of events of pregnancy.
Maintenance of endometrium for implantation of the fertilized ovum.
Leads to changes in the ovary and uterus / regeneration of endometrium through
proliferation.
Both B and C.
52.
Under which condition will the level of B continue to remain high on the 28thday?
A)
If next Menstrual cycle begins.
B)
If Uterus lining is broken down.
C)
In case of pregnancy.
D)
In case of no fertilisation of egg.
53.
Identify the incorrect information regarding menstrual cycle.
A)
Menstrual phase — 3 to 5 days (duration) B)
Ovulation — 18th day
C)
Luteal phase — 15th to 28th days
D)
Follicular phase — 1st to 14th day
54.
Which
A)
B)
C)
D)
55.
Fully grown male and female Drosophila are shown in figures (P and Q).
Select the correct statement.
56.
A)
P is male Drosophila with sex chromosome XY
B)
P is female Drosophila with sex chromosome XX
C)
Q is male Drosophila with sex chromosome ZW
D)
Q is female Drosophila with sex chromosome ZZ
Amino acid sequence of a relevant portion of
beta hemoglobin chain is shown in diagram.
Normally P amino acid in present at 6th position
which is replaced by Q amino acid in sickle cell anemia.
A
B
C
D
57.
one of the following is the correct matching of the events occurring during menstrual cycle?
Proliferative phase: Rapid regeneration of myometrium and maturation of Graafian follicle.
Secretory phase: Development of corpus luteum and increased secretion of progesterone.
Menstruation: Breakdown of myometrium and ovum not fertilised.
Ovulation: LH and FSH attain peak level and sharp fall in the secretion of progesterone.
P
Glutamic acid
Lysine
Valine
Glycine
Q
Valine
Glycine
Glutamic acid
Valine
A homozygous recessive white flowered pea plant was
crossed with another pea plant with unknown genotype
and phenotype to obtain following result. What was the
phenotype and genotype of that pea plant?
A)
Violet, homozygous
B)
Violet, heterozygous
C)
White, homozygous
D)
White, heterozygous
Std. 12
58.
59.
-8Central dogma is shown. Identify A, B and C.
A
B
C
A.
B.
C.
Transamination
Transcription
Replication
Replication
Replication
Transcription
Steroids
m-RNA
Translation
D.
Replication
Transcription
m-RNA
Identify the incorrect statement with
respect to given diagram.
A)
B)
C)
D)
60.
BIOLOGY
This experiment gave unequivocal
proof that DNA is genetic material and
was performed by Meselson and Stahl.
A - represents attachment of radioactive
phage to bacteria.
B - removal of viral coats by agitating
them in blender.
C - separation of viral particle from
bacteria by spinning.
A replication fork is shown in the figure.
Identify the template DNA.
A)
Strand C only
B)
Strand A only
C)
Strand B only
D)
Both Strand C and Strand B.
-x-x-x-x-x-x-x-x-x-