DELH
HI PUB
BLIC SCHOO
S
OL, RAN
NCHI
HALF YEARLY
Y
Y EXAM. -2
2015-16
Class: XII
C
T
Time:
3 Hrs
Subject: Bio
S
ology
M
M.M
: 70
General Innstructions:
There are a total of 266 questions annd five sectioons in the quuestion paper.. All questionns are
i)
compulsorry.
ii)
Section A contains queestions number 1 to 5, verry short – annswer type quuestions of 1 mark
each.
iii)
Section B contains quuestions numbber 6 to 10, short – answ
wer type I quuestions of 2 mark
each.
iv)
Section C contains queestions number 11 to 22, short – answer type II quuestions of 3 mark
each.
v)
Section D contains queestion numberr 23, value baased question of 4 marks.
vi)
Section E contains queestions numbeer 24 to 26, loong – answer type
t
questionns of 5 marks each.
vii)
There is no
n overall chooice in the quuestion paper.. However, ann internal chooice is providded in
one question of 2 markks, one questiion of 3 markks and all thee questions off 5 marks. In these
questions, an examinee is to attempt any one of thhe two given alternatives.
SECTION - A
1. What
W do you understand
u
byy the statemennt – “Genetic code is degennerate”. ?
[1]]
or analogous structures :2. Classify
C
the fo
ollowing into homologous
h
[½ + ½ =1]
a)) Flippers off Penguins annd Dolphins.
b)) Sweet potaato and potatoo.
3. Inn 1963 two en
nzymes responsible for resstricting the grrowth of baccteriophage inn E.coli were
issolated. Whatt were their fuunctions.
[½ + ½ =1]
4. Name
N
the first transgenic coow and the ennriched proteiin found in itss milk
1
[½ + ½ = 1]
5. What
W is ‘Monttreal Protocol’ and what was
w its aim.
SECTION - B
6. What
W is partheenogenesis? Give
G two exam
mples of organnisms which reproduce byy parthenogennesis.
OR
(b) Senescennt period
D
Define
: (a) Juv
venile periodd
7. Give
G two reaso
ons why both the strands of
o DNA are noot copied duriing transcripttion.
8. How
H is Darwin
ns concept off evolution diffferent from that
t of de Vriees?
9. Name
N
the sourrce of DNA – polymerase used
u
in PCR technique.
t
M
Mention
why itt is used ?
10. What
W is resourrce partitioninng? Give an example.
SECTION - C
11. a)) Draw a labeeled diagram of
o female gam
metophyte of an angiosperm
m. Label its any
a four partss.
[½ x 4=2]
[1]]
b)) Why is sporropollenin coonsidered the most resistannt organic matterial
12. Give
G a schemaatic representaation (only) of
o spermatogeenesis.
13. Why
W are humaan females rarrely haemophhilic? Explain. How do haeemophilic patiients suffer?
OR
N
Name
the geneetic disorder caused
c
by trissomy of 21st chromosome
c
i humans. Liist any four
in
chharacteristic features
f
in an indivisual suuffering from it.
14. Explain
E
the experiment perfformed by Grriffith on Strep
eptococcus pnneumoniae . What
W did he
coonclude.
15. Explain
E
any th
hree factors thhat are knownn of affect Harrdy – Weinbeerg equilibriuum.
16. a)) Name the teechnique usedd for separatioon of DNA frragments.
b)) On which prrinciple is it based?
b
c)) How is the separated
s
DN
NA visualised and extractedd for use in reecombinant DNA
D
technoloogy.
17. a) Name the source from which insulin was extracted earlier. Why is this insulin no more in use
by diabetic people?
b) Explain the process of synthesis of insulin by Eli Lily company.
18. What is ADA deficiency? Describe any two methods to cure it.
19. How are structural genes inactivated in the lac operon of E.coli. Draw diagram as well in support
of your explanation.
20. a) Why are herbivores considered similar to predators in the ecological context.
b) Differentiate between
i)
Mutualism & competition
ii) Commensalism & amensalism
21. Construct a pyramid of biomass starting with phytoplankton. Label upto three trophic levels. Is
the pyramid upright or inverted, explain.
22. Explain ‘Rivet Poppers’hypothesis. Name the ecologist who proposed it.
SECTION - D
23. The growth rate is our country is alarmingly high, and the government is forced to take serious
measures to check population growth.
a) What are the problems expected by such population explosion.(Give two points)
b) What are the possible options available to motivate people to have small families.( Give two
points)
c) How can contraceptive device contribute in checking population growth?
SECTION - E
24. a) Differentiate between cleistogamous&chasmogamous flowers ( Give 2 differences)
b) Give four characteristic of wind pollinated flowers.
c) Give 2 adaptations in plants which promote outbreeding.
OR
a) Draw a lebelled diagram of the microscopic structure of a human sperm and label its four
parts.
b) Differentiate between inner cell mass and trophoblast.
c) What is parturition? Explain the mechanism of parturition in human female.
25. a) A true breeding pea plant homozygous for violet flowers and green pods is crossed with
another pea plant with white flowers and yellow pods. Work out the cross to show the
phenotypes and genotypes of F1 and F2 generations.
b) State the law that can be derived from the above cross.
OR
Enumerate the steps involved in the process of DNA finger printing.
26. Describe the functioning of electrostatic precipitator along with a diagram.
OR
a) What is meant by productivity
b) What are seres?
c) Mention one similarity between hydrarch and xerarch succession.
d) In terrestrial ecosystems DFC and GFC are interconnected at certain levels. Justify the
statement.
e) Explain the function of ‘reservior’ in a nutrient cycle. List two types of nutrient cycles in
nature.