Download Biology Question Paper and Marking Scheme

1st Pre-board Exam (2014-15)
Class-XII
Subject-biology
Time:3 Hrs.]
[M.M.:70
General instructions1. All questions are compulsory.
2. Attempt all questions serially only.
3. Marks are assigned against each question.
SECTION-A
Q.1 What forms the backbone of a polynucleotide strand of a nucleic acid?
1
Q.2 Write the scientific name of the aquatic weed known as terror of Bengal.
1
Q.3 In insecticidal protein called Bt toxin has been used these days. What do the letter Bt stand
for?
1
Q.4 When do the oogenesis initiate in human females?
1
Q.5 Name the vector used for introducing the nematode specific gene in tobacco plant? 1
SECTION-B
Q.6 How do the tRNA molecules appear in(a) Two diamentional view.
(b) Three diamentional view.
2
Q.7 Write the names of the following.
(a) Semi dwarf, high yielding and disease resistant variety of wheat.
(b) One interspecific hybrid mammal.
2
Q.8 Mention the brain capacities of the following
(a) Homo habilis
(b) Neanderthal man
2
Q.9 Write the names of the organic materials, the exine and intine of an angiosperm pollen
grain are made up of?
2
Q.10 Expand the following.
(I) BAC
(II) YAC
2
SECTION-C
Q.11 (a) Write the name of the two species of filarial worms causing filariasis .
3
(b) How does the disease spread?
Q.12 A haemophilic man marries a normal homozygous women. What is the probability that
their daughter will be haemophilic. Explain with cross & give reason.
3
Q.13 Fill in the spaces a,b,c in the table showing certain events and their sites in human
(male/female) reproductive system.
3
S.N. Event
Site
1. Release of 1st polar body
a__________
2. Spermeiogenesis
b__________
3. Fertilisation
c__________
Q.14 (a) Name the phase all organisms have to pass through before they can reproduce
sexually.
3
(b) Name the vegetative propagules of.
(I) Bryophyllum
(II) Agave.
Q.15 Many patients reject the transplanted organ as it is not histocompatible with their
tissues.
3
(A) Which drug is used to prevent the rejection of the organ?
(B) From which organism is it derives?
(C) How it works?
Q.16 There are sixty four codons in the genetic code dictionary.
3
(A) How many of them code for amino acids?
(B) How many amino acids are coded?
(C) What general term is given to the codons which do not code for amino acids?
Q.17 Identify the pollutants responsible for causing the following effects.
3
(A) Biomagnification
(B) Eutrophication
(C) Snow blindness cataract.
Q.18 (a) what would be ploidy level of Endosperm if a tetraploid male plant is crossed with
diploid female plant?
3
(b) How many Meiotic and mitotic divisions would a microspore mother cell undergo to form
pollen-grain?
(c) How many Meiotic and mitotic divisions would a megaspore mother cell undergo to form
an embryo sac?
Q.19 Label ‘a’ ‘b’ ’c’ stages in central dogma & briefly describe.
‘a’
3
DNA –‘B’------→mRNA ---‘c’------→ Protein
Q.20 Name the type of interaction in each of the following -
3
(A) Sucker fish attached to shark
(B) Cockoo lays eggs in crow’s nest
(C) Sea anemone found on shell of hermit crab.
Q.21 (a) Expand MOET.
3
(b) Following are the steps in MOET programme for Herd improvement; in which cows have
been administered hormones like FSH. Arrange the steps in correct sequence .These are the
steps.
(A)Transferred to a Surrogate mother
(B)It is either mated with an elite bull or artificially inseminated.
(C)Fertilized eggs at 32 cell stage are recovered non surgically.
(D) It produces 6-8 eggs instead of one egg which they nor yield per cycle.
Q.22 Draw a simplified model of Phosphorus cycle in a teressrial ecosystem.
3
OR
Draw a simplified model of Carbon cycle in Biosphere.
SECTION-D
Q.23 A person on your group Housing Society has recently been diagnosed with AIDS. Many
members of the Society as they are scared of the spread of the disease.
4
(A) Give full scientific name of Causative agent.
(B) W rite the symptoms of the disease.
(C) Mention the routes of transmission of the disease.
(D) Write your view on the situation.
SECTION-E
Q.24 What are the five features required to facilitate cloning into a vector. Explain each with
suitable diagram with suitable example for each briefly explain the application of Biotechnology
in medicine.
5
Q.25 (A) List the three different allelic forms of gene I in humans. Explain the different
phenotypic expressions controlled by these three forms.
(B) A women with blood group A marries with blood group O. Discuss the possibilities of the
inheritance of the blood groups in the following starting with “yes” or “no” for each. (Make
cross foe each)
(I) They produce children with blood group “A” only.
(II) They produce children some with “O” blood group and some with “A”
Blood group.
OR
Name the scientists who proved experimentally that
(I)DNA is genetic material.
(II) DNA replication is semi conservative with the help of diagram describe the experiments.
Q.26 (a) Describe the particular type of agriculture which is also responsible for deforestation.5
(b) Study the population growth curves in the graph given below and answer the questions
which follow
(I)Identify the growth curves ‘a’ and ‘b’ explain.
(II) Which one of them is considered more realistic one and why?
(Iii) If dN/dt=rN[K-N/K] is the equation of one the growth curves , what does ‘k’ stands for .
(IV) What is symbolized by N?
OR
(a) Explain with the diagram and specific example for each that how hydrarch succession
proceeds from hydric to mesic condition to form a stable community.
(b) Why is secondary succession faster than primary succession.
Marking scheme
First pre-board examination 2014-15
Class XII
Subject : biology
SECTION-A
Q.1 sugar phosphate
1/2+1/2
Q.2 Eichhornia crassipes
1
Q.3 Bacillus thuringiensis
1
Q.4 In foetal ovary
1
Q.5 Argobacterium tumifaeeins
1
SECTION-B
Q,6 (a) Clover leaf like form
1
(b) ‘L’ shaped form
1
Q.7 (a) Kalyan ,sona,sonalika.
1/2*2
(b) Mule – female horse + male donkey
Q.8 (a) 600-800 c.c
1
(b) 1400 c.c
1
Q.9 Exine sporopollenin
1+1
Intine –cellulose
Q.10 (i)Bacterial artificial chromosome 1
(ii) Yeast artificial chromosome
1
1/2+1/2
SECTION-C
Q.11 (a) Wuchereria Bancrafti
1 +1
W.Malyi
(b) Bite of mosquito : vector
1
Q.12 Female XX * Xh Y
xx
Xh y
x
xxh
xy
y
xxh
xy
xxh
Normal
xy
Female
Normal
male
(carrier)
--All dauters are normal but carrier
1/2
-- x linked recessive gene diseases
1/2+ 3
-- pure, so male is always homozygous
--to be expressed in female it should be homozygous
I.e, xhxh
Q.13 (a) ovary
1*3
(b) seminiferous tubules
( c ) ampullary isthmic junction of fallopian tube
Q.14 (a) juvenile phase
1
(b) (i) buds on leaf
1
(ii) bulbils
1
Q.15 (a) Cyclosporins
1
(b) Trichoderma polysporum
1
(c ) Immuno suppresants
1
Q.16 (a) 61
1
(b)20
1
(c )Termination Nonscence condom 1
Q.17 (a) Excessive pesticides
1*3
(b) use of nitrogenous fertilizers /wastes washed to water bodies
(c) U.V.B radiation which affect cornea
Q.18 (a) Tetraploid – explaination for each
(b) One meiosis
1
1
(c ) One meiosis and three mitosis division 1
Q.19 (a) Replication
1*3
(b) Transcription
(c) Translation
Q.20 (a)commensalism – brief description
1/2+1/2 =1 *3
(b)Blood Parasitism - brief description
(c) mutualism
Q.21 (a) Multiple ovulation Embryo transfer technology 1
(b) D.C.B.A
1/2*4
Q.22 Refer N.C.E.R.T Page no.255 fig 14.7
1/2 *6
Or
Refer N.C.E.R.T Page no.253 fig 14.6
SECTION –D
Q.23 -Human Immuno Deficiency Virus
-Symtoms of AIDS
1
1
-Causes eg. Blood transfusion, used syringe ,unprotected sex, shaving blade
any other.
1
-it is not spread by mere contact like eating ,hugging ,they should treat
sympathetically and rehabitilate them .
1
SECTION- E
Q.24 1. Origin of replication .
1*5
2. selectable marker
3. cloning sites
4. insertional inactivation
5. Vectors for cloning genes in plants and animals
Or
(i)
(ii)
(iii)
Genetically Engineered Insulin + diagram
Gene Therepy
Molecular diagnosis
1+1
1+1/2
1+1/2
Brief explanation of each.
Q.25 (a) IA ,IB , i;
1/2
N.C.E.R.T Page no. 77 table 5.2
1+1/2
(b) (i) No – show cross if woman is heterozygous
1/2 *3
Reason and explanation
(ii) Yes – cross
1/2*3
Reason and explanation
OR
(i)
Alferd Hershey and Martha Chase – 1/2
experiment and diagram
refer N.C.E.R.T
(ii) Messelson and stahl
1/2
N.C.E.R.T Page 105 fig. 6.7
Diagram
1
Explaination
1
Q.26 (a) Jhum cultivation or slash and burn agriculture
Description
1/2+1/2
(b) (i) (a) exponential - explaination
1+1 (1/2*4)
(b) logistic - explaination
(ii) Ligistic – reason
(ii)
(iii)
1/2+1/2
Carrying capacity
Population density
Or
(a) N.C.E.R.T Page 251 diagram
2
Diagram page 252 explaination 2
Reason
1
1/2
1/2
1+1