PRACTICE PAPER SET -9

[Time: 3 hours] [Full Marks- 70]

SECTION - A
1. In E. coil, the Iac 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.
2. Study the following flowchart which depicts the selling of milk into curd. Identi& A and B, given in the flow chart

(a) A. Citric acid, B. Lactic acid (b) A. Lactic acid, B. Vitamin B12
(c) A. Lactic acid, B. Vitamin B6 (d) A. Lactic acid, B. Citric acid
3. Study the figure given alongside and select the incorrect statement about A, B, C and D.

(a) Cells labelled A form the egg apparatus.

(b) B represents the polar nuclei, which fuse to form a diploid secondary nucleus.
(c) C is the female gamete.
(d) The synergid cells have filiform apparatus (D) at their micropylar tip.
4. Which of the following statements is correct with regard to immunity?
(a) Preformed antibodies are injected to treat the bite of a viper snake.
(b) Antibodies are protein molecules that contain two light polypeptide chains and two heavy chains.
(c) Rejection of an organ transplant is the function of T-lymphocytes.
(d) All of these.
5. The two forms of opioid drugs are
(a) charas and morphine (b) heroin and ganja
(c) morphine and heroin (d) hashish and thorphine
6. RNA interference involves
(a) synthesis of cDNA using reverse transcriptase
(b) silencing of a specific mRNA due to complementary dsRNA
(c) interference of synthesis of RNA
(d) synthesis of mRNA from hnRNA
7. The hormone responsible for contraction of uterine muscles for parturition is A and it is released from the B.

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8. The population where the individuals in the pre-reproductive age group are more than that in the reproductive age
group will be a/an _________ population.
(a) declining (b) fluctuating (c) expanding (d) stable
9. Which of the following statements regarding the estimated number of species found on earth, is not correct?
(a) Insects constitute more than 70 percent of the animals.
(b) According to Robert May, the global species diversity is about 7 million.
(c) Plants constitute more than 72 percent of all the species recorded.
(d) The number of fungal species in the world is more than the combined total of the species of fishes, amphibians,
reptiles and mammals.
10. The biomass available in plants for consumption by herbivores and decomposers is called
(a) gross primary productivity (b) net primary productivity
(c) standing crop (d) secondary productivity
11. A biologist studied the population of rats in a barn. He found that the average natality was 130, average mortality 120,
immigration 20 and emigration 30. The net increase in the rat population mentioned above is
(a) 20 (b) 10 (c) 05 (d) Zero
12. The gene that controls the ABO blood group system in human beings has three alleles - IA , IB and i.A child has blood
group O. His father has blood group A and mother has blood group B. Genotypes of other off springs can be:

13. Assertion (A): The early embryos of all vertebrates, (fish, amphibians; reptiles, birds and mammals) are nearly
similar.
Reason (R): Ontogeny recapitulates phylogeny.
14. Assertion (A): A patient of ADA-deficiency requires periodic or repeated infusion of genetically-engineered
lymphocytes.
Reason (R): Lymphocytes are not immortal, but have a life span.
15. Assertion (A): Each of the ovaries of a new born female child contains about 60,000-80,000 primary oocytes.
Reason (R): Oogenesis in a female starts at the foetal stage and is suspended at the prophase I of meiosis in the
primary oocyte till puberty
16. Assertion (A): The interaction between a whale and the small barnacles on its back, is considered as
commensalism.
Reason (R): In the above association, neither of the species is benefitted.
SECTION-B
17. (a) Write the two crucial changes, the seeds undergo while reaching maturity that enable them to be in a viable state,
until the onset of favourable conditions. –
(b) Name the oldest viable seed excavated from Arctic Tundra as per the records.
18. Write the scientific name of the source plant from where cocaine is obtained. How does its use affect the human
body?
OR
In our country, NACO and other Non-governmental organisations are doing a lot to educate people about AIDS.
(a) Expand NACO.
(b) Enlist any three ways by which transmission of HIV-AIDS infection occurs.

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19. Find the phenotypic and genotypic ratios of a cross between pea plants with genotypes rrTt and Rrtt using a Punnett
square.
20. What is cryopreservation? Mention how it is used in conservation of biodiversity.
21. (a) Explain how to find whether an E.coli bacterium has transformed or not, when a recombinant DNA bearing
ampicillin-resistant gene is transferred into it.
(b) What does the ampicillin-resistant gene act as, in the above case?
SECTION-C
22. How does -galactosidase coding sequence act as a selectable marker? Explain. Why is it a preferred selectable
marker to antibiotic-resistance genes?
23. Describe the embryonic development of a zygote upto its implantation in humans.
24. Explain the process of making the heterogenous nuclear RNA (hnRNA) into a fully functional mRNA in eukaryotes.
Where does this process occur in the cell?
25. Name a bacterium that is used as a biocontrol agent and mention how it is used for this purpose.
26. State Gause’s Competitive Exclusion Principle. Give two evidences/examples for such competitive exclusion in
nature.
OR
(a) What is primary productivity?
(b) Mention the factors that affect primary productivity.
27. Name and explain the surgical methods advised to human males and females as a means of birth control. Mention its
one advantage and one disadvantage.
28. It is established that RNA is the first genetic material. Explain giving three reasons.
SECTION-D
Question No. 29 and 30 are case — based questions. Each question has subparts with internal choice in one
subpart.
29. Mendel’s work remained unrecognised for several years. Later, three scientists independently rediscovered Mendel’s
results. Also by this time, due to advancements in microscopy, scientists were able to carefully observe cell division.
The chromosome movements during meiosis had been worked out.
(a) When do the members of a homologous pair of chromosomes separate from each other during cell division cycle
What is this phenomenon called?
(b) Name the scientists who proposed the chromosomal theory of inheritance.
(c) Who provided experimental evidence for the chromosomal theory of inheritance? Write the scientific name
(binomial) of the organism, he worked on.
OR
(c) Give four reasons, why Mendel’s work remained unrecognised for a long time.
30. Sewage is generated in large quantities everyday in cities and towns. It contains large amount of organic matter and
microbes, many of which are pathogenic. This cannot be discharged directly into natural water bodies like rivers and
streams. Hence, sewage is treated in Sewage Treatment Plants (STPs) to make it less polluting. –

Microbes play a major role in treating waste water in the STPs. This technology has been practised for more than
century now, in almost all parts of the globe. Till date, no man-made technology has been able to rival the microbial
treatment of sewage.
(a) What is sewage?
(b) Name the two types of microbes that are naturally present in the sewage and carry out the sewage treatment.
(c) Name the two stages in which the treatment of sewage is carried out and mention the major/key difference
between the two.
OR
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 (c) Write the different components of activated sludge. Explain the different ways it can be used further in sewage
treatment process.
SECTION-E
31. (a) Write any six points on the salient features of human genome.
(b) Differentiate between template strand and coding strand in a transcription unit.
OR
(a) Name the primates that lived about 15 million years ago. List their characteristic features.
(b) Where were the fossils of man-like bones discovered?
(c) When did the modem Homo sapiens appear on this planet?
(d) Write the probable difference in the eating habits of Homo ,‘habilis and Homo erectus.
32. Ovaries are the female primary sex organs that produce the female gametes (ova) and secrete steroid hormones.
Ease ovary is covered by an epithelium, which encloses the ovarian stroma. The stroma is divided into two zones - a
periphery cortex and an inner medulla. Different developmental stages of the follicles can be seen in a cross section
of an ovary.
Observe the diagrammatic sectional view of a human ovary given below and answer the questions that
follow:

(a) Name (i) the hormone that influences the development of A into C and (ii) the hormone secreted by C.
(b) Name the process and the hormone responsible for the release of ‘D’ from the ovary.
(c) Identify ‘E’. Where is it formed from? Name the hormone that influences its formation and the hormone it secretes.
(d) Mention the events that take place in ‘B’
OR
A flower of tomato plant following the process of sexual reproduction produces 240 viable seeds.
Answer the following questions giving reasons.

33. (a) Explain the three steps involved in Polymerase Chain Reaction (PCR).
(b) What is the significance of use of Taq polymerase in PCR? Mention its source organism.
OR
(a) What are transgenic animals?
(b) Describe any three purposes for which such animals are produced.
(c) Mention the change that pro-insulin undergoes to become the functional mature insulin.

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