Class 12th Biology 2012 Set1 Outside Delhi Board Paper Solution

Section 1

Q1	Why is banana considered a good example of parthenocarpy?
Q2	State two different roles of spleen in the human body.
Q3	A garden pea plant produced axial white flowers. Another of the same species produced terminal violet flowers. Identify the dominant traits.
Q4	Why is it desirable to use unleaded petrol in vehicles fitted with catalytic converters?
Q5	Where is acrosome present in humans? Write its function.
Q6	Write the name of the following: a. The most common species of bees suitable for apiculture b. An improved breed of chicken
Q7	Comment on the similarity between the wing of a cockroach and the wing of a bird. What do you infer from the above, with reference to evolution?
Q8	Mention the role of cyanobacteria as a biofertiliser.

Section 2

Q9	(a) Draw a neat labeled diagram of a nucleosome. (b) Mention what enables histones to acquire a positive charge.
Q10	State one advantage and disadvantage of cleistogamy.
Q11	(a) Where do the signals for parturition originate from in humans? (b) Why is it important to feed the newborn babies on colostrums?
Q12	(a) A recombinant vector with a gene of interest inserted within the gene of α- galactosidase enzyme, is introduced into a bacterium. Explain the method that would help in selection of recombinant colonies from recombinant ones. (b) Why is this method of selection referred to as insertional inactivation?
Q13	Explain brood parasitism with the help of an example.
Q14	Give reasons for the following: (a) The human testes are located outside the abdominal cavity. (b) Some organisms like honey bees are called parthenogenetic animals.
Q15	Name the plant source of ganja. How does it affect the body of the abuser? OR Name the two special types of lymphocytes in humans. How do they differ in their roles in immune response?
Q16	(a) Mention the cause and body system affected by ADA deficiency in humans. (b) Name the vector for transferring ADA-DNA into the recipient cells in humans. Name the recipient cells.
Q17	How did Ahmed Khan, plastic sacks manufacturer from Bangalore, solve the ever increasing problem of accumulating plastic waste?
Q18	Name the bacterium that causes typhoid. Mention two diagnostic symptoms. How is this disease transmitted to others?

Section 3

Q19	(a) Explain the phenomena of multiple allelism and co-dominance taking ABO blood group as an example. (b) What is the phenotype of the following: (i) IAi (ii) i i
Q20	How does industrial melanism support Darwins theory of Natural Selection? Explain.
Q21	(a)What is the programme called that is involved in improving success rate of production of desired hybrid and herd size of cattle? (b)Explain the method used for carrying this programme for cows.
Q22	Explain the function of each of the following: i. Coleorhiza ii. Umbilical cord iii. Germ pores
Q23	How is the amplification of a gene sample of interest carried out using Polymerase Chain Reaction (PCR)?
Q24	Trace the life cycle of malarial parasite in the human body when bitten by an infected female Anopheles.
Q25	List the salient features of double helix structure of DNA. OR How are the structural genes activated in the lac operon in E.coli?
Q26	Alien species are highly invasive and are a threat to indigenous species. Substantiate this statement with any three examples.
Q27	(a) Tobacco plants are damaged severely when infested with Meloidegyne incognitia. Name and explain the strategy that is adopted to stop this infestation. (b) Name the vector used for introducing the nematode specific gene in tobacco plant.

Section 4

Q28	(a) Taking one example of habitat loss and fragmentation, explain how the two are responsible for biodiversity loss. (b) Explain two different ways of biodiversity conservation. OR (a) What depletes ozone in the stratosphere? How does this affect human life? (b) Explain biomagnification of DDT in an aquatic food chain. How does it affect the bird population?
Q29	The following is the illustration of the sequence of ovarian events a to i in a human female:
Q30	Describe Frederick Griffiths experiment on Streptococcus pneumonia. Discuss the conclusion he arrived at. OR (a) Explain a monohybrid cross taking seed coat colour as a trait in Pisum sativum. Work out the cross upto F₂ generation. (b) State the laws of inheritance that can be derived from such a cross. (c) How is the phenotypic ratio of F₂ generation different in a dihybrid cross?