Class 12th Biology 2017 Set1 Delhi Board Paper Solution

Section 1

Q1	Our government has intentionally imposed strict conditions for MTP in our country. Justify giving a reason.
Q2	State the fate of a pair of autosomes during gamete formation.
Q3	What role does an individual organism play as per Darwin’s theory of natural selection?
Q4	Suggest a method to ensure an anamnestic response in humans.
Q5	What is Biopiracy ?

Section 2

Q6	A mature embryo sac in a flowering plant may possess 7-cells, but 8-nuclei. Explain with the help of a diagram only.
Q7	Describe the structure of a nucleosome.
Q7	Mention the evolutionary significance of the following organisms: (a) Shrews (b) Lobefins (c) Homo habilis (d) Homo erectus
Q8	In an agricultural field, there is a prevalence of the following organisms and crop diseases which are affecting the crop yield badly: (a) White rust (b) Leaf and stripe rust (c) Black rot (d) Jussids Recommend the varieties of crops the farmers should grow to get rid of the existing problem and thus, improve the crop yield.
Q9	How does the application of the fungal genus, Glomus , to the agricultural farm increase the farm output?
Q10	Plenty of algal bloom is observed in a pond in your locality. (a) Write what has caused this bloom and how does it affect the quality of water. (b) Suggest a preventive measure.

Section 3

Q11	List the three stages the annuals and biennial angiosperms have to pass through during their life cycle.
Q11	List and describe any two vegetative propagules in flowering plants.
Q12	Draw a labelled diagram of the sectional view of a human seminiferous tubule (six parts to be labelled).
Q13	During a medical investigation, an infant was found to possess an extra chromosome 21. Describe the symptoms the child is likely to develop later in the life.
Q14	A number of passengers were severely burnt beyond recognition during a train accident. Name and describe a modern technique that can help hand over the dead to their relatives.
Q15	p2 + 2pq + q2 = 1 Explain this algebraic equation on the basis of Hardy-Weinberg’s principle.
Q16	What precaution(s) would you recommend to a patient requiring repeated blood transfusion?
Q16	If the advise is not followed by the patient there is an apprehension that the patient might contract a disease that would destroy the immune system of his/her body. Explain with the help of schematic diagram only how the immune system would get affected and destroyed.
Q17	What is inbreeding depression?
Q17	Explain the importance of ‘selection’ during inbreeding in cattle.
Q18	Describe how do ‘flocs’ and ‘activated sludge’ help in sewage treatment.
Q19	Explain the role(s) of the following in biotechnology. (a) Restriction endonuclease
Q19	Explain the role(s) of the following in biotechnology. (b) Gel-electrophoresis
Q19	Explain the role(s) of the following in biotechnology. (c) Selectable markers in pBR322
Q20	Write the steps you would suggest to be undertaken to obtain a foreign-gene-product.
Q21	Why do lepidopterans die when they feed on Bt cotton plant? Explain how does it happen.
Q22	In situ conservation can help endangered / threatened species. Justify the statement
Q22	Name and describe any three causes of biodiversity losses.

Section 4

Q23	Public all over India is very much concerned about the deteriorating air quality in large parts of North India. Alarmed by this situation the Resident’s Welfare Association of your locality organised an awareness programme entitled ‘Bury not burn’. They invited you, being a biology student to participate. (a) How would you justify your arguments that promote burying and discourage burning? (Give two reasons) (b) With the help of flow charts, one for each practice, depict the chain of events that follow.
Q24	Read the following statement and answer the questions that follows. ‘A guava fruit has 200 viable seeds.’ (a) What are viable seeds? (b) Write the total number of (i) Pollen grains (ii) Gametes in producing 200 viable guava seeds.
Q24	Prepare a flow chart to depict the post-pollination events leading to viable seed production in a flowering plant.
Q24	Arrange the following hormones in the sequence of their secretion in a pregnant woman. Mention their source and the function they perform. hcG ; LH ; FSH ; Relaxin (hPL)
Q25	State and explain the ‘law of independent assortment’ in a typical Mendelian dihybrid cross.
Q25	How do the observations made during moth collection in pre and post-industrialised era in England support evolution by natural selection?
Q25	Explain the phenomenon that is well-represented by Darwin’s finches other than natural selection.
Q26	What is an age pyramid?
Q26	Name three representative kinds of age pyramids for human population and list the characteristics for each one of them.
Q26	Discuss the role of healthy ecosystem services as a prerequisite for a wide range of economic, environmental and aesthetic goods and services.