Class 12th Biology 2017 Set2 Delhi Board Paper Solution

Section 1

Q1	What is ‘fitness of an individual’ according to Darwin?
Q2	What is Biopiracy ?
Q3	Suggest a method to ensure an anamnestic response in humans.
Q4	State the fate of a pair of autosomes during gamete formation.
Q5	Our government has intentionally imposed strict conditions for MTP in our country. Justify giving a reason.

Section 2

Q6	By taking two examples explain how has bio-fortification helped in improving food quality.
Q7	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.
Q8	How does the application of cyanobacteria help to improve agricultural output?
Q9	In a flowering plant, a microspore mother cell produces four male gametophytes while a megaspore mother cell forms only one female gametophyte. Explain.
Q10	Describe the structure of a nucleosome.
Q10	Mention the evolutionary significance of the following organisms: (a) Shrews (b) Lobefins (c) Homo habilis (d) Homo erectus

Section 3

Q11	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.
Q12	In situ conservation can help endangered / threatened species. Justify the statement
Q12	Name and describe any three causes of biodiversity losses.
Q13	Differentiate between an annual and biennial plant. Provide one example of each.
Q14	Draw a labelled diagram of the sectional view of a human seminiferous tubule (six parts to be labelled).
Q15	A criminal blew himself up in a local market when chased by cops. His face was beyong recognition. Suggest and describe a modern technique that can help establish his identity.
Q16	p2 + 2pq + q2 = 1 Explain this algebraic equation on the basis of Hardy-Weinberg’s principle.
Q17	Explain the role(s) of the following in biotechnology. (a) Restriction endonuclease
Q17	Explain the role(s) of the following in biotechnology. (b) Gel-electrophoresis
Q17	Explain the role(s) of the following in biotechnology. (c) Selectable markers in pBR322
Q18	Why do lepidopterans die when they feed on Bt cotton plant? Explain how does it happen.
Q19	Write the steps you would suggest to be undertaken to obtain a foreign-gene-product.
Q20	Describe how do ‘flocs’ and ‘activated sludge’ help in sewage treatment.
Q21	What is inbreeding depression?
Q21	Explain the importance of ‘selection’ during inbreeding in cattle.
Q22	A group of youth were having a 'rave party' in an isolated area and was raided by police. Packets of 'smack' and syringes with needles were found littered around. (a) Why is taking 'smack' considered an abuse?
Q22	Write the chemical name of 'smack' and the name of its source plant.
Q22	Syringes and needles used by the youth for taking the drug could prove to be very fatal. Why?

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	What is an age pyramid?
Q24	Name three representative kinds of age pyramids for human population and list the characteristics for each one of them.
Q24	Discuss the role of healthy ecosystem services as a prerequisite for a wide range of economic, environmental and aesthetic goods and services.
Q25	Read the statement and answer the questions that follows. A flower of brinjal has 520 ovules in its ovary. However, it produces a fruit with only 480 viable seeds. (a) What could have prevented the rest of the 40 ovules from maturing into viable seeds? Explain giving a reason.
Q25	Describe the development of a dicot embryo in a viable seed.
Q25	Why certain angiospermic seeds are albuminous, while others are exalbuminous? Explain.
Q25	Name the hormones secreted and write their functions : (i) By corpus luteum and placenta (any two). (ii) During follicular phase and parturition
Q25	Name the stages in a human female where : (i) corpus luteum and placenta coexist. (ii) corpus luteum temporarily ceases to exist
Q26	State and explain the ‘law of independent assortment’ in a typical Mendelian dihybrid cross.
Q26	How do the observations made during moth collection in pre and post-industrialised era in England support evolution by natural selection?
Q26	Explain the phenomenon that is well-represented by Darwin’s finches other than natural selection.