Class 12th Biology 2017 Set3 Delhi Board Paper Solution

Section 1

Q1	What is Biopiracy ?
Q2	Suggest a method to ensure an anamnestic response in humans.
Q3	State the fate of a pair of autosomes during gamete formation.
Q4	Our government has intentionally imposed strict conditions for MTP in our country. Justify giving a reason.
Q5	Rearrange the human activities mentioned below as per the order in which they developed after the modern Homo sapiens came into existence during ice age: 1. Human settlement 2. Prehistoric cave art 3. Agriculture

Section 2

Q6	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.
Q7	How do mycorrhizae help the plants to grow better?
Q8	Mention the ploidy of the different types of cells present in the female gametophyte of an angiosperm.
Q9	Describe the structure of a nucleosome.
Q9	Mention the evolutionary significance of the following organisms: (a) Shrews (b) Lobefins (c) Homo habilis (d) Homo erectus
Q10	"Growing Spirulina on a large scale is beneficial both environmntally and nutritionally for humans," justify.

Section 3

Q11	During a fire in an auditorium a large number of assembled guest got burnt beyong recognition. Suggest and describe a modern technique that can help hand over the dead to their relatives.
Q12	What is inbreeding depression?
Q12	Explain the importance of ‘selection’ during inbreeding in cattle.
Q13	p2 + 2pq + q2 = 1 Explain this algebraic equation on the basis of Hardy-Weinberg’s principle.
Q14	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.
Q15	Draw a labelled diagram of the sectional view of a human seminiferous tubule (six parts to be labelled).
Q16	Parthenocarpy and apomixis have been observed in some plants. Give an example of each. State a similarity and a difference observed between the two processes.
Q17	Describe how do ‘flocs’ and ‘activated sludge’ help in sewage treatment.
Q18	Explain the role(s) of the following in biotechnology. (a) Restriction endonuclease
Q18	Explain the role(s) of the following in biotechnology. (b) Gel-electrophoresis
Q18	Explain the role(s) of the following in biotechnology. (c) Selectable markers in pBR322
Q19	Why do lepidopterans die when they feed on Bt cotton plant? Explain how does it happen.
Q20	Show with the help of flow chart only, the life cycle of malerial parasite in humans.
Q21	In situ conservation can help endangered / threatened species. Justify the statement
Q21	Name and describe any three causes of biodiversity losses.
Q22	Write the steps you would suggest to be undertaken to obtain a foreign-gene-product.

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	State and explain the ‘law of independent assortment’ in a typical Mendelian dihybrid cross.
Q24	How do the observations made during moth collection in pre and post-industrialised era in England support evolution by natural selection?
Q24	Explain the phenomenon that is well-represented by Darwin’s finches other than natural selection.
Q25	What is an age pyramid?
Q25	Name three representative kinds of age pyramids for human population and list the characteristics for each one of them.
Q25	Discuss the role of healthy ecosystem services as a prerequisite for a wide range of economic, environmental and aesthetic goods and services.
Q26	A capsicum flower has 240 ovules in its ovary. But it produces a fruit with only 180 viable seeds. Explain giving a reason that could be respnsible for such a result
Q26	Describe the development of an endosperm in a viable seed. Why does endosperm development precedes embryo development?
Q26	Give an example of an angiosperm seed that has a perisperm. Name the part the persiperm develops from.
Q26	Where in the fallopian tube does fertilization occur in humans? describe the development of a fertilized ovum upto implantation.
Q26	How is polyspermy prevented in humans?