Class 12th Biology 2016 Set3 Delhi Board Paper Solution

Section 1

Q1	State a difference between gene and an allelle.
Q2	Suggest the breeding method most suitable for animals that are below average in milk productivity.
Q3	Suggest a technique to a researcher who needs to separate Fragments of DNA.
Q4	Excessive nutrients in a fresh water body cause fish mortality. Give two reasons.
Q5	Give an example of a codon having dual function

Section 2

Q6	Discuss the role of enzyme DNA ligase plays during DNA replication.
Q7	Distinguish between the roles of flocks and anaerobic sludge digesters in sewage treatments.
Q8	Name the caustive organism of the disease amoebiasis. List three symtoms of the disease. Or Identify A B C and D in the given table.
Q9	Plants that inhabit a rain-forest ‘are not found in a wetland. Explain.
Q10	Angiosperms bearing unisexual flowers are said to be either monoecious or dioecious. Explain with the help of one example each.

Section 3

Q11	What is a GMO ? List any five possible advantages of GMO to a farmer.
Q12	Suggest and describe a technique to obtain multiple copies of a gene of interest in vitro.
Q13	Name any two fowls other than chicken reared in a poultry farm.
Q13	Enlist four important components of poultry farm management.
Q14	Why is breast-feeding is recommended during the initial period of infant's growth? Give reasons.
Q15	Describe the experiment that helped Louis Pasteur to dismiss the theory of spontaneous generation of life.
Q16	Prior to a sports event blood and urine samples of sportspersons are collected for drug tests. (a) Why there is a need to conduct such tests ? (b) Name the drugs the authorities usually look for. (c) Write the generic name of two plants from which these drugs are obtained.
Q17	Give an example of an autosomal recessive trait in humans. Explain its pattern of inheritance with the help of a cross.
Q18	Explain with the help of suitable examples the three different ways by which organisms overcome their stressful conditions lasting for short duration.
Q19	How has RNAi technique helped to prevent the infestation of roots in tobacco plants by a nematode ?
Q20	Given below is a list of six micro-organisms. State their usefulness to humans. Nucleopolyhedrovirus Saccharomyces cerevisiae Monascus purpureus Trichoderma polysporum Penicillium notatum Propionibacterium sharnanii
Q21	“In a food-chain, a trophic level represents a functional level, not a species.” Explain. OR (a) Name any two places where it is essential to install electrostatic precipitators. Why it is required to do so ? (b) Mention one limitation of the electrostatic precipitator.
Q22	How would you find genotype of a tall pea plant bearing white flowers ? Explain with the help of a cross. Name the type of cross you would use.

Section 4

Q23	Reproductive and Child Healthcare (RCH) programmes are currently in operation. One of the major tasks of these programmes is to create awareness amongst people about the wide range of reproduction related aspects. As this is important and essential for building a reproductively healthy society. (a) “Providing sex education in schools is one of the ways to meet this goal.” Give four points in support of your opinion regarding this statement. (b) List any two ‘indicators’ that indicate a reproductively healthy society.
Q24	Answer the following questions based on Hershey and Chases’s experiments (a) Name the kind of virus they worked with and why ? (b) Why did they use two types of culture media to grow viruses in ? Explain. (c) What was the need for using a blender and later a centrifuge during their experiments ? (d) State the conclusion drawn by them after the experiments.
Q24	What is polygenic inheritance ? Explain with the help of a suitable example.
Q25	(a) Why should we conserve biodiversity ? How can we do it ? (b) Explain the importance of biodiversity hot-spots and sacred groves. OR (a) Represent diagrammatically three kinds of age pyramids for human populations. (b) How does an age pyramid for human population at given point of time helps the policy-makers in planning for future.
Q26	(a) Explain the post-pollination events leading to seed production in angiospersms. (b) List the different types of pollination depending upon the source of pollen grain. OR (a) Briefly explain the events of fertilization and implantation in an adult human female. (b) Comment on the role of placenta as an endocrine gland.