Class 12th Biology 2015 Set2 Delhi Board Paper Solution

Section 1

Q1	What is Biopiracy ?
Q2	State a reason for the increased population of dark coloured moths coinciding with the loss of lichens (on tree barks) during industrialization period in England.
Q3	Indiscrimate diagnostic practices using X-rays etc., should be avoided. Give one reason.
Q4	Name the transcriptionally active region of chromatin in a nucleus.
Q5	A geneticist interested in studying variations and patterns of inheritance in living beings prefers to choose organisms for experiments with shorter life cycle. Provide a reason.

Section 2

Q6	Many fresh water animals can not survive in marine environment. Explain. OR How are productivity, gross productivity, net primary productivity and secondary productivity interrelated ?
Q7	Name any two common Indian millet crops. State one characteristic of millets that has been improved as a result of hybrid breeding so as to produce high yielding millet crops.
Q8	Mention a product of human welfare obtained with the help of each one of the following microbes : (a) LAB (b) Saccharomyces cerevisiae (c) Propionibacterium shermanii (d) Aspergillus niger
Q9	Explain mechanism of sex-determination in birds.
Q10	After a brief medical examination a healthy couple came to know that both of them are unable to produce functional gametes and should look for an 'ART' (Assisted Reproductive Technique). Name the 'ART' and the procedure involved that you can suggest to them to help them bear a child.

Section 3

Q11	What is adaptive radiation ? When can adaptive radiation be referred to as convergent evolution ? Give an example.
Q12	A teacher wants his/her students to find the genotype of pea plants bearing purple coloured flowers in their school garden. Name and explain the cross that will make it possible.
Q13	(a) A DNA segment has a total of 1,500 nucleotides, out of which 410 are Guanine containing nucleotides. How many pyrimidine bases this segment possesses ? (b) Draw a diagrammatic sketch of a portion of DNA segment to support your answer.
Q14	Name the stage of human embryo at which it gets implanted. Explain the process of implantation.
Q15	A non biology person is quite shocked to know that apple is a false fruit, mango is a true fruit and banana is a seedless fruit. As a biology student how would you satisfy this person ?
Q16	Enlist the steps involved in inbreeding of cattle. Suggest two disadvantages of this practice.
Q17	Choose any three microbes, from the following which are suited for organic farming which is in great demand these days for various reasons. Mention one application of each one chosen. Mycorrhiza; Monascus; Anabaena; Rhizobium; Methanobacterium; Trichoderma.
Q18	Draw a labelled sketch of sparged-stirred-tank bioreactor. Write its application.
Q19	Following the collision of two trains a large number of passengers are killed. A majority of them are beyond recognition. Authorities want to hand over the dead to their relatives. Name a modern scientific method and write the procedure that would help in the identification of kinship.
Q20	Recombination DNA technology is of great importance in the field of medicine. With the help of a flow chart, show how this technology has been used in preparing genetically engineered human insulins.
Q21	Many plant and animal species are on the verge of their extinction because of loss of forest land by indiscriminate use by the humans. As a biology student what method would you suggest along with its advantages that can protect such threatened species from getting extinct ? OR "Determination of Biological Oxygen Demand (BOD) can help in suggesting the quality of a water body." Explain.
Q22	A team of students are preparing to participate in the interschool sports meet. During a practice session you find some vials with labels of certain cannabinoids. (a) Will you report to the authorities? Why? (b) Name of a plant from which such chemicals are obtained. (c) Write the effect of these chemicals on human body.

Section 4

Q23	Since October 02, 2014 "Swachh Bharat Abhiyan" has been launched in our country. (a) Write your views on this initiative giving justification. (b) As a biologist name two problems that you may face while implementing the programme in your locality. (c) Suggest two remedial methods to overcome these problems.
Q24	"Analysis of age-pyramids for human population can provide important inputs for long-term planning strategies." Explain. OR Describe the advantages for keeping the ecosystems healthy.
Q25	A flower of brinjal plant following the process of sexual reproduction produces 360 viable seeds. Answer the following questions giving reasons: (a) How many ovules are minimally involved? (b) How many megaspore mother cells are involved? (c) What is the minimum number of pollen grains that must land on stigma for pollination? (d) How many male gametes are involved in the above case? (e) How many microspore mother cells must have undergone reduction division prior to dehiscence of anther in the above case? OR Describe the changes that occur in ovaries and uterus in human female during the reproductive cycle.
Q26	Explain the genetic basis of blood grouping in human population. OR How did Hershey and Chase established that DNA is transferred from virus to bacteria?