Board Paper of Class 12-Science 2018 Biology (SET 3) - Solutions

How did a citizen group called Friends of Arcata Marsh Arcata, California, USA, help to improve water quality of the marshland using Integrated Waste Water Treatment? Explain in four steps. VIEW SOLUTION

Your advice is sought to improve the nitrogen content of the soil to be used for cultivation of a non-leguminous terrestrial crop.

(a) Recommend two microbes that can enrich the soil with nitrogen.

(b) Why do leguminous crops not require such enrichment of the soil?    VIEW SOLUTION

You have obtained a high yielding variety of tomato. Name and explain the procedure that ensures retention of the desired characteristics repeatedly in large populations of future generations of the tomato crop. VIEW SOLUTION

(a) Name the source plant of heroin drug. How is it obtained from the plant?

(b) Write the effects of heroin on the human body. VIEW SOLUTION

With the help of an algebraic equation, how did Hardy-Weinberg explain that in a given population the frequency of occurrence of alleles of a gene is supposed to remain the same through generations?
 
Although a prokaryotic cell has no defined nucleus, yet DNA is not scattered throughout the cell. Explain. VIEW SOLUTION

(a) Differentiate between analogous and homologous structures.
(b) Select and write analogous structures from the list given below : VIEW SOLUTION

How has the use of Agrobacterium as vectors helped in controlling Meloidegyne incognitia infestation in tobacco plants? Explain in correct sequence. VIEW SOLUTION

(a) 'India has greater ecosystem diversity than Norway." Do you agree with the statement? Give reasons in support of your answer.
(b) Write the difference between genetic biodiversity and species biodiversity that exists at all the levels of biological organisation. Explain the effect on the characteristics of a river when urban sewage is discharged into it. VIEW SOLUTION

Explain the mechanism of 'sex determination' in birds. How does it differ from that of human beings? VIEW SOLUTION

Explain out-breeding, out-crossing and cross-breeding practices in normal husbandry. VIEW SOLUTION

(a) Organic farmers prefer biological control of diseases and pests to the use of chemicals for the same purpose. Justify.

(b) Give an example of a bacterium, a fungus and an insect that are used as biocontrol agents. VIEW SOLUTION

(a) How has the development of bioreactor helped in biotechnology?
(b) Name the most commonly used bioreactor and describe its working. VIEW SOLUTION

Explain the roles of the following with the help of an example each in recombinant DNA technology :

(a) Restriction Enzymes
(b) Plasmids VIEW SOLUTION

Differentiate between Parthenocarpy and Parthenogenesis. Give one example of each. VIEW SOLUTION

Medically it is advised to all young mothers that breastfeeding is the best for their newborn babies. Do you agree? Give reasons in support of your answer. VIEW SOLUTION

Draw a diagram of a mature human sperm. Label any three parts and write their functions. VIEW SOLUTION

(a) Expand VNTR and describe its role in DNA fingerprinting.
(b) List any two applications of DNA fingerprinting technique. VIEW SOLUTION

Looking at the deteriorating air quality because of air pollution in many cities of the country, the citizens are very much worried and concerned about their health. The doctors have declared health emergency in the cities where the air quality is very severely poor.
(a) Mention any two major causes of air pollution.
(b) Write any two harmful effects of air pollution to plants and humans.
(c) As a captain of your school Eco-club, suggest any two programmes you would plan to organise in the school so as to bring awareness among the students on how to check air pollution in and around the school. VIEW SOLUTION

(a) Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments. Explain the correlation between linkage and recombination with respect to genes as studied by them.

(b) How did Sturtevant explain gene mapping while working with Morgan?
 
(a) State the 'Central dogma' as proposed by Francis Crick. Are there any exceptions to it? Support your answer with a reason and an example.

(b) Explain how the biochemical characterisation (nature) of 'Transforming Principle' was determined, which was not defined from Griffth's experiments. VIEW SOLUTION

(a) Following are the responses of different animals to various abiotic factors. Describe each one with the help of an example.
(b) If 8 individuals in a population of 80 butterflies die in a week, calculate the death rate of population of butterflies during that period.
(a) What is a trophic level in an ecosystem? What is 'standing crop' with reference to it?
(b) Explain the role of the 'first trophic level' in an ecosystem.
(c) How is the detritus food chain connected with the grazing food chain in a natural ecosystem? VIEW SOLUTION

(a) Describe any two devices in a flowering plant which prevent both autogamy and geitonogamy.

(b) Explain the events upto double fertilisation after the pollen tube enters one of the synergids in an ovule of an angiosperm.
 
(a) Explain menstrual cycle in human females.

(b) How can the scientific understanding of the menstrual cycle of human females help as a contraceptive measure? VIEW SOLUTION