Biology All India Set 3 2014-2015 Science (English Medium) Class 12 Question Paper Solution

What is a cistron?

How many chromosomes do drones of honey bees possess?

List two advantages of the use of unleaded petrol in automobiles as fuel.

Retroviruses have no DNA. However, the DNA of the infected host cell does possess viral DNA. How is it possible?

Suggest any two possible treatments that can be given to a patient exhibiting adenosine deaminase deficiency.

Select two pairs from the following which exhibit divergent evolution. Give reasons for your answer.

(i) Forelimbs of cheetah and mammals

(ii) Flippers of dolphins and penguins

(iii) Wings of butterflies and birds

(iv) Forelimbs of whales and mammals

A liverwort plant is unable to complete its life cycle in a dry environment. State two reasons

What is mutualism?

Mention any two examples where the organisms involved are commercially exploited in agriculture.

List any four techniques where the principle of ex-situ conservation of biodiversity has been employed.

Why are the plants raised through micropropagation are termed as somaclones?

Mention two advantages of micropropagation technique.

Explain the function of “anaerobic sludge digester” in a sewage treatment plant.

The F₂ progeny of a monohybrid cross showed phenotypic and genotypic ratio as 1:2:1 unlike that the Mendel’s monohybrid F₂ ratio. With the help of a suitable example, work out a cross and explain how it is possible.

Why are some seeds referred to as apomictic seeds?

Mention one advantage and one disadvantage to a farmer who uses them.

A heavily bleeding and bruised road accident victim was brought to a nursing home. The doctor immediately gave him an injection to protect him against a deadly disease.

(a) Write what did the doctor inject into the patient’s body.

(b) How do you think this injection would protect the patient against the disease?

(c) Name the disease against which this injection was given and the kind of immunity it provides.

“A very small sample of tissue or even a drop of blood can help determine paternity”. Provide a scientific explanation to substantiate the statement.

What does the following equation represent? Explain.

p² + 2pq + q² = 1

Describe any three potential applications of genetically modified plants.

How did an American Company, Eli Lilly use the knowledge of r-DNA technology to produce human insulin?

How do snails, seeds, bears, zooplanktons, fungi and bacteria adapt to conditions unfavourable for their survival?

Enumerate any six essentials of good, effective Dairy Farm Management Practices.

With the help of a flow chart, show the phenomenon of biomagnifications of DDT in an aquatic food chain.

State the medicinal value and the bioactive molecules produced by Streptococcus, Monascus and Trichoderma.

What are methanogens?

How do methanogens help to generate biogas?

Rearrange the following in the correct sequence to accomplish an important biological reaction:

(a) In vitro synthesis of copies of DNA of interest

(b) Chemically synthesized oligonucleotides

(c) Enzyme DNA-polymerase

(d) Complementary region of DNA

(e) Genomic DNA template

(f) Nucleotides provided

(g) Primers

(h) Thermostable DNA-polymerase (from Thermus aquaticus)

(i) Denaturation of ds-DNA

Your school has been selected by the Department of Education to organize and host an interschool seminar on “Reproductive Health – Problems and Practices”. However, many parents are reluctant to permit their wards to attend it. Their argument is that the topic is “too embarrassing.” Put forth four arguments with appropriate reasons and explanation to justify the topic to be very essential and timely.

How are Mendelian inheritance, polygenic inheritance and pleiotropy different from each other?

Explain polygenic inheritance pattern with the help of a suitable example.

Draw a labelled diagram of a “replicating fork” showing the polarity.

Why does DNA replication occur within such "forks"?

Name two enzymes involved in the process of DNA replication along with their properties.

List the different attributes that a population has and not an individual organism.

What is population density?

Explain any three different ways the population density can be measured, with the help of an example each.

“It is often said that the pyramid of energy is always upright. On the other hand, the pyramid of biomass can be both upright and inverted.” Explain with the help if examples and sketches.

(a) Plan an experiment and prepare a flow chart of the steps that you would follow to ensure that the seeds are formed only from the desired sets of pollen grains. Name the type of experiment that you carried out.

(b) Write the importance of such experiments

Describe the role of pituitary and ovarian hormones during the menstrual cycle in a human female.