Biology 57/3/2 2018-2019 Science (English Medium) Class 12 Question Paper Solution

Why are cucurbit plants said to be monoecious ?

Name the pollutant attributed to be the cause of ‘ozone-hole’ over the Antarctica region.

List the greenhouse gases other than carbon dioxide.

Write the scientific name of the organism Alexander Fleming worked on and discovered the first antibiotic.
Was the organism he worked on a fungus or a bacterium ?

Suggest a method to overcome excessive inbreeding depression.

According to de-Vries what is saltation?

Differentiate between a DNA and a RNA nucleotide.

Where exactly is the filiform apparatus present in the embryo sac of an angiosperm? States its function.

Explain the role of histones in forming a nucleosome.

What is ‘Ori’ ? State its importance during cloning of a vector.

Explain the importance of ‘Selectable marker’, with the help of a suitable example.

What is ‘carrying capacity’ of a species in a habitat ? Why is logistic growth model considered more realistic?

Why has the Indian Government set up the organisation named GEAC ? Give any two reasons.

Give a schematic representation of the transformation of a pro-insulin into insulin.

Explain the relationship between B-lymphocytes and T-lymphocytes developing an immune response.

“The pyramid of biomass is not always upright.” Explain the statement.

Draw a T.S. of a young anther of an angiosperm. Label the different layers of the wall and write their functions.

Why should a bacterium be made ‘competent’ ?

Explain the role of ‘microinjection’ and ‘gene gun’ in biotechnology

How do desert lizards cope with the variations in their environment ? Explain.

Name and explain the mode of action of any two types of IUDs.

List the advantges of using ‘Saheli’ as a contraceptive.

Write the scientific name of the source plant and the part from which opiods are extracted. What is it commonly and chemically called ?

Where in the human body are its specific receptors located ? How do opioids affect the human body ?

How does the human body respond when vaccine is introduced into it?

It is said that vaccinations are a must for a healthy society. Justify.

What is heterogamety ? Explain the mechanism of sex determinatin in Drosophila.

Explain the process of making heterogeneous nuclear RNA (hnRNA) into a fully functional mRNA in eukaryotes. Where does this process occur in the cell?

Write any six salient features of the human genome as drawn from the human genome project.

“Appearance of melanised moths post-industrialisation in England is a classic example of evolution by natural selection.” Explain.

Explain any three remedial measures to overcome the acute air pollution in our cities.

Write any three ways by which noise pollution affects the human body adversely. List any three steps that should be followed in order to reduce noise pollution.

What is the primary productivity of an ecosystem and how is it expressed?

Explain what does the equation given below show :
NPP = GPP – R

Name the type of detritus that decomposes faster. List any two factors that enhance the rate of decomposition.

Write the different steps taken in humification and mineralisation during the process of decomposition.

Write any two biochemical/molecular diagonostic procedures for early detection of viral infection. Explain the principle of any one of them.

Describe the steps that are followed during secondary treatment of sewage.

Explain the changes that occur in the ovary and uterus during menstrual cycle in human females. Mention the influence of pituitary and ovarian hormones in bringing these changes.

Compare the characteristic features of insect pollinated and wind pollinated flowers. Explain how the respective features assist in pollination.

Write the specific name of the genus Plasmodium that causes one of the most serious types of diseases in humans. Name the disease.

Describe the events in the life cycle of Plasmodium which take place in the female Anopheles.

Explain what happens in the RBCs of the humans when Plasmodium gains entry into them. How does the human body gets affected?

Explain the interrelationship between organic farming and biofertilizers, with the help of any three suitable examples.

How would you find out whether a given tall garden pea plant is homozygous or heterzygous? Substantiate your answer with the help fo Punnett squares.

Given below are the F₂ – phenotypic ratios of two independently carried monohybrid crosses :
(i) 1 : 2 : 1
(ii) 3 : 1
Mention what does each ratio suggest.

(a) Why did Hershey and Chase use radioactive 32P and 35S in their experiments? Explain.
(b) Following the experiments conducted by them, write what conclusion did they arrive at and how ?