Q24 of 43 Page 1

Analyse the effects of ‘Alien species invasion’ on the biodiversity of a given area. Provide two examples.

An alien species is any plant or animal species that is introduced in a new environment and where it flourishes and takes over the indigenous flora or fauna. Introduction of alien species causes decline or extinction of indigenous species due to tough competition for utilization of resources. The most famous example is that of water hyacinth. It was brought to India because of its beautiful leaves. However, once it got introduced, it spread like weed and was very difficult to control it.

Another example is that of the Nile perch. Nile Perch was introduced in lake Victoria and it led to the extinction of more than 200 species of Cichlid fish.


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(a) Suggest and explain a procedure for possible life-long (permanent) cure.


(b) Name any other possible treatment for this disease.


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Differentiate between an ‘Expanding age pyramid’ and a ‘Stable age pyramid’. Substantiate your answer with diagrams.

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Mendel crossed a homozygous pea plant having yellow and round seeds with another pea plant bearing green and wrinkled seeds. He found that in some of the F2 population new combination of parental characters were observed. How will you explain the appearance of a new combination of parental characters in F2-offsprings? Support your answer with the help of Punnett square.

OR


Describe S.L. Miller’s experiment. Comment on the observations he made and his contribution towards the origin of life on Earth.


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(a) Differentiate between active and passive immunity.

(b) Comment on the role of vaccination and immunization in keeping human population healthy.


OR


Describe the process of secondary treatment given to municipal waste water (sewage) before it can be released into fresh waterbodies. Mention another benefit provided by this process.