Evolution — BIOLOGY STD 12 Science — Question

Explain giving two reasons why pollen grains can be best preserved as fossils.

What are the three levels of diversity on earth?

Give a brief introduction of the process of recombinant DNA technology.

(a) Write scientific names of causal organism and vector organism of malaria and write symptoms of this disease.
(b) Write names of two diseases spread by Aedes mosquito.

State the role of AUG codon at the 5' end and UAG at 3' end of a certain mRNA during translation.

Even though each pollen grain has two male gametes, why are at least 10 pollen grains and not 5 pollen grains required to fertilise 10 ovules present in a particular carpel?

In a cross between two tall pea plants, some of the offsprings produced were dwarf. Show with the help of Punnett square how this is possible.

Apart from being part of the food chain, predators play other important roles. Mention any two such roles supported by examples.

What is sewage? In which way can sewage be harmful to us?

With the help of a Punnett square, find the percentage of heterozygous individuals in a F₂ population in a cross involving a true breeding pea plant with green pods and a true breeding pea plant with yellow pods respectively.