Biodiversity and Conservation — BIOLOGY STD 12 Science — Question

“It is possible that a species may occupy more than one trophic level in the same ecosystem at the same time.” Explain with the help of one example.

Differentiate between back cross and test cross.

1. What is teminism?
2. What do you understand by UTR? Mention its role in translation.

Rearrange the human activities mentioned below as per the order in which they developed after the modern Homo sapiens came into existence during ice age:

1. Human settlement.
2. Prehistoric cave art.
3. Agriculture.

Name the group of organisms which constitute 'flocs'. Write their influence in the level of BOD during biological treatment of sewage.
OR
Explain the role of flocs in sewage treatment.

1. Mention the number of primers required in each cycle of polymerase chain reaction (PCR). Write the role of primers and DNA polymerase in PCR.
2. Give the characteristic feature and the source organism of the DNA polymerase used in PCR.

In the following diagram the two DNA strands represented are ready for transcription.

1. Label the parts marked 1 to 4 and state their functions in transcription.
2. Which one of the two strands of DNA has nucleotide sequence similar to the mRNA that will be transcribed and why?

How was the earth's atmosphere formed?

Define the terms:
(a) Gross primary productivity (b) Net primary productivity

At the time of Independence, the population of India was 350 million, which exploded to over 1 billion by May 2000. List any two reasons for this rise in population and any two steps taken by the government to check this population explosion.