Biodiversity and Conservation — BIOLOGY STD 12 Science — Question

What are opium, morphine, heroin, pethidine and methadone collectively called?

Name the largest cell of the embryo sac.

Define the following terms and give one example for each:
Interspecific competition

Name the last of the human chromosome to be sequenced.

Why cannot the sewage be let into natural water bodies directly?

OR

Why is sewage treated in STPs before discharge into a natural water body?

In the grass family, the single cotyledon is called ________.

Why are yeasts used extensively for functional expression of eukaryotic genes?

What do you understand by the phenomenon, photonasty?

Read the following four statements (A-D) about certain mistakes in two of them.

1. The first transgenic buffalo, Rosie pro- duced milk which was human alpha-lac- talbumin enriched.
2. Restriction enzymes are used in isolation of DNA from other macro molecules.
3. Downstream processing is one of the steps of R-DNA technology.
4. Disarmed pathogen vectors are also used in transfer of R-DNA into the host.

Which are the two statements having mis- takes?

1. Statements (A) and (B)
2. Statements (B) and (C)
3. Statements (C) and (D)
4. Statements (A) and (C)

Suggest a technique to a researcher who needs to separate fragments of DNA.

Or

Mention the use of gel electrophoresis in biotechnology experiments.