Environmental Issues — BIOLOGY STD 12 Science — Question

A genetic code is specific and nearly universal. Justify.

Alien species invasion is one of the causes of biodiversity loss. Explain with the help of an example.
OR
Sometimes alien species affect the indigenous organisms leading to their extinction. Substantiate this statement with the help of any two examples.

Unsing a Punnett Square, work out the distribution of phenotypic features in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus.

Distinguish between primary sludge and activated sludge.

What is repetitive DNA? Explain graphically the experiment of Alfred Hershey and Martha Chase that 'DNA is a genetic material'.

In a nucleus, the number of ribonucleoside triphosphates is 10 times the number of deoxy x10 ribonucleoside triphosphates, but only deoxy ribonucleotides are added during the DNA replication. Suggest a mechanism.

Where are found leydig cells and what is their role in reproduction?

What are the major components of seminal plasma?

Write the name of the pathogen of amoeba. Write two symptoms of the disease and two sources of infection.

Differentiate between Homozygous & Heterozygous