Microbes in Human Welfare — BIOLOGY STD 12 Science — Question

In the United States, the total number of STDs of bacterial origin remains about the same each year, but the total number of STDs of viral origin increases each year. Explain the reason for this.

Why do we add an inoculum of curd to milk for curdling it?

OR

Why is 'starter' added to set the milk into curd? Explain.

OR

During the production of curd, a small amount of curd is added as a starter to the fresh milk at a suitable temperature. Explain the changes the milk undergoes when it sets into the curd.

OR

Why is a little curd added to milk to set it into curd? Explain.

An exotic variety of prickly pear introduced into Australia turned out to be invasive. How was it brought under control?

What type of creature was cromagnon on the basis of consuming human food?

In the course of human evolution, which human had a cranial capacity of 1400cc?

Why have Western Ghats in India been declared as biological hot spots?

Name two diseases whose spread can be controlled by the eradication of Aedes mosquitoes.

Name the component cells of the ‘egg apparatus’ in an embryo sac.

Name the two forms of reservoir of carbon, that regulate the ecosystem carbon cycle.

Why is the enzyme cellulase used for isolating genetic material from plant cells but not for animal cells?