Human Reproduction — BIOLOGY STD 12 Science — Question

What is a vaccine? How do they act to provide long term immunity to an individual, who is vaccinated?

OR

Write the events that take place when a vaccine for any disease is introduced into the human body.

OR

How does a vaccine for a particular disease immunise the human body against that disease?

OR

Name and explain the type of immunity that is provided by injecting microbes deliberately during immunisation into the human body.

Are there any homologous organs in male and female reproductive system? If yes, give examples.

Justify with the help of an example where a deliberate attempt by humans has led to the extinction of a particular species.

In order to obtain the F₁ generation, Mendel pollinated a true–breeding, say, tall plant with a true–breeding dwarf plant. But for getting the F₂ generation, he simply self-pollinated the tall F₁ plants. Why?

It is often observed that the chances of a person suffering from measles in his her life time are low if he or she has suffered from the disease in their early childhood. Justify the statement.

DNA being hydrophilic cannot pass through the cell membrane of a host cell. Explain how does recombinant DNA get introduced into the host cell to transform the latter.

Explain what is meant by Bio - fortification.

Human activities interfere with carbon cycle. List any two such activities.