Evolution — 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.

Explain metastasis. Why is it fatal?

A pedigree chart given below, present a particular generation which shows a trait irrespective of sexes (i.e., present in both male and female). Neither of the parents of the particular generation shows the trait. Draw your conclusion on the basis of the pedigree.

What is meant by total fertility rate? How does it differ from replacement level?

What is the name of network formed by the fusion of open ends of seminiferous tubules? Where does this network lead to?

What was the composition of the primitive atmosphere that favoured abiotic origin of life on earth?

Many proteins are secreted in their inactive form. This is also true of many toxic proteins produced by micro organisms. Explain how the mechanism is useful for the organism producing the toxin?

Group the following as nitrogenous bases and nucleosides: Adenine, Cytidine, Thymine, Guanosine, Uracil and Cytosine.

Why Hardy-Weinberg equilibrium is not applicable for large population size.

Explain any two devices by which autogamy is prevented in flowering plants.