Reproductive Health — BIOLOGY STD 12 Science — Question

What is ecological succession? Where and why would the rate of succession be faster, in a newly created pond or a forest destroyed by a forest fire?

Public all over India is very much concerned about the deteriorating air quality in large parts of North India. Alarmed by this situation the Resident's Welfare Association of your locality organised an awareness programme entitled "Bury not burn'. They invited you, being a biology student to participate.

1. How would you justify your arguments that promote burying and discourage burning? (Give two reasons).
2. With the help of flowcharts, one for each practice, depict the chain of events that follow.

Why is it difficult for DNA to pass through cell membranes? How can E.coli cells be made competent and who developed this method?

How do fossils help us in understanding the evolutionary history?

In peas, tallness is dominant over dwarfness, and red colour of flowers is dominant over the white colour. When a tall plant bearing red flowers was pollinated with a dwarf plant bearing white flowers, the different phenotypic groups were obtained in the progeny in numbers mentioned against them:
Tall, Red = 138
Tall, White = 132
Dwarf, Red = 136
Dwarf, White = 128
Mention the genotypes of the two parents and of the four offspring types.

Name and describe the technique that helps in separating the DNA fragments formed by the use of restriction endonuclease.

Now, sequencing of total genomes getting is getting less expensive day by the day. Soon it may be affordable for a common man to get his genome sequenced. What in your opinion could be the advantage and disadvantage of this development?

What are viruses parasitising bacteria called? Draw a well labelled diagram of the same.

During his studies on genes in Drosophila that were sex-linked T.H. Morgan found F2 -population phenotypic ratios deviated from expected 9:3:3:1. Explain the conclusion he arrived at.

Where is acrosome present in humans? Write its function.