Human Reproduction — BIOLOGY STD 12 Science — Question

Describe three manners in which fertilisation of human ovum by a sperm can be prevented.

Community Service department of your school plans a visit to a slum area near the school with an objective to educate the slum dwellers with respect to health and hygiene.

1. Why is there a need to organize such visits?
2. Write the steps you will highlight, as a member of this department, in your interaction with them to enable them to lead a healthy life.

Which one of the two in-situ or ex-situ biodiversity conservation measures help the larger number of species to survive? Explain.

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.

Bt cotton is resistant to pest, such as lepidopteron, dipterans and coleopterans. Is Bt cotton also resistant to other pests as well?

How have human activities caused desertification? Explain.

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?

Explain the sex determination mechanism in humans. How is it different in birds?

What are the properties of an antibiotic?