List of top Questions asked in PSEB XII

What would happen if the substance labelled A was not present?
Identify the plant shown in the diagram.
Name the drug obtained from the latex of this plant.
How does the drug affect the human body ?
A recombinant DNA is formed when sticky ends of vector DNA and foreign DNA Join. Explain how the sticky ends are formed and get jointed.
What are Cry proteins ? How have biotechnologists exploited these proteins to benefit farmers ?
What does this diagram represent ?
Which part is responsible for guiding the pollen tube into synergid ?
What will be the fate of polar nuclei after fertilisation ?
Which of the following structures is/are present at micropylar end ?
Are the thorn of Bougainvillea and tendril of Cucurbita homologous or analogous ? What type of evolution has brought such a similarity in them ?
Draw a labelled diagram showing the structure of an antibody molecule.
How do methanogens help in producing biogas ?
DNA being hydrophilic cannot pass through the cell membrane of a host cell. Explain how the host cell is made 'competent' to take up the recombinant DNA ?
Why is it essential to have ‘selectable marker’ in a cloning vector ?
Explain Gause’s competitive exclusion principle.
How did Hershey and Chase differentiate between DNA and protein in their experiment while proving that DNA is the genetic material ?
Discuss the nature of genetic code.
Darwin observed a variety of beaks in small black birds inhabiting Galapagos Islands. Explain what conclusions did he draw and how ?
Write any two points of difference between grazing food-chain and detritus food-chain.
What do you mean by ‘Rivet Popper’ hypothesis ?
What is meant by emasculation ? How is it useful in plant breeding programme ?
Draw labelled diagram for the structure of human sperm.
Amniocentesis for sex determination is banned in our country. Is this ban necessary ? Comment.
Briefly describe Zygote Intra Fallopian Transfer (ZIFT) technique practice to help infertile couples.