List of top Biology Questions asked in PSEB XII

Darwin observed a variety of beaks in small black birds inhabiting Galapagos Islands. Explain what conclusions did he draw and how ?
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 ?
Discuss the nature of genetic code.
How did Hershey and Chase differentiate between DNA and protein in their experiment while proving that DNA is the genetic material ?
What is incomplete dominance ? Give an example.
What is meant by emasculation ? How is it useful in plant breeding programme ?
Amniocentesis for sex determination is banned in our country. Is this ban necessary ? Comment.
Draw labelled diagram for the structure of human sperm.
What do you mean by ‘Rivet Popper’ hypothesis ?
Write any two points of difference between grazing food-chain and detritus food-chain.
Briefly describe Zygote Intra Fallopian Transfer (ZIFT) technique practice to help infertile couples.
Expand GEAC. What is the responsibility of GEAC, set up by the Indian Government.
Lactational amenorrhea and coitus interruptus are __________ methods of birth control.
The ability of malignant tumors to spread to distant sites in the body through the blood is called __________.
Antibiotics are chemical substances produced by some microbes that can kill or inhibit disease-causing microbes.
Thymus increases in size with age and reaches its maximum size during puberty.
The introduction of alien species usually enhances biodiversity by adding stability to native ecosystems.
Simple shake flasks are more effective than stirred-tank bioreactors for producing large quantities of recombinant proteins.
The following are some of the well-known fossils in the evolution of modern man :
$\bullet$ Homo habilis
$\bullet$ Homo erectus
$\bullet$ Homo sapiens
$\bullet$ Australopithecus
The correct sequence of their origin is :
The pyramid of ________ is always upright and can never be inverted.
X and Y are two birth control methods, commonly called sterilization methods. X and Y are generally advised for the male and female partner respectively to prevent pregnancies. These techniques are highly effective. Identify X and Y.
The structure that provides vascular connection between the foetus and uterus is called ________.