List of top Questions asked in PSEB XII

What are Intra-uterine devices (IUDs)? Discuss their mode of action.
What are the measures one has to take to prevent from contracting STDs?
Differentiate between homozygous and heterozygous individuals.
What is linkage? Discuss any two factors affecting linkage.
What is fertilization? In which part of the human female reproductive system does it occur? Explain, with the help of diagrams, various physical and chemical events of fertilization in humans.
What is meant by monosporic development of female gametophyte?
In what way, anaerobic sludge digestion is important in sewage treatments?
(a) Define transcription.
If the sequence of the template strand in a transcription unit is written as follws :
5' - ATGCATGCATGCATGC - 3'
what is the sequence of mRNA?
What is Human Genome Project? Why is the Human Genome Project called a Mega project?
Give the characteristics of genetic code.
How has the bacterium Bacillus thuringiensis helped us in controlling caterpillars of insect pests?
Briefly describe the role of microbes in household food processing.
List any four harmful effects caused by alcohol or drug abuse.
Briefly describe the Meselson and Stahl's experiment to prove that DNA replication is semi-conservative.
Define infertility. Explain any one assisted reproductive technology to check the problem of infertility.
What is Amniocentesis? For what purpose, it is used?
State and explain Mendel's law of dominance with the help of an example.
A woman carrier for haemophilia marries a normal man. Predict the possible genotypes and phenotypes of the offspring using a Punnett square. Also state percentages.
What happens to the corpus luteum in human females if the ovum is (a) fertilised (b) not fertilised?
Distinguish between innate and acquired immunity.
Define codominance. Explain the concept of co-dominance by taking an example of AB blood group in humans.
Menstrual cycle ceases during pregnancy.
Sex determination in honey bees is XX-XY type.
Floral parts are un-wettable in case of hydrophilous flowers.