List of top Biology Questions asked in CBSE Compartment XII

Assertion (A): Periodic abstinence is a method in which couples avoid coitus from day 10 to 17 of menstrual cycle.
Reason (R): Periodic abstinence has limited effectiveness because menstrual cycles are not always regular.
Which one of the following options gives the correct temperature condition and the mixture of the gaseous components that were used by S.L. Miller in 1953 to prove abiogenesis of life?
If a colour-blind woman marries a person whose mother is colour-blind, then what is the probability of colour blindness in their offspring?
Which one is not determined in the developing foetus by using amniocentesis?
How many billion tons productivity of oceans?
Assertion (A): Apple is false fruit.
Reason (R): Thalamus also contributes to fruit formation in apple.
How many number of biodiversity hotspots in the world right now?
Who proposed the competitive exclusion principle?
Which chemical is obtained from microorganism Aspergillus niger}?
The first r-DNA was constructed in which microorganism?
If a person is positive in Widal test, then that person is infected by which pathogen?
Genes which control $\alpha$-Thalassemia and $\beta$-Thalassemia are present on which number of chromosomes?
Distance between two consecutive base pairs of DNA is \rule{2cm}{0.1mm}
In a family tree of dinosaurs, which dinosaur was about 20 feet in height \& had huge fearsome dagger-like teeth?
They are useful to get rid of aphids.
Which scientist proposed that “embryo never pass through the adult stages of other animals”?
What is the correct name of AI technique in assisted reproductive technologies?
The flows of genetic information in central dogma are in which direction?
Which one of the following transgenic animals is being used to test the safety of the polio vaccine?
Which scientist proposed that "embryo never pass through the adult stages of other animals"?
Restriction Endonuclease – Hind II always cuts DNA molecules at a particular point by recognising a specific sequence of:
The type of bond represented by the dotted line ‘------’ in a schematic polynucleotide chain is:
In which of the following conditions/diseases is there a substantial increase in the activity of mast cells observed in the human body?
Lactobacillus} that sets milk into curd is categorised as:
The periodic abstinence by a couple for family planning should be from: