List of top Questions asked in CBSE CLASS XII

Assertion (A): The stirrer facilitates the even mixing of oxygen availability in a bioreactor. 
Reason (R): Stirred-tank bioreactors generally have a flat base.} 
 

Assertion (A): The zygote gives rise to heart-shaped embryo and subsequently proembryo in most angiosperms.
Reason (R): The zygote is present at the micropylar end of the embryo sac and develops into an embryo.

Which one of the following represents the correct annealing of primers to the DNA to be amplified in the PCR? 

The population growth curve applicable for a population of beetles growing in nature under unlimited resource conditions available to them will be:
In an experiment, {E. coli is grown in a medium containing \({}^{14}NH_4Cl\) (\({}^{14}N\) is the light isotope of Nitrogen) followed by growing it for six generations in a medium having the heavy isotope of nitrogen (\({}^{15}N\)). After six generations, their DNA was extracted and subjected to CsCl density gradient centrifugation. Identify the correct density (Light/Hybrid/Heavy) and ratio of the bands of DNA in CsCl density gradient centrifugation:}

The linking of the antibiotic resistance gene with the plasmid vector of Salmonella typhimurium by Stanley Cohen and Herbert Boyer was made possible by the enzyme:
 

A patient is suffering from the infection of the alveoli of lungs and is showing the symptoms of fever, chills, cough, headache, and bluish-colored lips and fingernails. The patient was diagnosed to be suffering from the infection of:
A Snapdragon plant bearing pink-colored flowers is crossed with a Snapdragon plant bearing white-colored flowers. Their F1 progeny will show:
In which of the following chromosomal disorders do the individuals have short stature, small head, furrowed tongue, and partially open mouth?
After the 1850s in the post-industrialization era in England, the expected effect of natural selection on the number of white-winged moths as compared to the dark-winged moths was:
A DNA fragment has 3000 nucleotides, out of which 160 are Guanine. How many bases having double hydrogen bonds between them does this DNA fragment possess?
The ploidy of apomictic embryos developing from the nucellus and antipodal cells respectively would be:
Options:
The origin of life according to the early Greek philosophers was transfer of unit of life from outer space to the different planets in the form of:
Embryo formation without fertilization is observed in some species of:
Explain the two syntax forms of ‘Lookup’ function:
Explain ‘Password Security’ and ‘Data Audit’ as security features of Computerised Accounting System:
State any four advantages of Computerised Accounting System:
Explain ‘Transparency and Control’ and ‘Accuracy and Speed’ as features of Computerised Accounting System:
Explain the terms ‘Doughnut’ and ‘Exploded Doughnut’ as types of charts:
Correct ##### appears:
From the following, identify the type of code used by a trading company:
\[ \begin{array}{|l|l|} \hline \textbf{Codes} & \textbf{Dealer Type} \\ \hline 100 – 199 & \text{Cycle tyres} \\ \hline 200 – 299 & \text{Cycle seats} \\ \hline \end{array} \]
How many categories of data can be plotted on a pie chart in Excel software?
When the accumulated data from various sources is processed in one shot, it is called:
Name the Accounting Information sub-system which deals with receipt and payment of cash and electronic funds transfer:
Data, \_\_\_\_\_\_, \_\_\_\_\_\_, Hardware, and Software are five pillars of Computerised Accounting System (CAS). From the following, which two pillars of CAS are missing in the above statement?