List of top Biology Questions asked in CBSE CLASS XII

Whose skulls ‘A’, ‘B’, and ‘C’ are shown below? Which of the two are more similar to each other?
\begin{figure}[h!] \centering \includegraphics[width=0.8\textwidth]{Screenshot 2025-01-16 122426.png} \caption{Skull} \end{figure}

Name the (i) ape-like (ii) man-like primates that existed 1.5 million years ago.

Name the group of drugs whose skeletal molecule is shown below:
\begin{figure}[h!] \centering \includegraphics[width=0.8\textwidth]{Screenshot 2025-01-16 122650.png} \caption{Drug} \end{figure}

Flocs

How has the use of \textit{Agrobacterium as vector helped in controlling \textit{Meloidogyne incognita} infestation in tobacco plants? Explain in correct sequence.}

Draw a schematic diagram of the \textit{E.coli vector pBR 322 and mark the following in it:}
(a) ori
(b) rop
(c) ampicillin resistant gene
(d) tetracycline-resistant gene
(e) restriction site Bam HI
(f) restriction site EcoRI

Explain brood parasitism with the help of a suitable example.

Mention any two ways by which HIV and Hepatitis-B can be transmitted to a healthy person.

Differentiate between grazing food chain and detritus food chain.

Biodiversity hotspots cover less than 2\% of Earth’s land area. Strict protection of these areas can reduce the rate of ongoing extinctions. Explain.

Name any two hotspots in India.

Why is an early detection of these diseases essential?

Explain the improvement in the quality of the milk produced by it.

Study the graph given below that represents the changes in the thickening of the uterine wall in women ‘X’ and women ‘Y’ over a period of one month: \textit{(Refer to the provided graph.)}
What does the graph with respect to woman ‘X’ and woman ‘Y’ indicate? Give a suitable reason.

Assertion (A): Some aquatic ecosystems have inverted biomass pyramids.
Reason (R): More energy is required by the organisms occupying higher trophic levels.

Name the first developed transgenic cow.

Assertion (A): A given fig species can be pollinated only by its partner wasp.
Reason (R): The wasp pollinates the fig inflorescence while searching for suitable egg-laying sites.

Assertion (A): Patents are granted by the government to an inventor.
Reason (R): Patents prevent others from commercial use of an invention.

Assertion (A): Plasmids are autonomously replicating circular extra-chromosomal DNA.
Reason (R): Plasmids are usually present in eukaryotic cells.

ELISA technique is based on the principle of:

Turner’s syndrome in humans occurs due to:

The ‘molecular scissors’ fall in the category of:

Select the option that gives the correct identification of ovum, morula, and blastocyst in a human female reproduction system as shown in the following diagram: \textit{(Refer to the provided diagram.)}

The commonly used vector for human genome sequencing was/were:

Identify the category of genetic disorder depicted in the pedigree chart given below: