List of top Biology Questions on Biogas Plant asked in CBSE Class Twelve Board Exam

(b) In which condition will the pyramid remain always upright?

State why plant breeders are interested in artificial hybridisation programme. How do they carry out this process?

Study the table given below:
$$\begin{array}{|c|c|} \hline \textbf{Contraceptive/Contraceptive Method} & \textbf{Mode of Action} \\ \hline \text{A. The pill} & \text{I. Prevent sperm reaching cervix} \\ \text{B. Condom} & \text{II. Prevent implantation} \\ \text{C. Vasectomy} & \text{III. Inhibits ovulation} \\ \text{D. CopperT} & \text{IV. Semen contains no sperm} \\ \hline \end{array}$$ Select the option where contraceptive/contraceptive method are correctly matched with their mode of action.

(b) Write the symptoms of malaria in humans and explain what causes these symptoms.

(iii) Work out a cross to explain how normal parents may have a sicklecell anaemic child.

(iii) Explain the charging of an adaptor molecule. Why this molecule needs to be charged?

(iii) List any two ‘out breeding devices’ in flowering plants. Explain why do plants develop such devices.

(a). Study the schematic diagram given below and answer the questions:
\begin{figure}[h!] \centering \includegraphics[width=0.5\linewidth]{Screenshot 20250115 144456.png} % Replace with the correct path to your image \caption{Diagram} \label{Diagram} \end{figure} (i) Identify the polarity from ‘X’ to ‘Y’ in the mRNA segment shown. Mention how many more amino acids can be added to the polypeptide that is being translated and why.

(b). Observe the picture of Commelina plant bearing two types of flowers:
\begin{figure}[h!] \centering \includegraphics[width=0.5\linewidth]{Screenshot 20250115 144128.png} % Replace with the correct path to your image \caption{Commelina} \label{Commelina} \end{figure} (i) Identify the two types of flowers labelled ‘A’ and ‘B’ in the picture.

(a) The given diagram shows the sectional view of a seminiferous tubule of Human testis.
\begin{figure}[h!] \centering \includegraphics[width=0.5\linewidth]{Screenshot 20250115 143912.png} % Replace with the correct path to your image \caption{Testis} \label{Testis} \end{figure} (i) Name and describe the process depicted in the diagram which results in the development of spermatozoa.

(b) Draw a schematic diagram of an antibody molecule and label any 4 parts. Mention their chemical nature. Name the cells which produce them.

Explain the role of transgenic animals in: (a) Production of Biological Products

Study the steps shown below, that are carried during a specific technique:
\begin{figure}[h!] \centering \includegraphics[width=0.5\linewidth]{Screenshot 20250115 143650.png} % Replace with the correct path to your image \caption{Steps} \label{Steps} \end{figure} (a) Identify the steps ‘A’ and ‘D’ in the diagram.

Explain the role of the following during the sewage treatment:
(a) Flocs
(b) Anaerobic sludge digester

(a) 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=0.5\linewidth]{Screenshot 20250115 143253.png} % Replace with the correct path to your image \caption{skull} \label{Skull} \end{figure}

(b) Name the (i) apelike (ii) manlike primates that existed 1.5 million years ago.

Draw a welllabelled diagram of sectional view of male gametophyte/microspore of an angiosperm and write the functions of any two parts labelled. (Any four labels).

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:
\begin{figure}[h!] \centering \includegraphics[width=0.5\linewidth]{Screenshot 20250115 143034.png} % Replace with the correct path to your image \caption{Graph} \label{Graph} \end{figure} What does the graph with respect to women ‘X’ and women ‘Y’ indicate? Give a suitable reason.

(a) Intensely lactating mothers generally do not conceive. Why?
Answer:
Lactational amenorrhea prevents ovulation during intense lactation. Prolactin, the hormone responsible for milk production, suppresses gonadotropin release. (b) Why has our government intentionally imposed strict conditions for MTP (Medical Termination of Pregnancy)?