CBSE EXAMINATION PAPER-2022

Gene of interest/alien gene is introduced by a cloning vector into a host cell to bring about a desired phenotypic expression in a host cell. The cloning vectors used are plasmid and bacteriophages. Biotechnologists in their labs, for desired results engineered specialised cloning vectors. One such vector is pBR322. Study the diagram carefully and answer the questions that follow.

Gene of interest/alien gene is introduced by a cloning vector into a host cell to bring about a desired phenotypic expression in a host cell. The cloning vectors used are plasmid and bacteriophages. Biotechnologists in their labs, for desired results engineered specialised cloning vectors. One such vector is pBR322. Study the diagram carefully and answer the questions that follow.

There are two different farm lands, one where Bt-cotton crop was cultivated and the other where non Bt-cotton crop (indigenous) was cultivated. Farmers responsible for this experimental cultivation were free to use the farming practices of their choice. During the cultivation period, the data was collected with respect to the amount of pesticide used, water required for irrigation and at harvesting time, the crop productivity. Based on the data collected, a bar graph was plotted which is shown below.

Gene of interest/alien gene is introduced by a cloning vector into a host cell to bring about a desired phenotypic expression in a host cell. The cloning vectors used are plasmid and bacteriophages. Biotechnologists in their labs, for desired results engineered specialised cloning vectors. One such vector is pBR322. Study the diagram carefully and answer the questions that follow.

The common bacterium found in the anaerobic sludge during sewage treatment and also in the rumen of cattle is:

Certain microbes used as biofertilizers fall under which taxonomic group?

Which of the following statements best describes the population growth pattern observed?

Which of the following diseases is not caused by a virus?

Which of the following diseases is not caused by a virus?

The pathogen Plasmodium is transmitted by:

The pyramid of biomass in a terrestrial ecosystem is:

Explain, giving two reasons, how immune response by "vaccine" is different from that by "antitoxin" in humans.

Mention the common bacterium found in the anaerobic sludge during sewage treatment and also in the rumen of cattle. How is this bacterium commercially useful ?

Some of the microbes used as biofertilizers are prokaryotes. Name the taxonomic group they come under. With the help of an example, mention how they act as biofertilizers.

Different species belonging to genus Trichoderma are useful to humans as well as to plants. Justify their roles by giving one instance of each.

The figures given below show the results of a lab experiment in which two microbial species A and B belonging to same genus were grown in three petri dishes having same culture medium. In Petri dish-I, Species-A was grown alone for 8 weeks. In Petri dish-II, Species-B was grown alone for 8 weeks. In Petri dish-III, both the species were grown together with the same number as Petri dish-I and Petri dish-II for 8 weeks.

What conclusion will you draw from the graphs in terms of impact of interaction on growth ? Explain, giving reason.

The graphs given below, A and B, represent population of elephants in two different National Parks (a hypothetical situation) at different times.

Study the graphs and comment upon the pattern of growth observed. Mention the possible reason for such patterns seen in nature.

Name the effective biocontrol agents of several plant pathogens belonging to group of viruses. Also write about the ways they support the environment.

The graph given below shows species-area relationship of a certain region.

(i) Study the graph and explain what it represents.

(ii) After a while, a small area was taken for constructing a road which divided the region into two. Write the impact this construction would have on species richness of the region.

What are the consequences of loss of biodiversity in a region ? Explain.

Bacillus thuringiensis plays an important role in Integrated Pest Management strategy. Explain how. Name any two crops that are protected efficiently from pests.

With the help of a storyboard or a flowchart only, explain all the stages of how human insulin is produced through r-DNA technology.

(a) Explain the roles of (i) primary, and (ii) secondary lymphoid organs that are responsible for developing defence to combat the action of pathogens/foreign antigens which enter our body.

(b) Doctors generally advise not to undergo surgery of tonsils. Why ?

Causative agents of HIV-AIDS and COVID-19 belong to the same group of viruses. To diagnose and amplify the genetic material for further study of COVID-19 virus, 'RT-PCR' test is carried out.

(a) What does 'RT-PCR' stand for?

(b) Explain the various steps of PCR technique.

How did Dr. David Tilman relate experimentally, the stability of a community and its species richness ? Explain.

As per a recent newspaper report, a particular country showed declining population growth rate. According to you, what could be the two most possible reasons for this decline and why ?

Explain how genetically modified organisms (GMOs) are created. Describe any three applications of GMOs in agriculture and medicine.

Describe the process of fertilisation in flowering plants. Explain the development of the endosperm and embryo after fertilisation.

Explain the structure of a human sperm and the process of fertilisation in humans.