Chapter 2: Previous Year Paper- 2022
General Instructions:
(i) This question paper contains 13 questions. All questions are compulsory.
(ii) The question paper has three Sections - Section A, B, and C.
(iii) Section - A has 6 questions of 2 marks each. Section - B has 6 questions of 3 marks each, and Section - C has a case-based question of 5 marks.
(iv) There is no overall choice. However, internal choices have been provided in some questions. A candidate has to attempt only one of the alternatives in such questions.
(v) Wherever necessary, neat and properly labelled diagrams should be drawn.
SECTION - A
1. Mention the parts of the human body that get affected by Pneumonia and common cold infections. Write the causative agents of the two diseases.
Answer: Pneumonia affects the lungs, leading to inflammation, fever, chest pain, and difficulty breathing. The causative agents of pneumonia are typically bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, and Mycoplasma pneumoniae, as well as viruses such as influenza and respiratory syncytial virus (RSV).
The common cold primarily affects the upper respiratory tract, particularly the nose and throat, causing symptoms such as a runny nose, cough, sore throat, and mild fever. The causative agents of the common cold are mainly rhinoviruses, though other viruses such as coronaviruses and adenoviruses can also cause it.
2. State the impact of constant mechanical agitation and pumping of air in the aeration tank on the sewage during the biological treatment.
Answer: The mechanical agitation and pumping of air in the aeration tank during the biological treatment process help to supply oxygen to aerobic microorganisms. These microorganisms break down organic matter in the sewage, converting it into simpler, non-polluting substances such as carbon dioxide and water. The process aids in reducing the organic load of sewage, improving water quality by removing harmful pollutants. Additionally, the constant agitation prevents the formation of scum and ensures better contact between the microorganisms and the organic matter, making the treatment process more efficient.
OR
(a) Cattle excreta is an important source for producing a domestic fuel. Name the fuel and write its main components.
Answer: The fuel produced from cattle excreta is called biogas. Its main components are methane (CH4), carbon dioxide (CO2), and small amounts of other gases like hydrogen sulfide (H2S). Biogas is produced through anaerobic digestion by microorganisms that break down organic material in the absence of oxygen.
(b) Write the biological process that is responsible for the production of this fuel.
Answer:
The biological process responsible for the production of biogas is anaerobic digestion. In this process, organic matter such as cattle excreta is broken down by microorganisms in the absence of oxygen. This produces methane (CH4) as the primary fuel, along with carbon dioxide (CO2) and small amounts of other gases.
3. (a) Give an example of a viral biocontrol agent.
Answer: An example of a viral biocontrol agent is the Baculovirus species, which is used to control insect pests such as caterpillars. These viruses are highly specific and infect only the target insect species, leaving other organisms unaffected.
(b) Why are they considered to be desirable when an ecologically sensitive area is being treated?
Answer: Viral biocontrol agents are considered desirable in ecologically sensitive areas because they are species-specific, meaning they target only the pest species without harming other organisms or disrupting the ecological balance. This minimizes the impact on non-target species, preserving biodiversity in sensitive ecosystems.
4. What is the importance of female Anopheles mosquitoes in the life of a malarial parasite Plasmodium?
Answer: The female Anopheles mosquito is the vector responsible for transmitting the Plasmodium parasite, which causes malaria. The parasite undergoes part of its life cycle in the mosquito before being transmitted to humans during a blood meal. The mosquito's role is crucial for the parasite's reproduction and survival, making it essential for the spread of malaria.
5. Study the graph given below, showing the population growth curves 'A' and 'B' respectively. Answer the following questions:
(a) What is 'Carrying Capacity' in respect of Curve 'B' indicative of?
Answer:
In the context of population growth curve 'B', the carrying capacity refers to the maximum population size that an environment can support sustainably without degrading the resources. It is the point at which the population stabilizes, as resources such as food, space, and water become limited and regulate population growth.
(b) Mention the action of possible natural forces that could have led to curve 'B'.
Answer:
Natural forces that could have led to curve 'B' include resource limitations such as insufficient food, water, and shelter. Additionally, predation, disease outbreaks, competition for resources, and environmental factors like extreme weather could have contributed to stabilizing the population size at the carrying capacity.
6. The histogram given below represents the data for annual shark harvest in the Great Barrier Reef / Coral Reef located on the east coast of Queensland, Australia. Study the histogram and answer the questions that follow.
(a) Write your interpretation of the data given.
Answer:
The histogram likely shows a fluctuating trend in the number of sharks harvested annually from the Great Barrier Reef. If the numbers show a consistent increase over the years, it could indicate overfishing or a decline in shark populations, whereas a decrease could reflect improved conservation efforts or reduced fishing activities.
(b) Write the impact on the biodiversity of the area that you can interpret on the basis of the given data.
Answer:
Over-harvesting sharks from the reef can negatively impact the biodiversity of the ecosystem. Sharks are apex predators, and their decline can lead to an imbalance in the food web. This could result in the overpopulation of prey species, which may damage coral reefs and other marine life, thereby reducing the overall biodiversity of the area.
OR
"Stability of community depends upon its species richness." How did David Tilman show this experimentally?
Answer:
David Tilman showed experimentally that community stability is linked to species richness through his long-term studies of grassland ecosystems. He found that communities with higher species diversity were more resilient to environmental disturbances, such as droughts, compared to those with lower species diversity. His experiments demonstrated that more diverse ecosystems are better able to maintain ecosystem functions under stress.
SECTION - B
7. The data collected based on the survey conducted for species richness of a group of mammals, in three different climatic regions of the world is shown in the bar graph given below.
(i) Based on the species richness, identify the location of these countries in the respective climatic regions given.
Answer: Panama, with the highest number of species, is located in the tropical region. Canada, with 301 species, is located in the temperate region. Denmark, with the lowest species richness, is in the temperate region as well, but at higher latitudes, where the climate is cooler.
(ii) Plants and animals do not have a uniform diversity in the world. Write the term given to this pattern of diversity and why?
Answer: This pattern of diversity is known as the Latitudinal Diversity Gradient. It refers to the increase in biodiversity as one moves from the poles toward the equator. Tropical regions near the equator generally have higher species richness due to more stable climatic conditions, abundant resources, and longer evolutionary times.
8. Bio-diversification of life started to occur almost 3 billion years ago. Since then new species have been evolving and then disappearing en masse from earth.
(a) How many episodes of mass extinctions of species have already taken place and which one is in progress in the current era?
Answer: There have been five major mass extinctions in Earth's history: the Ordovician-Silurian, Late Devonian, Permian-Triassic, Triassic-Jurassic, and Cretaceous-Paleogene events. Currently, a sixth mass extinction is underway, largely driven by human activities such as habitat destruction, pollution, and climate change.
(b) How is the current episode in progress different from the previous episodes and why? Explain.
Answer: The current episode of mass extinction is different from previous ones because it is primarily caused by human activities, unlike earlier extinctions that were triggered by natural phenomena such as asteroid impacts, volcanic activity, or climate changes. Human-induced factors such as habitat destruction, overexploitation, pollution, and climate change are accelerating the loss of biodiversity.
9. Name two naturally occurring sources, one that transfers pathogenic genes into a plant cell and the other into an animal cell respectively, for their benefit. Write how have these naturally occurring sources been used for the benefit of human race by the biotechnologists.
Answer: The bacterium Agrobacterium tumefaciens transfers pathogenic genes into plant cells, which has been harnessed by biotechnologists for genetic engineering to introduce new genes into plants for traits like pest resistance and enhanced...
