Worksheet Solutions: Life on the Earth | Geography Class 11 - Humanities/Arts PDF Download

Fill in the Blanks 

Q1: What does the biosphere consist of?
Ans: All living components of the earth
The biosphere encompasses all living components on Earth, which includes not only plants and animals but also micro-organisms and their interactions with the environment.

Q2: Ecology is the study of the relationships between _______ and their environment.
Ans: organisms
Ecology is the study of how living organisms (organisms) interact with each other and their environment, encompassing both biotic and abiotic factors.

Q3: Terrestrial ecosystems can be further classified into _______.
Ans: biomes
A grassland is an example of a terrestrial ecosystem, as it refers to an ecosystem found on land rather than in water.

Q4: The primary source of energy for life processes on Earth is _______.
Ans: the sun
The sun is the primary source of energy for life on Earth because it drives processes like photosynthesis, which provides energy for plants and, subsequently, the entire food web.

Q5: The structure of an ecosystem involves both _______ and _______ factors.
Ans: abiotic, biotic
Ecosystems consist of both abiotic (non-living) and biotic (living) factors. Abiotic factors include elements like temperature, soil conditions, and humidity, while biotic factors encompass all the living organisms, including producers, consumers, and decomposers. Together, these factors shape the structure and function of an ecosystem.

Q6: Producers in an ecosystem include _______ plants.
Ans: green
Producers are primarily green plants. These plants have the unique ability to perform photosynthesis, using sunlight to convert carbon dioxide and water into organic compounds, including carbohydrates. This process is why they are typically green, as they contain chlorophyll, the pigment responsible for photosynthesis.

Q7: The first level of a grazing food chain starts with _______.
Ans: plants
In a grazing food chain, the initial level consists of plants. These plants are the primary producers in the ecosystem, converting solar energy into chemical energy through photosynthesis. Herbivores, the primary consumers, feed on these plants, starting the food chain.

Q8: The carbon cycle is mainly the conversion of _______ into carbohydrates through photosynthesis.
Ans: carbon dioxide
The carbon cycle primarily involves the conversion of carbon dioxide (CO₂) into carbohydrates through the process of photosynthesis. During photosynthesis, green plants use sunlight to capture carbon dioxide from the atmosphere and combine it with water to produce carbohydrates, which store energy and form the basis of the food web.

Q9: Oxygen is the main by-product of _______.
Ans: photosynthesis
Oxygen is the primary by-product of photosynthesis. During photosynthesis, as plants produce carbohydrates from carbon dioxide and water using solar energy, they release oxygen into the atmosphere. This process is crucial for replenishing atmospheric oxygen and supporting aerobic respiration in living organisms.

Q10: Nitrogen is a major constituent of the _______ gases in the atmosphere.
Ans: atmospheric
Nitrogen is a major constituent of the atmospheric gases, making up approximately 79% of the Earth's atmosphere. This gaseous nitrogen is critical for many essential organic compounds and plays a significant role in various biogeochemical cycles, including the nitrogen cycle. However, only specific organisms can directly utilize gaseous nitrogen; most rely on fixed nitrogen compounds to meet their nitrogen needs.

Assertion and Reason Based

Q1: Assertion: Ecology is the study of the interactions of living organisms with their environment.
Reason: It focuses on how plants and animals live together as separate entities.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (a)
The assertion is correct as ecology indeed studies the interactions of living organisms with their environment. However, the reason provided is not accurate because ecology focuses on how these organisms interact with one another and their surroundings, emphasizing their interdependence.

Q2: Assertion: The carbon cycle involves the conversion of carbon dioxide through photosynthesis.
Reason: Carbohydrates produced by photosynthesis can only be used by plants.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (b)
The assertion is accurate as the carbon cycle includes carbon dioxide conversion through photosynthesis. However, the reason is partially correct because while photosynthesis produces carbohydrates primarily used by plants, other organisms, including animals, can also utilize these carbohydrates.

Q3: Assertion: The main source of energy for life on Earth is solar insolation.
Reason: Solar insolation is the energy generated during decomposition processes.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (c)
The assertion is correct as solar insolation is indeed a primary source of energy for life on Earth through photosynthesis. However, the reason provided is incorrect; solar insolation is not generated during decomposition processes.

Q4: Assertion: Biogeochemical cycles are largely energized by solar insolation.
Reason: In the sedimentary cycle, the main reservoir is the atmosphere and the ocean.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (c)
The assertion is partly correct, as solar insolation is an energy source for biogeochemical cycles, but it is not the main energy source for the sedimentary cycle. The reason is false because the sedimentary cycle's primary reservoir is not the atmosphere and the ocean; it's the soil and sedimentary rocks.

Q5: Assertion: Ecological balance is maintained by competition between different species.
Reason: In vast grasslands, herbivorous animals are controlled by carnivorous animals.
(a) Both assertion and reason are true, and the reason is the correct explanation of the assertion.
(b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion.
(c) Assertion is true, but the reason is false.
(d) Assertion is false, but the reason is true.
Ans: (a)
Both the assertion and reason are accurate. Competition and predation between different species help maintain ecological balance. In vast grasslands, herbivores are indeed controlled by carnivores, which contributes to the balance in the ecosystem.

Very Short Answer Type Questions

Q1: Define ecology.
Ans: Ecology is the scientific study of the relationships between organisms and their environment.

Q2: What are the two main components of an ecosystem?
Ans: The two main components of an ecosystem are biotic (living) and abiotic (non-living) factors.

Q3: Give an example of a terrestrial ecosystem.
Ans: Grassland.

Q4: What is the primary source of energy for life processes on Earth?
Ans: The sun.

Q5: Name two abiotic factors in an ecosystem.
Ans: Temperature and rainfall.

Q6: What is the main by-product of photosynthesis?
Ans: Oxygen.

Q7: What is the primary source of free nitrogen in the atmosphere?
Ans: The action of soil micro-organisms and plant roots.

Q8: Which biogeochemical cycle is mainly based on atmospheric reservoirs?
Ans: Gaseous cycle.

Q9: Name one example of a sedimentary cycle.
Ans: Phosphorus cycle.

Q10: What is ecological balance?
Ans: Ecological balance is a state of dynamic equilibrium within a community of organisms in an ecosystem.

Short Answer Type Questions

Q1: Explain what an ecosystem consists of and why it is important.
Ans: An ecosystem consists of both biotic (living) and abiotic (non-living) components in a specific area. It is important because it represents the intricate interactions between organisms and their environment. These interactions influence energy flows, material cycles, and ecological adaptations, which are crucial for the sustainability of life on Earth. Ecosystems provide essential services like food production, water purification, and climate regulation. They are also of great ecological and scientific interest as they help us understand how life on Earth is interconnected.

Q2: Describe the key components of an ecosystem.
Ans: An ecosystem has two main components: biotic and abiotic factors. Biotic factors include all living organisms in the ecosystem, such as plants, animals, and microorganisms. These organisms interact with each other, forming complex food chains and relationships. Abiotic factors encompass non-living elements like climate, temperature, sunlight, soil conditions, and inorganic substances. These factors influence the distribution and behavior of living organisms within the ecosystem.

Q3: Explain the water cycle and its significance in sustaining life on Earth.
Ans: The water cycle, also known as the hydrologic cycle, is a continuous process that circulates water in various forms (solid, liquid, gaseous) between the atmosphere, lithosphere, and living organisms. It plays a crucial role in sustaining life on Earth by ensuring the availability of freshwater for both terrestrial and aquatic ecosystems.
The water cycle begins with the evaporation of water from oceans, lakes, and rivers due to solar energy. This water vapor rises into the atmosphere, cools, and condenses to form clouds. When the clouds become heavy, precipitation occurs in the form of rain, snow, or hail, replenishing the Earth's surface water.
This water is essential for plant growth through photosynthesis, for animal survival, and for various ecological processes. It also helps maintain temperature and climate, regulate weather patterns, and replenish groundwater. Without the water cycle, life as we know it would not be sustainable, making it a fundamental process for all ecosystems.

Q4: Describe the carbon cycle and its significance in ecological processes.
Ans: The carbon cycle is a vital biogeochemical cycle that describes the movement of carbon in various forms through the Earth's ecosystems. It is significant in ecological processes because carbon is a fundamental element in all living organisms and plays a crucial role in energy transfer and the structure of organic compounds.
The carbon cycle begins with carbon dioxide (CO₂) in the atmosphere. Through the process of photosynthesis, green plants convert CO₂ into carbohydrates, such as glucose, which serve as an energy source and a structural component of plant tissues. These carbohydrates are consumed by herbivores and, subsequently, by carnivores.
During this process, carbon dioxide is released through respiration and returned to the atmosphere. When plants and animals die or produce waste, the remaining organic matter is decomposed by microorganisms. This decomposition process releases carbon back into the environment, which can then be used again by green plants.
The carbon cycle is essential for maintaining the balance of atmospheric carbon dioxide, supporting plant growth, and providing energy for all living organisms. It also influences climate regulation as excessive carbon dioxide in the atmosphere contributes to global warming.

Q5: Explain the nitrogen cycle and its importance in ecosystems.
Ans: The nitrogen cycle is a crucial biogeochemical cycle that describes the movement of nitrogen in various forms through ecosystems. Nitrogen is an essential component of amino acids, proteins, and nucleic acids, making it vital for all living organisms. The nitrogen cycle's significance lies in its role in providing a continuous supply of nitrogen, a limiting nutrient, to support plant growth and sustain ecosystems.
The nitrogen cycle begins with atmospheric nitrogen gas (N₂), which is inert and cannot be directly utilized by most organisms. However, certain nitrogen-fixing bacteria can convert N₂ into ammonia (NH₃) or nitrate (NO₃^-) ions. This "fixed" nitrogen is available for plants, which assimilate it for their growth.
Herbivores consume plants and obtain nitrogen, and carnivores, in turn, consume herbivores. When organisms die or produce nitrogenous waste, bacteria decompose the organic matter, converting it into ammonia and nitrate. Some bacteria can further convert nitrate into atmospheric nitrogen through denitrification.
The nitrogen cycle is essential for maintaining soil fertility, supporting plant growth, and ensuring the availability of amino acids for all organisms. It plays a critical role in ecosystem dynamics and nutrient cycling, making it a fundamental process in ecological systems.

Q6: Explain the concept of ecological balance and how it is maintained in ecosystems.
Ans: Ecological balance refers to a state of dynamic equilibrium within an ecosystem or habitat, where the diversity and interactions of living organisms remain relatively stable over time. This balance is essential for the sustainability and health of ecosystems.
It can be achieved and maintained through various ecological mechanisms:

• Competition and Cooperation: Within ecosystems, species interact through competition and cooperation. Some species may compete for resources like food, territory, or mates. This competition helps regulate population numbers and prevents one species from dominating. Cooperation, on the other hand, can involve mutualistic relationships where two species benefit from each other's presence.
• Predator-Prey Relationships: Predatory relationships help control prey populations. Carnivores and herbivores maintain a balance, preventing overgrazing or overpopulation of herbivores.
• Succession: Ecological succession is a natural process where the composition of species in an ecosystem changes over time. This change can be due to environmental disturbances or gradual transitions from one species to another. Succession helps maintain the overall balance by allowing ecosystems to adapt to changing conditions.
• Food Webs: Complex food webs in ecosystems involve multiple species, each with specific roles. This diversity helps ensure that one species' decline or increase doesn't disrupt the entire ecosystem.
• Human Intervention: In some cases, humans may need to intervene to maintain ecological balance, such as in conservation efforts to protect endangered species or restore damaged ecosystems.

By maintaining ecological balance, ecosystems remain resilient, adaptable, and sustainable over time, supporting the diverse life forms within them.

Long Answer Type Questions

Q1: Describe the structure and functions of an ecosystem, highlighting the roles of abiotic and biotic factors.
Ans: Ecosystems are complex systems consisting of both biotic (living) and abiotic (non-living) factors.
The structure and functions of an ecosystem are as follows:

• Structure:
  • Biotic Factors: These include all living organisms in the ecosystem, such as plants, animals, and microorganisms. They interact through various ecological relationships.
  • Abiotic Factors: These are non-living elements, such as climate, temperature, sunlight, soil conditions, and inorganic substances. Abiotic factors influence the distribution and behavior of biotic factors.
• Functions:
  • Energy Flow: The primary source of energy for ecosystems is the sun. Producers, like green plants, capture solar energy through photosynthesis. This energy is transferred through various trophic levels as consumers feed on one another.
  • Material Cycles: Nutrient cycles like the carbon, nitrogen, and water cycles ensure the availability of essential elements for living organisms.
  • Ecological Adaptation: Different ecosystems exhibit varying ranges of environmental conditions, and various species adapt to these conditions through evolution.

Biotic and abiotic factors interact in intricate ways, influencing the ecosystem's stability, diversity, and ecological processes.

Q2: Explain the importance of the water cycle in maintaining life on Earth, emphasizing its impact on ecosystems.
Ans: The water cycle, also known as the hydrologic cycle, is of paramount importance in maintaining life on Earth, and its impact on ecosystems is profound.
Here's why:

• Essential for Life: Water is a fundamental requirement for all living organisms. It is involved in various biological processes, including photosynthesis, respiration, and digestion. Without a continuous water supply, life as we know it would not be sustainable.
• Ecosystem Health: Ecosystems rely on the water cycle to maintain their health and function. Water sustains plant life, providing them with the necessary moisture for growth. Plants, in turn, support herbivores, which are essential for the food web. The water cycle also maintains wetlands and aquatic ecosystems, providing habitats for diverse species.
• Climate Regulation: The movement of water through the atmosphere and across the Earth's surface helps regulate climate. Evaporation cools the environment, and condensation forms clouds, influencing local and global weather patterns.
• Purification: The water cycle acts as a natural purification system. Water evaporates, leaving behind impurities, and condenses into clean freshwater. This process helps maintain water quality in ecosystems.
• Sustainability: The water cycle ensures the sustainable use of water resources. It replenishes groundwater, fills lakes and rivers, and provides water for agriculture and human consumption.

In summary, the water cycle is essential for the functioning and survival of ecosystems and is crucial for the sustainability of life on Earth.

Q3: Describe the role of the carbon cycle in supporting life and influencing climate.
Ans: The carbon cycle plays a pivotal role in supporting life and influencing climate on Earth.
Here's how it functions:

• Life Support: Carbon is a fundamental element in all living organisms. Green plants, through photosynthesis, convert atmospheric carbon dioxide (CO₂) into carbohydrates, like glucose. These carbohydrates serve as a source of energy and as structural components for plant tissues. Animals, in turn, consume these carbohydrates.
• Energy Transfer: Carbon compounds produced during photosynthesis are essential for the energy transfer between trophic levels. Herbivores consume plants, carnivores consume herbivores, and so on. This transfer of carbon compounds ensures the flow of energy through ecosystems.
• Climate Influence: The carbon cycle is intimately linked to climate regulation. The accumulation of excessive CO₂ in the atmosphere contributes to the greenhouse effect, trapping heat and leading to global warming. Thus, human activities that release more CO₂, such as burning fossil fuels, have significant climate implications.
• Carbon Sequestration: Natural systems, like forests and oceans, act as carbon sinks, sequestering carbon and helping mitigate the greenhouse effect. Trees, for instance, store carbon in their biomass and in soil.

The carbon cycle's balance is crucial for life on Earth and the regulation of global climate. Disruptions to this cycle, such as increased carbon emissions, can have adverse effects on ecosystems and climate patterns.

Q4: Explain the significance of ecological balance in maintaining the stability and health of ecosystems, providing examples where necessary.
Ans: Ecological balance is critical for maintaining the stability and health of ecosystems. It ensures that the diverse living organisms within an ecosystem coexist harmoniously and thrive.
Here's why ecological balance is significant, with examples:

• Population Control: Ecological balance regulates the populations of different species. For example, in a grassland ecosystem, herbivorous animals like deer, zebras, and buffaloes are kept in check by carnivorous animals like tigers and lions. This prevents overgrazing and overpopulation.
• Biodiversity Maintenance: Ecological balance supports biodiversity by preventing the dominance of a single species. In a coral reef ecosystem, various species of fish, corals, and other marine life coexist, creating a diverse and resilient ecosystem.
• Ecosystem Resilience: A balanced ecosystem is more resilient to environmental changes. For instance, in a forest ecosystem, diverse plant species can adapt to disturbances and natural succession, maintaining the ecosystem's health.
• Food Web Stability: Complex food webs in ecosystems help maintain stability. In a wetland ecosystem, numerous species of insects, frogs, and birds interact in a web of dependencies, ensuring that no one species disrupts the entire ecosystem.
• Human Benefits: Ecological balance benefits humans by providing ecosystem services like clean air, water purification, and pollination. For example, bees play a crucial role in pollinating plants, supporting agriculture.

Ecological balance is essential for the functioning and sustainability of ecosystems, promoting the well-being of both the environment and its inhabitants.