Get summay, questions, answers, solutions, notes, extras, PDF, competency-based questions of chapter- 2/unit I, Ecological Concept: AHSEC Class 11 Environmental Education, which is part of the present syllabus. These solutions, however, should only be treated as references and can be modified/changed.
Summary
Ecology is the study of how living things interact with each other and their natural home, or environment. It looks at the connections between all parts of nature, including plants, animals, and micro-organisms. There are many connections between the different parts of nature. For example, a plant takes water and nutrients from the soil to grow. An animal like a deer might eat the plant. When the deer dies, tiny organisms like bacteria and fungi break down its body. This process returns nutrients like nitrogen and carbon back to the soil, which helps new plants grow.
To understand ecology, we can look at different levels of organization. The smallest level is an organism, which is any single living being. A group of similar organisms that can breed together is called a species. A group of the same species living in one area is a population. Many different populations living and interacting in the same area form a community. When you include the community and the non-living things around it, like soil, water, and sunlight, you have an ecosystem.
Ecosystems can be natural or artificial. Natural ecosystems, like forests or oceans, exist without human help. Artificial ecosystems, such as farms or man-made ponds, are created by people and need human care to stay in balance. Every ecosystem has living parts, called biotic components, and non-living parts, called abiotic components. The living parts are grouped by how they get food. Producers, like plants, make their own food using sunlight. Consumers get their food by eating other living things. Animals that eat plants are herbivores, while those that eat other animals are carnivores. Decomposers break down dead plants and animals.
Energy moves through an ecosystem in a food chain, which shows who eats whom. For instance, grass is eaten by a grasshopper, which is then eaten by a bird. Many food chains connected together form a food web. A food web is like a spider’s web because it shows many different paths for energy, as most animals eat more than one type of food. Each step in a food chain is a trophic level. Plants are the first level, herbivores are the second, and so on. We can draw these levels as an ecological pyramid, which shows how the amount of energy decreases at each higher level.
Textual/Exercise
1. Define the term ecology.
Answer: The word ‘ecology’ is derived from the Greek words oikos (means- home) and logos (means – study). So ecology deals with the study of organisms in their natural homes interacting with their surroundings or environment. In other words, ecology is the study of the interconnections and interdependence of plants, animals and their environment.
2. What do you mean by ecosystem?
Answer: An ecosystem is a community of organisms involved in a dynamic network of biological, chemical and physical interactions between themselves and with the non-living components. Such interactions sustain the system and allow it to respond in changing conditions. Thus, an ecosystem includes the biological components, the non-living components (physical environment) and their interactions.
3. Classify the ecosystems.
Answer: Ecosystem is of two major types:
a) Natural ecosystem
b) Artificial or man-made ecosystem
Natural ecosystem is again divided into:
a) Terrestrial ecosystem (for example – forest ecosystem, grassland ecosystem, desert ecosystem) and
b) Aquatic ecosystem, which can be fresh water ecosystem and marine ecosystem.
Man-made ecosystems are created by man. For example – cropland ecosystem, fisheries etc.
4. What are lotic and lentic ecosystems ? Give examples.
Answer: A fresh water ecosystem may be lotic, which is a free flowing type, for example, rivers. A lentic ecosystem is a standing type, for example, ponds and lakes.
5. What are producers, consumers and decomposers ?
Answer: Producers are known as autotrophs. They can produce their food themselves by making use of carbon dioxide present in air and water in the presence of sunlight by involving chlorophyll, through the process of photosynthesis. Some micro-organisms can also produce organic matter through oxidation of certain chemicals in the absence of sunlight.
Consumers are known as heterotrophs. They cannot produce their food by themselves and get their organic food from the producers. The animals that consume the producers either directly or indirectly are called macro consumers.
Decomposers are micro consumers. They are certain living organisms that derive their nutrients by decomposing or breaking down dead plants and biotic compounds in the environment. Examples include bacteria and fungus.
6. Write briefly on structure and functions of an ecosystem.
Answer: The structure of an ecosystem is constituted by the composition and organization of its biotic and abiotic components. The biotic structure is formed by the plants, animals, and micro-organisms present in the ecosystem. The abiotic structure is constituted by the physical and chemical components. This includes physical factors like sunlight, temperature, and rainfall, as well as soil factors. Chemical components include major nutrients like carbon and nitrogen, and compounds like carbohydrates and proteins present in soil and water.
The function of an ecosystem is performed in a systematic way under natural conditions. It receives energy from the sun and passes it to different components at different levels. The function of an ecosystem can only be considered as a whole, as every part has a functional effect on another. The major functional characteristics of an ecosystem may be described in terms of food chain, food webs and trophic levels, energy flow, and nutrient cycles.
7. What are food chain and food web ?
Answer: In an ecosystem, the sequential chain of eating and being eaten is called a food chain.
A food web is a network of food chains where different types of organisms are connected at different trophic levels. A number of food chains interwoven with one another give rise to interlocking patterns, which are called food webs. This provides a number of options for eating and being eaten at each trophic level.
8. What is trophic level.
Answer: Every organism in an ecosystem can be assigned a feeding level, referred to as the trophic level. The living organisms which derive energy from the same source are said to belong to the same trophic level. For example, green plants are in the first trophic level (producers), herbivores are in the second trophic level (primary consumers), and carnivores are in the third (secondary consumers), and so on.
9. What do you mean by ecological pyramids? Name the different types of ecological pyramids.
Answer: The graphical representation of the trophic structure and functions of an ecosystem with producers at the base and successive trophic levels of consumers forming the higher layers (apex) is known as ecological pyramids.
The three basic types of ecological pyramids are:
- The pyramid of numbers: Here the numbers of individual organisms are depicted.
- The pyramid of biomass: This is based on the total dry weight or other measures of the total amount of living matter.
- The pyramid of energy: In this pyramid, the energy assimilated and/or productivity at successive trophic levels is shown.
10. Mention the main characteristics of food chain and food web.
Answer: The main characteristics of a food chain are that it is a sequential chain of eating and being eaten, and it is always unidirectional. There are two types: the grazing food chain, which starts from green plants, and the detritus food chain, which starts with detritus produced by green plants.
The main characteristics of a food web are that it is a network of several interconnected and interwoven food chains. It shows the feeding relationships in an ecosystem where different organisms are connected at different trophic levels, providing a number of options for eating and being eaten.
Extra/additional questions and answers
1. From which Greek words is the term ‘ecology’ derived?
Answer: The term ‘ecology’ is derived from the Greek words oikos and logos. ‘Oikos’ means home, and the Greek word ‘logos’ means study.
48. Write a short note on Ecological Pyramids.
Answer: The graphical representation of the trophic structure and functions of an ecosystem with producers at the base and successive trophic levels of consumers forming the higher layers (apex) is known as ecological pyramids. Ecological pyramids are of three basic types: the pyramid of numbers, the pyramid of biomass, and the pyramid of energy. Ecological pyramids are used for comparing biomass and energy flow between trophic levels. Such comparisons can be used for identifying or comparing which ecosystems and communities are more efficient in terms of energy transfer.
Extra/additional Fill in the Blanks
1. The word ‘ecology’ is derived from the Greek words oikos and ______
Answer: logos
25. The pyramid of ______ is based on the total dry weight or total amount of living matter.
Answer: biomass
Get notes of other classes and subjects