Ecosystem Mind map for NEET and Class 12 Biology Chapter 14 -
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NCERT Solutions for Class 12 Biology Chapter 14 Ecosystem
1. Fill in the blanks.
(a) Plants are called as————- because they fix carbon dioxide.
(b) In an ecosystem dominated by trees, the pyramid (of numbers) is————- type.
(c) In aquatic ecosystems, the limiting factor for the productivity is————- .
(d) Common detritivores in our ecosystem are————- .
(e) The major reservoir of carbon on earth is————- .
Ans:
(a) Autotrophs
(b) Spindle
(c) Sunlight
(d) Earthworm, bacteria & fungi of decay and vulture
(e) Oceans
2. Which one of the following has the largest population in a food chain?
(a) Producers
(b) Primary consumers
(c) Secondary consumers.
(d) Decomposers
Ans: (d) Decomposers has the largest population in a food chain.
3. The second trophic level in a lake is-
(a) Phytoplankton
(b) Zooplankton
(c) Benthos
(d) Fishes
Ans: (b)
4. Secondary producers are
(a) Herbivores
(b) Producers
(c) Carnivores
(d) None of the above
Ans: (d)
5. What is the percentage of photo synthetically active radiation (PAR), in the incident solar radiation?
(a) 100%
(b) 50 %
(c) 1-5%
(d) 2-10%
Ans: (b)
6. Distinguish between
(a) Grazing food chain and detritus food chain
(b) Production and decomposition
(c) ‘Upright and inverted pyramid
(d) Food chain and food web
(e) Litter and detritus
(f) Primary and secondary productivity
Ans. (a) Grazing food chain (GFC) starts with producers or plants. Grazing food chain is the major conduit for energy flow in aquatic ecosystem. The Detritus food chain (DFC) starts with detwitters or the material which is to be decomposed. Detritus food chain is measure conduit for energy flow in terrestrial ecosystem.
(b) Production is the phenomena in which a system produces biomass. Producers like plants and phytoplankton synthesize organic compounds by the process of photosynthesis. Decomposition is the process of breakdown or degradation of something. The substance which is decomposed is called as detritus and the organisms which help in decomposition are known as Detritivores.
(c) The sequence of trophic level in a pyramid from bottom to top is primary producers, primary consumers, secondary consumer and tertiary consumer. When the number of primary producers are more than consumers then the pyramid form is upright. For example pyramid of number in a grassland ecosystem is upright. If the number of primary producers are less than consumers then the pyramid is inverted. For example pyramid of biomass in aquatic ecosystem is inverted.
(d) A food chain shows the path of flow of energy by forming a chain different organism in a sequence. A food chain almost never exists in nature. Food web shows a network of different food chain that are possible in the nature.
(e) Litter is the dead or greater material fallen on the surface of soil, for example leaf and branches fallen from a tree. The Detritus is the substance which is decomposed by various organism. So if the litter remains on the soil, it will start decomposing and will be called as detritus.
(f) Primary productivity is the rate of production of biomass by producers, like plants and phytoplanktons. Secondary productivity is the rate of biomass production by consumers. It is very small compared to primary productivity.
7. Describe the components of an ecosystem.
Ans. The structural component of ecosystem include biotic and abiotic factors. Biotech factor include all living organism of an ecosystem like plants, animals, insects, and decomposers etc. Abiotic components includes factors like temperature, water, sunlight soil, etc.
The functional component of an ecosystem has 4 parts. These are - Productivity, Decomposition Energy flow and Nutrient cycling.
8. Define’ecological pyramids and describe with examples, pyramids of number and biomass.
Ans. Ecological pyramids are used to represent the number, biomass or energy of all organism at different trophic levels. It is the graphical representation of an ecological parameter (number, biomass, energy) sequence wise in various trophic levels of a food chain with producers at the base and herbivores in the middle and carnivores at the top tiers. It can be upright, inverted, or spindle shaped.
9. What is primary productivity? Give brief description of factors that affect primary productivity.
Ans. The rate of production of biomass by primary producers (plants and phytoplankton) is called primary productivity. This biomass is produced by the producers through the process of photosynthesis. Factors affecting primary productivity are -
• Types of plants in an area - Different plants have different photosynthetic capability. So this effects the biomass production of overall area.
• Temperature - temperature also effect biomass production because plants are more productive at their suitable range of temperature.
• Soil - type of soil and amount of nutrients that are present in it also affect primary productivity.
• Sunlight - sense photosynthesis requires sunlight it is also an important factor that affect food production.
10. Define decomposition and describe the processes and products of decomposition.
Ans. The process by which decomposers break down complex organic remains of plants and animals to inorganic substances like carbon dioxide, water and nutrients is called decomposition. The organic remain which is broken down is called detritus. Example - fallen leaf, branch, dead insects etc.
The organisms which help in the process of decomposition are called as Detritivores. These include organisms like earthworm, fungi, bacteria etc.
Process of decomposition - decomposition occurs in five steps. These are fragmentation, leaching, catabolism, humification and mineralisation. Fragmentation includes break breaking of detritus into small particles. By the process of leaching inorganic nutrients go below the layer of soil and get precipitated as unavailable salts. The formation of humus is called humification. The process by which the inorganic nutrients in humus are released into soil is mineralisation.
Products of decomposition include carbon dioxide, water, minerals and nutrients.
Other Questions will be available soon.
An ecosystem is a complex and dynamic network of living things and their environment in which the interactions between them determine the overall structure and functioning. It is a collection of organisms and their environment that interact as a system. Ecosystems are constantly changing, and the maintenance of balance between different species is essential for life.
All ecosystems on our planet depend on the sun for energy. Plants capture this energy from sunlight through photosynthesis and turn it into chemical energy. This energy is then passed through the food chain, from producers to consumers. Producers, such as plants, are able to take energy from the sun and convert it into food. Consumers, such as animals, take energy from the food produced by plants.
Ecosystems also depend on the water cycle for energy. Water evaporates from the ocean and eventually rains back down, providing a source of energy and nutrients for plants and animals. The water cycle also helps to clean the air by taking pollutants out of the atmosphere and depositing them on land and in the ocean.
The climate of an ecosystem can also affect its functioning. Warmer temperatures can cause certain plants and animals to become more active, while colder temperatures can cause some species to become less active or even dormant. The amount of rainfall or snowfall in an area also affects the availability of water and nutrients in an ecosystem.
Ecosystems can be small, such as a pond, or large, such as a rainforest. All ecosystems are connected, and changes in one can impact the others. For example, deforestation can lead to increased temperatures and decreased rainfall in nearby ecosystems. Therefore, it is important to protect and conserve all ecosystems, as they are essential for the survival of all life on Earth.
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