CBSE Solutions Class 12 Biology Chapter 12 Ecosystem

*As per the revised curriculum of CBSE Syllabus 2023-24, this chapter, previously known as Chapter 14, has now been renumbered as Chapter 12. Stay updated with the latest changes in the curriculum.

Ecosystem Class 12 NCERT Solution is all about the different components of the ecosystem, and how they interact with each other. These NCERT Solutions are prepared by our Top Biology Experts in order to take care of all Important Topics that might be asked in the upcoming examination 2023. So, Students can also refer to these solutions for their final Examination preparation.

These CBSE Class 12 Biology Chapter 12 Ecosystem NCERT Solutions are carefully developed using easy-to-understand language while adhering to the guidelines for solving NCERT Solutions for Class 12. Working through these solutions can be highly beneficial for students in their board exams, as well as in preparing for future competitive Exams.

Ecosystem Class 12 Questions and Answers

NCERT Solutions for Class 12 Ecosystem explains the role of an Ecosystem varies greatly in size from a small pond to a large forest or a sea. An ecosystem is a functional unit of nature and comprises abiotic and biotic components. Revise the basic concept of the Ecosystem for quick revision and class notes.

Q1: Fill in the blanks.

• (a) Plants are called ———- 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 productivity is ———
• (d) Common detritivores in our ecosystem are ———
• (e) The major reservoir of carbon on earth is ——-

Answer:

• Plants are called Autotrophs because they fix carbon dioxide. Autotrophic nutrition is a process in which organisms produce their own food from simple inorganic materials such as carbon dioxide, water, and mineral salts in the presence of sunlight.
• In an ecosystem dominated by trees, the pyramid (of numbers) is Inverted type because when the ecosystem is dominated by trees, the number of animals like insects and birds is much higher than the number of trees. It is because a single tree is home to many insects and birds.
• In aquatic ecosystems, the limiting factor for productivity is light. It is because plants and algae cannot grow in the absence of sunlight.
• Common detritivores in our ecosystem are earthworms. It is because they get nutrients from decaying organic matter.
• The major reservoir of carbon on Earth is Ocean. The deep trenches in the ocean and water in the ocean have rich dissolved carbon, the nutrient leaching and precipitation which occur in the ocean play a major role in making the ocean the large reservoir of carbon.

Q2: Which one of the following has the Largest Population in a Food chain?

• (a) Producers
• (b) Primary consumers
• (c) Secondary consumers
• (d) Decomposers

Answer:

Correct option (c) Decomposers are the largest population in a food chain because they decompose the organic matter, releasing carbon and other benefits for their growth as well as the development of plants.

 Q3: The Second Trophic Level in a Lake is

• (a) Phytoplankton
• (b) Zooplankton
• (c) Benthos
• (d) Fishes

Answer:

The correct option is (b) Zooplankton is the second tropic level in the lake because Zooplankton is the primary consumer in the aquatic food chain that feed upon phytoplankton that is why they are present at the second tropic level in a lake.

Q4: Secondary producers are

• (a) Herbivores
• (b) Producers
• (c) Carnivores
• (d) None of the above

Answer:

The correct option is (a) Secondary producers are Herbivores. Herbivores are those which feed on trees, fruits, plants and it is a food for predators.

Q5: What is the Percentage of Photosynthetically active radiation (PAR) in the incident Solar Radiation?

• (a) 100%
• (b) 50 %
• (c) 1-5%
• (d) 2-10%

Answer:

The correct option is (b) 50% of the total radiation from sunlight falls under photosynthetically active radiation and supports the process of photosynthesis. It constitutes the light of 400- 700 nm wavelength which is absorbed by chlorophyll pigment and only 2 -10% are captured by plants.

Q6: 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

Answer:

• (a) Grazing food chain and detritus food chain

Grazing food chain	Detritus food chain
It starts with the primary producer which is a plant.	It proceeds from dead bodies and organic remains.
It is comparatively less energy flow.	Much large amount of energy flows from it.
It binds to inorganic nutrients.	It releases the inorganic nutrients bound in organic matter.
The food chain is usually large.	It is usually smaller as compared to the grazing food chain.

• (b) Production and decomposition

Production	Decomposition
It is performed by autotrophs or plants.	It is performed by derive and saprophytes.
Sunlight is required by the plant for primary production.	Sunlight is not required for decomposition by decomposers.
It depends on the photosynthetic capacity of the producers.	It occurs with the help of decomposers.
Example- plant	Examples- bacteria, fungi

(c) Upright and inverted pyramid

Upright	Inverted pyramid
The number of consumers decreases and becomes least towards the apex.	The number of consumers decreases and becomes largest in the top of the consumers.
The pyramid of energy is always upright.	The pyramid of biomass and the pyramid of numbers can be inverted.
In the upright pyramid, the number and biomass of the producer level is the highest.	In the inverted pyramid, the number and biomass of the producer level is the lowest.
Examples – grassland and cropland ecosystem	Example – tree ecosystem

• d) Food chain and Food web

Food chain	Food web
It is the flow of energy through a single straight pathway from the lower tropic level to the higher tropic level.	It is the multiple linked food chains through which the flow of energy happens in the ecosystem.
Food chains include 4-6 trophic levels of different species.	The food web includes multiple tropic levels of different populations of species.
The food chain consists of only one straight chain.	The food web consists of many interconnected food chains.
Examples- food chain in a grassland ecosystem	Examples- food web of a grassland ecosystem

• (e) Litter and detritus

Litter	Detritus
Litter consists of all kinds of wastes generated by human activity above the ground.	Detritus is composed of the remains of dead plants and animals.
It is above the ground.	It can be both above the ground or below the ground.
The litter contains both biodegradable and non-biodegradable matter.	Detritus contains only biodegradable matter.

• (f) Primary and secondary productivity

Primary productivity	Secondary productivity
It is the rate at which organic matter is built up by producers.	It is the rate at which organic matter is built by consumers.
Generally, Primary productivity is very high.	Generally, secondary productivity is very low and also decreases at each tropic level.
It is due to photosynthesis.	It is due to the herbivory and predation.
The productivity of autotrophs, such as plants is called primary productivity.	The productivity of heterotrophs, such as animals is called secondary productivity

Q7: Describe the components of an ecosystem.

ANSWER:

There are two components of an ecosystem.

1. Biotic components (all living organisms) such as fungi, bacteria, animals, plants, etc. There are three types of biotic components:
   1. Producer: it includes trees that fulfill all the requirements of other organisms for food and oxygen.
   2. Consumers: it includes carnivores, herbivores, and omnivores
   3. Decomposers: Also known as Saprophytes. They are the organism that feeds on the dead and decay and convert them into organic compounds.
2. Abiotic components (non-living organisms) like water, light, temperature, humidity, soil, nutrients, etc. affect in the terms of growth, development, reproduction, and maintenance. all these are also known as ecological factors. factors. There are three types of abiotic components:
   1. Edaphic factors: it means floor or ground surface.
   2. Topographic Factors: include surface exposure altitude, slope, etc.
   3. Climate Factors: based on the atmosphere and include light, temperature, humidity, and wind.

Q8: Define Ecological Pyramids and describe with examples, Pyramids of number and biomass.

Answer:

An ecological pyramid is a graphical representation of the relationship between organisms of different tropic levels that can be expressed in terms of number, biomass, or energy. For example, in the grassland of the ecosystem, the number of plants is the highest and followed by the primary consumer which is mice.

In most ecosystems, the pyramid of numbers is upright that is producers are more in number than herbivores, and herbivores are more in number than carnivores but, the pyramid can be inverted as in a forest, where the number of insects (primary consumers ) is greater than the number of trees (producers).

The pyramid of biomass represents the amount of biomass produced at each tropic level and it is also upright, generally, as the biomass of producers is more than the herbivores and that of herbivores is more than the biomass of carnivores. But it is inverted in many ecosystems like in sea ecosystem like in sea ecosystems, where the biomass of fishes (primary consumers) far exceeds that of phytoplankton (producers).

Q9: What is Primary productivity? Give a brief description of Factors that affect Primary productivity.

Answer:

Primary productivity is defined as the amount of organic matter or biomass produced per unit area over a period of time. Primary productivity has two features: Gross primary productivity and Net primary productivity.

• Gross Primary productivity: Solar energy which trapped by the photosynthetic organism or overall rate of energy capture is known as gross primary productivity. It depends upon the photosynthetic activity and environmental factors.
• Net Primary Productivity: It is the rate at which the energy is stored as biomass by plants or primary producers and made available to the consumers in an ecosystem.

NPP= GPP Energy is lost in respiration.

Factors influencing primary productivity are:

• Temperature; It controls the enzyme-mediated dark reaction of photosynthesis.
• The availability of nutrients and the photosynthetic capacity of plants can influence the rate of primary productivity.
• Species succession is the regulating factor.

Q10: Define Decomposition and describe the Processes and products of Decomposition.

Answers:

Decomposition is the process of breakdown of complex organic matter into inorganic substances so that they can be reused. The steps which are involved in decomposition are;

• Fragmentation
• Leaching
• Catabolism
• Humification
• Mineralization

Products of decomposition are carbon dioxide, water, and nutrients, Examples are nitrogen, calcium, potassium, etc.

Q11: Give an account of Energy Flow in an Ecosystem.

Answers:

The energy flow in an ecosystem takes place in the Food web and Food chain. In this process, the energy flow in the ecosystem, plant being the producers and absorbing the sunlight with the help of the chloroplast, and a part of it is transformed into chemical energy in the process of photosynthesis.

Key Features of NCERT Solutions Class 12 Biology Chapter 12 Ecosystem

• They enhance the conceptual knowledge of the students.
• Clear and Comprehensible Content.
• Aid in Competitive Exam Preparation.
• The answers are provided by Top subject experts.
• Readily available and easily accessible.

FAQs on Ecosystem Class 12 NCERT Solution

Q1: What is the name of chapter 12 of NCERT class 12 Biology?

Answer:

Class 12 Biology Chapter 2 name is Ecosystem which explains all the components and their interaction with each other, biodiversity, and its conservation.

Q2: Where can I find NCERT solutions for Class 12 Biology Chapter 12?

Answer:

NCERT solutions for Class 12 Biology Chapter 12 can be found on various online platforms such as the official NCERT website, GeeksForGeeks, and more.

Q3: Why are NCERT Solutions for Class 12 Biology Chapter 12 beneficial for the students??

Answer:

The benefits of using the NCERT Solutions for Class 12 Biology Chapter 12 are:

1. Completely solved answers for all the questions present in the NCERT textbook are available in PDF format.
2. Simple and easy-to-understand language is used to make learning fun for the students.
3. Top Subject matter experts prepare the solutions after conducting vast research on each concept.
4. The solutions not only help students with their board exam preparation but also for various competitive exams like JEE, NEET, etc.