NCERT Solutions Class 12 Biology Chapter 14

NCERT Solutions for Class 12 Biology Chapter 14

Biology is a vast science that studies life in various sizes, from single molecules to complexed species to the entire ecosystems. Biologists can work in all these domains of study and applied sectors such as health and medicine, environmental protection, education, and various other fields. Furthermore,  Ecology is the study of how organisms interact with their surroundings..

The Chapter 14 of Class 12 is ‘’Biology is Ecosystem’’. Ecosystem Structure and Function, Productivity, Decomposition, Energy Flow, Ecological Pyramids, Ecological Succession, Nutrient Cycling, and Ecosystem Services are all discussed in this chapter. 

Some students find Biology to be a complex and lengthy subject. A topic such as an Ecosystem can be  a bit vast. For this reason, Extramarks has come up with Class 12 Biology Chapter 14 NCERT Solutions; these solutions comprehensively include  precise & important information of the chapter . After significant research, the subject matter experts of Extramarks have prepared  Chapter 14 Biology Class 12 NCERT Solutions. 

Apart from this , Extramarks is a powerhouse of quality study material. Material such as NCERT books, CBSE revision notes, CBSE sample papers, CBSE previous year question papers, and more can be easily found on the Extramarks’ website for all classes.

Key Topics Covered in NCERT  Solutions for  Class 12  Biology Chapter 14

Mentioning below all the key topics that are covered in NCERT Solutions for Class 12 Biology Chapter 14- Ecosystem: 

These topics help students comprehend the different shades and complexity of the Earth’s current Ecosystems. Also, this is one of the most critical and high-scoring topics in the Class 12 Biology syllabus. Let us look at Extramarks in-depth information on each subtopic in NCERT Solutions for Class 12 Biology Chapter 14- Ecosystem.

Ecosystem- Structure and Function

NCERT Solutions for Class 12 Biology Chapter 14 explain Ecosystem and biosphere concepts.

The Ecosystem is a natural functional unit in which living species interact with one another and their physical surroundings.

The interaction of biotic and abiotic components will result in a physical structure that is characteristic of each type of ecosystem. Identification and enumeration of different plant and animal species of an ecosystem give its species composition. The vertical distribution of different species occupying different levels is called stratification. For example, trees occupy the top vertical strata or top layer of a forest, shrubs are the second layer and herbs, grasses, etc., occupy the bottom layers. 

The different components of the ecosystem are seen to function as a unit when we consider the below aspects:

1. Productivity; 2. Decomposition; 3. Energy flow; and 4. Nutrient cycling.

To better understand the ethos of an aquatic ecosystem, let us take a small pond as an example. This is fairly a self-sustainable unit and a rather simple example that explains even the complex ecosystem interactions that exist in an aquatic environment. A pond is a shallow water body in which all the above-mentioned four basic components of an ecosystem are well exhibited. The water with all the inorganic and organic substances and the rich soil deposit at the bottom form the abiotic component. The solar rays, the cycle of temperature, day and night length, and other climatic conditions will regulate the rate of function for the pond ecosystem. The autotrophic components consist of the phytoplankton, algae, and marginal plants found at the edges of the pond. Zooplankton, the free-swimming and bottom-dwelling forms, can be considered as the consumers. Bacteria, fungi and flagellates, which are abundant in the bottom of the pond, will be the decomposers.

This pond ecosystem performs all the functions of any ecosystem and of the biosphere as a whole.

Productivity 

A steady supply of solar energy is a necessity for any ecosystem.

Plants create biomass per unit area in each period during photosynthesis, which is referred to as primary production. It is measured in grammes (gm-2) or calories per metre squared (kcal m-2).

Productivity: The rate at which the biomass is produced is defined as Productivity. It is written as gm-2 yr-1 or (kcal m-2) yr-1.

Gross Primary Productivity (GPP): GPP (gross primary Productivity) is the rate at which organic matter is produced during photosynthesis in an ecosystem.

Net Primary Productivity: The net primary productivity (NPP) is defined as gross direct output fewer respiration losses (R) (NPP). 

The net primary productivity is the amount of biomass available for heterotrophs, herbivores, and decomposers to consume.

Secondary Productivity refers to the rate at which consumers create new organic matter.

Plant species and numerous environmental conditions determine the primary Productivity of an ecosystem and hence vary by location.

The yearly net primary production of the biosphere is around 170 billion tonnes (dry weight) of organic matter. Despite covering approximately 70% of the planet’s surface, the production by sea is just about 55 billion tonnes.

In the above section, NCERT Solutions for Class 12 Biology Chapter 14 discusses different topics under Productivity, such as primary Productivity, secondary Productivity and more. Refer to Extramarks to know more about these.

Decomposition 

NCERT Solutions for Class 12 Biology Chapter 14 defines Decomposition as the activity of decomposers on complex organic matter to break it down into simpler inorganic components like carbon dioxide, water, and nutrients.

Steps in Decomposition:

Dead plant remains such as leaves, bark, flowers and dead remains of animals, including faecal matter, constitute detritus, which is the raw material for decomposition. The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification and mineralisation

• Fragmentation: Detritivores break down the trash into smaller particles, known as fragmentation.
• Leaching: Water-soluble nutrients sink to the soil horizon and precipitate as salts that aren’t accessible, known as leaching.
• Catabolism: Catabolism is the degradation of detritus by bacterial and fungal enzymes into simpler inorganic nutrients.
• Humification: Humification is the process of forming and depositing a dark-coloured organic amorphous material known as humus. Humus is extremely resistant to microbial activity and decomposes at a glacial pace. In addition, it works as a nutrition reservoir because of its colloidal nature.
• Mineralisation: Mineralisation is when some bacteria break down humus further to produce simple inorganic nutrients.

Energy Flow

NCERT Solutions for Class 12 Biology Chapter 14 explains that for all ecosystems on Earth, the Sun is the ultimate source of energy (except for the deep-sea hydrothermal Ecosystem).

PAR (Photosynthetically Active Radiation): Solar radiation plants may be used for photosynthesis. Only half of all incidents of solar energy are PAR. Plants can only catch 2-10 per cent of the PAR, yet this energy keeps entire life on Earth alive.

The energy from the Sun goes unidirectionally from the Sun to the producers and then to the consumers. As a result, all species rely on the Sun directly or indirectly. Therefore, the First and Second Laws of Thermodynamics apply to all ecosystems.

• The first law of Thermodynamics: States that energy may be changed from one form to another in the presence of work, heat, and internal energy but that it cannot be generated or destroyed under any conditions.
• The second law of Thermodynamics: The Second Law of Thermodynamics says that the entropy of the entire universe, seen as an isolated system, will constantly rise with time. The second law states that changes in the entropy of the cosmos can never be negative.

Ecosystems require a steady energy source to create the chemicals they need to combat the general trend toward greater disorderliness.

The food chain serves as a conduit for energy transfer in the environment.

All green plants in the environment use solar energy for photosynthesis. Therefore, they are usually obligate autotrophs.

Producers: All green plants which synthesise their own food through photosynthesis using  solar energy are called producers . They are autotrophs.

Consumers: All heterotrophs that rely on plants for nutrition, whether directly or indirectly, are referred to as consumers. Organisms are classified as primary, secondary, tertiary, or quaternary based on their position in the food chain.

The Grazing Food Chain (GFC) is the primary energy channel in an aquatic environment. However, a substantially more significant portion of energy passes through the detritus food chain (DFC) in a terrestrial environment than the GFC. Students can visit Extramarks website or app to get detailed information on DFC and other components.

Ecological Pyramids

NCERT Solutions for Class 12 Biology  Chapter 14 states that a graphical depiction of the interaction between different creatures in an environment is an ecological pyramid.

Each trophic level, as well as its order, is represented by a bar on the pyramid. The sequence is determined by who is being eaten. This is a representation of energy flow.

The producers or first trophic level are represented at the base of each pyramid, while the tertiary or top-level consumers are shown at the apex of the pyramid. .

The following are the three most widely researched ecological pyramids:

• Pyramid of energy
• Pyramid of number
• Pyramid of biomass

NCERT Solutions for Class 12 Biology Chapter 14 discuss that a single creature can be a component of many food chains and hence, belongs to multiple trophic levels. In most ecosystems, the biomass, energy, and number of pyramids are upright. The producers outnumber the herbivores, the herbivores outnumber the carnivores, and so on.

The number and biomass pyramids can be inverted in rare circumstances, but the energy pyramid is always upright. This is because some energy is wasted as heat when it moves from one level to another.

Ecological Succession

NCERT Solutions for Class 12 Biology Chapter 14 explains Ecological succession as the gradual change in the composition of an ecological community’s species through time. For example, after a significant extinction, the period might be decades or perhaps millions of years. This transformation happens logically and systematically, in tandem with changes in the physical world.

• Pioneer Species: Pioneer species are species that conquer a barren region.
• Pioneer Community: A pioneer community can infiltrate a barren area.
• Climax Community: The climax community is a community that is almost in balance with its surroundings.
• Sere: From the original pioneer community to the last climax community, a series of ecological communities emerge in a given region.

NCERT Solutions for Class 12 Biology Chapter 14 explains namely two types of Successions:

• Primary succession: The biological and ecological succession of plant life is primary succession. It happens in a situation when a new substrate is being deposited. There are no plants or other creatures on this new substrate. It is also frequently devoid of soil and organic materials. It can be found on land following a lava flow or in the region left behind by a receded glacier where no organisms ever exited, like a bare rock
• Secondary succession: Secondary succession is a natural and ecological plant succession that occurs in a previously occupied ecosystem that has been disrupted or degraded. Regions where vegetation has been eradicated, for example (due to tree-felling in a woodland or destructive events such as fires).

Nutrient Cycling

NCERT Solutions for Class 12 Biology Chapter 14 says that Nutrient cycling is the flow of nutrients through the many components that make up an ecosystem. It’s also called biogeochemical cycles (bio: living organism, geo: rocks, air, and water).

Types of the nutrient cycle:

• Gaseous
• Sedimentary

The reservoir for gaseous nutrient cycles  (carbon and nitrogen), lies in the atmosphere  Whereas for  the sedimentary nutrient cycle (sulphur, phosphorus, etc.) the reservoir is in  the Earth’s crust. Environmental variables control the rate at which nutrients are released into the atmosphere. The reservoir works to compensate for the shortfall caused by an imbalance in input and outflow.

Ecosystem Services

Ecological services are the effects or outcomes of ecosystem activities.

NCERT Solutions for Class 12 Biology Chapter 14 explains that the Healthy Forests Ecosystems provide the following services:

• Air and water purification
• Drought and flood mitigation.
• Nutrient cycling is essential.
• Fertile soils are created.
• Providing wildlife with habitat.
• Biodiversity preservation
• Crop pollination is the process of transferring pollen from one plant to another.
• To provide a carbon storage facility.
• Aesthetic, cultural, and spiritual qualities are provided.
• The cost of these ecosystem services is estimated to be US $ 33 trillion per year on average. This is about twice the size of the world’s gross domestic product (US$ 18 trillion).

NCERT Solutions for Class 12 Biology Chapter 14 Exercise and Solutions

Extramarks’ website and app provides students with abundant quality study material. This website has proven to be a one-stop solution for students of all classes. Click on the below links to view NCERT Solutions for Class 12 Biology Chapter 14:

Students may access NCERT Solutions for Class 12 Biology Chapter 14 and other chapters by clicking here. In addition, students can also explore NCERT Solutions for other classes below.

Students can easily understand all the Ecosystem concepts by getting access to NCERT Solutions for Class 12 Biology Chapter 14.

Key Features of NCERT Solutions for Class 12 Biology Chapter 14

As discussed above, Extramarks is a one-stop solution for students of all classes. There are various platforms in the market, but Extramarks manages to stand out because of its high-quality educational content. Here are  some more reasons for choosing Extramarks:

• Extramarks NCERT Solutions are exclusively and authentically produced for students by subject specialists.
• These solutions have been prepared to keep in mind all the guidelines laid by CBSE .
• These  solutions help students in revising their concepts through detailed answers of the chapter end questions. By this, they also get a fair idea of how to attempt questions in exams and how to manage time efficiently. .