BSEB Class 12 Biology Ecosystem Textbook Solutions PDF: Download Bihar Board STD 12th Biology Ecosystem Book Answers

BSEB Class 12 Biology Ecosystem Textbook Solutions PDF: Download Bihar Board STD 12th Biology Ecosystem Book Answers

BSEB Class 12th Biology Ecosystem Textbooks Solutions and answers for students are now available in pdf format. Bihar Board Class 12th Biology Ecosystem Book answers and solutions are one of the most important study materials for any student. The Bihar Board Class 12th Biology Ecosystem books are published by the Bihar Board Publishers. These Bihar Board Class 12th Biology Ecosystem textbooks are prepared by a group of expert faculty members. Students can download these BSEB STD 12th Biology Ecosystem book solutions pdf online from this page.

Bihar Board Class 12th Biology Ecosystem Textbooks Solutions PDF

Bihar Board STD 12th Biology Ecosystem Books Solutions with Answers are prepared and published by the Bihar Board Publishers. It is an autonomous organization to advise and assist qualitative improvements in school education. If you are in search of BSEB Class 12th Biology Ecosystem Books Answers Solutions, then you are in the right place. Here is a complete hub of Bihar Board Class 12th Biology Ecosystem solutions that are available here for free PDF downloads to help students for their adequate preparation. You can find all the subjects of Bihar Board STD 12th Biology Ecosystem Textbooks. These Bihar Board Class 12th Biology Ecosystem Textbooks Solutions English PDF will be helpful for effective education, and a maximum number of questions in exams are chosen from Bihar Board.

Bihar Board Class 12th Biology Ecosystem Books Solutions

Board	BSEB
Materials	Textbook Solutions/Guide
Format	DOC/PDF
Class	12th
Subject	Biology Ecosystem
Chapters	All
Provider	Hsslive

How to download Bihar Board Class 12th Biology Ecosystem Textbook Solutions Answers PDF Online?

1. Visit our website - Hsslive
2. Click on the Bihar Board Class 12th Biology Ecosystem Answers.
3. Look for your Bihar Board STD 12th Biology Ecosystem Textbooks PDF.
4. Now download or read the Bihar Board Class 12th Biology Ecosystem Textbook Solutions for PDF Free.

BSEB Class 12th Biology Ecosystem Textbooks Solutions with Answer PDF Download

Find below the list of all BSEB Class 12th Biology Ecosystem Textbook Solutions for PDF’s for you to download and prepare for the upcoming exams:

Bihar Board Class 12 Biology Ecosystem Text Book Questions and Answers

Question 1.
Fill in the blanks :
(a) Plants are called as producers because they fix carbon dioxide.
(b) In an ecosystem, dominated by trees, the pyramid (of numbers) is inverted type.
(c) In aquatic ecosystems, the limiting factor for the productivity is nitrogen, iron.
(d) Common detritivores in. our ecosystem are earthworm.
(e) The major reservoir of carbon on earth is atmosphere, ocean, fossil fuel.

Question 2.
Which one of the following has the largest population in a food chain?
(a) Producers
(b) Primary consumers
(c) Secondary consumers
(d) Decomposers
Answer:
(a) Producers.

Question 3.
The second trophic level is a lake is …………. .
(a) Phytoplankton
(b) Zooplankton
(c) Benthos
(d) Fishes
Answer:
(b) Zooplankton

Question 4.
Secondary producers are
(a) Herbivores
(b) Producers
(c) Carnivores
(d) None of the above
Answer:
(d) None, of the above.

Question 5.
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:
(b) 50%.

Question 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
Answer:
(a) Grazing food chain and detritus food chain: In grazing food chain, green plants constitute the first step. The plant are producers which are eaten by herbivores (consumers), which are further eaten by carnivores (secondary consumers). For e.g. grassland ecosystem-
grasses → herbivores → carnivores

The grazing food chains are directly dependent on solar radiations as a source of energy.
Detritus food chains depend on the dead organic matter, from dead animal bodies or fallen leaves. These do not depend on solar radiations. These start front detritus The detritus is eaten by decomposers like bacteria and fungi. They release the inorganic elements into the ecosystem by breaking down the complex organic matter. For e.g. decomposition of fallen leaves of mangrove trees.

(b) Production and decomposition: Production is the amount of organic matter (biomass) produced per unit area over a period of time. It can be expressed in two ways :
Primary productivity and secondary productivity. Production varies with different ecosystems and climatic conditions.
Decomposition: Decomposition is the process of breaking down a substance into its constituents parts like CO₂.H₂O and nutrients. It is done by decomposers like fungi and bacteria.

(c) Upright and Inverted pyramids: Pyramids of numbers and biomass can be upright or inverted depending upon the number, of producers. For e.g. it will be upright in a pond ecosystem (pyramid of number) and pyramid of biomass will be inverted.

(d) Food chain and Food web :
(i) Food chain is a sequence of populations or organisms of an ecosystem through which the food and energy passes through different trophic levels;
(ii) A food chain is always straight, with unidirectional flow of energy;
(iii) It usually contains 4 or 5 trophic levels, always begins with photosynthesis and ends with decay,
(iv) for e.g.
Grass → grasshopper → frog → snake → peacock

(i) Food web is a network of food chains which become interconnected to form a number of feeding connections between different organisms of a biotic community;
(ii) Food webs are never straight, they provide alternate pathways for food, and help in checking overpopulations;
(iii) Food webs increase the stability of the ecosystem by providing alternate food source and allowing endangered populations to grow in size;
(iv) For e.g. A terrestrial food web.

(b) Litter and detritus: Dead remains of plants and animals are called detritus. Detritus is of two types – Above ground detritus and below-ground detritus. Above ground detritus is made up of dried parts of plants like leaves, bark, flowers etc. and dead remains of animals and their faecal matter which fall on earth’s surface, it is also called as litter. Below ground detritus is made up of dead roots of plants which are below the surface of the soil.

(c) Primary and Secondary productivity:
(i) Primary productivity is the amount of energy accumulation or amount of biomass produced per unit area over a time period;
(ii) It is expressed as gm^-2 yr^-1 or Kcal m^-2 y^-1;
(iii) It is of two types, gross primary productivity (GPP) and net primary productivity (NPP).

They are related as: GPP-R=NPP, where R is respiratory losses.
(i) Secondary productivity is the rate of formation of new organic matter by consumer;
(ii) It is also of two types Gross Secondary productivity (GSP) and Net Secondary Productivity (NSP)
NSP = GSP – R Where R is respiratory losses

Question 7.
Describe the components of an ecosystem.
Answer:
The components of an ecosystem are broadly divided into two types – biotic component and abiotic component. Biotic component contains various kinds of organisms. They are interconnected through food. According to the mode of obtaining food, organisms are categorised into plants (producers), animals (consumers) and microorganisms (decomposers).

Producers make their own food from simple inorganic materials. Plants convert solar energy into chemical energy. Consumers are organisms that depend upon producers for their food. They can be herbivores or primary consumers and carnivores or secondary and tertiary consumers. Decomposers degrade dead organic matter or detritus to obtain energy and nutrients. They replenish the lost nutrients to the ecosystem.

Abiotic components are non-living, physicochemical factors of the environment. They include inorganic substances, organic substances and climatic factors. These abiotic components affect the structure, behaviour and interrelationships of organisms of ecosystem. Inorganic substances include carbon, nitrogen, oxygen, CO₂, water etc., Organic substances are proteins, carbohydrates, lipids, and humic substances, climatic factors include solar radiations, temperature, light and rainfall atmospheric gases and edaphic factors like soil, topography, mineral, pH etc.

Question 8.
Define ecological pyramids and describe with examples, pyramids of number and biomass.
Answer:
Ecological pyramid may be defined as a graphic representation of the numbers or biomass or status of accumulated energy at different trophic levels in a food chain in an ecosystem.
Pyramid of numbers is the graphic representation of the arrangement of number of individuals of different trophic levels in a food chain in an ecosystem. For e.g. in a pond ecosystem, the size of organisms increases with each tropical level and their number decreases i.e. from producer level to top carnivore level:

Fig.: Pyramids of numbers (A) in pond ecosystem; (B) in parasitic food chain Pyramid of biomass is the graphic representation of biomass present per unit area n different trophic levels. Like pyramid of numbers, this can also be upright or inverted. There is gradual decrease in biomass of organisms at successive trophic levels from producers to top carnivores. ,

Question 9.
What is primary productivity? Give brief description of factors that affect primary productivity.
Answer:
Primary productivity is the amount of biomass or organic matter produced per unit area over a period of time by plants during photosynthesis. It is expressed as gm^-2 or energy Kcalm^-2. It is of two types – Gross primary productivity (GPP) is the rate of production of organic matter during photosynthesis. Some amount of GPP is lost in respiration (R). Net primary productivity (NPP) will be GPP – R = NPP.

Primary productivity depends on a variety of environmental factors like sunlight, temperature, rainfall, availability of nutrients and photosynthetic capacity of plants. The productivity increases from polar regions towards the tropics due to increasing sunlight and temperature. Due to lack of nutrients or water also productivity decreases.

Question 10.
Define decomposition and describe the processes and products of decomposition.
Answer:
Decomposition is the process of breaking down a substance into its constituent parts. Decomposition helps to release the nutrients from the dead organic matter.
Dead remains of plants and animals are called detritus. The process of decomposition is complex and involves enzymatic degradation of detritus. It takes place in following steps :
(i) Fragmentation of detritus: Detrivores are microscopic invertebrates which break the detritus into smaller fragments. Fragmentation increases the surface area of detritus particles.

(ii) Catabolism: Decomposers by enzymatic action decompose detritus particles into simpler compounds and inorganic substances.

Humification: By this process, simplified detritus is converted into humus, which is a dark amorphous substance. Human is the reservoir of nutrients, it undergoes extremely slow decomposition.
Mineralisation: k helps to release inorganic substances like CO₂, H₂O and nutrients to the soil.

Question 11.
Give an account of energy flow in an ecosystem.
Answer:
Energy flow in an ecosystem is unidirectional. Sun is the source of energy. Out of total incident solar radiation, only 50% is photosynthetically active radiation (PAR). Plants capture only 2-10% of PAR. All organisms of ecosystem depend upon producers, directly or indirectly, for food. Thus the energy flows from sun to producers to consumers. Producers convert solar energy into chemical energy.

Some of it is used for their growth and metabolism and the rest is lost as heat. The energy stored in the producers is passed to consumers. There is a decrease in useful energy at each trophic level due to respiration loss and heat loss. The unutilised net primary production is converted into dead biomass (detritus) which serves as energy source for decomposers.

Question 12.
Write important features of a sedimentary cycle in an ecosystem.
Answer:
In the sedimentary cycle, the reservoir for the nutrient elements lies in the sediments of the earth. The sedimentary cycles are very slow and less perfect because the element may get locked in the reservoir pool and go out of circulation. For example phosphorus cycle.
Phosphorus is a component of cell membranes, nucleic acids and cellular energy transfer systems. It is a constituent of bones, teeth and shells. Phosphorus also participates in respiration, photosynthesis and other metabolic reactions.

The main reservoir of phosphorus is phosphate rocks and fossil bone deposits. There is.no atmospheric phase in phosphorus cycle. When rocks weathered, some phosphates get dissolved in soil solution which is absorbed by plant roots. Herbivores eat plants and get this phosphorus. Carnivores get it from herbivores. The waste products and dead organisms are decomposed by phosphate-solubilising bacteria and release phosphorus to the environment. A simple model of phorus cycle can be represented as follows :

Question 13.
Outline salient features of carbon cycling in an ecosystem.
Answer:
In the biosphere, the major reservoirs of carbon are atmosphere, ocean and fossil fuels. Carbon availability is a crucial factor in the maintenance of plants and animals die main features of carbon cycle are as follows: Carbon in the form of carbon dioxide is drawn from the biosphere by various activities like
(i) photosynthesis by green plants, around 7 ×10¹³kg carbon is fixed by producers annually, and
(ii) by corals for making calcareous skeletons.

Carbon is added to the biosphere by
(i) respiration in organisms,
(ii) decay of organic wastes and dead organisms,
(iii) burning of fuel,
(iv) weathering of rocks and
(v) by volcanic activities.
Carbon cycle can be thoroughly understood by following representation :

Bihar Board Class 12 Biology Ecosystem Additional Important Questions and Answers

Very Short Answer Type Questions

Question 1.
Name the three major biotic components of an ecosystem.
Answer:
These are plants, animals and micro-organisms.

Question 2.
Why producers are also named transducers?
Answer:
Because they can change radiant or light energy into chemical form.

Question 3.
Define an ecotone.
Answer:
Ecotone is the transitional zone between two vegetation regions.

Question 4.
Define biomass.
Answer:
Biomass is the amount of living material or organic matter present in an organisms, community Or biome.

Question 5.
Name the edaphic factors of an ecosystem.
Answer:
The edaphic factors include those which are connected with soil or substratum like topography, background, mineral elements, pH, etc.

Question 6.
What is a photoperiod?
Answer:
Photoperiod is duration of sunlight in a day.

Question 7.
What are two kinds of decomposers?
Answer:
They are fungi and bacteria.

Question 8.
What are epiphytes? Give example.
Answer:
Epiphytes are plants that grow on trees, e.g. mosses.

Question 9.
Name two types of producers.
Answer:
Photoautotrophs and chemoautotrophs.

Question 10.
What are detrivores?
Answer:
Detrivores are animals which feed on decaying organic matter or dead organisms.

Question 11.
Name two types of biogeochemical cycles with example.
Answer:
Gaseous cycle e.g. carbon cycle and sedimentary cycle e.g. phosphorus cycle.

Question 12.
What are the main sources of carbon?
Answer:
Air, water, fossil fuel and rocks.

Question 13.
Oxygen content of the air is not affected by human activities, why?
Answer:
Because oxygen is replenished by photosynthesis.

Question 14.
What is the life span of the ecosphere?
Answer:
It’s as much as the life span of the sun.

Question 15.
Which regions of the biosphere lack life?
Answer:
Frozen mountain peaks, poles, extremely dry regions, live volcanoes and toxic sea basin.

Question 16.
What is the main source of nitrogen for the plants? How. is nitrogen important for plants?
Answer:
Nitrate ions(NO₃^–)of soil and water, nitrogen is a component of proteins, nucleic acids and energy carriers.

Question 17.
What is Timberline?
Answer:
It lies between 55°- 60° latitude. Beyond this, trees cannot grow.

Question 18.
What are microphytes?
Answer:
Microphytes are phytoplanktons, these are major autotrophs of aquatic ecosystem and are microscopic organisms.

Question 19.
What is Biodeterioration?
Answer:
It’s the unwanted breakdown by micro-organisms of materials like foodstuff, surface coating, rubber and lubricants.

Question 20.
What is a patent?
Answer:
A patent is an official document giving the patent holder, sole rights to make, use or sell an invention and prevent others from imitating it.

Short Answer Type Questions

Question 1.
Why it is difficult to draw sharp boundaries between eco-systems?
Answer:
The different ecosystems do not have sharp boundaries between them. There are present transitional zones, between the adjacent ecosystems. These are called ecotones, these harbours some organisms from each of the adjacent ecosystems and some peculiar to themselves.

Question 2.
What is an ecosystem? How material and energy transformation occurs in an ecosystem?
Answer:
An ecosystem is a structural and functional unit of the biosphere which consists of living organisms and their non-living environment.

Question 3.
Differentiate between Autotrophs and Heterotrophs.
Answer:

AUTOTROPHS	HETEROTROPHS
1. Prepare their organic nutrients themselves.	1. Do not prepare organic nutrients themselves.
2. Get inorganic materials from outside.	2. Get both organic and inorganic materials from outside.
3. Obtain energy from sunlight or inorganic chemical reactions.	3. Obtain energy from organic nutrients.
4. Usually add O2 to the environment.	4. Add CO2 to the environment.
5. Are of 2 types : photoautotrophs and chemoautotrophs.	5. Are of 2 types: phagotrophy and saprotrophs.
6. They are producer organisms.	6. They are consumer organisms.
7. Include plants, some protists and certain bacteria.	7. Include animals, many protists and bacteria and bacteria and fungi of decay.

Question 4.
What are special consumers? Give a brief account.
Answer:
Special consumers are organisms which have special mode of food intake. These may include parasites, double consumers, both producers and consumers and scavengers, (a) Parasites like bacteria, protists and animals may be considered as secondary consumers or some higher-order consumers. (b) double consumers like ants, bear, man. These are omnivores.

They belong to more than one category for e.g. man is a primary consumer when vegetarian and a secondary consumer when non-vegetarian, (c) Both producers and consumers, there are insectivores plants which are producers and secondary consumers. (d) Scavengers or detrivores are animals which feed on decaying organic matter or dead organisms like earthworms, termites, vultures etc.

Question 5.
What is the significance of decomposers?
Answer:
The decomposers are bacteria and fungi who obtain their food from organic molecules of dead producers and consumers and their waste products. The decomposers play an “important role of returning the chemical nutrients to the environment. They also make space for the new producers by consuming the dead and decaying matter, otherwise, all the nutrients would remain locked in the dead remains of plants and animals and will not be available for recreation.

Question 6.
Draw a scheme to show decomposition of detritus.
Answer:
Dead remains of plants and animals are called detritus. The decomposition of detritus is a complex and enzymatic process, that involves step-wise degradation.

Question 7.
What is a food chain? Enlist its important characters.
Answer:
The sequential inter-linking of organisms involving the transfer of food energy from the producers, through a series of organisms is known as a food chain. Its main characteristics are :

• In food chain there occurs repeated eating and it involves nutritive interaction between the living organisms;
• It is always straight;
• It has unidirectional flow of energy;
• It usually contains 4 to 5 trophic levels;
• Mostly 80-90% of energy is lost as heat.

Question 8.
With the help of a generalised scheme show how the biotic components of an ecosystem are related.
Answer:

Question 9.
What is a food web? Give example:
Answer:
Food web is a network of food chains which become inter-connected at various trophic levels to form a number of feeding connections among different organisms of a biotic community. Food webs provide stability to the ecosystem.
For example food web in a pond.

Question 10.
What is photosynthetic efficiency, net production efficiency, Assimilation efficiency and ecological efficiency?
Answer:
1. Photosynthetic efficiency: It is the percentage ratio between gross primary productivity and incident total solar radiation. It generally varies from 1 to 5 per cent.
Photosynthesis efficiency = 𝐺𝑟𝑜𝑠𝑠𝑝𝑟𝑖𝑚𝑎𝑟𝑦𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑣𝑖𝑡𝑦𝐼𝑛𝑐𝑖𝑑𝑒𝑛𝑡𝑡𝑜𝑡𝑎𝑙𝑠𝑜𝑙𝑎𝑟𝑟𝑎𝑑𝑖𝑎𝑡𝑖𝑜𝑛 × 100

2. Net production efficiency: It is the percentage ratio between net primary productivity and gross primary productivity. It is around 50%.
Net production efficiency = 𝑁𝑒𝑡𝑝𝑟𝑖𝑚𝑎𝑟𝑦𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑣𝑖𝑡𝑦𝐺𝑟𝑜𝑠𝑠𝑝𝑟𝑖𝑚𝑎𝑟𝑦𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑣𝑖𝑡𝑦 × 100

Important efficiency measures for consumers include –
1. Assimilation efficiency: It is the percentage ratio between food energy assimilated and food energy ingested at one trophic level.
Assimilation efficiency =𝐹𝑜𝑜𝑑𝑒𝑛𝑒𝑟𝑔𝑦𝑎𝑠𝑠𝑖𝑚𝑖𝑙𝑎𝑡𝑒𝑑𝐹𝑜𝑜𝑑𝑒𝑛𝑒𝑟𝑔𝑦𝑖𝑛𝑔𝑒𝑠𝑡𝑒𝑑 × 100

2. Ecological efficiency: It is the percentage ratio between energy in biomass production at one trophic level and energy in biomass production at previous trophic level. It is also called trophic level efficiency. Energy in biomass production at one trophic level

Ecological efficiency = 𝐸𝑛𝑒𝑟𝑔𝑦𝑖𝑛𝑏𝑖𝑜𝑚𝑠𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛𝑎𝑡𝑜𝑛𝑒𝑡𝑟𝑜𝑝ℎ𝑖𝑐𝑙𝑒𝑣𝑒𝑙𝐸𝑛𝑒𝑟𝑔𝑦𝑖𝑛𝑏𝑖𝑜𝑚𝑎𝑠𝑠𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛𝑎𝑡𝑝𝑟𝑒𝑣𝑖𝑜𝑢𝑠𝑡𝑟𝑜𝑝ℎ𝑖𝑐𝑙𝑒𝑣𝑒𝑙 × 100.

Question 11.
Differentiate between Gaseous cycles and Sedimentary cycles.
Answer:

GASEOUS CYCLES	SEDIMENTARY CYCLES
1. Pertain to gases (C2, N2, O2).	1. Pertain to minerals (Ca, P, S, K, Mg).
2. Have reservoir pool in air or water.	2. Have reservoir pool in rocks.
3. Occur quickly and take less time to complete.	3. Occur very slowly and take a long time to complete.
4. Are relatively perfect systems as the elements remain uniformly in circulation.	4. Are less perfect systems as the elements get locked in reservoir pool for long periods.

Question 12.
What is greenhouse effect? How it is produced?
Answer:
The occurrence.of higher temperature inside a greenhouse than outside, even though the interior receives less solar radiation, is called greenhouse effect. The glass walls of greenhouse and high CO₂ content and high water vapour content inside the greenhouse let the short-wave solar radiation enter but stop the exit of longwave radiation entitled by the earth’s surface. This makes the greenhouse air warmer than outside air.

Question 13.
Industries can cause rise and fall in the temperature of biosphere. How?
Answer:
Industries add CO₂ and particulate matter to the air. The CO₂ acts as a greenhouse gas arid increases the temperature of the air, whereas the particulate matter decreases the amount of sunlight reaching the earth and reduces the temperature on earth.

Question 14.
Due to uncontrolled excessive hunting, the population of tigers in a forest becomes zero. Discuss the long-term effect of this situation on the population of deer in that forest. (C.B.S.E. 2005)
Answer:
In a forest ecosystem the food chain occurs like this: Grass → Deer → Tiger
As a result of excessive hunting, the tiger population in a forest becomes zero. This will lead to an increase in the population of deer. Consequently, the amount of grass in the forest decreases. In long term, is such a situation exists it will be a decrease in deer population due to competition among deer for grass. Due to excessive grazing, the forest may turn into a desert after a long time.

Question 15.
Why soil is rich in nutrients in the tropical rain forests?
Answer:
Soil in tropical rain forests is rich in minerals and humus because the high temperature and moisture are favourable for the decomposition of fallen leaves and dead organic matter by the decomposers.

Long Answer Type Questions

Question 1.
Describe a biotic community (near your home or school) stating the relationships that exist between the common species comprising it.
Answer:
Biotic community: It includes all the living things present in a particular area having various food relationships. Abiotic community is organised into three kinds of living things producers, consumers and decomposers. All ‘the three interact with each other in relation to their food and dependent upon each other for their food. Now let us take the example of a biotic community i.e. pond found near the vicinity of the school.

In the pond we can identify all the three components mentioned below:
1. Autotrophs: These are green plants which grow and live in water. The common examples of autotrophs (green plants) found in a freshwater pond are: Hydrilla Vallisneria, water weeds, lotus and other Species of aquatic plants ese plants capture the sun’s energy (high energy) and with the help in their green parts produce food with the help of CO₂ and H₂O. This process is called photosynthesis. These plants manufacture their food themselves, so they are termed as autotrophs.

2. Consumers: Consumers present in the pond are small animals, insect larvae, Cyclops, protozoan, snails. These organisms feed on aquatic plants and get their energy. On these small animals, feed bigger fishes which form consumer No. 3, finally, birds, mammals and even man feed on them.

3. Decomposers: These are microorganisms such as bacteria and fungi which help in the decay of dead living things (organic matter). These help in the recycling of the materials in the biosphere.

Question 2.
Give an account of factors affecting rate of decomposition.
Answer:
Factors affecting decomposition: Rate of decomposition of detritus is regulated by climatic factors and chemical quality of detritus. The key role is played by temperature and soil moisture through their regulatory effect on the activities of soil microbes. Detritus decomposes are rapidly, within a few weeks or month, in a climate characterized by higher temperature (>25°C) and moist conditions (e.g. in humid tropical regions. Low temperature (<10°C) sharply reduces decomposition rate even if moisture is in plenty.

In regions of high latitude (or altitude) complete decomposition of detritus can take several years or decades. The composition rate is low under prolonged soil dryness even if the temperature remains high as in tropical deserts.

Accumulation of some substance in the detritus increases decomposition rate. Chemical quality of detritus is determined by the relative proportions of water-soluble substances, sugars, polyphenols, lignin and nitrogen. Under same climatic conditions, decomposition rate is slower if the detritus is rich in substances such a lignin and chitin. The nitrogen-rich detritus (having low amounts of lignin) decomposes relatively, quickly. The actual rate of decomposition of detritus in natural conditions depends upon the integrated effect of environmental conditions and detritus quality also.

Question 3.
Diagrammatically show how energy flows from one trophic level to another trophic level.
Answer:
Energy is lost as heat from each successive trophic level. This can be shown as follows :

Sun serves as a source of energy in the biosphere; Producers trap a small amount of this energy and transfer it to other members of food chain (consumers and decomposers). Thus producers have highest energy level. The pyramid of energy is always straight i.e. it decreases from bottom to top.

Question 4.
Briefly describe tropical forest biomes.
Answer:
Tropical forest are of two types: Tropical rain forests, and tropical deciduous forests.
Tropical rain forests or evergreen forests occur near the equator. In India they are along the Western Ghats in the north-eastern region. The climate is warm and moist, and with no seasonal variations. Rain fall is high (200 cm or more) and uniform with no dry periods, sunlight is strong, soil is rich in minerals and humus. They have excellent conditions for plant growth throughout the year.

Life is abundant with about 71 to 80% of world’s insect species and 80-85% of birds species. The dense vegetation is vertically stratified into 4 to 5 strata, each storey in inhabited by different animals. The soil is highly leached. Nutrients are stored in tall vegetation and soil storage is low. Tropical fain forests have highest standing crop biomass among all the biomes.

Tropical deciduous forests: These are distributed rn northern and southern parts of India. The climate is warm, with alternate wet and dry periods. Rainfall is high around 100 to 200 cm per annum. Sunlight is strong, soil is rich in mineral and humus. In wet period, the forest is green with dense foliage and thick herbaceous layer. The epiphytes and climbers are fewer than tropical rain forests. The trees shed their leaves during dry seasons. They have trees like sal, teak, mahua, amla, Jamun, senwl etc. These forests are rich in animal population too. The common animals are deer, elephants, pigs, lion, birds, reptiles, insects and worms.

Question 5.
Give major characteristics of desert biome.
Answer:
Deserts are located in rain shadow areas, where dry air from the equator falls from upper atmosphere. Their main characteristics are :

• prolonged scarcity of rainfall,
• period of dryness and evaporation from soil higher,
• The annual rainfall is below 70mm to 120mm,
• There is variation of temperature during day and night,
• There is no permanent or temporary flowing water. The sunlight is strong and abundant,
• The soil is sandy or rocky,
• The desert biome has less life and organisms which have adaptation to extreme temperature and arid conditions can only survive,
• The desert plants include ephemeral annual herbs which grow during rainy season,
  succulent xerophytes like cactus, euphorbias, thorny shrubs, small trees like Prosopis, Salvadora, Tamarix. The most common grass in deserts in Cenchrus.
• Animals in desert biome are arthropods, scorpions, spiders, insects, rattlesnakes, lizards, camels, jackrabbits, desert rats, cactus woodpeckers, roadrunners, burrowing owls. Mostly animals are small and nocturnal,
• The biomass and primary productivity levels in deserts are low.

One Word Type Questions

Question 1.
Give an alternate term for ecological pyramids.
Answer:
Eltonian pyramids.

Question 2.
Name any vesperal animal.
Answer:
Rabbit.

Question 3.
How deep in sea, producers are present?
Answer:
Up to 200 m.

Question 4.
Name anyone Eutrophic lake.
Answer:
Dal lake in Kashmir.

Question 5.
Name any denitrifying bacteria.
Answer:
Pseudomonas aeruginosa.

Question 6.
For how long the entire CO₂ of the air can last with its use in photosynthesis by green plants?
Answer:
1 year.

Question 7.
Name the dark coloured amorphorus substance accumulated as a result of humification.
Answer:
Humus.

Question 8.
What is unit of energy measurement for energy pyramids?
Answer:
Kcalm^-2yr^-1.

Question 9.
Which is the most stable ecosystem?
Answer:
Oceans.

Question 10.
In a food chain, the maximum population is of which organisms?
Answer:
Producers.

BSEB Textbook Solutions PDF for Class 12th

• BSEB Class 12 Textbook Solutions PDF: Download Bihar Board STD 12th Book Answers
• BSEB Class 12 Biology Textbook Solutions PDF: Download Bihar Board STD 12th Biology Book Answers
• BSEB Class 12 Biology Reproduction in Organisms Textbook Solutions PDF: Download Bihar Board STD 12th Biology Reproduction in Organisms Book Answers
• BSEB Class 12 Biology Sexual Reproduction in Flowering Plants Textbook Solutions PDF: Download Bihar Board STD 12th Biology Sexual Reproduction in Flowering Plants Book Answers
• BSEB Class 12 Biology Human Reproduction Textbook Solutions PDF: Download Bihar Board STD 12th Biology Human Reproduction Book Answers
• BSEB Class 12 Biology Reproductive Health Textbook Solutions PDF: Download Bihar Board STD 12th Biology Reproductive Health Book Answers
• BSEB Class 12 Biology Principles of Inheritance and Variation Textbook Solutions PDF: Download Bihar Board STD 12th Biology Principles of Inheritance and Variation Book Answers
• BSEB Class 12 Biology Molecular Basis of Inheritance Textbook Solutions PDF: Download Bihar Board STD 12th Biology Molecular Basis of Inheritance Book Answers
• BSEB Class 12 Biology Evolution Textbook Solutions PDF: Download Bihar Board STD 12th Biology Evolution Book Answers
• BSEB Class 12 Biology Human Health and Disease Textbook Solutions PDF: Download Bihar Board STD 12th Biology Human Health and Disease Book Answers
• BSEB Class 12 Biology Strategies for Enhancement in Food Production Textbook Solutions PDF: Download Bihar Board STD 12th Biology Strategies for Enhancement in Food Production Book Answers
• BSEB Class 12 Biology Microbes in Human Welfare Textbook Solutions PDF: Download Bihar Board STD 12th Biology Microbes in Human Welfare Book Answers
• BSEB Class 12 Biology Biotechnology Principles and Processes Textbook Solutions PDF: Download Bihar Board STD 12th Biology Biotechnology Principles and Processes Book Answers
• BSEB Class 12 Biology Biotechnology and its Applications Textbook Solutions PDF: Download Bihar Board STD 12th Biology Biotechnology and its Applications Book Answers
• BSEB Class 12 Biology Organisms and Populations Textbook Solutions PDF: Download Bihar Board STD 12th Biology Organisms and Populations Book Answers
• BSEB Class 12 Biology Ecosystem Textbook Solutions PDF: Download Bihar Board STD 12th Biology Ecosystem Book Answers
• BSEB Class 12 Biology Biodiversity and Conservation Textbook Solutions PDF: Download Bihar Board STD 12th Biology Biodiversity and Conservation Book Answers
• BSEB Class 12 Biology Environmental Issues Textbook Solutions PDF: Download Bihar Board STD 12th Biology Environmental Issues Book Answers

Bihar Board Class 12th Biology Ecosystem Textbooks for Exam Preparations

Bihar Board Class 12th Biology Ecosystem Textbook Solutions can be of great help in your Bihar Board Class 12th Biology Ecosystem exam preparation. The BSEB STD 12th Biology Ecosystem Textbooks study material, used with the English medium textbooks, can help you complete the entire Class 12th Biology Ecosystem Books State Board syllabus with maximum efficiency.

FAQs Regarding Bihar Board Class 12th Biology Ecosystem Textbook Solutions

How to get BSEB Class 12th Biology Ecosystem Textbook Answers??

Students can download the Bihar Board Class 12 Biology Ecosystem Answers PDF from the links provided above.

Can we get a Bihar Board Book PDF for all Classes?

Yes you can get Bihar Board Text Book PDF for all classes using the links provided in the above article.

Important Terms

Bihar Board Class 12th Biology Ecosystem, BSEB Class 12th Biology Ecosystem Textbooks, Bihar Board Class 12th Biology Ecosystem, Bihar Board Class 12th Biology Ecosystem Textbook solutions, BSEB Class 12th Biology Ecosystem Textbooks Solutions, Bihar Board STD 12th Biology Ecosystem, BSEB STD 12th Biology Ecosystem Textbooks, Bihar Board STD 12th Biology Ecosystem, Bihar Board STD 12th Biology Ecosystem Textbook solutions, BSEB STD 12th Biology Ecosystem Textbooks Solutions,