Life Processes in Living Organisms Science Notes
Important Points :
- In any environment, there are biotic and abiotic components.
- There are interactions among these components. All such interactions make an ecosystem.
The different components in the ecosystem are as follows :
- Abiotic components: Air, water, soil, sunlight, temperature, humidity, etc.
- Biotic components : All the types of living organisms, like bacteria, fungi, plants and animals.
→ Primary consumers, secondary consumers, tertiary consumers or apex consumers are the different types of consumers. These types are according to the trophic level to which they belong
→ The birds on the tree depend on the aquatic organisms in the lake for their feeding. Birds stay on the trees which are in the vicinity of the lake, so that it is easier for them to capture fishes, frogs, etc. They must also be using the same lake water for drinking.
→ In every ecosystem, there are always interactions between producers, consumers and decomposers. This sequence of feeding interactions is called food chain. In every food chain there are links between four to five trophic levels constituting the producers, primary consumers, secondary consumers. tertiary consumers, etc. The links of food chain are in linear sequence.
→ But food web is a complex network of many small food chains. In fact, food web is the collection of many small food chains. Thus, when many food chains are interwoven, they form food web.
→ By utilizing the solar energy, the green plants perform photosynthesis. Thus, they are producers of the food chain. This food is consumed by the grasshopper. Thus, it is primary consumer. Frog is secondary consumer as its diet consists of insects like grasshopper.
→ Snake is tertiary consumer as it feeds on frogs, while the hawk is apex consumer as it can kill the snake and feed on it. Last picture in the food chain is of fungi which are acting as decomposers. Few bacteria are shown in the picture, act on all the levels and bring about decomposition.
→ If this food chain has to be converted into a food web, there should be interactions between the different components. Any living organism can be prey to different predators. Moreover, a predator can also be a prey for other. Frog eats different insects. The same frog can be either eaten by snake or by hawk.
Ecosystem – A review :
- Biotic and abiotic factors and their interactions with each other form an ecosystem. Every factor has important role to play for functioning of the ecosystem.
- Plants are producers of the ecosystem.
- Various herbivores like deer, goats, sheep, cattle, horses, camels, etc. feed upon producers.
- Carnivorous predators e.g. lion and tiger control the population of the herbivores.
- The decomposers and scavengers like caterpillars, termites, insects present in the dung carry out decomposition and thus clean the environment.
- Existence of human beings is dependent on the balanced ecosystem.
→ Only by decomposition the elements and molecules trapped in the bodies of organisms can be sent back to nature. These various components help in formation of the bodies of plants and animals. If they are not sent back to nature, the cyclic flow of these elements will halt.
→ Only by the decomposition process, foliage in forest, dead trees, and carcasses are sent back to nature. If such decomposition halts for years, the entire earth will be covered by heaps of unwanted garbage. The entire balance of nature would be lost.
→ ‘Jivo Jivasya Jivanam’ is a Sanskrit saying which means that one living organism makes the living on the other. All the food chains occurring in the nature, function on this principle. Prey and predator interactions are based on the above concept. While discussing, students should give various examples that occur in their surrounding environment.
→ The different trophic levels in food chain are producers (First trophic level), primary consumers (Second trophic level), secondary consumers (Third trophic level), tertiary consumers (Fourth trophic level), etc.
→ Energy pyramid is the diagrammatic representation, that depicts the energy levels at the various trophic levels. There are interactions in the form of energy transfer in all the food chains and food web. The energy pyramid shows how energy travels up a food chain.
→ The bird is a part of both the ecosystems. For shelter, the bird builds nest on the tree. That means it takes advantage of tree ecosystem (terrestrial ecosystem). Moreover, it feeds on the fish from the pond. Being a predator, the bird maintains the fish population of the pond and thus it also becomes the part of the pond ecosystem too.
→ Complete the chart: Fill up the blank boxes and display the completed chart in classroom. (Answers are directly given in bold print.)
→ In South India in various places there is paddy cultivation on a large scale → Frequent attack of the grasshoppers on fields → Predator frogs in large numbers → Snakes to feed on the frogs
→ If the population of frog declines, then there will be rise in the population of grasshoppers. The paddy fields will hence be infested with insect pests.
→ The food chain if altered, results in imbalance in the ecosystem. “Paddy → Grasshoppers → Frog Snake’, this food chain is natural. When by any reason there is decline in the number of frogs, thus secondary consumer will also decline. Due to this decline, snake which is at tertiary consumer level will also decline. The primary consumers i.e.grasshoppers will increase as there is now no check on their population.
→ Due to increase in their population the paddy production will be reduced. Due to reduced number of snakes, rats and other rodents from neighbouring areas would also rise, which are also secondary consumers.
→ If frogs’ population declines, there would be imbalance of entire ecosystem. The number of prey and predator populations will change and thus the food chain will come to an end. Everything that is around a living organism is called environment. Environment includes physical, chemical and other natural factors which surround the living organism.
Relationship between Environment and Ecosystem :
- Environment is the collective term for physical, chemical and biological factors that surround the living organisms.
- Many biotic, abiotic, natural and artificial factors together constitute conditions of the environment.
→ Two main types of environment:
- Natural environment: Air, atmosphere, water, land, living organisms, etc.
- Anthropogenic/Manmade/Artificial environment.
→ Two main factors in environment :
- Biotic factors
- Abiotic factors.
→ Continuous interactions occur between all the factors in the environment.
- Artificial environment, directly or indirectly affects the natural environment.
- Ecology : Ecology is the science that deals with the study of interactions between biotic and abiotic factors of the environment
- Ecosystem : Ecosystem is the basic functional unit used to study the ecology.
- Many ecosystems together form an environment.
→ Ecosystems constitute biotic and abiotic factors occupying a definite geographical area and their interactions. In environment there are bio-geochemical cycles. These are of two types, viz. Gaseous cycles e.g. nitrogen cycle, oxygen cycle, etc. and sedimentary cycles e.g. phosphorus cycle.
→ Importance of bio-geochemical cycle :
- Plants require water, CO2, phosphorus, potassium, nitrogen, etc. as nutrients while animals require, carbohydrates, proteins, fats, etc. as nutrients.
- Producers and consumers after their death undergo decomposition and release elements which mix with the soil.
- The cyclic movement of nutrients is possible through bio-geochemical cycle.
- The cyclic movement of elements like carbon, nitrogen, phosphorus, etc. continuously occur on the earth.
- By the bio-geochemical cycles, the environmental balance is always maintained.
- If the environment is in proper condition, then human existence is possible. Therefore, it is our responsibility to preserve nature and maintain environmental balance.
- The planet Earth was given to us on lease from our future generations and not as an ancestral property from our ancestors. Therefore, we must conserve it for ourselves and for future generations.
Environmental Conservation :
→ The natural as well as artificial or manmade factors affect the environment. Among natural factors, the sudden changes in the weather, the different types of natural disasters, etc. affect the normal environment. Due to such changes there are problems in the interrelationships that exist between food chain and food web.
→ Due to various man-made causes, there are extreme destruction of environment. Industrialization, the pollution due to such industries, Urbanization, hunting and poaching of wild animals, construction of dams, roads, bridges, etc. are all man-made changes that cause lot of damage to environment.
→ If number of consumers increase gradually, it will create the scarcity of prey organisms. Then due to lack of prey, the number of consumers will also decline.
→ If there are industries established on the river bank, then there is threat to the aquatic ecosystem. It is most likely that the hazardous effluents can be released into the river water. This can cause water pollution resulting into mortality of aquatic organisms.
→ Moreover, this water will no longer remain potable. Hence the health of resident population may also be affected. The food chains and the food web in the river may be terminated due to such pollution
→ The environment is affected due to some natural factors of environment and some man-made factors such as pollution. Such factors create imbalance in the environment which in turn affect the existence of biota. Earth is suffering from many environmental problems caused due to effect of various natural and artificial factors.
→ Environmental pollution : Pollution brings about environmental degradation. It is largely due to natural or man-made causes. Pollution contaminates and makes the unnecessary and unacceptable changes in the surrounding environment. This causes direct or indirect changes in physical, chemical and biological properties of air, water and soil. These changes are usually harmful for all living beings, including human.
→ Reasons for pollution : Population explosion, fast industrialization, and indiscriminate use of natural resources, deforestation, and unplanned urbanization are factors that pollute environment.
→ Our responsibility : Pollution of air, water, noise, soil, thermal, light pollution, etc. are different types of pollution that cause adverse effects. It ultimately affects existence of all the living organisms on the earth. Thus it is our responsibility to curtail polluting substances and aim at environmental conservation.
→ Air pollution, water pollution and soil or land pollution are main types of pollution. In addition to these, light pollution, plastic pollution, noise pollution and radioactive pollution are also other hazardous types of pollution.
→ The pollution which is caused by natural sources and due to natural processes is called natural pollution. E.g. Earthquake and eruption of lava. The pollution that is caused due to human activities is called artificial or man-made pollution.
→ Radioactive pollution : Radioactive pollution is caused by following two causes:
- Natural radiations : Natural processes such as UV and IR radiations.
- Man-made or artificial radiations : X-rays and radiations emitted from atomic energy plants.
→ Major mishaps on the international level: Chernobyl, Windscale, and Three Miles Island mishaps. Due to these accidents thousands of people have been affected for long term.
→ Effects of radiations :
- Cancerous ulcerations due to X-rays.
- Destruction of body tissues.
- Change in the genes.
- Adverse effect on vision.
→ Need of environmental conservation:
- Discussion of the environmental problems – In 1972 at UNO, Stockholm, (Conference arranged on human and environment.)
- Later establishment of United Nations Environment Program (UNEP).
- In India, discussion of environmental issues took place in IV th planning commission.
- A separate environmental department was established later.
- Ministry of environment and forests started various programmes since 1985 in planning, inducting and increasing awareness about environment and forest.
→ People’s participation :
- Awareness about environment conservation rules and laws should be developed for common people.
- Large scale participation of the people in environment conservation can bring about environmental protection and effective conservation.
- Values like positive attitude towards environment and knowledge and quest for the conservation should be imbibed right from school days. Increasing environmental awareness through schools and colleges is essential.
- Every nation has their own future plans about environmental protection and for this purpose they have formulated the laws.
→ Environmental Conservation. Our social responsibility
- Human – environment interrelationship existed since origin of man.
- Human being has become supreme on the earth due to his intelligence, memory, imaginations, creative ability etc.
- Human has used up natural resources without any thought. The development processes have caused extreme damage to the environment.
- Maintaining the environmental balance is the duty of humans.
- Since we have disturbed the environmental balance, only we should think of protection and conservation of nature.
→ Butterflies carry out pollination. This results into reproduction of the plants. The flora is increased due to such increased pollination. Many weeds in the nature are consumed by the butterflies as their food. Some butterflies also consume harmful insects as their prey.
→ Due to beautiful coloured butterflies the environment becomes pleasant and joyful. Butterflies avoid polluted and barren areas. Thus, they indicate the health of the environments. Thus, the ecosystem is said to be in balance if there is presence of butterflies in its surroundings.
→ Laws enacted about environmental conservation :
|Law||Year||Inclusion in the law||Punishment if the law is not followed|
|1980||Prohibition on the use of the land which is reserved for forest conservation.||Imprisonment for 15 days.|
|Environmental Conservation Act||1986||Control of pollution and action on the persons or institutes that harm environment.||Five years imprisonment or fine up to Rs. 1 lakh.|
|National Green Tribunal||2010||Effective implementation of environment related laws.||Court case.|
|Wildlife Protection Act||1972||Protection of the wild life.||Various punishments.
|Clause 49 A||Complete ban on trading of rare animals.|
|Clause 49 B||Complete ban on use of articles prepared from skin or organs of wild animals.|
|Clause 49 C||Compulsory disclosure of the stock of artifacts made from rare wild animals.|
→ Jadav Molai Payeng from Assam has made barren land into a forest which now stands on 1360 acres of land. Now, this forest is known as ‘Molai Jungle’. It is rightly said that “Many people come together to destroy the forest, but a single person, if determined, can establish a new forest”! We must also have such a vision.
Environmental management : Environmental Conservation and Biodiversity :
→ Environmental pollution affects the living organisms and reduces biodiversity.
Living world had a rich biodiversity. This richness of biodiversity is getting depleted at a very high rate only due to various activities of human beings.
→ Biodiversity: The richness of living organisms in nature due to presence of varieties of organisms, ecosystems and genetic variations is called biodiversity. Biodiversity occurs at following three different levels.
→ Levels of biodiversity :
|Genetic Diversity||Species Diversity||Ecosystem Diversity|
|Diversity among the organisms of same species. The genetic constitution of each organism may be different.
|Diversity in the species of organisms that occur in the nature.
E.g. Various types of plants, animals and microbes.
|Many ecosystems are present in a particular region. Diversity of the different ecosystems E.g. Natural and artificial ecosystems.|
→ Every ecosystem is different from others. It has its own characteristic animals, plants, microbes and abiotic factors.
→ Sacred Groves :
- Some green forest patches were conserved in the name of god by the locals and tribal people. These are considered sacred and hence the name sacred grove.
- These groves are ‘sanctuaries’ conserved by the society.
- Sacred groves have special protection because they are conserved as god’s abode.
- Such patches of thick forests are mostly present in Western Ghats.
- In India, more than 13000 sacred groves have been reported.
→ How can biodiversity be conserved :
- Protection of the rare species.
- Creating National Parks and Sanctuaries.
- Declaration of ‘Bioreserves’, thus offering protection to resident species.
- Conservation of special species by carrying out projects.
- Conservation activities for all living organisms.
- Strictly following the environmental protection rules.
- Recording and maintaining traditional knowledge.
- There are many state-level, national and international level institutes that work for conservation of the environment.
Hotspots of Biodiversity :
- Highly sensitive biodiversity spots in world : 34
- Areas of the Earth were occupied by these hotspots : 15.7%
- Currently, sensitive areas that are destroyed : 86%
- Presently left over sensitive spots on the earth: 2.3%
- Hotspots have 1,50,000 plant species which are 50% of the world count.
- In Eastern India jungles, 85 species are found out of 135 species of animals.
- In Western Ghats about 1,500 endemic plant species.
- Out of the total plant species in the entire world, 50,000 are endemic.
→ Three Endangered Heritage Places of the Country:
|Which one?||Where?||Problem? .||Impact|
|The Western Ghats||Gujarat, Maharashtra, Goa, Tamil Nadu and Kerala||Endangered animals due to mining industry and search for natural gas.||Habitats of Asiatic lion and wild bison under threat.|
|Manas sanctuary||Assam||Dams and indiscriminate use of water.||Tiger and rhino under threat.|
|Sunderbans sanctuary||West Bengal||Dams, deforestation, excessive fishing, trenches dug.||The tiger population and overall local environment is seriously challenged.|
- Animals : Asiatic cheetah (Acinonyx jubatus venaticus)
- Namdapha flying squirrel (Biswamoyopterus biswasi)
- Himalayan wolf (Canis himalayensis)
- Elvira rat (Cremnomys elvira)
- Andaman shrew (Crocidura andamanensis)
- Jenkins’ shrew (Crocidura jenkinsi)
- Nicobar shrew (Crocidura nicobarica)
- Bird : Pink-headed duck
- 22nd May is observed as a World Biodiversity Day.
- International Union for Conservation of Nature (IUCN) prepares the ‘Red List’.
- Red list contains the names of endangered species from different countries.
- The names of endangered species are on pink pages.
- The names of previously endangered but presently safe species are on green pages.
→ Classification of Threatened Species :
|Type of Species||Endangered Species||Rare Species||Vulnerable Species||Indeterminate Species|
|Information||Number of organisms is declined. Shrunken habitat which can lead to extinction.||Considerably declined number of these organisms. Endemic organisms may become extinct very fast.||Extremely less number of organisms which further declines. Continuous declining number of organisms is a threat.||Organisms appear to be endangered. The data is not enough as they have typical behavioural habits (like shyness)|
|Examples||Lion tailed monkey, Lesser florican.||Red panda, Musk deer||Tiger, Lion.||Giant squirrel, Our state animal: ‘Shekhru’|
→ If as per report of WWF, 30% of the animal species faced extinction during last 30 years, then it is very alarming. Once lost the flora and fauna will never get replenished. If in future, this rate of extinction continues, there will not be a single animal left on the earth. Only human species will outnumber all others due to no concern for the nature.
→ Some important slogans to spread environmental wisdom:
- Destroying a plant is to destroy everything.
- Practise afforestation to conserve environment.
- Forest is Wealth.
- Environmental protection is value education.
- Provident use of paper is prevention of deforestation.
- To practise the environmental protection is to develop human society.
- Pure air, pure water is key to healthy life.