Biology Chapter 5: Diversity for Sustenance PDF

```markdown # DIVERSITY FOR SUSTENANCE This earth is full of organisms of various shapes and sizes. Biodiversity refers to the number of different species living in the regions. Diversity of organisms adds charm to nature. It represents the biological wealth in nature. Life forms are diverse, but n...

```markdown # DIVERSITY FOR SUSTENANCE This earth is full of organisms of various shapes and sizes. Biodiversity refers to the number of different species living in the regions. Diversity of organisms adds charm to nature. It represents the biological wealth in nature. Life forms are diverse, but no organism in nature exists in isolation. An ecosystem (or ecological system) consists of all organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Through this chapter we can study food chain, trophic levels, ecological interactions in the ecosystems and the importance of biodiversity etc. ## In this unit ... 1. Biosphere and ecology 2. Food web 3. Trophic level 4. Ecological interactions 5. Diverse ecosystems 6. Importance of biodiversity 7. Biodiversity depletion 8. Let us preserve diversity ## 1. Biosphere and ecology * **Biosphere:** It is the part of earth where life exists. It extends to soil, atmosphere and water. * **Ecology:** It is the study of interaction between organisms and also between the organisms and their surroundings. This branch of study includes different types of ecosystems, interaction between organisms, environment protection etc. * **Features of biosphere** * Sun is the primary source of energy in the living world. * Biotic and Abiotic factors are essential for the existence of biosphere. * Abiotic factors are sunlight, air, soil and water. * Green plants convert light energy to chemical energy through photosynthesis. * This energy gets transferred to other organisms through food chain. Plants that perform photo synthesis are called Producers while organisms that depend on plants directly or indirectly for food are called consumers. * **Primary consumers:** The consumers that directly depend on plants are called primary consumers. * **Secondary consumers:** Organisms that feed on primary consumers are called secondary consumers. * **Tertiary consumers:** Organisms that feed on secondary consumers are called tertiary consumers. ## 2. Food chain and food web The image shows a food web with the sun shining on grass at the bottom. Herbivores such as grasshoppers and rabbits eat the grass. A frog eats the grasshopper, a snake eats the frog, and a hawk eats the snake. A fox eats the rabbit. A rat eats the grass and is eaten by both a snake and a hawk. * **Food chain** Food chain is a group of organisms linked in order of the food they eat, from producers to consumers, and from prey, to predators, scavengers, and decomposers. Examples are * Grass $\rightarrow$ Grasshopper $\rightarrow$ Frog $\rightarrow$ Hawk. * Grass $\rightarrow$ Grasshopper $\rightarrow$ Rat $\rightarrow$ Fox. * Grass $\rightarrow$ Rabbit $\rightarrow$ Fox. * Grass $\rightarrow$ Rat $\rightarrow$ Snake $\rightarrow$~Hawk. * Grass $\rightarrow$ Rat $\rightarrow$~Hawk. * **Food web** Food web is a complex network of interconnecting and overlapping food chains showing feeding relationships within a community. Natural interconnections between food chains make it a food web. ## 3. Trophic level * The term indicates the position of an organism in the food chain. * Since the food chain starts with plants, they represent the first trophic level. * Herbivores that derive food directly from plants are included in the second trophic level. * Carnivores that depend on herbivores for food are included in the third trophic level. * Predators that prey on carnivores represent the fourth trophic level. * As the food web turns increasingly complex, the same organism may represent different trophic levels * The illustration by including the organisms of the food web at various trophic levels is given below: | Trophic level | Organism | | :------------------------------------ | :---------------- | | Tertiary consumers (Those who feed on carnivores too | Peacock, snake | | Fourth trophic level | | | Secondary consumers (Carnivores) | frog, snake | | Third trophic level | | | Primary consumers (Herbivores) | Rat, grass | | Second trophic level | | | Producers (Plants) | Paddy, grass | | First trophic level | | The same organism occupy more than one trophic level. There is possibility of a fifth trophic level. Eg: Grass $\rightarrow$ Grass hopper $\rightarrow$ Frog $\rightarrow$ Snake $\rightarrow$ Eagle ## 4. Ecological interactions * Different ecological interactions are given below There are four images showing biological interactions between organism. The first image shows a flower and a butterfly labeled as mutualism. The second image shows a deer and tiger labeled as predation. The third image shows a mango tree with loranthus (parasitic plant) labeled as parasitism. The fourth image shows a mango tree with Vanda (orchid) labeled as commensalism. The fifth image shows paddy and weeds labeled as competition. * **Predation:** Beneficial to one but harmful to the other. Prey becomes the food of the predator. Eg. Deer and tiger * **Parasitism:** Beneficial to one and harmful to the other. The parasite depends on the host for nutrition. Eg. Mango tree and Loranthus * **Competition:** Harmful to both in the beginning. Then beneficial to the one who wins. Eg.Paddy and weeds * **Mutualism:** Beneficial to both the organisms. Eg. flower and butterfly * **Commensalism:** Beneficial to one and neither beneficial nor harmful to the other. Eg. Mango tree and vanda These interactions maintain the balance and stability of the ecosystems. Food relations are visible instances of interaction among organisms. ## 5. Diverse ecosystems Forest, tundra, ocean, wetland, grassland and desert are examples of different types of ecosystems. ### Biodiversity Biodiversity includes all the diverse organisms that inhabit the earth along with their ecosystems. Biodiversity includes various levels like ecosystem diversity, species diversity and genetic diversity. This term which denotes the richness of the biosphere was first used by a British environmentalist, Walter. G. Rosen. Restoring and protecting nature is one of the greatest strategies for tackling climate change, but not just for the obvious reason that it sucks carbon out the air. Forests, wetlands, and other ecosystems act as buffers against extreme weather as they protecting houses, crops, water supplies and vital infrastructure. ## 6. Importance of biodiversity * **Biodiversity - Services** a. Availability of essential materials * Food * Medicine * Fuels * Construction materials b. Ecological Services * Soil formation * Prevention of soil erosion * $O_2 - CO_2$ balance * Availability of fresh water * Control of flood * Climate control * Formation of rain c. Auxiliary Services * Nutrient cycling * Pollination * Biological control * Seed dispersal d. Cultural Services * Aesthetics * Recreation * Study * Rituals and their practice * Arts ## 7. Biodiversity depletion Birds are found everywhere. Birds fall easy victims to changes in the ecosystem. The image has six images of birds in different habitats in nature. Included are a pelican wading in the ocean, shore birds wading at the shoreline, ducks wading in a pond, and different sparrows in tree branches. Reasons for the decrease in the diversity of birds * Excessive use of chemicals in agricultural fields. * Natural calamities and uncontrolled hunting of birds are the reasons of their extinction. * Not protecting the natural habitat of birds. * Large scale destruction of ecosystems. * Over exploitation of the natural resources. * **Lost links** **The given are pictures of certain extinct species** * **Dodo:** A kind of flightless bird, was common in the island of Mauritius. * **Passenger pigeons:** These birds flew in lakhs along the North American skies * **Quagga:** A wild zebra variety from the southern part of Africa. Humans contribute to the extinction of species by destroying the species environments, over hunting, polluting the water, deforestation, forest fires, etc. The book *Silent Spring* published in 1962 by an American researcher, Rachel Carson attracted attention worldwide because it elaborated on the environmental and health hazards caused by pesticides like DDT. If not protected, these too...! There are many organisms on the verge of extinction due to several reasons. Some examples are given below. There are four images of animals at risk of extinction. An ashoka tree, a maramanjal, a malabar civet cat, a nilgiri tahr, a lion-tailed macaque, and the malabar hornbill. ## 8. Let us preserve diversity IUCN (International Union for Conservation of Nature) is an organization for environmental protection, operating in different countries. Under the auspices of IUCN, a list of endangered plants and animals is prepared every year. This is known as Red Data Book. There are many national and international organizations and legal systems working for the conservation of biodiversity. * Two types of conservation methods are prevalent. They are: A) In-situ conservation method in which organisms are protected in their natural habitats. Wild Life Sanctuary, National Parks, Community Reserves B) Ex-situ conservation method in which organisms are protected outside their natural habitats. A) In-situ conservation examples #### Wild life sanctuary Protection of ecosystems Prevent extinction of wild animals eg. Wayanad, Periyar, Peppara wild life sanctuaries #### National parks Wild life conservation Conservation of natural resources eg. Iravikulam, Silent valley, Pambadumshola #### Community reserve Conservation of nature with people's participation, Protection of ecological zones between human settlements eg. Kadalundi community reserve #### Biosphere reserve Protect important habitats, Protect biodiversity eg. Neelagiri, Agasthyarkoodam #### Ex-situ conservation examples #### Zoological gardens They also function as conservation centers of organisms which have become extinct in wild. There are zoological gardens at Thiruvananthapuram and Thrissur in Kerala. #### Botanical gardens These are wide research centers where rare and important plants of diverse species are protected. Jawaharlal Nehru Tropical Botanical Garden and Research Institute(JNTBGRI) at Palode in Thiruvananthapuram and Malabar Botanical Garden (MBG) at Olavanna in Kozhikode are examples. #### Gene Banks These are research centers with facilities to collect seeds and gametes to preserve them for a long time. Organisms can be recreated out of them whenever required. Rajiv Gandhi Centre for Biotechnology at Thiruvananthapuram is an example. * **The scope of ex-situ conservation** It protects endangered species from external threats like predation and poaching by keeping them in specialised environment and by providing suitable conditions for reproduction. Rare species of plants can be conserved. Ex situ conservation is carried out in artificial environments, thus adding additional supervision. * **Significance of gene banks** The gene banks are the biorepository where the biological material is stored and preserved for future use. They ensure plant species can be conserved and revived when they are in endangered situations. This helps in maintaining the genetic diversity of the plants. **IUCN** (International Union for Conservation of Nature): IUCN is a Switzerland based independent organisation working for the protection of biodiversity. **WWF** (World Wide Fund for Nature): Biodiversity conservation, prevention of exploitation and pollution of natural resources are the objectives of WWF. Its headquarters is also in Switzerland. It is our duty to conserve and keep bioresources for future generations. If we do not act with this realization, our existence itself will be in danger. ## SECTION 1 QUESTION & ANSWERS #### Question 1. Is a single organism involved in more than one food chain? #### Answer: Yes,same organism belongs to different food chains. #### Question 2. How do food chain and food web differ from each other? #### Answer: The chain of animals that eat and being eaten constitute food chain. But in nature different food chains are interrelated and this network is called food web. Eg. Food Chain Grasshopper $\rightarrow$ Frog $\rightarrow$ Snake $\rightarrow$ Eagle Green plant Rabbit $\rightarrow$ Fox Rat Cat $\rightarrow$ Mongoose #### Question 3. How does the variation in the number of a particular organism in the food chain affect the existence of other organisms? #### Answer: When the number of an organisms decrease, it adversely affects the existence of another group that depend them for their food. The increase and decrease in the number of organisms adversely affect the equilibrium of environment. #### Question 4. Define secondary consumers #### Answer: Organisms that feed on primary consumers are called Secondary Consumers #### Question 5. Does the same organism occupy more than one trophic level? #### Answer: The same organism is included in different trophic levels as the complexity of food web increases. #### Question 6. Is there any possibility of a fifth trophic level ? #### Answer: The number of trophic levels in an ecosystem is not constant. Even though in nature the food chains are not too long, there may be a fifth trophic level. #### Question 7. How does the elimination of organisms from the higher trophic levels affect the ecosystem? #### Answer: The loss of organisms in higher levels cause tremendous increase in the number of organisms in the lower levels. It disrupt the equilibrium of environment. #### Question 8. Discuss and complete the illustration given below suitably. ###### Answer: There is an illustration that is completed: * Sunlight (Photosynthesis) $\rightarrow$ Abiotic factors * Abiotic factors has three arrows pointing to: * Soil * Air * Water a. Nutrition. b. Respiration. c. Physiological activities #### Question 9. Define the following terms a) Producer b) Consume #### Answer: a) The plants that perform photosynthesis are called producers b) Organisms that depend on plants directly or indirectly for food are called consumers ## SECTION 2 QUESTION & ANSWERS #### Question 1. Are all ecosystems alike in biodiversity? #### Answer: No. all ecosystems are not alike in biodiversity #### Question 2. Are all organisms seen in an ecosystem also seen in another ecosystem? #### Answer: Organisms adapted to the conditions of particular ecosystems. The physical and chemical structure of each ecosystem is different. So organisms seen in one ecosystem may not be present in another ecosystem. #### Question 3. What is the need for protecting natural ecosystems? #### Answer: Natural ecosystem is to be conserved for the existence and conservation of organisms. Eco ## STANDARD VIII Question 4. Find two examples of such animal relashionships | Type | Beneficial to one and harmful to other | Harmful to both the organisms | Beneficial to both the organisms | | :--------------- | :------------------------------------- | :------------------------------ | :-------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Predation | Deer and Tiger | | | | Parasitism | Mango tree - Loranthus | | | |Mutualism | | | Flower and butterfly | |Commensalism | | | Mango tree and vanda | | Competition | Crops - Weeds| | | Question 5. Complete the illustration Suitably Answer: a. Environmental / Ecological services b. Cultural services c. Nutrient Cycle, Pollination d. Food, Medicine Question 6. List different types of ecosystems Answer: • Forest • Ocean • Grassland • Tundra • Wetland • Desert Question 7. Complete the given table below Answer: #### SECTION 3 QUESTION & ANSWERS #### Question 1. How does over exploitation of the natural resources affect bird diversity #### Answer: The unwise interference of human beings destroys our ecosystem with rich biodiversity. It adversely affects the bird diversity in our locality. Many species of birds disappeared due to habitat loss. The pesticides like DDT, endosulfan used in agricultural field kills or drives away the birds that come in search of food. #### Question 2. Name some animals that are facing extinction. Answer: • Nilgiri Tahr • Musk deer • Indian wild Ass • Lion-tailed Macaque • Malabar civet cat • Rhinoceros • The large Indian Bustard • Tiger • Kashmir deer • Himalayan Tig • Silver owl Question 3. Name the extinct wild variety zebra from southern part of Africa Answer: Quagga #### Question 4. Do humans beings have any role in the extinction of above organisms #### Answer: Yes, Due to Overexploitation of the natural resources #### Question 5. The book silent spring was published by... #### Answer: Rachel carson #### Question 6. Fill in the blanks Passenger pigeon : North America Dodo: a. Mauritius Quagga : b. South Africa Question 7. Write the fill form of IUCN Answer: International Union for Conservation of Nature Question 8. Give some examples of extinct animals Answer: Quagga Dodo Passenger pigeon ## STANDARD VIII SECTION 4 QUESTION & ANSWERS #### Question 1. What is the scope of ex-situ conservation? #### Answer: It is possible to conserve the endangered animals by keeping them in specialized environment and by providing suitable conditions for reproduction. Rare species of plants tan be concerned. #### Question 2. What is the significance of gene banks? #### Answer: Gene banks are research centers with facilities to collect seeds, gametes, etc and to preserve them for long periods. Organisms can be recreated out of them whenever required. Examine the statements given below and rewrite if there are errors. Extinct species are included in the Red Data Book. WWF is an organisation working with the ob jective of protection of biodivesity. Gene banks are included in in-situ conserva tion. #### PREVIOUS YEAR QUESTIONS Question 1. Observe the given food chain and wright the name of organisms which represents secondary consumer and the second trophic level. Grass $\rightarrow$ Grass hopper $\rightarrow$~Frog $\rightarrow$ Snake Answer: Secondary Consumer - Frog