Biology - Our Environment Class Notes PDF

# **UDAAN** ## Biology - Our Environment - One Shot Lecture - By- Samridhi Ma'am ## Today's Targets 1. Ecosystem: Types, Components and function 2. Food chain and food webs 3. Ozone layer and its depletion 4. Waste Management ## Environment Environment is the sum total of all the external facto...

# **UDAAN** ## Biology - Our Environment - One Shot Lecture - By- Samridhi Ma'am ## Today's Targets 1. Ecosystem: Types, Components and function 2. Food chain and food webs 3. Ozone layer and its depletion 4. Waste Management ## Environment Environment is the sum total of all the external factors, substances, living beings and conditions that surrounds a particular organism. ## Ecosystem - Biotic (Living) - Abiotic (Non-Living) Ecosystem (ecological system) is a geographical area of our environment which consist of distinct biotic community and the physical factors (such as air, water, sunlight etc) both interacting and exchanging materials between them. ### Components of Ecosystem - **Biotic components** (Living Component of Ecosystem) - Plants - Animals - Fungi - Bacteria - **Abiotic components** (Non-Living Component of Ecosystem) - Air - Water - Soil - Temperature - Rainfall - pH ### Types of Ecosystem | Ecosystem | Description | |---|---| | **Forest Ecosystem** | | | **Grassland Ecosystem** | | | **Mountain Ecosystem** | | | **Desert Ecosystem** | | | **River Ecosystem** | | | **Ocean Ecosystem** | | | **Pond Ecosystem** | | #### Types of Ecosystem - **Natural Ecosystem** - Ecosystems which operate in the nature by themselves without any human interference. - **Terrestrial Ecosystem**(Land-based Ecosystem) - Desert - Grass Land - Forest - Mountain - **Aquatic Ecosystem**(Water based ecosystem) - River - Pond - Lakes - Sea - **Fresh Water Ecosystem** - **Marine Ecosystem** - **Artificial Ecosystem** (Man-made Ecosystem) - Ecosystems which are maintained due to human interference operate in the nature. - **Man-made Ecosystem** - Crop-field (Agricultural land) - Garden - Parks - Aquarium - Poultry farms - Zoo ## **Classification of Biotic community of an ecosystem** - **Producers** - **Consumers** - **Decomposers** ## **Producers** - **Autotrophic** - Organisms which produce/Synthesise food (glucose) in an ecosystem - Green plants - Cyanobacteria (Blue-green algae) - Various types of algae ## **Consumers** - Dependent on other living Organisms to fulfil their food demands - **Herbivore** - Plant based diet - Ex. cow, goat, deer - **Carnivore** - Animal based diet - Ex. Lion, Tiger, Eagle - **Omnivore** - Both animal & plant based diet - Ex. Human, dog, Cat ## **Decomposers** - **Saprotrophic** - Feed on dead & decaying matter - Bacteria - Fungi - Convert the complex organic matter into simpler substances like Carbon dioxide, water and other minerals. These minerals are then used by the producers. ## **Food Chain** Food chain is a linear series of organisms which represents the sequence in which a particular organism eats the other and becomes a source of food for the other in an ecosystem. ## **TROPHIC LEVEL** - **It is the position an organism occupies in a food chain.** - **Each link in the food chain represents one trophic level.** - **Producer (Autotrophic)** - Green plants - Some Bacteria - **Consumer (Heterotrophic)** - Herbivores - Carnivores - Omnivores - **Decomposer (Saprotrophic)** - Microorganisms (bacteria and fungi) ## **10% law of energy transfer** - **Proposed by Reymonds Lindeman in 1942** - **According to this law only 10% of energy is transferred from one trophic level to next successive trophic level.** ## **Functioning of ecosystem** 1. **Producer** : The producers synthesise complex food with the help of solar energy, carbon dioxide sunlight and minerals (Soil) 2. **Consumer** : The consumers eat up plants and other animals as food, so energy is transferred to the next organism. 3. **Decomposer** : When plants and animals die, then decomposers act/feed on dead remains of their bpd and decompose them into simple materials like CO2, water and minerals. ## **Food Web** Food web is a network of interconnected food chains operating in an ecosystem. ## **Food chain Vs Food Web** | **Food Chain** | **Food Web** | |---|---| | **Linear:** The sequence of living organisms in which one organism consumes another organism to transfer food energy | **The network of interlinked food chains.** | | Organisms at high trophic level feed upon single type of organism. | Organisms at high trophic level feed upon **multiple** types of organism. | | Comprised of single chain | Comprised of may food chains | | Removal of one group of organism disturbs whole chain | Removal of one group of organism does not cause much disturbance in ecosystem | ## **Biomagnification** Biomagnification is the increase in the concentration of toxins or non-biodegradable substances in the body tissues of organisms as it moves from one trophic level to the next. ## **Ozone layer and its depletion** ### **Causes of Ozone Layer Depletion** - Chlorofluorocarbon (CFC) - Hydrochlorofluorocarbon (HCFC) - Methyl bromide - Methyl chloroform ### **Effects of Ozone Layer Depletion** - Skin cancer - Cataract - DNA damage - Reduced Immunity - Sunburns - Low crop productivity - Destruction of marine life ### **Steps of Ozone Layer Depletion** 1. Chlorofluorocarbon (CFC) emissions reach the ozone layer. 2. CFCs are broken down by the Sun's ultraviolet (UV) rays, releasing chlorine atoms into the ozone layer. 3. Active chlorine atoms break down the ozone molecules, causing ozone layer depletion. 4. More ultraviolet rays reach the Earth, threatening human health. ### **Stratospheric ozone production** UV Radiation $O_2$ → O + O O + $O_2$ → $O_3$ (ozone gas) ## **Waste Management** ### **Types of Waste** | **Biodegradable Waste** | **Non-biodegradable Waste** | |---|---| | Material that can be decomposed (broken down into simpler substances) by the action of microorganisms | Material that can not be decomposed (broken down into simpler substances) by the action of microorganisms | | Safe for environment | Not Safe for environment and caused pollution | | Made up of natural substances | Made up of synthetic materials| | Biodegradable substances persist for less time in the environment. | Non Biodegradable substances persist for longer time in the environment. | | E.g. Wool, paper, fruit vegetable peels, wood etc. | E.g. Aluminium cans, iron nails, silver foil D.D.T. and radioactive waste | ### **What are the problems caused by the biodegradable wastes that we generate?** - The non-biodegradable wastes are non-decomposable and the prime reasons for land, air, soil, and water pollution. - Waste material around us cause bad odour and sometimes becomes breeding ground for disease-causing organisms. - The wastes like pesticides **decline the fertility of the soil**, with continuous application, the **pH level** of the soil turns unsuitable for vegetation. - The pesticides also get accumulated progressively at each trophic level and thus exhibit a harmful effect on the organisms. ### **Waste Management** - **Preparation of compost:** Biodegradable wastes can be converted into compost by burying in a pit. - **Land Fills:** Disposal of wastes by putting it in low lying area of ground and covering it with soil. - **Incineration:** Burning of waste substances at high temperature to form ash. - **Sewage treatment:** When sewage water is treated, it becomes clean water that can be discharged in river. It also produces manure and sewage gas (biogas). - **Recycling:** Solid waste like paper and metals can be recycled. ## **Reuse, Reduce, Recycle** ### **What do you think are the advantages of disposable paper-cups over disposable plastic cups?** - *Biodegradable* → decomposable. - *Eco friendly* → do not cause pollution. ## **Questions** 1. **Select the correct combination of abiotic components of an ecosystem.** - (**B**) Temperature, oxygen, pH, soil 2. **Which of the following organisms can acts as producers in aquatic food chain?** - (**B**) Phytoplankton 3. **Which of the following type of nutrition is shown by decomposers?** - (**D**) Saprotrophic 4. **If 100 kJ energy is available at the producer level in a food chain then the energy available to the 4th trophic level will be?** - (**D**) 0.01 J 5. **Pyramid of energy is always** - (**A**) Upright 6. **Which of the following type of nutrition is shown by cyanobacteria?** - (**A**) Photo autotrophic 7. **Ozone gas is made up of** - (**C**) 3 oxygen atoms