Food Chains and Food Webs PDF

# Food Chains and Food Webs ## How Living Organisms Depend on Each Other - All living organisms depend on each other for food. - Food gives them the energy to live, grow, and carry out life processes. ## What is a Food Chain? - A food chain is a sequence of who eats whom in an ecosystem to get e...

# Food Chains and Food Webs ## How Living Organisms Depend on Each Other - All living organisms depend on each other for food. - Food gives them the energy to live, grow, and carry out life processes. ## What is a Food Chain? - A food chain is a sequence of who eats whom in an ecosystem to get energy. - Every organism in the chain is essential. ### Example of a Food Chain 1. Grasshopper eats grass. 2. Frog eats the grasshopper. 3. Snake eats the frog. 4. Eagle eats the snake. **Energy and nutrients from the grass are transferred to the grasshopper, then to the frog, then to the snake, and finally to the eagle.** ## Links in a Food Chain - Every living organism forms a link in the food chain. - All food chains begin with plants which are producers. They are the first link in the food chain. - If one link in the food chain is removed, the entire food chain will be affected. ## Vocabulary - **Food Chain:** A sequence of who eats whom in an ecosystem to get energy. ## Toxins and Food Chains - When plants and animals become infected due to environmental contamination, pollutants from their body enter the food chain. - For instance, fish may get infected when contaminated water enters its body. - The infected fish when consumed by other living organisms results in transfer of toxins. ## What is a Toxin? - A number of substances, including fertilizers, pesticides, and insecticides can contaminate the soil and water. - When plants, which are regarded as producers, are grown using contaminated soil and water, they become toxic. - The contaminants in the producers are transferred to the next link of the food chain when they are consumed. - With the passage of time, toxins build up in animal fat and tissues through a process known as bioaccumulation. - They then travel up the entire food chain from preys to predators. - Therefore, animals at the top of the food chain typically have the largest quantity of toxins. ## What is Bioaccumulation? - Bioaccumulation is the process by which toxins build up in animal fat and tissues through a process known as bioaccumulation. ## Chapter 3: Human Activities and the Ecosystem ### Deforestation - The cutting down of trees on a large scale. - Industries keep burning fuels and adding harmful substances, like smoke, dust, and gases to the air. ### Overgrazing - Another practice that destroys grasses, shrubs and plants. ### Polluted Water - Harmful chemicals and other substances are discharged into rivers and streams. ### Excessive use of Fertilizers and Pesticides - Flow into water bodies, polluting them. ## What are Predators and Prey? - A predator is an animal that hunts and eats other animals. - Prey is an animal that is hunted by another animal. ### Examples of Predators and Prey - Predators: Lions, owls, cheetahs - Prey: Deer, mice, grasshoppers ## Interactions Between Predators and Prey - Animals interact with each other in different ways in an ecosystem. - One type of animal can use another type of animal as a source of food. ## Omnivores - An organism that consumes both plants and animals. - Omnivores greatly impact food chains. - Each food chain has a diverse group of omnivores. ### Examples of Omnivores - Bears, birds, dogs, raccoons, foxes, some insects, and even humans. ## Food Webs - A network of connections that shows the general relationships among organisms through multiple food chains in a given ecosystem. - Each food chain is a link in a larger food web. - A food web is made up of a number of food chains. - Energy and nutrients move through the food web. ## Human Activities and the Ecosystem - Humans are responsible for causing changes in the environment. - These changes can upset the natural balance of ecosystems. ### Think About It - Can you think of any other examples of predators and they? - Suppose all the lions in an ecosystem disappeared. What do you think would happen to ecosytem? ## Biodegradable and Non-Biodegradable Materials - Many of the objects that we use in our daily lives lose their usefulness after some time. - We often throw such items away as garbage. - Garbage is generated every day from homes, industries, and commercial places. - Garbage is not all of the same type and can be divided into two categories - biodegradable and non-biodegradable. ### Biodegradable Materials - Easily decomposed or broken down by microorganisms present in nature. - Made of organic matter, such as animal waste, like tea leaves, vegetable peels, and leftover food items. - It also includes waste paper and wood items. ### Non-Biodegradable Materials - Cannot be broken down easily by nature. - Examples: Metal, tin, glass, plastics. - They stay in their original form for centuries and keep polluting the environment. ## Land Pollution - When harmful substances are mixed in soil, they affect the soil quality. - This leads to land pollution. ## Causes of Land Pollution - The activities that cause land pollution: - Cutting down trees at a fast rate: Deforestation affects the quality of soil and makes the land infertile. - Use of plastics and chemicals: Use of solid wastes (cans and plastic bottles), and chemicals (pesticides and fertilizers) cause land pollution - Industrial waste: Waste from industries. ## Effects of Land Pollution - Land pollution poses many threats to living beings as well as the environment. - People often throw garbage into piles, which create large open dumps that attract flies, mosquitoes and rats. These dumps become a breeding ground for diseases. - Mass cutting of trees damages the soil. The soil becomes loose and can be easily washed away by rain or blown away by the wind. This loss of fertile topsoil is called soil erosion. Once the soil is polluted, it affects plant growth as plants do not grow well in polluted soil. Plants that grow in polluted soil are not fit to be eaten by humans or animals and might make them ill. ## It's a Fact - The water that is supplied to our homes may not be germ free and pure. We can try to purify it either by boiling it or using an electric water filter. ## What is Air Pollution - Air pollution is when harmful gasses and particles are added to the air. - It can be caused by: - Burning of fuels: Fuels, such as coal, petrol, and diesel release poisonous gases when burnt. - Smoke from factories: Dirty smoke released from factories also adds harmful gases in the air. - Eruption from volcanoes: Harmful gasses and ash are released into the air during volcanic eruptions. - Burning of firecrackers: The burning of firecrackers is another cause of air pollution. ## Effects of Air Pollution - All of us need to breathe clean air to stay alive. - If we breathe polluted air, our lungs can get affected. - It can result in respiratory problems, such as asthma. ### Think About It - What happens if too many trees are cut down, across a wide area? - What happens to: - The animals who live there? - The soil? - The air quality? ## What is Smog - It is a type of air pollution that reduces visibility. - It is common in industrial areas, particularly during winters. ## What is the Ozone Layer? - The ozone layer protects us from the harmful ultraviolet light of the Sun. ## What are Chlorofluorocarbons (CFCs)? - Gases that are released mainly from air conditioning systems and refrigerators. - When released into the air, CFCs damage the ozone layer and exposes us to the damaging UV rays of the Sun. ## What is Water Pollution? - The contamination of water bodies, like lakes, rivers, and oceans by household, agricultural, and industrial waste. ## What is the Discharge of Water Waste? - Refers to releasing water waste into water bodies. ## Causes of Water Pollution - Some common causes of water pollution: - Throwing garbage in water: Throwing plastic waste and other garbage in water causes water pollution. - Washing and bathing near water bodies: Washing clothes, bathing in ponds, and defecating near water bodies, also leads to water pollution. - Discharge of industrial wastage in water bodies: Discharge of untreated industrial wastage into rivers not only pollutes the river water but is also harmful for aquatic plants and animals. ## Vocabulary - **Fertiliser:** A chemical or natural substance added to soil to supply it with more nutrients. - **Overhunting:** Hunting in excess that causes a great decrease in the population of an animal. - **Overfishing:** Catching an excessive number of fish which could cause the number to decrease. - **Famine:** A scarcity of food. - **Drought:** Shortage of water because of no rain for a long time. - **Global:** Relating to the whole world. - **Submerge:** Under water. - **Volcanic Eruption:** A volcano ejecting lava, ash, and gasses. - **Breeding:** Reproducing. - **Fertile:** Capable of producing a large amount of crops.