Ecosystems

• Human actions that negatively affect the environment include wasting food, using more electricity and water than needed, creating excessive waste, and improper disposal of waste
• Human actions that conserve the environment include reducing the use of fossil fuels, reducing consumption, introducing environmentally friendly practices, and reforestation
• Physical factors such as air, water, temperature, light, minerals, and acidity/alkalinity affect the lives of organisms in ecosystems
• Different environments are distinguished by physical factors like light, temperature, air, water, minerals, and acidity or alkalinity
• Plants need light for photosynthesis, and the amount of light available determines the kinds of plants and animals found in a habitat
• Temperature affects the activities of all organisms, with low temperatures slowing down processes like photosynthesis in plants and blood circulation in animals
• Air contains gases that organisms need to live, with plants needing carbon dioxide for photosynthesis and organisms needing oxygen to respire
• Water is essential for all organisms to survive, and the volume of water in a habitat affects the number and types of organisms present
• Mineral salts are important for the production of chlorophyll and nutrients like proteins and vitamins
• Plants and animals do not grow well without mineral salts
• Plants obtain mineral salts through absorption from the soil, while animals get mineral salts from the food they eat
• The amount of mineral salts dissolved in water affects the salinity of the environment
• Some aquatic organisms adapt to live in very salty water like the sea, while others adapt to live in streams and freshwater ponds
• Both land plants and aquatic organisms are sensitive to the pH level of their habitats
• Most organisms cannot survive in extremely acidic or alkaline environments
• Freshwater organisms can tolerate a pH of about 7, while marine organisms can tolerate a pH of about 8
• Aquatic plants can affect the pH level of water by using dissolved carbon dioxide in water to carry out photosynthesis, which decreases water acidity and increases pH
• Plants can only tolerate a small range of pH levels in soil, ideally from 6.0 to 6.5
• A suitable combination of physical factors allows plants to grow, providing food and shelter for animals to survive and reproduce
• Only organisms adapted to their environment or with adaptive traits can grow well and survive in their environment
• Adaptive traits can be structural or behavioral
• Structural adaptations are physical characteristics that help organisms survive in their habitat
• Behavioral adaptations refer to different behaviors that help organisms survive in their habitat
• Examples of organisms with structural adaptations include the female Phyllium asekiense and crocodile
• Examples of organisms with behavioral adaptations include wild geese and trees shedding leaves in autumn
• Food chains represent the flow of energy and nutrients between organisms
• Multiple food chains exist in every ecosystem
• Food webs show how food chains are interconnected and give an overall picture of all organisms involved in energy and nutrient transfer
• In an ecosystem, the flow of energy occurs with the flow of nutrients
• Photosynthesis and respiration are involved in the flow of energy and nutrients
• Producers absorb light energy to produce food through photosynthesis
• Consumers obtain energy by feeding on plants and animals
• Decomposers feed on remains of dead organisms and release energy through respiration
• About 90% of energy is lost to the environment at each stage
• The flow of energy in a food chain or food web is one-directional
• The last organism in the food chain receives the least amount of energy from the sun
• Nutrients are transferred from producers to consumers and then to predators
• Decomposers break down remains of dead organisms and return nutrients to the environment
• Fungi and bacteria play a significant role in decomposing nutrients
• Nutrients are recycled by decomposers in a cyclical manner