Biology Standard SB4 (b)

1. Biology Standard SB4 (b) The flow of matter and energy through ecosystems

2. The flow of energy • In a food chain, energy is passed from one link to another. When a herbivore eats, only a fraction of the energy (that it gets from the plant food) becomes new body mass; the rest of the energy is lost as waste or used up by the herbivore to carry out its life processes (e.g., movement, digestion, reproduction). Therefore, when the herbivore is eaten by a carnivore, it passes only a small amount of total energy (that it has received) to the carnivore. Of the energy transferred from the herbivore to the carnivore, some energy will be "wasted" or "used up" by the carnivore. The carnivore then has to eat many herbivores to get enough energy to grow.Because of the large amount of energy that is lost at each link, the amount of energy that is transferred gets lesser and lesser ...The further along the food chain you go, the less food (and hence energy) remains available.

3. The energy pyramid Carnivores are the fewest in numbers in a healthy ecosystem. The carnivore has to eat a lot to get enough energy to live. Carnivores are contained on the top level. The primary consumers are herbivores they eat the plant life. A percentage of the energy is used by the herbivores the rest becomes waste. Your primary consumers are in level two. Level one houses the producers. Producers get their energy from the sun. In a healthy ecosystem this is the largest group.

4. Photosynthesis

5. The Water Cycle • The Water Cycle (also known as the hydrologic cycle) is the journey water takes as it circulates from the land to the sky and back again. The Sun's heat provides energy to evaporate water from the Earth's surface (oceans, lakes, etc.). Plants also lose water to the air (this is called transpiration). The water vapor eventually condenses, forming tiny droplets in clouds. When the clouds meet cool air over land, precipitation (rain, sleet, or snow) is triggered, and water returns to the land (or sea). Some of the precipitation soaks into the ground. Some of the underground water is trapped between rock or clay layers; this is called groundwater. But most of the water flows downhill as runoff (above ground or underground), eventually returning to the seas as slightly salty water.

6. This is how the water cycle works

7. The Nitrogen Cycle •   Nitrogen is a component of many organic molecules.  It forms an essential part of amino acids (which make up proteins) and DNA.  Nitrogen is essential for all living cells. • What is the nitrogen cycle?    Nitrogen is the major component of earth's atmosphere.  It enters the food chain by means of nitrogen-fixing bacteria and algae in the soil.  This nitrogen which has been 'fixed' is now available for plants to absorb.  These types of bacteria form a symbiotic relationship with legumes--these types of plants are very useful because the nitrogen fixation enriches the soil and acts as a 'natural' fertilizer.  The nitrogen-fixing bacteria form nitrates out of the atmospheric nitrogen which can be taken up and dissolved in soil water by the roots of plants.  Then, the nitrates are incorporated by the plants to form proteins, which can then be spread through the food chain.  When organisms excrete wastes, nitrogen is released into the environment.  Also, whenever an organism dies, decomposers break down the corpse into nitrogen in the form of ammonia.  This nitrogen can then be used again by nitrifying bacteria to fix nitrogen for the plants.

8. The Nitrogen cycle in the soil

9. The Carbon Cycle • Carbon moves from the atmosphere to plants.In the atmosphere, carbon is attached to oxygen in a gas called carbon dioxide (CO2). With the help of the Sun, through the process of photosynthesis, carbon dioxide is pulled from the air to make plant food from carbon. • Carbon moves from plants to animals.Through food chains, the carbon that is in plants moves to the animals that eat them. Animals that eat other animals get the carbon from their food too. • Carbon moves from plants and animals to the ground.When plants and animals die, their bodies, wood and leaves decay bringing the carbon into the ground. Some becomes buried miles underground and will become fossil fuels in millions and millions of years. • Carbon moves from living things to the atmosphere.Each time you exhale, you are releasing carbon dioxide gas (CO2) into the atmosphere. Animals and plants get rid of carbon dioxide gas through a process called respiration

10. The carbon cycle

11. Phosphates in the web of things • Phosphate is mainly present in bones in animals, but is incorporated in most tissues of plants and animals - and through digestion gets absorbed and incorporated in a person's body and is dynamically present, being released and excreted through urine and feces. Thus excreted phosphate returns to the environment where it is available for uptake into plants and into the food web.

12. Phosphates are everywhere

13. The process as a whole The plants produce energy from the sun. The energy from the sun is partly stored within the plant, which is eaten by the herbivores. Some of the energy taken from the plants is stored and the rest is waste which falls back to the soil and becomes nutrients that feeds the soil. The carnivores and omnivores then eat and some of that energy is used and the rest is waste. The decomposers turn the waste into a fuel source that keeps a healthy ecosystem.