Cycles in Nature

Water, Carbon, and Nitrogen  Living things need water, carbon, and nitrogen.  These materials flow (cycle) through an ecosystem.  Link Link  (Remember we talked about carbon with photosynthesis and cellular respiration.)  Illuminating Photosynthesis Illuminating Photosynthesis Illuminating Photosynthesis

The Water Cycle  The sun evaporates water from lakes and oceans. As the air rises, it cools.  The water vapor condenses into tiny droplets of water. The droplets crowd together and form a cloud.  Link Link

The Water Cycle  Wind blows the cloud towards the land. The tiny droplets join together and fall as precipitation (rain, snow, sleet) to the ground.  The water soaks into the ground and collects in rivers and lakes. Eventually, the water returns to the ocean or collects underground.

The Water Cycle The Water Cycle

Diagram Wordbank Clouds (Condensation) EvaporationOceanPrecipitationSun

Diagram Answers 1.The Sun 2.Clouds (Condensation) 3.Evaporation 4.Precipitation 5.The Ocean

The Carbon Cycle 1. During photosynthesis, plants take carbon in the form of carbon dioxide from the atmosphere and lock it into their food (glucose).

The Carbon Cycle 2. Animals get their carbon from eating either plants or other animals which they then digest. This carbon is released in cellular respiration and exhaled by animals.

The Carbon Cycle 3.Carbon in an animal’s waste is released and is digested by decomposers - mainly microbes and fungi. The decomposers also go through cellular respiration, releasing carbon dioxide.

The Carbon Cycle 4. When animals die, their remains may be either eaten by scavengers (for example, crows) or digested by decomposers. Both scavengers and decomposers go through cellular respiration, giving off more carbon dioxide.

The Carbon Cycle 5. In certain conditions both animal and plant remains may become fossilized, eventually forming fossil fuels (coal, oil and gas) which contain carbon.

The Carbon Cycle 6. Both fossil fuels and plant material (wood) may later be burned - releasing still more carbon dioxide to the environment.

The Carbon Cycle

The Nitrogen Cycle   Although we are surrounded by nitrogen gas, and organisms need nitrogen to live, most organisms cannot use the nitrogen gas around them.

The Nitrogen Cycle   Nitrogen must be combined with other elements, such as hydrogen, to be usable by organisms.   Nitrogen cycles through an environment.

The Nitrogen Cycle   The process of nitrogen combining with other elements is called nitrogen fixation. This can be done in two ways:

Nitrogen Fixation 1.The process can be performed by a special type of bacteria that grows on the roots of certain (leguminous) plants. Beans, peas, clover, alfalfa, locust trees, and acacia trees are all legumes.

Nitrogen Fixation 2. A lightning bolt can split the two nitrogen atoms, allowing the "free" nitrogen atoms to react with oxygen and hydrogen atoms.

Nitrogen Fixation

The Nitrogen Cycle  The following diagrams show how nitrogen moves from one place to another in the environment.

Nitrogen Fixation

Nitrogen in the soil is absorbed by plants then is taken into animals when the animals eat the plants.

Nitrogen in the animal can be released into the air through breathing, sweating, and urinating. It can be returned to the soil through the animal’s waste.

Nitrogen in the animal’s body is returned to the soil when the animal dies and decomposes.

Questions 1.What is an ecosystem? 2.What is a biotic factor? List some examples. 3.What is an abiotic factor? 4.What are three abiotic factors needed by living things?

Questions 5.What is the difference between evaporation, condensation, and precipitation? 6.What role do plants play in the carbon cycle? 7.What roles do animals play in the carbon cycle? 8.Why do cars, buses, trucks, etc. put more carbon in the air?

Questions 9.What is nitrogen fixation? 10.What are two ways this process happens? 11.Describe how nitrogen can move from the soil, to a plant, to an animal, and back to the soil?

Questions 1.What is an ecosystem? An ecosystem is made up of living and non- living things in an area. It includes the interactions among these organisms.

Questions 2. What is a biotic factor? List some examples. A biotic factor is a living thing. Examples are plants and animals.

Questions 3. What is an abiotic factor? An abiotic factor is a non-living organism in an ecosystem.

Questions 4. What are three abiotic factors needed by living things? Three abiotic factors needed by living things are water, nitrogen, and carbon.

Questions 5. What is the difference between evaporation, condensation, and precipitation? Evaporation is the process where heat turns water into water vapor. Condensation is the cooling and collecting of water vapor. Precipitation is when the condensed water vapor falls from the clouds.

Questions 6. What role do plants play in the carbon cycle? Plants play an important role in the carbon cycle. Plants take in carbon dioxide from the atmosphere during photosynthesis and lock it into the glucose created. The carbon in glucose is then transferred to the consumer(s) that eat the plant.

Questions 7. What roles do animals play in the carbon cycle? Animals play an important role in the carbon cycle. They consume the stored carbon from producers. Carbon is released in cellular respiration and re-enters the atmosphere.

Questions 8. Why do cars, buses, trucks, etc. put more carbon in the air? Cars, buses, trucks, etc. put more carbon in the air because they burn fossil fuels— fuels made from fossilized remains of plants and animals (that contained carbon).

Questions 9.What is nitrogen fixation? Nitrogen fixation is the combining of nitrogen with other elements so that it can be used by animals.

Questions 10.What are two ways this process happens? Nitrogen fixation happens in two ways: Bacteria that grows in the roots of certain plants can help nitrogen attach to other elements. A lightning bolt can split two nitrogen atoms which frees them to attach to other elements.

Questions 11. Describe how nitrogen can move from the soil, to a plant, to an animal, and back to the soil? Nitrogen can move from the soil, to a plant, to an animal, and back to the soil. It is absorbed by a plant, eaten by an animal, and returned to the soil through wastes excreted (to the atmosphere) from the animal or the dead animal’s decaying body.