Section 1.9 Pages 30-33 Follow along with your notes hand- out. Words that look like this represent the blanks on your notes handout for the section. Why your neighbour has an awesome green lawn. while yours is a blah yellow mess? If you have a pale yellow lawn, it is probably lacking in an important element called Nitrogen! It is the fourth most common element in living tissues. 1. Oxygen 2. Carbon 3. Hydrogen 4. Nitrogen What do you already know about Nitrogen? Nitrogen is important for life on Earth: Amino Acids Proteins Genetic Material Nitrogen is important for life on Earth: Amino Acids Proteins Genetic Material Nitrogen is important for life on Earth: Amino Acids Proteins Genetic Material Many chemical processes are controlled by special proteins called enzymes. Example: Growth Many chemical processes are controlled by special proteins called enzymes. Example: Digestion Many chemical processes are controlled by special proteins called enzymes. Example Reproduction Animals get their Nitrogen by eating plants or other animals. Plants rely on nitrogen on nitrogen to grow! If plants need it, it is very important to everything in an ecosystem! Like carbon, nitrogen is limited and it must be recycled. For plants it is much more difficult to get nitrogen! Remember Carbon: plants got their carbon from the atmosphere even though only 0.03% of the air is CO 2 Nitrogen makes up 79% of the atmosphere! But plants cannot use nitrogen when it is a gas! It needs to be changed into a chemical called Nitrate first! This is where the nitrogen cycle becomes important! Nitrate Nitrogen Cycle the process by which nitrogen from the atmosphere, dead organisms, and urine/feces is made available to plants in a form they can use. Nitrogen Fixation is the process by which Nitrogen Gas (N 2 ) is removed from the atmosphere and enters the soil. Two Ways 1) Lightning 2) Bacteria found on roots of legumes 1) Lightning Changes N 2 in air directly into chemicals called Nitrates (NO 3 ). Plants can use this right away. However, only 5% of nitrates are formed this way!! 2) Bacteria This bacteria can be found: a) freely in the soil b) attached to the roots of special plants called Legumes. (Clovers, beans, even peanut plants!) 2) Bacteria These bacteria change Nitrogen gas (N 2 ) into a chemical called Ammonium (NH 4 + ) Ammonium must be changed into Nitrates (NO 3 ) before plants can use them! Nitrification: the process by which Bacteria change Ammonium into Nitrates Ammonium is provided by: Nitrogen-fixing bacteria And Animal bodies and waste (urine and feces) Plants need nitrogen in the form of nitrates. Nitrates are formed directly from Lightning in the air Nitrates are formed indirectly from legumes and animal waste AFTER nitrification has occurred. The cycle is completed by Denitrification Denitrification: process by which bacteria converts Nitrates (NO 3 ) into N 2 gas and releases it into the atmosphere. Over time, lawns can lose their bright green colour. This happens following an increase in denitrifying bacteria. Nitrates that are not used by or converted back into nitrogen gas can experience Leaching. Leaching: the process by which water carries Nitrates deeper into the soil and ground water. Quick Recap: Plants need nitrogen in the form of nitrates. Animals eat plants to survive, so therefore we rely on nitrates too. Sources of Nitrates for plants include: Lightning changing Nitrogen gas directly into Nitrates. Bacteria changing Nitrogen gas into ammonia and then into Nitrates! Animal bodies or waste are decomposed and changed into Nitrates. Nitrates leave the soil and become unavailable to plants: due to denitrifying bacteria turning them back into Nitrogen gas water causing leaching by dragging nitrates deep into the soil National Geographic National Geographic (first 3-4 min, then from 10-15) More Eutrophication More Eutrophication