1. Section 1.9 Pages 30-33

2.  Follow along with your notes hand- out.  Words that look like this represent the blanks on your notes handout for the section.

3. Why your neighbour has an awesome green lawn….

4. while yours is a blah yellow mess?

5.  If you have a pale yellow lawn, it is probably lacking in an important element called Nitrogen!

7.  It is the fourth most common element in living tissues. 1. Oxygen 2. Carbon 3. Hydrogen 4. Nitrogen

8.  What do you already know about Nitrogen?

9. Nitrogen is important for life on Earth:  Amino Acids  Proteins  Genetic Material

10. Nitrogen is important for life on Earth:  Amino Acids  Proteins  Genetic Material

11. Nitrogen is important for life on Earth:  Amino Acids  Proteins  Genetic Material

12.  Many chemical processes are controlled by special proteins called enzymes.  Example: Growth

13.  Many chemical processes are controlled by special proteins called enzymes.  Example: Digestion

14.  Many chemical processes are controlled by special proteins called enzymes.  Example Reproduction

15.  Animals get their Nitrogen by eating plants or other animals.

16.  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.

17.  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

18.  Nitrogen makes up 79% of the atmosphere!

19.  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

20. 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.

21. 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

22. 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!!

23. 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!)

24. 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!

25. 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)

26.  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.

27.  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.

28.  Over time, lawns can lose their bright green colour. This happens following an increase in denitrifying bacteria.

30.  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.

31. 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

33.  National Geographic National Geographic (first 3-4 min, then from 10-15)  More Eutrophication More Eutrophication