diff --git a/Grade 9/Science/SNC1DZ/Unit_3_Biology_Study_Sheet.md b/Grade 9/Science/SNC1DZ/Unit_3_Biology_Study_Sheet.md
index f4d99ce..b1aed78 100644
--- a/Grade 9/Science/SNC1DZ/Unit_3_Biology_Study_Sheet.md	
+++ b/Grade 9/Science/SNC1DZ/Unit_3_Biology_Study_Sheet.md	
@@ -43,6 +43,8 @@
 - `Intraspecifict`: Same species fighting.
 - `Watershed`: An area or ridge of land that separates waters flowing to different rivers, basins, or seas.
 - `Intertidal Zone`: The intertidal zone, also known as the foreshore and seashore, is the area that is above water at low tide and underwater at high tide.
+- `Limiting Factor`: Any factor that restricts the size of a population.
+- `Tolerance Range`: The abiotic conditions within which a species can survive.
 
 ## The Spheres of Earth
 
@@ -168,7 +170,7 @@ efficiency varies from `5%` to `20%` energy available between successive trophic
     - Evaporation, Condensation, Precipitation, Percolation (Infiltration, water seeping into ground), Run-off, transpiration (plants losing water to air)
     - Forms: Solid (ice), Liquid (water), Gas (vapour)
 
-### STEPS/PROCESS:
+### Steps/Process:
 - Exchange of energy leads to:
     - Temperature Change, Climate
     - Condenses 🡪 occurs during cooler temp
@@ -193,7 +195,7 @@ efficiency varies from `5%` to `20%` energy available between successive trophic
 - Building block of all living things
 - Main Pathway – in and out of living matter
 
-### STEPS/PROCESSES
+### Steps/Process
 - All living organisms contain carbon.
 - CO<sub>2</sub> is a waste product of cellular respiration
 - Plants use carbon dioxide and water to form simple sugars (photosynthesis)
@@ -225,7 +227,7 @@ efficiency varies from `5%` to `20%` energy available between successive trophic
     - Most living organisms are `unable` to use this form of nitrogen
     - Therefore, must be **converted** to a usable form!
 
-### STEPS/PROCESSES
+### Steps/Process
 <img src="https://image.slidesharecdn.com/lab-11methodsforestimatingdenitrificationprocess-130414125752-phpapp01/95/lab11-methods-for-estimating-denitrification-process-4-638.jpg?cb=1365944316" width="300">
 
 ### Nitrogen Fixation
@@ -378,9 +380,32 @@ efficiency varies from `5%` to `20%` energy available between successive trophic
 * Heavy precipitation on leeward side of mountains
 * `Species` Elk, cougar, large coniferous trees, ferns.
 
+## Biodiversity
+- The importance 
+
+
 ## Introducing Ecosystems
 - Most ecosystems are **SUSTAINABLE**.
 
+<table class="table">
+<tr>
+<th>Ecosystem</th><th>Key abiotic factors</th><th>Human action and result</th>
+</tr>
+<tr>
+<th>Terrestrial Ecosystems</th>
+<td>Light availability <br><br>Water availability<br><br>Nutrient availability<br><br>Temperature</td>
+<td>Clear-cutting and fire remove shade and expose the remaining organisms to much more light<br><br>Damming rivers and draining swamps and marshes change water availability. Irrigation increases water availability<br><br>Farming practices may increase or decrease nutrient levels in the soil.<br><br>Global warming is decreasing suitable habitat for many cool-adapted species.</td>
+</tr>
+<tr>
+<th>Aquatic Ecosystems</th>
+<td>Light availability<br><br><br>Nutrient availability<br><br><br>Acidity<br><br><br>Temperature<br><br>Salinity<br><br></td>
+<td>Activities that increase erosion or stir up the bottom cloud the water and reduce light penetration.<br><br>Nutrient runoff from agriculture and urban enviornments increases the nutrient content of <br> surface water and groundwater, causing algal blooms<br><br>Acidic air pollution results in acid precipitation. Carbon dioxide emissions <br>produced by the burning of fossil fuels are increasing the acidity of the oceans.<br><br>Industries and power plants release heated waste water into lakes and rivers, killing fish and other organisms.<br><br>Salting highways and long-term irrigation practices can cause salt to accumlate.<br></td>
+</tr>
+</table>
+
+- `Limiting factors` can be something such as access to water, availability of food. Can be **both** `abiotic` and `biotic`. Human influences often act as `limiting factors`. 
+- The carry capacity of an ecoystem is a limit where the organisms in that ecosystem can sustain themselves, human impacts often lower the `carry capacity`, as things such as pollution, destruction of habitats drastically lowers the `sustainability` of a ecosystem. In general, `limiting factors` link directly to `carrying capacity` as the the factors tell us the size that that the ecosystem can sustain itself. Which is essentially the `carrying capacity`.
+
 ### Ecosystem Services/Products
 - **Cultural Services**
     - Benefits relating to our enjoyment of the environment.

Ecosystem	Key abiotic factors	Human action and result
Terrestrial Ecosystems	Light availability Water availability Nutrient availability Temperature	Clear-cutting and fire remove shade and expose the remaining organisms to much more light Damming rivers and draining swamps and marshes change water availability. Irrigation increases water availability Farming practices may increase or decrease nutrient levels in the soil. Global warming is decreasing suitable habitat for many cool-adapted species.
Aquatic Ecosystems	Light availability Nutrient availability Acidity Temperature Salinity	Activities that increase erosion or stir up the bottom cloud the water and reduce light penetration. Nutrient runoff from agriculture and urban enviornments increases the nutrient content of surface water and groundwater, causing algal blooms Acidic air pollution results in acid precipitation. Carbon dioxide emissions produced by the burning of fossil fuels are increasing the acidity of the oceans. Industries and power plants release heated waste water into lakes and rivers, killing fish and other organisms. Salting highways and long-term irrigation practices can cause salt to accumlate.