diff --git a/Grade 9/Science/SNC1DZ/Study_Sheet.md b/Grade 9/Science/SNC1DZ/Study_Sheet.md
index 66c925a..0000f6f 100644
--- a/Grade 9/Science/SNC1DZ/Study_Sheet.md	
+++ b/Grade 9/Science/SNC1DZ/Study_Sheet.md	
@@ -105,6 +105,7 @@
   - smell, taste, touch, hearing, sight
   - scales, tape, measuring meter
   
+
 ## Qualitative and Quantitative Properties
 
  |Type|Definition|Example|
@@ -171,9 +172,11 @@
     - Using electricity
     - Adding thermal energy
  
+
 ## Catalyst
 - Substance that accelerates a chemical change without being consumed OR changed itself
   
+
 ## Uses of Hydrogen Peroxide
 - On cuts/scraps
   - Blood has a catalyst = see bubbling O<sub>2</sub>
@@ -183,5 +186,110 @@
   - React with compounds that provide color
   - RESULT = no colour (bleach blond hair/teeth)
   
-# Unit 3
-Sustainability: the ability to maintain
+
+# Unit 3: Biology
+
+## The Sphere's of Earth
+### Atmosphere
+- The layer of `gases` above Earth's surface, extending upward for hundreds of kilometers.
+    - `78% nitrogen gas`.
+    - `21% oxygen gas`.
+    - `< 1% argon, water vapour, carbon dioxide & other gases`.
+- Critical to (almost all) life on Earth.
+- Acts like a **blanket & moderates surface temperature**.
+- Insulation prevents excessive **heating** during the day & **excessive cooling** during the night.
+- Average surface temperature droup from **15C to -18C**.
+- Blocks some **solar radiation (most ultraviolet light)**.
+
+    
+### Biosphere
+- The regions of Earth where `living organisms` exist.
+- Describes **the locations in which life can exist within the lithosphere, atmosphere and hydrosphere**.
+- Biosphere is thin in comparison to diameter of the Earth.
+- ALL conditions required for **life must be met and maintained within this thin layer of ground, water, and nutrients to survive**.
+
+### Hydrosphere
+- All the `water` found on Earth, above and below the Earth's surface.
+- Includes
+    - **Oceans**
+    - **Lakes**
+    - **Ice**
+    - **Ground Water**
+    - **Clouds**
+- 97% of water on Earth **is in the oceans**.
+
+
+### Lithosphere
+- The `hard part` of Earth's surface.
+- **Rocky outer shell of Earth**.
+- Consists of:
+    - **Rocks and minerals that make up mountains, ocean floors, and Earth's solid landscape**
+-Thickness: **50 - 150km**.
+    
+
+### Terms
+- `Biotic`: Living components (their remains AND features)
+    - Bears, insects, micro-organisms, nests
+- `Abiotic`: Non-living components
+    - Physical/chemical components
+    - Temperature, wind, humidity, precipitation, minerals, air pressure
+- `Sustainability`: **The ability to maintain natural
+ecological conditions without interruption,
+weakening, or loss of value.**
+- `Population`
+    - All of the individuals of a single species in a particular area
+- `Community`
+    - Individual from all of the DIFFERENT populations (communities of different species)
+- `Ecosystem`
+    - Term given to the community and its interactions with the abiotic environment 
+
+- `Sustainable Ecosystem`
+    - An ecosystem that is maintained through natural processes
+
+## Types of Energy
+- #### Radiant Energy
+    - Energy that travels through EMPTY SPACE
+- #### Thermal Energy
+    - Form of energy TRANSFERED DURING HEATING/COOLING
+    - Keeps the Earth's surface warm
+    - CANNOT provide organisms with energy to grow & function
+## Successions
+- `Succession`: The gradual and usually predictable changes in the composition of a community and the abiotic condtions following a disturbance.
+    - ### Primary
+        - on newly epxposed  ground, such asa following a volcanic eruption.
+    - ### Secondary
+        - in a partially distrubed ecosystem, such as following a forest fire. 
+        - Human caused disturbances.
+#### Light Energy
+- VISIBLE forms of radiant energy
+- Can be used by some organisms (CANNOT be stored)
+
+#### Chemical Energy
+- Used by living organisms to perform functions (growth, reproduction, etc.)
+- MUST be replaced as it is used
+
+## It starts with the sun …
+- Energy radiates from the sun (UV)
+- Earth is hit with the UV or light energy
+- 70% of radiant energy is absorbed by `Hydrosphere` & `Lithosphere`
+- Converted into **thermal** energy
+- Warms the atmosphere, evaporates water & produces winds
+- What happens with the rest?
+- Approx. `30%` is reflected back into space
+- `0.023%` absorbed by living organisms through photosynthesis
+
+
+## Benefits of Succession
+- Provides a mechanism by which ecosysmtems maintain their long term sustainability.
+- Allows ecosystems to recover from natural or human caused distrubances.
+- Offers hope (New Orleans, New Jersey, Florida, Puerto Rica).
+- Time needed is very long.
+- Original cause o disturbance must be eliminated.
+- Not all disturbances can be repaired.
+- Disturbances can be repaired through humans actions that support the natural processes of succession.
+
+## Biodiversity
+- The variety 
+- 
+
+