diff --git a/Grade 10/Science/SNC2DZ/Unit 2: Biology.md b/Grade 10/Science/SNC2DZ/Unit 2: Biology.md
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--- a/Grade 10/Science/SNC2DZ/Unit 2: Biology.md	
+++ b/Grade 10/Science/SNC2DZ/Unit 2: Biology.md	
@@ -5,5 +5,23 @@
 
 ## Celular Biology
 A person contains roughly 100 billion cells
-    - there are roughly to different types of cell s found in mammals
-    - cells are roughly 20 $`\um`$ (micrometer)
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+- there are roughly to different types of cell s found in mammals
+- cells are roughly 20 $`\um`$ (micrometer, $`10^{-6}`$ m), around 250 cells / cm
+
+## Cell Theory
+1. All living things are composed of cells 
+2. cells are the basic units of living organisms
+3. all cells came from pre-existing cells
+
+## Types Of Cells
+`Prokaryotic cell`: Meaning before/lacking
+
+`Eukaryotic cell`: Has organelles, meaning true, complete.
+
+|Part Of Cell|Prokaryotic|Eukaryotic|
+|:-----------|:----------|:---------|
+|DNA|In nucleoid region|Usually in membrane, bound nucleus|
+|Size|Usually smaller|Usually larger|
+|Organelles|No membrane, bound organelles|Membrane, bound organelle, the bigger, the more complex|
+|Organization|Usually singler celled|Often multicellular|
+|Metabolism|May not need oxygen|Usually needs oxygen to exist|
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