diff --git a/Grade 10/Science/SNC2DZ/Unit 2: Biology.md b/Grade 10/Science/SNC2DZ/Unit 2: Biology.md
index 6537acb..24594cc 100644
--- a/Grade 10/Science/SNC2DZ/Unit 2: Biology.md	
+++ b/Grade 10/Science/SNC2DZ/Unit 2: Biology.md	
@@ -246,3 +246,135 @@ A person contains roughly 100 trillion cells
  - Testing drugs on specific target cells
  - Lab-grown meat for vegetarian purposes
  - Regenerative medicine to replace tissues (e.g., blindness, bone marrow transplant, cancers, limb regrowth)
+
+## Telomeres
+
+## Cancer
+ - Group of diseases that involve out-of-control cell division which may spread throughout the body
+ - `Tumour`: Uncontrolled lump of cells that do not perform normal cellular functions
+ - `Benign`: Cells that do not metastasise or interfere with normal cell function (harmless)
+ - `Malignant`: Cells that interefere with normal cell activity and metastasise
+ - `Carcinoma`: Cancerous/cancer
+ - `Metastasis`: Primary (original) tumour spreading throughout the body to create secondary tumours
+ - `Carcinogens`: Anything that can cause cancer, e.g., chemicals, radiation/energy, some viruses
+ - `Neoplasm`: A solid or fluid-filled sac that the body forms to isolate defective from healthy cells (e.g., cysts)
+ - Random mutations can also lead to a cancer cell due to irregular DNA replication
+ - Generally, multiple mutations in several key genes are required for a cell to become cancerous
+ - Cancer is *not* contagious, neither can it be inherited
+    - A genetic predisposition to cancer *can* be inherited
+ - By the time cancer is detected, it can contain millions of cells that have been growing for years
+
+### Cancer screening
+ - PAP smear for cervical cancer
+ - Mammogram for breast cancer
+ - Colonoscopy for colorectal cancer
+ - PSA blood test for prostate cancer
+
+### Cancer diagnosis
+ - Endoscopy (using a flexible camera with tissue extractor to search for cancers of the respiratory and/or digestive systems)
+ - X-rays
+ - Ultrasounds for soft tissues
+ - CAT/CT scan (more x-rays)
+ - MRI scan (uses radio waves and magnetic fields)
+
+### Cancer treatments
+ - Surgery
+    - Physically removing tumour with stabby things
+    - Ineffective if cancer has metastasised
+    - If even one cell escapes the stabby cancer can regrow
+ - Radiation therapy
+    - Blasting radiation at tumours so that their DNA becomes so damaged that DNA replication, and, as a result, cell division is impossible
+    - Can harm neighbouring cells
+    - Ineffective if cancer has metastasised
+ - Chemotherapy
+    - Blasting drugs that kill dividing cells
+    - Does not feel very good for the patient
+    - Fast-growing cells may die off (e.g., hair, skin cells)
+ - Biophonics
+    - Using light beams to detect and treat cancer
+
+## Organ systems
+**Business model for organ/organ systems**
+| Business thing | Corresponding organ/organ system |
+| :--- | :--- |
+| Management | Central nervous system (brain) |
+| Messaging | Endocrine + peripheral nervous systems |
+| Workplace | Body | 
+| Transport | Circulatory, digestive, urinary systems (internal, import, export, respectively) |
+| Storage | Fats |
+| Cash flow | Digestive + respiratory systems |
+| Security | Immune + integumentary (skin) systems |
+| Workers | Cells + muscular system |
+
+## Tissues
+ - `Tissues`: Different cell types grouped together performing the same task
+ - Organisms have a hierarchical organisation
+ - Basic tissues: Connective, muscle, nervous, and epithelial tissues
+ - Epithelial tissue
+    - Tightly packed cells that line body surfaces, e.g., skin
+ - Connective tissue
+    - Produces collagen fibres that support organ structures and bone, e.g., ligaments (bone -> bone), tendons (muscle -> bone)
+ - Muscle tissue
+    - Fibrous tissue that can be subdivided into cardiac (heart), smooth (digestive), and skeletal (voluntary) muscle tissues
+    - They contract
+ - Nervous tissue
+    - Responds to external/internal stimuli, e.g., brain, nerves
+
+## Digestive system
+ - Two types of digestive systems
+ - Bag digestive system
+    - One way in, same way out (e.g., coral, jellyfish)
+ - Tube digestive system
+    - One way in, another way out (e.g., worms, humans)
+    - Mouth -> esophagus -> stomach -> small intestine -> large intestine -> rectum -> anus all part of the tube
+    - Gallbladder, liver, salivary glands, and pancreas produce digestive enzymes/juices in humans
+    - Process of eating food: **Ingestion** (eat) -> **digestion** (physical and chemical breakdown) -> **absorption** (of nutrients to bloodstream) -> **egestion** (poo)
+    - Flies digest before ingesting
+    - `Jujunum`: Centre of small intestine
+    - `Duodenum`: Beginning of small intestine
+    - `Ileum`: End of small intestine
+    - `Rectum`: Holds waste to be excreted voluntarily
+    - `Anus`: Controls waste to be defecated voluntarily
+    - `Appendix`: Used to be used to digest plant matter, now virtually useless in humans
+    - `Gallbladder`: Stores and secretes bile as buffer between liver and small intestine that helps break down fats (lipids)
+    - `Ruminants`: Herbivores that digest food using a chambered tube
+        - Chew -> Reticulum and rumen (first and second stomachs) -> regurgitate and rechew -> Omasum (third stomach) -> Abomasum (fourth stomach) -> small intestine -> large intestine -> waste
+    - `Eoprophagy`: Consumption of feces
+
+### Human digestive system
+ - Mouth ingests food
+ - Teeth, tongue, and salivary glands work to begin digestion
+ - Esophagus squeezes food down in waves (peristalsis) down its smooth muscle tube
+ - Stomach
+    - Mixes hydrochloric acid with digestive enzymes to break down food
+        - Hydrochloric acid is diluted and does not break down the food itself much, enzymes are more effective at a lower pH
+    - Liquifies food and kills bacteria
+    - **Goblet cells** produce **mucous**, which lubricates the stomach and intestines, protecting the stomach
+    - Made of smooth muscle to churn food, somewhat like cooking with enzymes or a washing machine
+ - Intestines
+    - Pancreas makes most digestive enzymes and pumps them in the duodenum
+    - Absorbs nutrients and water to bloodstream
+    - Duodenum digests food chemically even more
+    - Forms and excretes feces
+    - Contains smooth muscle to continue peristalsis
+    - Contains plenty of blood vessels for faster nutrient absorption
+    - Intestinal epithelium
+        - Optimised for surface area
+        - Folds contain `villi` (singular, "villus")
+        - Villi contain capillaries and absorbing and goblet cells
+        - Absorbing cells caintain microvilli, which absorb nutrients via diffusion
+
+### Respiratory system
+ - Exchanges oxygen gas and carbon dioxide gas between red blood cells and the surrounding air, which is required for cellular respiration
+ - Diaphragm contracts to lower itself, causing the rib cage to rise, which increases lung volume, which subsequently causes pressure to decrease and air to rush in to the lungs
+ - Diaphragm relaxes to return everything to its normal position
+ - Air is warmed and moisted while passing through nasal cavity blood vessels
+ - Trachea and bronchi are made of rigid cartilage rings
+    - Prevents airways from closing, similar to a vacuum hose
+ - Respiratory epithelium
+    - Contains goblet and ciliated cells
+    - `Cilia`: Singular "cilius", sweep mucous out of the lungs and throat
+    - Nose hairs and mucous trap debris which is swept out by cilia
+ - Alveoli (singular "alveolus") epithelial tissue is one cell thick
+    - Surrounded with capillaries which exchange gases via diffusion
+ - Trachea -> 2 bronchi -> bronchioles -> alveoli
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