- C3 ✏︎ Organisms -
C3.1 - Brain & Integration (SL/HL)
LECTURE VIDEO
DESCRIPTION
Is your body run by lightning-fast neural texts, or slow hormonal newsletters? The truth is, it’s a messy, brilliant co-op. Your brain sends urgent “RUN!” texts via nerves, while your hormones slide into your bloodstream with a casual “hey, maybe panic a little?” weeks later.
Tour the two competing headquarters:
- Nervous System HQ: Central Command (Brain & Spinal Cord) and the Peripheral Network (nerves). How a hot pan triggers a reflex arc before your brain even gets the text.
- Autopilot Control: How your brainstem runs the boring but vital departments (heart, lungs, digestion) on autopilot, so you can focus on more important things, like TikTok.
- Hormone Hangout: Meet the endocrine squad. The adrenal gland’s adrenaline for emergency panic mode, the pineal gland’s melatonin for when you’re scrolling past bedtime, and the hypothalamus-pituitary duo—the ultimate power couple bossing around all the other glands.
See how instant reflexes and slow-mo hormones work together to keep you alive, alert, and somehow still tired before your 8 a.m. class.
TIMESTAMPS
STUDY RESOURCES
00:00:00 – Outline Of This Video
00:01:00 – Levels Of An Organism (04:32 meant to say pancreas)
00:08:48 – Intro To Concept Of Integration
00:10:59 – Role Of Nervous & Endocrine Systems
00:18:32 – CNS & PNS
00:25:03 – Neurons & Nerve
00:28:23 – Brain Anatomy [Structure]
00:35:55 – Brain Function
00:43:50 – Receptors
00:50:15 – Motor and sensory pathway
00:58:10 – The Reflex Arc
01:04:21 – Feedback Control Of The Heart
01:20:18 – Feedback Control Of The Lung
01:24:54 – Feedback Control Of The Alimentary Tract
01:28:54 – Adrenal Gland & Epinephrine
01:31:55 – Pineal Gland & Melatonin
01:38:45 – Hypothalamus & Pituitary Gland
01:45:16 – Questions & Answers
NOTES – All you need to know in one place!
QUESTIONS – Test your Big Brain!
C3.1 - Plant System Integration (HL)
LECTURE VIDEO
DESCRIPTION
Plants don’t have brains, but they are masters of chemical gossip. From bending toward the sun to staging a dramatic, all-at-once fruit ripening, they run on invisible hormone signals. The real question is: are we measuring their drama in numbers or in shades of “yikes”?
Tour the green gossip network:
- Phytohormone Squad: Introducing the plant’s chemical crew, with a spotlight on auxin—the shady influencer that makes plants bend by telling some cells to grow and others to chill.
- Fruit Ripening: The role of ethylene—the “everyone panic ripen NOW!” gas that turns a hard avocado into mushy guac overnight. It’s the ultimate plant group chat meltdown.
- Data Drama: How scientists measure plant sass. Quantitative data (counting leaves, measuring growth in cm) vs. Qualitative data (“the plant looks sad,” “the fruit smells funky”). One gives you numbers, the other gives you vibes.
Discover how plants gossip their way through life, and learn whether to trust the spreadsheet or your gut when a plant is throwing shade.
TIMESTAMPS
STUDY RESOURCES
00:00 – Overview Of This Video
00:56 – Phytohormones
09:36 – Auxin [Purpose, Production & Transport]
21:37 – Auxin [Mechanism Of Action]
29:21 – Fruit does fruit come form?
32:42 – Ethylene & Fruit ripening
36:24 – Qualitative & Quantitative Data
39:05 – Questions & Answers
NOTES – All you need to know in one place!
QUESTIONS – Test your Big Brain!
C3.2 - Defence Against Infectious Disease (SL/HL)
LECTURE VIDEO
DESCRIPTION
Your body is a VIP club, and germs are always trying to crash the party. Good thing you have a security team that includes bouncers at the door, plumbers for leaks, ninja assassins inside, and a memory bank that never forgets a face.
Meet your internal defence & repair squad:
- First Line Bouncers: Skin, mucus, and stomach acid—the ultimate “you shall not pass!” barriers.
- The Emergency Plumber: Platelets forming a sticky plug and the clotting cascade that patches up leaks fast.
- Innate Response Ninjas: Macrophages and natural killer cells that swarm invaders fast, no questions asked.
- Adaptive Special Forces: T-cells and B-cells—the elite troops that learn a pathogen’s mugshot and make custom antibodies.
- Vaccine Logic: How a training dummy (vaccine) teaches your immune system a bad guy’s face before the real fight, so the response is instant.
- HIV: The Security System Hack – How HIV specifically targets and destroys the T-cells that coordinate the whole defence, leaving the body open to every other infection.
Find out how your body patches wounds, fights infections, learns from vaccines, and what happens when a virus hacks the entire security command centre.
TIMESTAMPS
STUDY RESOURCES
00:00:00 – Table Of Contents
00:00:57 – Immune System Defined
00:01:57 – What Are Pathogens?
00:04:19 – Quarantine (Self-Isolation)
00:05:13 – First Line Of Defence
00:11:31 – Character Profile
00:12:00 – Blood Clotting
00:22:51 – Summary Of Blood Clotting
00:23:35 – Innate Immunity (Non-Specific Immunity)
00:29:08 – Phagocytosis By Macrophage
00:32:01 – Quick Recap
00:32:34 – Adaptive Immunity (Specific Immunity)
00:47:57 – Adaptive Immunity Summary
00:49:32 – Quick Recap
00:50:54 – Immune Response Curve
00:55:11 – Vaccines
01:01:08 – Herd Immunity
01:05:24 – HIV (Human Immunodeficiency Virus)
01:10:38 – Questions & Answers
01:17:52 – Summary
NOTES – All you need to know in one place!
QUESTIONS – Test your Big Brain!
C3.2 - Blood Groups (SL/HL)
LECTURE VIDEO
DESCRIPTION
Your red blood cells are walking around with little protein name tags, and your immune system is a bouncer that attacks any blood that doesn’t match the club’s dress code. Type O? You’re basically wearing a grey tracksuit—no frills, no drama.
Figure out which club stamp you’re rocking:
- The A, B, AB, O Squad: Type A has A tags. Type B has B tags. AB has both—fancy diplomat energy. Type O? No tags. You’re incognito. Naked cell energy.
- Why Transfusions Go Wrong: Your body makes antibodies (microscopic weapons) against the tags it doesn’t Give an A-person B-blood? Instant clump fest. The bouncer handcuffs the intruders into sticky blobs. It’s not pretty.
- Rh Factor: Not a Rap Name: Rh positive means you’ve got the Rhesus protein. Rh negative means you don’t. Mix them wrong, and your immune system throws a full tantrum. (Don’t worry, there’s a shot for that.)
- The Ultimate Donor & Receiver: Type O negative is the universal donor—no tags means no one attacks it. Type AB positive is the universal receiver—accepts everyone’s tags like a generous eater at a buffet.
Find out why your blood type is basically a club membership, and why Type O is out there saving lives while asking for nothing in return. Absolute legend behavior.
TIMESTAMPS
STUDY RESOURCES
00:00 – Contents Of This Video
00:38 – Pathogens & Red Blood Cells
03:30 – Blood Composition
04:30 – What Is Blood Transfusion?
08:33 – Introducing ABO & Rh Blood Groups
12:31 – Blood Groups Antigens & Antibodies Summary Table
14:16 – Donor (AB) VS Recipient (O)
16:15 – Agglutination (Clumping)
16:35 – Donor (O) VS Recipient (AB)
17:59 – Donor (A) VS Recipient (B)
19:03 – Donor (B) VS Recipient (B)
21:20 – Donor (O+) VS Recipient (AB-)
23:08 – General Rules Summary
25:36 – Questions & Answers
NOTES – All you need to know in one place!
QUESTIONS – Test your Big Brain!
C3.2 - Antibiotics (SL/HL)
LECTURE VIDEO
DESCRIPTION
Imagine having a magic bullet that only kills bacteria and leaves your human cells completely alone. That’s antibiotics. Now imagine everyone using them wrong until they stop working. That’s where we’re at.
Your crash course in bacterial warfare:
- Antibiotics vs. Antibodies: Antibodies are your body’s homemade protein bullets—custom-made for specific invaders. Antibiotics are pharmaceutical carpet bombs that wipe out whole bacterial armies. One is internal security, the other is external backup.
- Why Antibiotics Don’t Work on Viruses: Bacteria are independent little freaks that run their own metabolism. Viruses are just genetic material in a trench coat hijacking your cells. Antibiotics break bacterial machinery. Viruses don’t have any machinery to break—they’re using YOURS.
- Sensitive vs. Resistant: Sensitive bacteria die on contact. Resistant bacteria laugh, multiply, and teach their friends. Every time you misuse antibiotics, you’re basically hosting a survival-of-the-fittest boot camp for superbugs.
- Finish the Course: That lingering infection isn’t “basically gone.” Those last few surviving bacteria are the toughest ones. Stop early, and you just weeded out the weaklings, leaving the Terminators to throw a victory party and start a resistant dynasty.
Learn why antibiotics are precious, viruses are untouchable, and your prescription label is not a suggestion. Finish the bottle. The bacteria finished first grade and they’re ready for war.
TIMESTAMPS
STUDY RESOURCES
00:00 – Contents Of This Video
00:36 – Antibodies
02:59 – Prokaryotic & Eukaryotic Cells
04:13 – Bacteria
05:56 – Antibiotics Explained
09:01 – Our Own Cells VS. Antibiotics?
10:00 – Virus VS. Antibiotics
13:04 – Summary Table (Antibiotics VS. Antibodies)
13:21 – Antibiotics In The Lab
17:15 – Development Of Resistant Bacteria (MRSA)
19:27 – Why Finish Prescribed Antibiotics?
21:56 – Questions & Answers
NOTES – All you need to know in one place!
QUESTIONS – Test your Big Brain!
C3.2 - Zoonotic Diseases (SL/HL)
LECTURE VIDEO
DESCRIPTION
Sharing is caring—unless it’s a virus jumping from a bat to a pig to your respiratory system. Zoonotic diseases are nature’s reminder that we’re not the only ones hosting parties, and sometimes the guests bring really terrible gifts.
Meet the animal-to-human pipeline:
- What Is a Zoonosis? Any infectious disease that jumps from vertebrate animals to humans. It’s the ultimate unwanted souvenir from your camping trip, wet market, or just existing near a bat.
- Tuberculosis (TB): The classic comeback kid. Primarily airborne between humans, but certain strains (like M. bovis) remind us that cows can share too—thanks, I guess?
- Japanese Encephalitis: A mosquito-borne virus that hangs out in pigs and wild birds before crashing your brain via a mosquito Uber. Most infections are mild, but when it hits the nervous system, it hits.
- COVID-19: The pandemic poster child. Probably started in bats, maybe passed through another animal, then learned the devastating power of human coughs and international air travel.
- Rabies: The 99.9% fatal, vaccine-preventable horror show. Once symptoms appear, it’s game over. Transmission is usually via saliva (nasty bites from infected dogs, bats, or raccoons with boundary issues).
Learn how diseases cross the species border, why we’re always one mosquito bite away from trouble, and why vaccinating animals is sometimes the best way to protect ourselves.
TIMESTAMPS
STUDY RESOURCES
00:00 – Contents Of This Video
00:41 – Pathogens
02:05 – Zoonotic Diseases Defined
02:43 – Rabies
04:12 – Tuberculosis
05:44 – Japanese Encephalitis
06:52 – COVID-19
07:58 – Summary
NOTES – All you need to know in one place!
QUESTIONS – Test your Big Brain!