🔥 Pearson Edexcel IGCSE Biology FULL SYLLABUS Marathon | Quick Revision in 1 Shot (2025 Exam Ready!)

Pearson Edexcel IGCSE Biology FULL SYLLABUS Marathon - Comprehensive Notes

1. Summary

This video is a comprehensive revision marathon for the Pearson Edexcel IGCSE Biology (4BI1) syllabus, designed for quick revision before the 2025 exams. The video covers the entire syllabus chapter-by-chapter, focusing on key definitions, diagrams, processes, exam tips, and common mistakes. The presenter emphasizes understanding key terms, the interconnectedness of biological concepts, and the importance of past paper practice. The video covers the five main sections of the syllabus, including characteristics of living organisms, cell structure and function, biological molecules, transport in organisms, and ecology and the environment. Exam techniques are also covered.

2. Key Takeaways

* **Syllabus Coverage:** The video provides a chapter-by-chapter review of the entire Pearson Edexcel IGCSE Biology syllabus.

* **Exam Focus:** Includes key definitions, diagrams, processes, and addresses common exam pitfalls.

* **Key Concepts:** Emphasizes understanding key terms and the interconnectedness of biological topics.

* **Exam Technique Advice:** Highlights the importance of command words and past paper practice.

* **Main Sections:** Organizes the content around the five main sections: Characteristics of Living Organisms, Cell Structure and Function, Biological Molecules, Transport in Organisms, and Ecology and the Environment.

3. Detailed Notes

**I. Introduction and Exam Strategies (0:00:03 - 0:02:27)**

* **Welcome:** Introduction to the Edexcel IGCSE Biology marathon.

* **Channel Encouragement:** Encouragement to subscribe for more exam-focused videos.

* **Syllabus Overview:** The syllabus contains five main sections.

* **Exam Focus:** Emphasis on key concepts, common pitfalls, and essential practicals for each section.

* **Key Advice Before Starting:**

* Command words are key to answering exam questions.

* Understand the difference between command words like "state," "describe," "explain," and "suggest."

* Recognize that biological concepts are interconnected (e.g., respiration and nerve impulses).

* Past paper practice is *non-negotiable*. Practice papers from at least 3 years.

* Past papers are the best way to apply the student’s knowledge.

**II. Section 1: Characteristics of Living Organisms (0:02:27 - 0:03:13)**

* **Characteristics of Living Organisms (Mrs. Gren):** The 7 characteristics, abbreviated by *Mrs. Gren*:

* **M** - Movement

* **R** - Respiration

* **S** - Sensitivity

* **G** - Growth

* **E** - Excretion

* **R** - Reproduction

* **N** - Nutrition

* **Definitions:**

* **Movement:** The whole organism or part of the organism changes location.

* **Respiration:** Chemical reactions that release energy from nutrients. (Glucose + Oxygen -> Carbon Dioxide + Water + Energy (ATP)) - *Distinguish from breathing.*

* **Sensitivity:** The ability to detect and respond to changes in the environment.

* **Growth:** A permanent increase in the size of an organism by mass.

* **Excretion:** The removal of waste products of metabolism, e.g., carbon dioxide (lungs), urea (kidneys).

* **Reproduction:** The process of producing new offspring. *Sexual and asexual reproduction.*

* **Nutrition:** Taking in materials for energy, growth, and development (e.g., carbohydrates, proteins, fats).

* **Common Mistake:** Excretion vs. Ejection - The removal of undigested food is ejection; waste products of metabolism is excretion.

* **Kingdoms:** Five main kingdoms to know (Animale, Plantae, Fungi, Protoctista, Monera/Bacteria).

* **Key Features of the 5 Kingdoms:**

* **Animalia:** Multicellular, no cell walls, no chlorophyll, heterotrophic (consume other organisms), strong nervous coordination.

* **Plantae:** Autotrophic (make their own food), multicellular, cellulose cell walls, chlorophyll for photosynthesis.

* **Fungi:** Can be unicellular (yeast) or multicellular (mushrooms), cell wall of chitin, not autotrophic (seproes), food is stored as glycogen.

* **Protoctista:** Diverse, mostly unicellular. Examples include *Amoeba* (animal-like), *Chlorella* (plant-like), *Plasmodium* (causes malaria).

* **Bacteria (Monera):** Prokaryotic (no nucleus), cell wall of peptidoglycan, some photosynthesize, classified by shape (cocci, bacilli, spirilla).

* **Viruses:** Not included in the 5 kingdoms, not living organisms (protein coat and genetic material), parasitic. Examples: HIV, Influenza, Tobacco Mosaic Virus.

**III. Section 2: Structure and Function of Living Organisms (0:12:22 - 0:22:27)**

* **Subtopics:**

* Cell structures

* Biological molecules

* Movement of substances

* Human digestion system

* Photosynthesis

* Respiration and gas exchange

* Transport of materials (Plants and Humans)

* Coordination and Responses

* Reproduction (Plants and Humans)

* **A. Cell Structures (0:13:12 - 0:15:29)**

* **Animal Cell:** No cell wall, nucleus, cytoplasm, cell membrane, mitochondria, ribosomes.

* **Plant Cell:** Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes, cell wall (cellulose), chloroplasts (chlorophyll), permanent vacuole.

* **Differences between Plant and Animal Cells:**

* Plant cells have cell walls; animal cells do not.

* Plant cells have chloroplasts; animal cells do not.

* Vacuoles: Large and permanent in plant cells; small and multiple in animal cells.

* Shape: Plant cells are regular; animal cells are irregular.

* **B. Functions of Organelles (0:15:33 - 0:17:40)**

* **Nucleus:** Contains genetic material; controls cell activity.

* **Cytoplasm:** Where most chemical reactions occur.

* **Cell Membrane:** Phospholipid structure; controls the movement of substances in and out (selectively permeable)

* **Mitochondria:** Powerhouse; site of aerobic respiration.

* **Ribosomes:** Protein synthesis. Can be free or attached to the ER.

* **Chloroplasts:** Photosynthesis occurs here; contain chlorophyll.

* **Cell Wall:** Provides support and is fully permeable.

* **C. Biological Molecules (0:17:43 - 0:20:51)**

* **Carbohydrates:** Carbon, hydrogen, and oxygen. Source of energy (sugars).

* Starch (plants), glycogen (animals).

* Smaller = sweet taste. Complex = tasteless (starch, glycogen, cellulose).

* **Proteins:** Made of amino acids. Structure: Carbon, nitrogen, oxygen, hydrogen.

* Growth, repair, and enzymes.

* 10 essential and 10 non-essential amino acids.

* **Lipids (Fats):** Carbon, hydrogen, and oxygen.

* Fatty acids and glycerol. Energy storage, insulation, and cell membrane.

* **Water:** Essential solvent for chemical reactions and transport.

* **Enzymes:** Biological catalysts (proteins) that speed up reactions; specific in temperature and pH.

* Made of proteins.

* Lock and key model for enzyme action.

* Denatured by too much heat (37 degrees centigrade).

* **D. Movement of Substances (0:22:29 - 0:24:28)**

* **Diffusion:** Net movement of particles from high to low concentration (down the concentration gradient). Passive, no energy.

* **Osmosis:** Net movement of water molecules from high to low water potential (dilute to concentrated solution) through a semi-permeable membrane. Very important for plant support.

* **Active Transport:** Movement from low to high concentration *against* the concentration gradient; requires energy (ATP).

* **E. Human Digestive System (0:24:59 - 0:27:55)**

* **Mouth:** Mechanical digestion (teeth), chemical digestion (amylase in saliva converts starch to maltose).

* **Stomach:** Turns food; pepsin (protease) at pH 2 digests proteins.

* **Small Intestine:** Digestion and absorption; duodenum and ileum.

* Duodenum: Bile (from liver, stored in gall bladder) neutralizes stomach acid and emulsifies fats; pancreatic amylase.

* Ileum: Absorbs digested food via villi (increased surface area).

* **Large Intestine:** Absorbs water; forms and stores feces; excreted via the anus.

* **F. Photosynthesis (0:28:15 - 0:30:17)**

* **Definition:** Production of food using carbon dioxide and water.

* **Word Equation:** Carbon Dioxide + Water (in presence of chlorophyll and light energy) -> Glucose + Oxygen

* Light intensity increases photosynthesis rate up to an optimum, then decreases.

* Carbon dioxide concentration also increases the rate.

* Temperature affects enzyme activity, too high and enzymes denature (e.g. 45°C).

* Leaf adaptations: Large surface area, thin (short diffusion), chlorophyll, stomata, air spaces.

* **G. Respiration and Gas Exchange (0:30:17 - 0:34:04)**

* **Definition:** Releasing energy using glucose for all life processes in the mitochondria (Aerobic and Anaerobic).

* **Aerobic Respiration:** Glucose + Oxygen -> Carbon Dioxide + Water + ATP

* **Anaerobic Respiration:** Occurs in the absence of oxygen.

* In muscles: Glucose -> Lactic Acid + Little Energy (Oxygen debt).

* In yeast (fermentation): Glucose -> Ethanol + Carbon Dioxide + Little Energy (used in baking and brewing).

* **Gas Exchange (Alveoli in the lungs):**

* Alveoli (many for large surface area) are site of gas exchange

* Inhalation and Exhalation.

* **H. Transport in Plants and Animals (0:34:04 - 0:41:19)**

* **Xylem and Phloem (Plants):**

* **Xylem:** Transports water and mineral ions from roots to leaves. Only upwards. Dead cells.

* **Phloem:** Transports dissolved sugars (sucrose) from leaves to other parts (translocation). Can move up and down. Living cells.

* **Transpiration:** Loss of water from leaf surfaces.

* **Human Transport System:** Double circulatory system; blood passes through the heart twice per circuit.

* Heart structure: 2 atria, 2 ventricles. Right atrium/ventricle to lungs. Left atrium/ventricle to body.

* Valves prevent backflow.

* Blood Vessels:

* **Arteries:** Carry blood away from the heart (thick, muscular, elastic walls, high pressure).

* **Veins:** Carry blood to the heart (thinner walls, valves to stop backflow, low pressure).

* **Capillaries:** Connect arteries and veins (one cell thick for efficient diffusion).

* Blood Components: Red blood cells (hemoglobin to carry oxygen), white blood cells (immune system), platelets (blood clotting), plasma (carries substances).

* **I. Coordination and Responses (0:40:12 - 0:47:19)**

* **Nervous System:** Fast coordination. Electrical impulses.

* Stimulus -> Receptor -> Sensory neuron -> CNS (coordinator) -> Motor neuron -> Effector -> Response.

* **Reflex Arc:** Rapid, involuntary response (bypasses the brain).

* **Hormonal System:** Slower coordination. Chemical messages in the blood.

* Insulin (lowers blood glucose), glucagon (raises blood glucose), adrenaline (fight or flight).

* **Homeostasis:** Maintaining a constant internal environment. Blood glucose (insulin and glucagon), body temperature (thermoregulatory center in the brain).

* **Tropism in Plants:**

* Phototropism (light): Shoots grow towards light (positive); roots grow away (negative).

* Geotropism (gravity): Roots grow towards gravity (positive); shoots grow away (negative).

* **J. Reproduction (0:44:26 - 0:47:26)**

* **Sexual vs. Asexual Reproduction:**

* **Asexual:** One parent; genetically identical offspring (clones)

* Bacteria, potato tubers, strawberry runners.

* **Sexual:** Fusion of male and female gametes; genetic variation.

* **Flowering Plants:**

* Stamen (male - anther (produces pollen), filament)

* Carpel (female - stigma (catches pollen), style, ovary (contains ovules))

* Pollination (transfer of pollen from anther to stigma) by insects or wind.

* Fertilization (in ovary, pollen tube grows down style; male nucleus fuses with female ovule; ovule becomes seed; ovary becomes fruit).

* **Human Reproduction:**

* Male: Sperm (gametes); produced in the testicles.

* Female: Eggs (gametes); produced in the ovaries.

* Menstrual Cycle (28 days); hormonal control (FSH, oestrogen, LH).

* FSH (matures the egg in the ovary; stimulates estrogen production)

* Oestrogen (repairs the uterus lining; inhibits FSH; stimulates LH)

* LH (triggers ovulation, release of egg)

**IV. Section 3: Ecology and Environment (0:52:30 - 0:55:28)**

* **Key Terms:**

* **Population:** All organisms of one species in a habitat.

* **Community:** All the populations of different species in a habitat.

* **Ecosystem:** Interaction of a community with non-living (abiotic) parts of the environment.

* **Habitat:** The place where an organism lives.

* **Food Chains and Webs:** Producers, herbivores, carnivores, omnivores.

* Primary, secondary, and tertiary consumers.

* Pyramids of biomass.

* **Cycles:** Carbon and nitrogen cycles.

* Carbon cycle (photosynthesis, respiration, feeding, combustion, decomposition).

* Water cycle (evaporation, condensation, precipitation, runoff, infiltration, transpiration).

* **Human Impacts:** Deforestation, water pollution, air pollution, and conservation.

* **Yield can be increased by fertilizers (replaces the mineral ions) and pesticides (kill the pests).**

* **Fish farming.**

* **Microorganisms:** used for food like yeast is used in bread and beer production. Bacteria lactobacillus is used in yogurt.

* **Selective breeding:** choosing the organism with desirable characteristics over there.

* **Genetic engineering is the mod genetic modification like transferring a gene for a desirable characteristic from one organism to another and to identify and cloning**.

**V. Exam Techniques and Mindset (0:55:29 - 0:57:43)**

* **Read questions carefully.** Underline key terms and command words.

* **Manage your time.**

* **Show your working.** (In genetic crosses, calculations; get method marks even if the final answer is incorrect).

* **Use correct terminology.** (e.g., "enzyme denatures" - not "enzyme dies").

* **Be specific.** (e.g., "protease enzymes breaks down proteins into amino acids.").

* **Check your answers, especially at the end.**

* "You've learned an incredible amount of biology, and you are prepared. Go into the exam with confidence and show the examiner what you know."