CIE iGCSE Biology-21.2 Biotechnology- Study Notes- New Syllabus
CIE iGCSE Biology-21.2 Biotechnology- Study Notes – New syllabus
CIE iGCSE Biology-21.2 Biotechnology- Study Notes -CIE iGCSE Biology – per latest Syllabus.
Key Concepts:
Core
- Describe the role of anaerobic respiration in yeast during the production of ethanol for biofuels
- Describe the role of anaerobic respiration in yeast during bread-making
- Describe the use of pectinase in fruit juice production
- Investigate and describe the use of biological washing powders that contain enzymes
Supplement
- Explain the use of lactase to produce lactose-free milk
- Describe how fermenters can be used for the large-scale production of useful products by bacteria and fungi, including insulin, penicillin and mycoprotein
- Describe and explain the conditions that need to be controlled in a fermenter, including: temperature, pH, oxygen, nutrient supply and waste products
Anaerobic Respiration in Yeast & Ethanol Production
Key Statement:
Yeast carries out anaerobic respiration (fermentation) to produce ethanol, which is used as a renewable biofuel.
🔬 What Happens in Anaerobic Respiration?
- In the absence of oxygen, yeast breaks down glucose to release energy.
- This process produces ethanol (alcohol) and carbon dioxide.
🧪 Word Equation:
Glucose → Ethanol + Carbon dioxide
Role in Biofuel Production
- Large fermenters are used to grow yeast in oxygen-free conditions.
- Yeast ferments sugar from crops (like sugarcane or corn).
- The ethanol is collected, purified, and used as a fuel.
📌 Bioethanol can be blended with petrol to reduce fossil fuel use in vehicles.
🌍 Why It Matters
- Ethanol is a renewable, carbon-neutral fuel.
- Helps reduce greenhouse gas emissions.
- Supports sustainable energy goals.
🧠 In Summary:
Yeast respires anaerobically to convert glucose into ethanol. The ethanol is collected and used as a biofuel, making transport more eco-friendly.
Anaerobic Respiration in Yeast During Bread-Making
Key Idea:
Yeast respires anaerobically during bread-making to produce carbon dioxide, which causes the dough to rise.
🔬 What Happens:
- In the dough, yeast feeds on sugars and respires without oxygen.
- This produces:
- Carbon dioxide (CO₂) – forms bubbles in dough
- Ethanol (alcohol) – most of it evaporates during baking
🧪 Word Equation:
Glucose → Ethanol + Carbon dioxide
Why It’s Important:
- CO₂ gets trapped in the dough, forming air pockets.
- This makes the bread rise and gives it a soft, fluffy texture.
- The ethanol evaporates due to oven heat and does not remain in the bread.
🧠 In Summary:
During bread-making, yeast uses anaerobic respiration to produce carbon dioxide, which causes the dough to rise and gives bread its light texture.
Use of Pectinase in Fruit Juice Production
What Is Pectinase?
Pectinase is an enzyme that breaks down pectin, a jelly-like substance found in the cell walls of fruits.
🍹 Role in Fruit Juice Production:
- Pectin gives fruits structure and makes juice cloudy or thick.
- When pectinase is added to crushed fruit:
- It breaks down pectin in the cell walls.
- More juice is released from the pulp.
- The juice becomes clearer and easier to filter.
📌 Result: Higher juice yield and better-quality juice from the same amount of fruit.
🧠 In Summary:
Pectinase breaks down fruit cell walls to extract more juice, making it clearer, smoother, and increasing the overall amount during production.
Pectinase is commonly used in juice production from apples, grapes, and oranges.
Biological Washing Powders and Enzymes
What Are Biological Washing Powders?
These are detergents that contain enzymes to break down stains on clothes more efficiently, especially at lower temperatures.
🔍 Enzymes Used and Their Function:
| Enzyme | Breaks Down | Example of Stains Removed |
|---|---|---|
| Protease | Proteins | Blood, egg, sweat |
| Lipase | Fats (lipids) | Grease, butter, oil stains |
| Amylase | Starch | Food stains (rice, pasta, sauces) |
🧪 Investigation Idea (Lab-style Summary):
Aim: To test the effectiveness of biological washing powder on different types of stains.
Method Summary:
- Prepare two cloth samples stained with the same substance (e.g., egg yolk).
- Wash one with biological powder and the other with non-biological powder or water.
- Keep all conditions constant (temperature, time, amount of powder).
- Compare how clean each cloth becomes.
Expected Result: The biological powder should clean better, especially at low temperatures, due to enzyme action.
Advantages of Biological Powders:
- Work well at low temperatures (30–40°C) → saves energy
- Break down tough stains more effectively
- Eco-friendly due to reduced energy use
⚠️ Note: Not suitable for delicate fabrics (e.g., wool) as enzymes can damage natural fibres.
🧠 In Summary:
Biological powders contain enzymes like protease, lipase, and amylase that remove stains efficiently even at low temperatures.
Production of Lactose-Free Milk Using Lactase
What Is Lactase?
Lactase is an enzyme that breaks down lactose – the natural sugar found in milk.
🧪 How It Works:
Some people are lactose intolerant – they cannot digest lactose properly due to low levels of lactase.
To help them, manufacturers add lactase to milk during processing. The enzyme breaks down lactose into:
- Glucose
- Galactose
📌 These simpler sugars are easier to absorb and don’t cause digestive discomfort.
Process Summary:
- Regular milk is treated with the lactase enzyme.
- Lactose is converted into glucose and galactose.
- The result is lactose-free milk suitable for lactose-intolerant individuals.
🧠 In Summary:
Lactase is used in the dairy industry to break down lactose, producing a milk product that can be safely consumed by people with lactose intolerance.
Large-Scale Production Using Fermenters
What is a Fermenter?
A fermenter is a large, sterile container used to grow microorganisms (such as bacteria or fungi) under controlled conditions to produce useful substances.
🔍 Key Features of a Fermenter:
- Stirrer or air bubbles: Mix nutrients and oxygen evenly.
- Temperature control: Maintains optimal enzyme activity.
- pH control: Prevents denaturation of enzymes.
- Sterile conditions: Avoids contamination from unwanted microbes.
🧫 What Microorganisms Are Used?
| Product | Organism | Type |
|---|---|---|
| Insulin | Genetically modified E. coli | Bacteria |
| Penicillin | Penicillium | Fungus |
| Mycoprotein | Fusarium species | Fungus |
🧠 How the Process Works:
- Microorganisms are added to a sterile nutrient solution in the fermenter.
- Conditions like temperature, pH, and oxygen are carefully controlled.
- Microbes grow and produce the desired product:
- Insulin is secreted by modified bacteria.
- Penicillin is produced naturally by fungi.
- Mycoprotein is harvested from fungal biomass.
- The product is then extracted, purified, and packaged.
💡 In Summary: Fermenters are used to grow microbes at scale under sterile, controlled conditions to produce valuable products like insulin, penicillin, and mycoprotein.
Conditions to Control in a Fermenter
A fermenter is used to grow bacteria or fungi on a large scale to produce useful products (e.g. insulin, penicillin, mycoprotein). To keep the microorganisms healthy and productive, several conditions must be carefully controlled.
1. Temperature
- Why control it? Microbial enzymes work best around 30–40°C.
- Too high? Enzymes may denature and stop working.
- Too low? Growth and production slow down.
✅ Heating or cooling systems maintain the correct temperature.
2. pH
- Why control it? Enzymes in microbes are pH-sensitive.
- Too acidic/alkaline? Enzymes may denature or become inactive.
✅ Buffers or pH regulators keep the pH stable for optimal microbial function.
3. Oxygen (for aerobic fermentation)
- Why control it? Aerobic microbes need oxygen for respiration and energy.
- Too little oxygen? Growth slows and product yield drops.
✅ Air is pumped in to supply sufficient oxygen.
4. Nutrient Supply
- Why control it? Microbes need nutrients to grow and produce the desired product.
- Low nutrients? Growth and production stop.
✅ Nutrients are added regularly or continuously during fermentation.
5. Removal of Waste Products
- Why control it? Waste like acids or CO₂ can:
- Change pH
- Poison the microbes
✅ Vents release gases and liquids are removed or neutralised as needed.
🧠 In Summary – Why Control Is Important:
| Condition | Reason for Control |
|---|---|
| Temperature | Prevent enzyme denaturation or slow growth |
| pH | Maintain enzyme activity |
| Oxygen | Ensure energy supply for aerobic microbes |
| Nutrients | Fuel microbial growth and product formation |
| Waste removal | Avoid toxic build-up and pH imbalance |