🔬 Welcome to the Use of Biological Resources! 🌍
Hello future scientists! This chapter is incredibly important because it looks at how humans use living organisms—from tiny microbes to massive fish stocks—to meet our needs, especially for food and medicine.
The core challenge? We need to use these resources smartly and sustainably so they don't run out. Don't worry if this seems tricky at first; we will break down the big ideas into simple, clear steps!
Key Areas We Will Cover:
- Farming methods (Intensive vs. Free-range)
- How fertilisers cause pollution (Eutrophication)
- Controlling pests (Chemical vs. Biological)
- The role of microorganisms in industry
- Sustainable management of fish stocks
1. Feeding the World: Farming Methods
To feed the growing human population, we need to produce huge amounts of food. Farmers use different methods, each with advantages and disadvantages related to efficiency, cost, and ethics.
1.1 Intensive Farming (Maximum Efficiency)
Intensive farming aims to produce the maximum possible yield (the amount of food) from the smallest possible area, often using high inputs of resources (like feed and chemicals).
Imagine a factory farm for chickens: thousands are kept close together in large sheds.
- High Yields: Produces a lot of food quickly and cheaply.
- Lower Costs: Requires less space and energy per unit of food produced.
- Drawbacks:
- Poor Animal Welfare: Animals often have limited movement and stressful conditions.
- Disease Spread: High density makes it easier for infections to spread rapidly.
1.2 Free-Range Farming (Focus on Welfare)
Free-range farming allows animals more space and freedom, often closer to their natural environment.
Imagine chickens roaming freely outdoors during the day.
- Improved Welfare: Animals live in better conditions, leading to better health and quality of life.
- Lower Stress: Reduced need for antibiotics (sometimes).
- Drawbacks:
- Lower Yields: Animals use more energy moving around (which they don't convert to meat/milk).
- Higher Costs: Requires more land and is therefore more expensive for the consumer.
We face a constant choice: Is it more important to produce cheap food (Intensive) or to ensure good animal conditions (Free-range)?
2. Improving Crop Yields: Fertilisers and Pest Control
Just like we take vitamins, plants need essential nutrients (minerals) to grow healthy and strong. These nutrients are often supplied using fertilisers.
2.1 The Role of Fertilisers
Fertilisers add key mineral ions back into the soil, typically Nitrogen (N), Phosphate (P), and Potassium (K).
The Benefit: Plants absorb these minerals and use them to build proteins (Nitrogen) and grow large, resulting in dramatically increased crop yields.
2.2 The Problem with Fertilisers: Eutrophication
While great for crops, synthetic fertilisers can pollute water systems when rainwater washes them off the land into rivers or lakes. This pollution process is called Eutrophication.
- Leaching: Excess fertiliser minerals wash (leach) from the soil into a nearby water body (river, lake).
- Algal Bloom: The sudden rush of nutrients causes algae on the surface to grow extremely quickly. This is called an algal bloom.
- Light Blockage: The thick layer of algae blocks sunlight from reaching the plants below the surface. These plants die.
- Decomposition: Bacteria decompose the dead plants and algae.
- Oxygen Depletion: This decomposition process uses up massive amounts of dissolved oxygen in the water (aerobic respiration).
- Fish Die: The lack of oxygen causes fish and other aquatic organisms to suffocate and die.
🔑 Key Takeaway: Eutrophication is dangerous because the extra nutrients lead to a total loss of oxygen in the water.
2.3 Controlling Pests
Pests (insects, fungi, weeds) can destroy crops, reducing the yield. We have two main ways to fight back: chemical and biological control.
A. Chemical Control (Pesticides)
Pesticides kill the target pest quickly.
- Advantage: Fast, effective, and simple to apply.
- Disadvantage:
- They can harm non-target species (like useful insects).
- They can build up in the food chain (bioaccumulation).
- Pests can develop resistance over time, making the pesticide useless.
B. Biological Control
This method uses natural predators, parasites, or diseases to reduce the pest population.
Analogy: If you have greenfly (pests) on your roses, you might introduce ladybirds (natural predators) to eat them.
- Advantage: Specific to the pest, non-polluting, and the pest cannot develop resistance to the predator.
- Disadvantage: It is often slower than pesticides, and the predator might not survive or might move away from the crop.
3. Microorganisms in Industry (Biotechnology)
Microorganisms (like bacteria, yeast, and fungi) are essential biological resources used extensively in manufacturing food, medicines, and fuels. This use is often called biotechnology.
3.1 Food and Drink Production
Microbes are vital for changing ingredients through fermentation or other metabolic processes:
- Yeast (Fungus): Used in baking (producing CO\(_2\) to make bread rise) and brewing alcohol (anaerobic respiration).
- Bacteria: Used to produce dairy products like yoghurt and cheese (by changing lactose into lactic acid).
3.2 Production of Antibiotics and Drugs
Many life-saving drugs are produced using fungi:
Did you know? The first antibiotic, Penicillin, is produced by the mould Penicillium. This mould naturally produces the chemical to kill off competing bacteria.
3.3 Production Conditions: Fermenters (Bioreactors)
To mass-produce useful microbes or their products (like antibiotics), they must be grown in large containers called fermenters or bioreactors.
The conditions inside the fermenter must be carefully controlled to ensure the microbes grow optimally and efficiently.
Controlled Conditions Needed:
- Nutrients/Substrate: A supply of food for the microbes to grow and respire.
- Temperature: Kept at the optimum level for the microbe's enzymes (usually using a cooling jacket, as respiration generates heat).
- pH: Maintained at the optimum level (using buffers or acids/bases).
- Oxygen/Sterility: Usually pumped in (for aerobic respiration). The whole vessel must be sterile to prevent contamination by unwanted microbes.
4. Sustainable Use of Biological Resources
If we use biological resources faster than they can naturally replenish, we risk losing them forever. Sustainability means meeting our needs today without harming the ability of future generations to meet theirs.
4.1 The Challenge of Overfishing
Ocean fish are a vital food resource, but modern fishing technology makes it easy to catch fish faster than they can reproduce. Overfishing leads to dramatic declines in fish stocks and even the collapse of entire populations.
4.2 Methods of Sustainable Fishing
To ensure fish stocks remain healthy, governments implement conservation measures:
- Fishing Quotas: Imposing strict limits (a maximum amount) on the total number or weight of fish that can be caught in a specific area. This is like being given a limited budget.
- Net Size Restrictions: Requiring fishermen to use nets with large mesh sizes. This allows smaller, juvenile fish to escape and grow old enough to breed.
- Exclusion Zones (No-Fishing Zones): Protecting specific areas where fish breed or feed, especially during breeding seasons.
- Legislation: Banning the fishing of endangered or vulnerable species entirely.
Managing biological resources is a balance: we must take what we need, but we must ensure nature has enough time and space to recover and maintain biodiversity.
You've made it through the chapter! Remember to review the impact of fertilisers and the methods of sustainable fishing, as these are frequent exam topics!