Pearson Science Double Award Biology 5: Use of Biological Resources

Biological resources are managed by changing growing conditions, selecting organisms or modifying DNA. Each method can increase production, but its mechanism, time scale and trade-offs differ.

These notes cover Pearson Double Award 4SD0 Issue 4 Topic 5. The separate practical hub owns investigation design for yeast and related contexts.

Increasing food production

Glasshouses and polythene tunnels allow growers to control temperature, light, carbon dioxide, water and pests. Increasing carbon dioxide or temperature can raise photosynthesis and yield only until another factor becomes limiting. Heating, lighting and carbon dioxide enrichment also cost money and energy.

Fertilisers replace mineral ions removed through harvesting and can increase growth. Excess use wastes resources and can cause eutrophication after leaching or runoff.

Pesticides can act quickly and protect large areas, but may harm non-target organisms, leave residues and select resistant pests. Biological control introduces or supports a predator, parasite or pathogen of the pest. It can reduce chemical use and provide longer control, but the agent may act slowly, fail to establish or affect non-target species. “Biological” does not mean risk-free.

Microorganisms in production

Yeast respires anaerobically, producing carbon dioxide that makes bread dough rise. Lactobacillus converts lactose to lactic acid during yoghurt production. The acid changes milk proteins and inhibits some unwanted microorganisms.

An industrial fermenter supports microorganism growth or product formation. Nutrients provide raw materials. Temperature and pH are monitored near optimum values. Oxygenation is supplied for aerobic processes, while agitation distributes organisms, nutrients, oxygen and heat. Cooling removes heat released by respiration. Aseptic precautions reduce competition and contamination.

Conditions must match the desired organism and process. Supplying oxygen to an anaerobic stage or choosing the fastest growth temperature without considering product formation can reduce yield.

Selective breeding

Selective breeding uses existing inherited variation. Humans choose parents with desired phenotypes, breed them and select suitable offspring over many generations. Crops may be selected for yield, disease resistance or uniform ripening; animals may be selected for growth, milk production or temperament.

The method can combine useful alleles but is slow and limited to alleles already present in breeding populations. Repeated use of a few parents reduces genetic diversity and can increase inherited health problems or vulnerability to new disease.

Genetic modification

Genetic engineering transfers selected DNA more directly. Restriction enzymes cut DNA at specific sites, ligase joins DNA fragments, and plasmids or viruses can act as vectors carrying recombinant DNA into cells. A transgenic organism contains genetic material transferred from another species.