Food Production

How do glasshouses and polythene tunnels increase the yield of crops?

Glasshouses and polythene tunnels increase the yield of crops as they provide an enclosed environment in which farms can, to some extent, control the climate and conditions inside to increase their crop yield

What is an example about how glasshouses increase crop yield (CO2 and light intensity)?

A farmer can increase the light intensity and the concentration of CO2 in the air to increase the rate of photosynthesis, therefore leading to more rapid growth and more yield

What is an example about how polythene tunnels increase crop yield?

Polythene tunnels prevent the entry of pests that can damage or kill plants.

Why does increasing the temperature in a glasshouse increase the yield of crops?

Increasing the temperature means that the particles in the plant have more kinetic energy, meaning the enzymes controlling the reactions such as photosynthesis can work faster, leading to more growth and therefore more yield. This trend only leads up to a certain point, as the enzymes will denature

How do fertilisers increase crop yield?

Fertlisers increase the amount of key nutrients and minerals in the soil for crop plants, meaning that they can grow larger, faster and are more healthy, which increases yields

What are the three main minerals in fertlisers, and their role

Nitrates - essential for making amino acids which are the building blocks for proteins

Phosphorus - essential for making DNA and cell membranes

Potassium - essential for enzyme reactions to take place to produce ATP in respiration

Why do farmers use pest control?

Pests such as insects, plants, fungi and other animals can damage and kill crops, decreasing their yield. They can be killed by pesticides, which will increase the crops yield

What are the pesticides for insects, plants and fungi respectively

Insecticides, herbicides, fungicides

Advantages of pesticides

They control pests very effectively and kills the whole population

Have an immediate effect

Safe to transport, store and supply

Disadvantages of pesticides

They are non-specific, and kill other harmless, beneficial organisms such as bees

They are very slow to break down, and can accumulate in great concentrations at the top of food chains (bioaccumulation)

Need to be repeatedly applied

What is biological control?

Biological control involves introducing a natural predator to eat pest species and reduce the impact of pests on crop yields

Advantages of biological control

There is no pollution, therefore does not lead to bioaccumulation

It is long lasting as the predators shouldn’t die out

Does not need to be repeatedly applied

Disadvantages of pest control

Takes a longer period of time to be effective

May eat other harmless, beneficial organisms instead of pest

Not as effective as can not kill the entire population - some pests will always be present

What is the role of yeast in the production of food including bread?

Yeast is added to the bread dough, and it respires anaerobically producing ethanol and CO2. The carbon dioxide is trapped in small air-pockets in the dough, causing it to rise. When baked at very high temperatures, the ethanol evaporates and the yeast is killed

What is the role of bacteria (Lactobacillus) in the production of yoghurt?

Milk is pasteurised at 85-95 degrees Celsius to kill unwanted bacteria; it is then cooled to 40-45 degrees Celsius and Lactobacillus is added. The mixture is incubated for several hours while the Lactobacillus digests milk proteins and ferments the lactose to lactic acid. This thickens the milk and increases the sourness, turning it into yogurt. It is finally cooled to 5 degrees Celsius to halt the action of the Lactobacillus

What is the use of an industrial fermenter?

An industrial fermenter is used to grow microorganisms that can be used for fermentation, such as brewing beer and making yoghurt

Why are conditions in a fermenter controlled?

Conditions are controlled in a fermenter to maximise growth of microorganisms and increase product yield

How and why is controlling aseptic precautions important?

Fermenter is cleaned by steam to kill microorganisms and prevent chemical contamination, which ensures only desire microorganisms will grow

Why is controlling nutrients important?

Nutrients are needed for use in respiration to release energy for growth and to ensure the microorganisms are able to reproduce

How and why is controlling the temperature important?

Temperature is maintained using the water jacket to ensure an optimum temperature for enzymes to increase their activity (if temperature is too high they will denature, and if it is too low they will work slowly)

Why is controlling pH important?

pH is adjusted using acids and alkalis to ensure an optimum pH for the enzymes to increase their activity

Why is controlling oxygen concentration important?

Oxygen is needed for respiration to take place which allows microorganisms to reproduce and grow

Why is controlling agitation important?

Stirring paddles mix the contents to ensure that microorganisms, nutrients, oxygen, temperature and pH are evenly distributed throughout the fermenter

Why is the maintenance of water quality important when fish farming?

The water is filtered to remove waste and harmful bacteria which could cause disease. Water is also cleaned to maintain high levels of oxygen for aerobic respiration

Why is the control of intraspecific predation important when fish farming?

Species of the same fish are separated by size and age so that they do not fight, eat or kill each other

Why is the control of interspecific predation important when fish farming?

Species of different fish are separated by fences or tanks to prevent fighting

Why is the control of disease important when fish farming?

The fish are very tightly confined so disease spreads quickly. Antibiotics are given to the fish to prevent disease, and they are also kept in small numbers to minimise the spread

Why is the removal of waste products important when fish farming?

Waste products are filtered out of the water to ensure clean water and remove things which could cause disease

Why is the quality and frequency of feeding important when fish farming?

Fish are fed food that is high in nutrients to ensure fast growth. They are fed frequently but in small amounts so that they do not over eat or start eating each other

Why is the use of selective breeding important when fish farming?

Fishes are separated by gender so that only fish with the desired characteristics farms want are able to reproduce