Biology ocr f212 - diet and food production

diet and food production following specification of ocr as level

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  • Created by: sophie
  • Created on: 14-12-11 11:54

Balanced diet

A balanced diet is a diet containing the full range of nutrients in the approximate correct proportions required for healthy growth and activity

Malnutrition is the result of an unbalanced diet

Obesity is caused by overeating and is when a person is severely overweight (bmi 30)

Obesity is caused by eating nutrients that contain more energy than the body uses. The energy is stored as fat and builds up under the skin and around organs

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Coronary Heart Disease

CHD is a common disorder of the blood vessels that supply the cardiac muscle with oxygenated blood

The ability for the cardiac muscle to contract relies on the continuos supply of oxygen, used for respiration and contraaction of the muscle

Salt increases blood preasure. People may get hypertension, increasing the risk of CHD. Artery walls thicken and stiffen, increasing risk of damage to epithilium

The process occurs rapidy in those with: high BP or high level of LDLs (transport cholesterol around the body) which hapens of someone eats too much cholesterol, found in sat fat

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Cholesterol and its effects

Atherosclerosis occurs when the lining of a vesselis damaged. Over time, cells divide in the damaged wall and there is a buildup of lipids. This can block arteries, making the lumen narrower so less blood flows through, reducing supply to the organ.

Cholesterol is transported around the blood in lipoproteins in plasma.

LDLs deposit lipids in in damaged artery walls, forming most of the atheromous plaque. High levels in the blood indrease the risk of CHD and heart attacks

LDLs are found in saturated fat

HDLs remove cholesterol from tissues

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Food chains

Plants are producers in food chains

They create carbohydrates (photosynthesis) and use this to manufacture proteins and lipids

Plants are staple food, providing slow releasing energy. Rice, Bread, Potato.

People eat animals that eat plants

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Selective Breeding - Plants

Selective breeding is done to retain favourable characteristics

High yielding

The required wheat is bred with a high yielding wheat. The highest yielding wheats are bred again, the others are discarded until the new high yielding required wheat is produced and given a pedigree name

Disease resistance

Asia: many wheats have different resistance to leaf rust. If 2 wheats with the resistance breed, the rust fungus can evolve and evade the defences, killing them all. Genes are interbread to be more resistant

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Selective Breeding - Animals

For beef

The biggest bulls are bread with the biggest cows. Semen is collected and the cows impregnated by artificial insemination. Characteristics can be specified.

For milk

Bulls with high-yielding milk relatives are used.

However, there may be health problems for certain characteristics and vet bills may be more than the selective breeding is worth.

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Fertilisers and Pesticides


Added to nutrient deficient soils to help plant growth

Expensive - cost of fertiliser can outweigh yeild price

Soil tests can be done to add only the ions needed in optimum quantities

Can leach from soil into rivers, causing pollution


DDT doesnt break down in organisms, so accumulates in animals at the top of the food chain, causing population crashes

Broad-spectrum insecticides kill all insects not just pests

Specific pesticides are expensive

Traces may linger in food we eat

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Chemicals that kill bacteria without harming the infected organism

In intensive conditions, disease spreads easily

Animals are regularly treated with antibiotics even if no symptoms are present

Reduces chance of disease, so animals grow bigger, stronger

Antibodies can destroy bacteria in the gut that can stop nutrient digestion

However, the more antibiotics use, the more likely bacteria will evelve and become resistant

This can reduce usefulness of antibiotics in animals and humans

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Micro-organisms for Food Production

Yoghurt and cheese are preserved forms of milk

Mycoprotein Advantages

Rich in protein (fungus) but low in fat

Cheaper than farm animals or crops

Can be cultured in a small area, anywhere in the world - fermenters

Grown all year round in waste products



Lab and equiptment can be expensive for poor countries

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Low temperatures

Slows growth microbes. Water in cells is frozen. Cells not killed

Salting and sugaring

Solution has lower water potential, water moves out of microbe cells by osmosis down a concentration gradient, crenating cells and killing them


Proteins in microbes lose their tertiary shape in acidic solutions

Heat Treatment

Most microbes are killed by high temperatures. Pasturised and UHT milk is heat treated


Radiation with gamma rays kills microbes without affecting food

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Taj Dogra

yea great presentation helps loads :)

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