Biology ocr f212 - diet and food production
diet and food production following specification of ocr as level
- 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
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
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
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
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
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.
Fertilisers and Pesticides
Fertilisers
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
Pesticides
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
Antibiotics
Antibiotics
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
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
Disadvantages
Boring/bland
Lab and equiptment can be expensive for poor countries
Preservation
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
Pickling
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
Iradiation
Radiation with gamma rays kills microbes without affecting food
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