AS OCR biology - diet and food production
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| What is nutrition? | Nutrition is nourishment - the nutrients taken into an animal or plant for use in metabolism
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| What is a balanced diet? | A balanced diet contains all nutrients required for good health in appropriate proportions, the energy intake is balanced with the energy use
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| What are the components of a balanced diet and what are their functions? | Carbohydrate-energy source. Protein-growth + repair of muscle + bone. Fat-waterproofing, cell membranes, energy storage, insulation, protection. Water- metabolic reactions, transport medium. Vitamins (organic)/ minerals (inorganic), fibre
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| What is malnutrition? | Where an unbalanced diet leads to a person becoming overweight (e.g. obese) or underweight
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| What is obesity? | Condition where excessive fat deposition in adipose tissues impairs health, BMI is 30+, caused by eating too much energy-containing food. Increases risk of mortality, cancer, type2 diabetes, cardiovascular disease, gallstones, hypertension, osteoarthritis
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| How do you calculate BMI? | mass (kg) / height ^2 (m)
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| What is CHD? | Mutlifactorial disease of heart caused by malfunction of coronary arteries. Caused by atherosclerosis- fatty plaques are deposited under the endothelium in the walls of the coronary arteries, narrows lumen, restricts blood flow to heart, oxygen starvation
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| What are the symptoms of CHD? | Angina - severe chest pain. Myocardial infarction - death of part of heart muscle due to a thrombus in a coronary artery. Heart failure - heart can't pump enough blood to meet metabolic needs of the body, caused by valve damage or blocked coronary artery
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| What factors related to diet increase the risk of CHD? | Excess salt in diet reduces water potential of blood so more water is held in blood, hypertension, diastolic + blood pressure are kept at high level, damages inner lining of arteries, part of atherosclerosis. High intake of saturated fats e.g. animal fat
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| Continued | Absence of unsaturated fats and antioxidants (vitamin A,C,E) from diet. High blood cholesterol concentration, associated with animal fats. Obesity
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| What other factors increase the risk of CHD? | Genetic factors (family history of cardiovascular disease), old age, gender (men are more likely to suffer from CHD under the age of 50), physical inactivity, diabetes, stress, smoking cigarettes
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| Where is cholesterol found in the body? | In cell membranes and skin
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| What is the function of cholesterol? | Makes steroid hormones (oestrogen, testosterone) and bile
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| How is cholesterol transported around the body? | Insoluble in water so it is transported as lipoproteins - small balls of lipid, cholesterol and protein
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| What are HDLs? | Formed by the combination of unsaturated fat, protein and cholesterol. Carry cholesterol from body tissues to liver, bind to receptor sites on liver cells to enter the cells. In the liver, cholesterol is broken down or is used in metabolism to make bile
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| What are LDLs? | Formed by combination of saturated fat, protein + cholesterol. Carry cholesterol from liver to body tissues, bind to receptor sites. High concentration causes deposition of cholesterol in the artery walls
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| What is the impact of saturated fats on blood cholesterol concentration? | Increase concentration of low-density lipoproteins. Saturated fats reduce the activity of LDL receptors so as LDL concentration increases, less are removed from the blood
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| What is teh impact of unsaturated fats on cholesterol concentration in the blood? | Increased number of HDLs. Poly and monounsaturated fats increase the activity of LDL receptors so lower LDL concentration in the blood, reduce and reverse atherosclerosis
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| What is a healthy diet in terms of cholesterol? | Low overall intake of fats for low conc of lipoproteins. Avoid saturated fats. Eat more unsaturated fats to increase the ratio of HDLs to LDLs (optimum is 4:1) and increase activity of LDL recetpros. Cholesterol concentration should be below 5.2mmol/dm3
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| What are plants in the food chain? | Autotrophs + producers - use an external energy source and inorganic molecules to form complex organic molecules e.g. manufacture starch from photosyntehisis and amino acids by absorbing nitrate from the soil
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| What are humans in the food chain? | Heterotrophs + consumers - gain nutrition directly from plants and indirectly from herbivorous animals
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| What is selective breeding? | Where humans choose individual organisms with desired characteristics to breed, then the offspring with the best combination of characteristics are bred, so over time the desired trait is exaggerated. 3 stages: isolation, artificial selection, inbreeding
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| Continued | Humans apply a selection pressure: artificial selection is an external force that drives evolution in a particular direction, rather than natural selection. marker assisted selection - a section of DNA is used as a marker for the trait, early selection
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| What is the purpose of selective breeding for plants? | High yields, high growth rate, resistance to pests and diseases (e.g. the allele responsible for resistance to the yellow leaf curl virus was bred into a domestic variety of tomato plant), good responses to fertiliser
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| What is the purpose of selective breeding for animals? | high productivity - high growth rate, high yield (meat, milk eggs), resistance to disease, good quality e.g. lean meat
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| How can chemicals be used to improve food production? | Fertilisers increase mineral content in soil- increase rate of growth & size- NO3-, Mg2+. Pesticides kill insects that reduce yields, fungicides reduce fungal growth leaves/roots. Antibiotics treat infected animals, disease impairs growth, reproduction
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| How do microorganisms spoil food? | Obtain nutrition by digesting organic matter, leave waste products. Visible growth of mould colonies. External digestion, enzymes break down food molecules, smells sweet. Bacterium Clostridium botulinum releases botulin, botulism. Infection - salmonella
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| How should we avoid food being spoilt? | Eat food quickly while fresh or treat it. Methods of treatment: cooking denatures proteins kills microorganisms, pasteurising (heat to 72º, 15 secs, cool to 4º) denatures proteins kills microorganism, cooking doesn't kill microorganisms but slows enzyme..
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| Continued | activity so growth/reproduction are slow. Salting/sugar/drying dehydrate, water leaves by osmosis. Smoking antibacterial chemicals, heat denatures proteins. Pickling- acid denatures proteins kills microorganisms. Irradiation-disrupts DNA structure, death
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| what food products are microorganisms involved in the production of? | Yoghurt, cheese, bread, wine, quorn
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| How are microorganisms used to make yoghurt? | Lactobacillus bacteria convert lactose in milk to lactic acid via anaerobic respiration (bacterial fermentation), milk protein thickens, bacteria partially digest milk
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| How are microorganisms used to make bread? | Yeast respire aerobically then anaerobically when o2 runs out - releases co2 which gets trapped in dough and causes it to rise
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| How are microorganisms used to make quorn? | the fungus Fusarium venenatum manufactures mycoprotein, a single-cell protein, and can be grown on waste materials in fermenters
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| How are microorganisms used to make wine? | Yeast respire aerobically using glucose and fructose in grapes to produce enthanol, respiration
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| How are microorganisms used to make cheese? | Lactobacillus bacteria convert lactose in milk to lactic acid via anaerobic respiration (bacterial fermentation), casein protein coagulates, milk separates into solid curds and liquid whey, curds are flavoured
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| What are the advantages of using microorganisms for food production? | production can be increased & decreased according to demand, no animal welfare issues, quorn is protein source for veges + no saturated fat/cholesterol + high in fibre, microorganisms grow quickly, fermenters can be anywhere, grown in waste materials
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| What are the costs of using microorgansism for food production? | Food from fermentors has to be purified which expensive, fermentors can become infected because conditions are ideal for pathogens, difficult to isolate food from fermentors, customer resistance to new foods
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