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What does a healthy diet consist of?
A healthy diet has the right balance of food types. Carbohydrate, fat and protein are used by the body to release energy + build cells. Mineral ions + vitamins are needed to keep the body healthy. If unbalanced, one can become malnourished.
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When you exercise, more energy is used by the body, but how does it affect your metabolism?
Exercise increases the metabolic rate (chemical reactions in cells work faster) but the proportion of muscle to fat in your body + your inherited factors can also affect your metabolic rate.
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Why is it important for good health to get the energy balance correct?
If energy taken in = energy used -->mass will stay the same. Eating too much can lead to becoming overweight + obese. Long term obesity can lead to i.e. type 2 diabetes. These problems can be reduced less carbs + more exercise.
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What are two types of cholesterol?
You need ‘good’ cholesterol for your cell membranes + to make vital substances but small numbers of the population inherit ‘bad’ cholesterol which can lead to heart disease.
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Which environmental factors can affect cholesterol levels in our blood?
Foods rich in saturated fat can increase levels whilst regular exercise can lower cholesterol levels.
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What are pathogens?
Micro-organisms (usually viruses or bacteria) that cause infectious diseases, reproducing rapidly when they enter our body + make us feel ill by producing toxins. Viruses are much smaller than bacteria + reproduce inside cells, damaging them-feel ill
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What did a doctor called Semmelweis realise before bacteria + viruses had been discovered?
That infection could be transferred from person to person in a hospital. He told his staff to wash their hands between treating patients but other doctors didn’t take him seriously
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What are our bodies’ defence mechanisms to pathogen?
Skin prevents pathogen getting in, mucus traps them + stomach acid traps them. WBC’s can ingest pathogens, produce antibodies to destroy particular pathogens, & produce antitoxins to counteract toxins released by pathogen.
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What do antibiotics do?
They kill infective bacteria in the body, i.e penicillin, discovered by alexander Fleming in 1928 but viruses are difficult to kill as they reproduce inside body cells so any treatment could also damage the body cells but are usually overcome by immu
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How can pure cultures of non-pathogenic bacteria be used?
For laboratory investigations to find the effect of antibiotics on bacteria. Investigations need uncontaminated cultures as other bacteria including pathogen could grow. Contamination could come from your skin, the air, the soil or the water around y
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How do you grow micro-organisms in a laboratory?
Give them a culture medium – liquid/gel containing nutrients, carbohydrates (energy source), minerals + sometimes other chemicals. Agar Jelly is used. Provide warmth + oxygen + keep incubated at 25oC in school labs + at 35o in industry.
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How do we keep the culture pure?
Kill all bacteria on equipment – pass metal loops through flame, boil solutions and agar & prevent micro-organisms from the air getting into the equipment.
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How can disease spread quickly as a result of mutations within pathogen?
Some pathogens, (esp. viruses) can mutate and as very few people are immune to the mutated pathogens, disease can spread quickly. A disease that has spread across the country is called an epidemic, across countries = pandemic.
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What is MRSA?
The MRSA “super bug” is a bacterium that has evolved through natural selection. MRSA and other bacteria have become resistant to the common antibiotics.
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Why shouldn’t antibiotics be used for mild infections?
In order to slow down the rate of development of resistant strains.
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How does natural selection occur in pathogens?
Mutations of pathogens produce new strains + some are resistant to antibiotics. Antibiotics kill individual pathogens of the non-resistant strain. The resistant bacteria survive and reproduce and a whole population of a resistant strain develops.
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What is a vaccination?
Dead/Inactive forms pathogen that can be injected into the body causing the WBCs to react by producing antibodies preventing further infection because the body responds quickly by producing more antibodies.
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Give an example of a vaccination and how antibodies can recognise the pathogen?
The MMR vaccination (immunisation) is one of several vaccines + is given to prevent Measles, Mumps + Rubella. The antibodies produced by WBCs recognise the antigen (protein shape) of the pathogen.
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Why do most people in a population need to be vaccinated?
To protect society from serious diseases such as measles which can lead to long term damage to the body i.e. blindness and often death. Some vaccines cause side effects which may be mild or serious – pros + cons.
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What is Follicle Stimulating hormone and Luteinising hormone?
FSH is made by the pituitary gland and causes eggs to mature and oestrogen to be produced. LH is made by the pituitary gland + stimulates the mature egg to be released from the ovary (ovulation).
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What is Oestrogen?
Produced by the ovaries and inhibits (stops) the further production of FSH. It stimulates the production of LH and also stimulates the womb lining to develop the fertilised egg.
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What are the contents and purpose of the Contraceptive pill (oral contraceptive)?
The contraceptive pill may contain oestrogen and progesterone (prg only pills have fewer side effects) and prevents the production of FSH so no eggs mature. The first birth-control pills contained large amounts of oestrogen=significant side effects.
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What is fertility treatment?
If a woman cannot produce mature eggs, then FSH (causes eggs to mature) and LH (stimulates ovulation) can be given.
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What does IVF involve?
Giving FSH&LH to stimulate the maturation of eggs which are collected and fertilised by sperm from the father. The zygotes develop into embryos + 1 or 2 embryos are inserted into the mother’s uterus.
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What are the advantages and disadvantages of contraceptive pills?
Have helped to reduce family size which has reduced poverty in some areas + allows women to plan their pregnancies but can cause side effects and some people object to its use for ethical/religious reasons.
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What are the advantages and disadvantages of fertility drugs/IVF?
Fertility drugs can help infertile couples whom are having IVF + IVF helps couples to have a baby but IVF is an expensive process, extra embryos produced are stored/destroyed and some people think that it’s unethical for older women to have IVF babie
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What are the internal conditions controlled by the body?
Water content (leaves the body in urine + when we breathe/sweat), ion content (lost through urine/sweat) temperature (as enzymes will denature if not constant), Blood sugar level (energy source for cells) – controlled by pancreas.
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How do hormones control plant growth?
Auxin is a hormone which controls phototropism (shoots grow towards light) & gravitropism (roots grow down towards gravity). Unequal distribution of auxin causes unequal growth-results in bending of shoot/root. Roots also grow towards water.
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How are hormones used in women?
Contraceptive pill (to prevent unwanted pregnancies/help plan when to have a baby). Fertility treatment + IVF. Long term use can lead to side effects in some women. Women are given fertility drugs as their own levels of FSH=too low.
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How can plant hormones be used by farmers and gardeners?
Weedkillers to kill unwanted plants. To encourage roots to grow when cuttings are taken from a plant before the cutting is planted. Used to encourage fruit to ripen. If used incorrectly, can harm to the environment - weedkillers may harm crops.
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How does auxin (hormone) allow plants to be sensitive to light, moisture and gravity?
Their shoots grow towards light + against the force of gravity (phototropism). Their roots grow towards moisture and down towards gravity (gravitropism). This is controlled by auxin. Unequal distribution of auxin=unequal growth=bending of shoot/root
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How is drug testing carried out?
In the laboratory, using cells, tissues + live animals. In clinical trial involving healthy volunteers + patients. Low doses of drug given at start of clinical trial. If drug is found to be safe, further clinical trials are carried out to find optimu
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Describe double blind trials.
Some patients are given a placebo which doesn’t contain the drug. Neither doctors nor the patients know who as received a placebo and who has received the drug until the trial is complete.
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How are placebos used in some trials?
Placebos do not contain a drug. Half the patients have the drug, the other half are given the placebo. This is to check that the drug being tested really does have an effect on the patient. In double-blind trials, neither the doctor nor patient knows
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What was thalidomide?
It was a developed as a sleeping pill, but doctors realised it could control morning sickness in pregnant women. Unfortunately it had not been tested for use in pregnancy + some babies were born with limb abnormalities as a result.
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What was done after doctors realised babies were born with limb abnormalities as a result of their mothers taking thalidomide?
The drug was banned and the rules for drug testing was improved. More recently it has been used to treat other conditions i.e. leprosy
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What are Statins?
Drugs which lower the amount of ‘bad’ cholesterol carried in the blood, given to older people + taken daily. Trials shows that the incidence of heart disease + stroked reduced by over 40%
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What is used as an alternative if people prefer to take drugs not prescribed by doctors?
Herbs are often used instead i.e. St John’s wort often used to treat depression instead of Prozac. The only way to test that the herb works well is through a double blind trial. (to check it works as well as the prescribed alternative + not phsycolog
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What are recreational drugs?
Drugs used by people for pleasure i.e Heroin and cannabis which are addictive + illegal. It is also argued that using cannabis can lead to taking ‘harder drugs’. If you try to stop taking addictive drugs you will suffer from withdrawal symptoms.
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What are the effects of using recreational drugs?
They affect the brain + nervous system (its easy to become addicted). Also may have adverse effects on the heart + circulatory system. Health problems associated: alcoholic poisoning, lung cancer from smoking, liver cirrhosis.
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What are medicinal drugs?
Developed over many years + used to control disease to help people that are suffering. May are only available by prescription from a doctor. Some are taken illegally i.e. stimulants used by athletes
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To survive and reproduce, organisms require materials from their environment + from other organisms living there. What do plants + animals compete for?
Animals- water, food, space (territory), mates + breeding sites. Predators compete with their prey. Prey compete with each other to escape predators. Plants- light, space + nutrients from soil. I.e. woodland -some smaller plants flower before trees a
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What is an adaptation?
Special feature that makes an organism well suited to its environment
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How do plants have to be adapted?
Plants are adapted to obtain light + other materials efficiently in order to make food by photosynthesis.
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Most organisms live in temperatures below 40oC so that their enzymes work. Why are extremophiles different?
Extremophile are micro-organisms adapted to live in conditions where enzymes wouldn’t normally work as they would denature.
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How are animals in cold climates adapted to survive in their environment?
Often have thick and fat under the skin (blubber) to keep them warm. Some animals in the arctic (i.e. arctic hare) are white in the winter + brown in the summer so that they’re camouflaged. Also may have small SA:V ratio to conserve heat.
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How are animals in hot climates adapted to survive in their environment?
They’re adapted to conserve water + to stop them getting too hot. Desert animals may hunt in the night when it’s cool to stay cool in the day. May also have large SA:V ratio to stay cool.
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How can plants be adapted (take into consideration that they need water, space + nutrients to survive?
Water lost through holes in the leaf (stomata). Small/waxy leaves to conserve water. Swollen/extensive stem to store water. Poisons/thorns/warning colours to put off animals. Thick stems, leaves low to the ground. Extensive root system to collect wat
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How can animals be adapted?
Small SA: V ratio to retain heat. Large SA: V to lose heat. Camouflage. Spines/horns to hurt predator. Streamlining/long limbs so that the prey can outrun the predator. Large ears/position of eyes so that predators are detected earlier=escape sooner
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How can plants be adapted to ensure that they don’t compete with themselves?
Some use animals to spread their fruits and seeds. Some use the wind (i.e sycamore) or mini-explosions (i.e.broom) to spread their seeds.
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Some animals have very unusual adaptations which make them successful competitors. Give an example.
Female fig wasps have specially shaped heads for getting into fig tree flowers + ovipositors that allow them to place the eggs deep inside the flower. Some male fig wasps spend their lives inside the flowers waiting for a female.
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How are star-nosed moles (a) and Venus fly (b) traps adapted for survival?
(a) lives underground + is almost blind but is very sensitive to touch and smell. (b) are insect eating plants that have sweet sticky nectar and are bright red inside
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What environmental factors can affect the distribution of living organisms?
Non-living factors include; temp, rainfall, light & oxygen). Living factors include; arrival of a new predator/disease, intro of new plants which might provide food/habitats.
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Name some pollution indicators.
Lichens (air pollution-the more lichen growing the cleaner the air), Freshwater invertebrates (the wider the range of FwIs the cleaner the water) & Equipment (rain gauges, thermometers, PH/Oxygen sensors + data loggers)
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What may have cause the fall in the bee population?
By several factors including the use of chemical sprays by farmers, a viral disease or possible changes in flowering patterns in plants due to climate change.
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Describe how the sun contributes to pyramids of biomass + the food chain.
Radiation from the Sun is the source of energy for most communities of living organisms. Green plants + algae absorb a small amount of the light that reaches then + transfer it to chemical energy in photosynthesis. This energy is stored.
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What is biomass?
The mass of living material in plants and animals. Green plants transfer solar energy to chemical energy which is then passed through the food chain.
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What does a pyramid of biomass represent?
The mass of the organisms at each stage in a food chain. It may be more accurate than a pyramid of numbers i.e. a bush may have many insects feeding on it but the mass of the bush is far greater than that of the insects.
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What are Sankey diagrams?
A type of graph that’s used to show energy intake and energy use or transfer in an animal. Go to page 25.
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What is organic waste?
Waste vegetables + peelings from the kitchen or grass cuttings + clippings from trees in the garden contain organic waste. The council also collects garden waste and use shredders and large bins to the compost material.
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How can organic waste be composted?
The most efficient ways of composting allow waste to be mixed with oxygen and moisture. They also allow energy to escape by heating the surroundings. Gardeners may add worms + garden soil to composters to speed up the process.
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Where can genes be found?
The nuclei of cells contain chromosomes (thread-like structures) which carry genes. The nuclei of gametes (sex cells) contain only one set of chromosomes + therefore only contain one set of genes
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What do genes control?
Different characteristics of the offspring, passed from parents to offspring during reproduction. In most body cells (except gametes) the chromosomes are in pairs (1 set from the female + 1 set from the male gamete)
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What is asexual reproduction?
Reproduction that doesn’t involve the fusion of gametes. All genetic info comes from one parent. All of the offspring are identical to the parent, so there’s little variety (clones).
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What is sexual reproduction?
Reproduction that involves the fusion of gametes. Mixture of genetic information, so the offspring show variation. Offspring are similar to both patents but not identical as they have a combo of 2 sets of genes.
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How can variation in offspring be advantageous to their survival?
As some characteristics may give offspring a better chance of surviving
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What causes differences in the characteristics of individuals of the same species?
Differences in the genes they’ve inherited, the conditions in which they developed + a combo of both genetic + environmental causes. Genes = most important factor.
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What causes differences in the characteristics of plants of the same species?
Lack of light, nutrients or space to grow. Weaker plants may have the same genes but can’t grow as well if deprived of nutrients.
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What causes differences in the characteristics of animals of the same species?
Too much or too little food can alter their characteristics. Human development can be affected during pregnancy i.e. if mother smokes/drinks-->baby may have small birth weight.
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How is cloning used in farming and agriculture?
To produce new individuals that are useful in farming + agriculture. In plants, the process of cloning can be cheap + effective as they can be cloned by taking cuttings + growing them or using tissue culture.
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What does tissue culture involve and why may it be used?
Taking small groups of cells from part of a plant + growing them under special conditions (tissue culture) is more expensive, but can be used to reproduce large numbers of a rare/top quality plant.
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What are embryo transplants used for?
To clone animals – an embryo with unspecialised cells is split into smaller groups of cells. Each group of genetically identical cells is transplanted + allowed to develop in a host animal.
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What are the benefits of adult cell cloning?
Development of cloned animals, genetically engineered to produce valuable proteins in their milk. These have uses in medicine. Cloning can save animals from extinction.
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What are the disadvantages of adult cell cloning?
Concerns about the ethics of cloning. Cloning limits the variation in a population (limits the gene pool), which can be a problem for natural selection if the environment changes. Concerns about using technique to clone humans in the future.
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What is genetic engineering ad when is it used in agriculture?
A technique that involves changing the genetic make-up of an organism. New genes can be transferred to crop plants. Crops with changed genes are called GM crops + may be insect/herbicide resistant + usually have increased yields.
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What was Jean-Baptiste Lamarck’s theory of evolution called?
The inheritance of acquired characteristics. Lamarck’s theory stated that characteristics which develop during an organism’s lifetime can be passed onto the next generation. i.e. his theory predicts that a bodybuilder’s muscles will be passed on to h
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What did Darwin’s theory of evolution by natural selection suggest (1)?
That all species of living things have evolved from simple life forms that first developed more than 3 bill years ago.
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What did Darwin’s theory of evolution by natural selection state (2)?
Small changes in organisms took place over a long time. All organisms vary and therefore some are more likely to survive, those best adapted breed + pass on their characteristics.
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Why was Darwin’s theory of evolution by natural selection only gradually accepted? (3)
Insufficient evidence at the time. Mechanism of inheritance/variation not known until 50 years afterward. Theory undermined idea that God made all plants & animals that live on earth (creationism).
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Which birds did Darwin observe to find evidence for evolution?
The finches on the Galapagos Islands. He tried to show that they could change over time if they lived under different environmental conditions.
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How evolution occur via natural selection?
Individual organisms within a species may show a wide range of variation due to mutation in their genes. Individuals with characteristics most suited to their environment are more likely to survive + breed successfully passing on the genes to the nex
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How can mutations and variation be particularly important in natural selection?
If the environment changes. I.e. if the rabbit disease myxomatosis killed most the rabbits in the UK a few rabbits with the mutated gene survived to breed.
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What are evolutionary trees?
Models that can be drawn to show the relationships between different groups of organisms.
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