- Created by: KieranFifield
- Created on: 05-05-17 17:57
Diet and Metabolic Rate (Pg. 13)
A Balanced Diet
- Provide the energy you need.
- Balance of the right foods:
- Carbohydrates (release energy); Fats (keep warn and release energy); Proteins (cell repair, replacement, and repair); Fibre (keep everything moving in the digestive system); Vitamins & Minerals (healthy skin, bones, and blood)
- Depends on your metabolism
- Metabolism is "the chemical processes that occur within a living organism in order to maintain life."
- Metabolism varies, depending on the person: little exercise = less energy = less fats and carbohydrates.
- High muscle:fat ratio = higher metabolism
- Bigger people = higher metabolism
- Men tend to have a higher metabolism
- Regular exercise increases metabolic rates.
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Factors Affecting Health (Pg. 14)
- Malnourished = unbalanced diet (either too fat or thin, or unhealthy in other ways)
- Excess carbohydrates or fat leads to obesity:Excess saturated fat = increase in blood cholestrol levels
- 20% or more over the recommended body mass.
- Hormonal problems; bad diet; overeating; and lack of exercise all cause obesity.
- Can cause arthritis (inflammation of joints); type 2 diabetes (inability to control sugar levels); high bloody pressure and heart disease.
- Excess salt = high blood pressure; heart problems
- Eating too little = slow of growth; fatigue; poor resistance to infection; irregular periods
- Deficiency diseases = lack of vitamins or minerals (i.e. lack of Vitamin C = scurvy)
- Exercise increases amount of energy used; decreases amount of stored fat.
- You can be fit and unhelathy - physically fit but malnourished.
- Inherited factors:
- Underactive thyroid gland = lower metabolic rates; can cause obesity.
- Blood Cholestrol level = fatty substances in blood (essential); too much increases heart disease chance.
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Evaluating Food, Lifestyle and Diet (Pg. 15)
- In the exam, you may have to evaluate information about how food affects health.
- You may get asked to evaluate lifestyle choices (what you eat and do).
- You must use your own knowledge to answer these questions in the exam.
Watch out for slimming claims that aren't scientifically proven
- Lots of slimming products (e.g. diet pills) and slimming programmes (e.g. the Atkins Diet) claim they'll help you lose weight.
- Look out for:
- Scientific study evidence; qualified author; sample range; other study comparison.
- There has to be a large survey for it to be assured.
- To lose weight, you have to take in less energy than you use:Some claims may also be true, but misleading (i.e. low in fat cereal bars, but no overall effect on health).
- Eat less fat or carbohydrate.
- Do more exercise.
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Fighting Disease (Pg. 16)
- Bacteria are very small living cells
- Small cells (1/100th of you body cell)
- Make you feel ill by: damaging your cells; producing toxins (poisons)
- Viruses are not cells - they're much smallerSkin, hairs, and mucus stop a lot of pathogen.
- 1/100th of a Bacterium
- Replicate themselves by invading your cells to make copies; cells burst releasing virus.
- Cell damage makes you feel ill.
- Skin, hairs, mucus stop pathogen getting in your body.
- Platelets help blood clots appear when you cut yourself, stopping pathogen entry.
- White Blood Cells [WBCs] (part of the Immune System) can:
- Consume them (engulf and digest foreign cells)
- Produce AntibodiesProducing Antitoxins (counteracts toxins produced by invading bacteria).
- WBCs produce proteins [antibodies] to lock on and kill invading cells; only designed for one cell type; antibodies are produced rapidly and kill similar bacterium or viruses; WBCs will recreate these antibodies if person becomes reinfected.
- Produce Antitoxins (counteract toxins from invading bacteria)
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Fighting Disease - Vaccination (Pg. 17)
- Vaccinations - small amounts of dead/inactive microorganisms.
- Carry antigens, body produces antibodies to attack them; WBCs remember the type of antigen and will produce antibodies to rapidly kill invading microorganisms (i.e. MMR vaccination).
- Some vaccinations wear off over time, boosters may be needed.
- Pros of vaccinations:
- Controls a lot of infectious diseases (i.e. Smallpox); prevents epidemics
- Cons of vaccinations:
- Don't always work (don't give you immunity); may have a bad reaction (though this is very rare)
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Fighting Disease - Drugs (Pg. 18)
- Some relieve symptoms, others cure problems.
- Painkillers (i.e. Aspirin) relieves symptoms; antibiotics (i.e. Penicillin) kill bacteria, doesn't stop a virus
- Bacteria can become resistant to Antibiotics (Antibiotic Resistance)
- Bacteria mutate; infection becmes rantibiotic resistant; non-resistant bacteria killed; resistant survive and reproduce; mutations cause serious infections; slow mutations by not over-prescribing antibiotics.
- Investigate Antibiotics by Growing Microorganisms in the Lab
- Grow them in "culture medium" (usually agar jelly) containing carbohydrates, minerals, proteins, and vitamins.
- Hot agar jelly poured into Petri Dishes; when cooled use an inoculating loop to put microorganism in jelly.
- Paper discs soaked in antibiotics and placed on jelly; resistant bacteria survive.
- All equipment must be steralised before use - pass through a flame; lid is used to stop other microorganisms.
- Microorganisms are usually stored at 25C at school - harmful pathogens cannot grow; temperature much higher in industrial conditions.
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Fighting Disease - Past and Future (Pg. 19)
- Semmelweis - observed women dying from puerperal feer after childbirth; doctors spreading diseases through unwashed hands. He told doctors to wash hands - death rates to 2% from 12%. Antiseptic kill bacteria, but there was no evidence of this; nowadays basic hygiene is essential (though MRSA has started spreading)
- More Common Antibiotic Resistance - death rates fallen; overuse of antibiotics means resistance; can't easily treat; big problem in modern world; suberbugs (bacteria resistant to most antibiotics) are more common.
- Mutate to new strains; antibiotic resistant; can cause epidemic
- Mutate often (hard to develop vaccines); huge problem in regard to deadly and infectious virus evolution; vaccines and antiviral drugs could be developed; potential pandemic.
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The Nervous System (Pg. 20)
- Sense organs detect stimuli (change in the environment) - eyes (light receptiors), ears (sound receptors), nose (smell receptior), tongue (taste receptor), skin (touch, pressure, pain receptor); they change stimulus energy to electrical impulses.
- Do not get sense organs (eyes, ears, etc.) mixed up with receptors (light receptor, sound receptor, etc).
- The Central Nervous System (CNS) coordinates the response.
- Organises where information from sense organ is sent, and where reflexes are coordinated (brain and spinal cord only).
- Sensory Neurones carry electrical impulses from receptor to the CNS.
- Relay Neurones carry signals from the sensory neurones to the motor neurone.
- Motor Neurones carry impulses from CNS to the effector.
- Effectors are muscles or glands that contract in response to nervous impulse, or secrete hormones.
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Synapses and Reflexes (Pg. 21)
- Synapses connect neurones; nerve signals transfer by checmicls which diffuse across the gap.
- Reflexes help prevent injury; automatic responses; passage of information in reflex (receptor - effector) is a reflex arc.
- Reflex Arc goes through the CNS - neurones go through spinal cord or unconscious part of the brain.
- Stimulus - Sensory Neurone - Synapse - Relay Neurone - Synapse - Motor Neurone - Effector
- Quicker than a normal response because you don't have to think about it.
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Hormones (Pg. 22)
- Hormones are chemical messages sent in the blood; carried in blood plasma; affects target cells; hormones control things in organs and cells that need constant adjustment; produced and secreted in various glands.
- Pituitary Gland - produces many important hormones such as FSH and LH for the menstrual cycle.
- Ovaries (females only) produce oestrogen, used in the menstrual cycle.
- Very fast; act for a short time; target one area.
- Slower; act for a long time; general area.
- If response is quick, it is probably nervous; if a response is long lasting, it's probably hormonal (i.e. adrenaline)
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The Menstrual Cycle (Pg. 23)
- Four Stages
- Day 1 - Bleeding Starts; Day 4-14 - Uterus Lining builds up; Day 14 - Egg Released; Day 14-28 - Wall is maintained, and will break down if no fertilised egg is present.
- FSH (Follicle-Stimulation Hormone) - Produced in Pituitary Gland; causes egg to mature in ovaries; stimulates ovaries to produce oestrogen.
- Oestrogen - Produced in obaries; causes pituitary to produce LH; inhibits further release of FSH.
- LH (Luteinising Hormone): Produced by Pituitary Gland; stimulates release of an egg in middle of cycle
- Progesterone is another hormone involved in the cycle - produced by ovaries.
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Controlling Fertility (Pg. 24)
- Oestrogen can prevent egg release - keeping levels high inhibits FSH production, stopping egg development.
- Progesterone reduces fertility - stimulates thich cervical mucus to prevent gamete fusion.
- The Pill (oral contraceptive) - lower dose of Oestrogen than in 1950s, fewer side effects.
- Pros - 99% Effective; reduces cancer risk.
- Cons - Not 100%; side effects (headaches, nausea, irregular menstrual bleeding); doesn't stop STDs
- There's a progesterone-only pill - fewer side effects; not as effective.
- FSH/LH can inject, up levels to produce eggs; Pros - helps women get pregnant; Cons - not 100%; too many eggs.
- In vitro fertilisation (sperm and egg mixed in labs), planted in Uterus once cells grow; FSH/LH given.
- Pros: Infertile couples can have children; Cons: strong reactions, increased cancer risk, multiple births.
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Plant Hormones (Pg. 25)
- Auxin (plant hormone) in shoot/root tips; controls growth to light (phototropism), gravity (geotropism) and moisture.
- Moves backwards to promote cell elongation, occurs just behind the tip. Extra auxin = shoot grow, not roots.
- Shoots grow towards the light (auxin accumulates on shady side)
- Shoots grow away from gravity (unequal distribution of auxins to the lower side)
- Roots grow towards gravity (extra auxin inhibits the growth, so root bends down)
- Plant hormones are used in agriculture (i.e. Weed Killers don't affect crops)
- Rooting powder will allow plant cuttings to grow in soil - good to clone really good plant quickly
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Homeostasis (Pg. 26)
- Ion content, water content, sugar content, and temperature need to be monitored and constant.
- Ions regulated in kidney; taken in by food, absorbed in blood, excess ions removed; lost in sweat or urine.
- Water taken in by food/water; lost through sweat (skin), breath (lungs), and urine (kidneys)
- Cold days = more urine (less concentrated), less sweat; hor days = less urine (more concentrated), more sweat
- Body temperature controlled by brain (enzymes work best at 37C) - own personal thermostat.
- Carbyhydrates put glycose into blood from gut; more exercise = more removed; insulin maintains glucose levels.
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Drugs (Pg. 27)
- Drugs - change body chemistry; leads to addiction; can cause withdrawal symptoms if stopped.
- Medical Drugs (medically useful); Recreational Drugs (fun - legal or illegal); Performance-enhancing Drugs (sport).
- Performance-enhancing drugs include anabolic steroids (increase muscle size), stimulants (increase heart rate); negative effects (high blood pressure); some are illegal, all are banned by sporting bodies.
- Against Drugs: Unfair for an advantage; athletes may be misinformed of risks.
- For Drugs: Athletes have the right to their own decision; drug-free sport isn't always "fair".
- Statins: Prescribed drugs; lower risk of heart/circulatory disease; lower cholesterol; original research by Government (6000 patients); two groups of pateints (statin users and non-statin users).
- Cannabis: illegal drug; varied results into mental health problems; no definite evidence.
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Testing Medicinal Drugs (Pg. 28)
- Stage One: testing on human cells/tissues in labs; cannot test drugs that affect whole body.
- Stage Two: live animal testing (best dosage and toxicity of drug); two mammal restriction for testing (cruel ethically).
- Stage Three: healthy human volunteers; low dose increased over trial; then tested on ill patients; tested in two groups (drug users and placebo - see effects - blind tests).
- Thalidomide (1950s) intended to be sleeping pill but could cure morning sickness; wasn't tested in advance; caused abnormal limb development (could affect the fetus and penetrated the placenta); 10,000 babies affected by thalidomide, half survived; drug banned and more rigorous testing introduced.
- Thalidomide used in treatment of leprosy and other diseases.
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Recreational Drugs (Pg. 29)
- Recreational Drugs - legal or illegal; hard (more addictive/harmful) and soft; all can cause heart/circulatory problems.
- Reasons for use: enjoyment; relaxation; stress relief; sometimes influenced by background.
- Canabis classification: desire to try hard drugs; contact drug dealers; genetic influence.
- Some legal drugs have more impact than illegal.
- Smoking: can cause heart, blood vessel, and lung disease; tobacco smoke causes cancers; nicotine is addictive.
- Alcohol: slows down body's reactions; impairs judgement; can cause liver and brain damage.
- Tobacco and alcohol has bigger impacts in UK; NHS overrun by lung diseases and alcohol crime.
- Sorrow and anguish for people affected directly and indirectly.
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Adaptations (Pg. 31)
- Desert Animals to save water and keep cool: Large SA to Volume Ratio (lose body heat); Water Efficient (concentrated urine, little sweat); Good in Hot Conditions (thin body fat/coat); Camouflage (avoid predators, sneak up on prey).
- Artic Animals to reduce heat loss: Small SA to Volume Ratio (round shape, minimise SA); Well Insulated (thick layer of blubber, energy store); Camouflage (avoid predators, sneak up on prey).
- Desert Plants adapt to little water: Small SA to Volume Ratio (spines instead of leaves reduce water loss); Water Storage Tissues (i.e. cactus stores in thick stem); Maximising Water Absorption (shallow/extensive roots).
- Deter Predators: Armour (thorns/sharp spines/shells); Poisons (i.e. bees and poison ivy); Warning Colours.
- Microorganisms: Some are known as extremophiles (adapted to live in extreme conditions - i.e. volcanic vents, salty lakes, high pressure)
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Competition and Environmental Change (Pg. 32)
- Organisms compete for resources to survive: Plants - light/space/water/minerals; Animals - territory/food/water/mates
- Compete with other/like species (i.e. Red/Grey Squirrels: Grey win the food, therefore Reds are in decline).
- Environmental Change by Different Factors: Living Factors - infectious diseases/predators/prey/food availability/competitors; Non-Living Factors - temperature/rainfall/air or water pollution.
- Change affects populations differently: Population increase (prey increase = predator increase); Population decrease (pesticides/less food/more disease); Population distribution (i.e. temperature)
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Measuring Environmental Change (Pg. 33)
- Measured using living indicators: Litchen (sulfur dioxide sensitive for air pollution); Mayfly Larvae (dissolved oxygen sensitive for water cleanliness);.
- Other invertebrate species adapt to their conditions (i.e. MAggots and Sludgeworms living in high water polution levels).
- Measured using non-living indicators: Satellites (temperature/snow or ice cover); Automatic Weather Stations (atmospheric temperatures/rainfall - use dissolved oxygen meters to measure water pollution).
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Pyramids of Biomass (Pg. 34)
- USUALLY as you move up the pyramid, less organisms are feeding - consider biomass and not numbers)
- Represent food chain: mass of the living animal (practically always pyramid-shaped).
- Bottom bar = producer; next bar = primary consumer, next bar = secondary consumer, etc.
- Need to explain (i.e. Thousands of aphids feed on a tree, then a lot of ladybirds eat aphids, few patridges eat ladybirds).
- Biomass always decreases as you go up.
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Energy Transfer and Decay (Pg. 35)
- Sun energy = energy for all life; Green plants and algae use energy for photosynthesis; respiration produces heat energy - lost into surroundings; food and energy lost through waste.
- Explains why biomass pyramids decrease as you go up (rarely more than five trophic levels).
- Elements are cycled to start of food chain by decay: living things are made up of what they take in (i.e. plants - Carbon, Oxygen, Hydrogen, and Nitrogen); elements returned through waste products/death (become broken down by microorganisms - work best in warm/moist/oxygenated conditions); important elements recycled by decay (constant in a sable community).
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The Carbon Cycle (Pg. 36)
- Carbon Dioxide removed from atmosphere by photosynthesis.
- Some returned to atmosphere by plant respiration; some becomes part of pats and proteins in animals.
- Some returned to atmosphere by animal respiration.
- Plants/algae/animals die (or produce waste), detritus feeders and microorganisms feed on the remains/waste, and return Carbon Dioxide to atmosphere through respiration.
- Some products are burnt (combustion) and releases Carbon Dioxide into the atmosphere.
- Carbon is constantly being cycles, from air, through food chains, and eventually back to the air.
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Variation (Pg. 37)
- Same Species have Differences - different hair/noses/heights etc (variation in species - genetic or environmental).
- Different Genes = variation; parents' characteristics (inherited genes passed on through sex cells (gametes)); mix of genes from both parents (genetic variation, with the exception of identical twins).
- Some characteristics dependent only on genes (i.e. eye colour, blood group, inherited diseases).
- Environmental Variation (environmental influence) - losing toes in piranha attack, suntan, yellow leaves, etc.
- Most factors are a mix of both (i.e. weight, height, skin colour, etc.) - example is that maximum height is determined by genes, but real height is dependent on its environment (i.e. how much food).
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Genes, Chromosomes and DNA (Pg. 38)
- Most cells have a nucleus (genetic material in the form of a chromosome - 23 pairs to carry genes (characteristics)).
- Gene = short length of a chromosome = long length of DNA (coiled up to form the arms of the chromosome)
- Different versions of the same gene (called alleles).
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Reproduction (Pg. 39)
- Sexual Reproduction (genetically different cells) - two different organisms combine genetic information for offspring.
- Produced through gametes; 23 chromosomes from each parent (46 overall/23 pairs); egg and sperm cell fuse.
- SEXUAL REPRODUCTION INVOLVES THE FUSION OF MALE AND FEMALE GAMETES. BECAUSE THERE ARE TWO PARENTS, THE OFFSPRING CONTAIN A MIXUTE OF THEIR PARENTS' GENES.
- Mixture of genetic material inherited from both parents.
- Asexual Reproduction (genetically identical cells) - divind into two; exactly the same genetic information as parent.
- IN ASEXUAL REPRODUCTION THERE'S ONLY ONE PARENT. THERE'S NO FUSION OF GAMETES, NO MIXING OF CHROMOSOMES AND NO GENETIC VARIATION BETWEEN PARENT AND OFFSPRING. THE OFFSPRING ARE GENETICALLY IDENTICAL TO THE PARENT - THEY'RE CLONES.
- Each chromosome is split down the middle, a membrane forms around each set of half chromosomes, and replicates.
- How all plants and animal grow replacement cells; offspring production (i.e. bacteria and certain plants)
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Cloning (Pg. 40)
- Plants cloned from cuttings (plant good cuttings them to produce genetically identical plants - quick and cheap) and Tissue Culture (few plants cells put in growth medium with hormones; grow to be new plants (clones of parents) - quick, little space, grown all year).
- Animal clones from Embryo Transplant (sperm from prize bull and egg from prize cow; artificially fertilise to split; implanted in other cows to grow into baby calves (genetically identical to parents); hundreds of "ideal" offspring) and Adult Cell Cloning (remove genetic material from unfertilised egg and replace with a complete set of chromosomes from an adult body cell (e.g. skin cell); cell stimulated with electric shock to form ball fo cells; implanted into adult female (surrogate mother) to grow the clone - used to create Dolly the Sheep).
- Issues - reduced genetic pool (no different alleles, vulnerable to disease); may affect health; unsuccessful rates.
- Advantages - greater understanding of embryo development and age related diseases; preserve endangered species).
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Genetic Engineering (Pg. 41)
- Enzymes to cut and paste Genes - cut useful gene from one organism's chromosome using enzymes; cut out of another organism's chromosome and insert the useful gene; used to cut human insulin gene to be inserted into bacteria to produce human insulin.
- Genes transferred into animals and plants - Genetically Modified (GM) Crops have genes modified (i.e. disease/insect/herbicide resistance); sheep modified to produce substances (like drugs) in milk to treat human diseases; Cystic Fibrosis (genetic disorder) caused by faulty genes - gene therapy by scientists trying to stop this.
- Genetic Engineering Controversy - can solve many problems; not overly popular; may cause unplanned problems.
- GM Crops Cons: affect number of weeds/flowers (and insect population), reducing biodiversity; may not be safe; transplanted genes may get into the environment (i.e. superweed which is resistant).
- GM Crops Pros: increase product yield; improve nutience in plants; grown often without problem.
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Evolution (Pg. 42)
- Everything is related in groups: plants make their own food (photosynthesis) and are fixed in one place; animals move but cannot make their own food; microorganisms are different to plants and aminals (i.e. single-cell bacteria)
- Studying all organisms shows evolutionary relationships (similar characteristscs (common ancestor); look alike; evolutionary trees show common ancestors and relationships) and ecological relationships (similar characteristics may mean competition (i.e. for same food source); difference between organisms in the same environment can show predator-prey relationships (i.e. Dolphins (swim in small groups) hunt Herring (swim in giant sholas).
- Natural Selection explains evolution - Darwin's Theory: Differences in genes; better adapted characteristics for environment meant better survival chance = more breeding; advantageous genes passed on to next generation.
- Evolution occurs due to mutations - mutation = change in an organism's DNA; can be beneficial by producing a useful characteristic (better chance of survival and reproduction); passed on by natural selection; accumulate in population (i.e. bacteria and antibiotic resistance).
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More About Evolution (Pg. 43)
- Not everyone agreed with Darwin: against creationism (religion); couldn't give a good explanation (didn't know about genes or mutations until 50 years after the theory publication); wasn't enough evidence to convince scientists.
- Lamarck had different ideas - more use of a characteristic = more developed during lifetime; aquired characteristics would be passed onto the next generation (i.e. rabbit offspring would have longer legs to escape predators).
- Scientists can develop different hypotheses from similar observations - different beliefs (i.e. religious) or influence (i.e. other scientists) or they just think differently.
- Have to find evidence to either support or disprove each hypothesis (i.e. Lamarck and Darwin had different hypotheses)
- Lamarck's hypotheses eventually rejected (no experimental support) - dying a hamster's fur bright pink will not affect offspring fur colour; genetics supported Darwin's idea (provided an explanation of how organisms born with beneficial characteristics can pass them on).
- Darwin's theory is now accepted because there's so much evidence for it.
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