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118 Cards in this Set
- Front
- Back
What must the genotype of an organism that has a recessive phenotype look like?
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Two of the recessive form of the allele must be inherited, e.g. rr
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Heterozygous means ..... whereas homozygous means .....
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differing alleles in the genotype, will display the dominant characteristic both alleles of the gene are the same.
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What must the genotype of a sufferer of sickle cell anaemia look like?
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aa
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Describe the symptoms of sickle cell anaemia
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easily become tired, shortness of breath , joint pain
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Why may CF sufferers loose weight?
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Excess mucus blocks some tubes that carry enzymes to the small intestine to digest food.
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CF and sickle cell anaemia are both...
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recessive genetic disorders
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Define homeostasis
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the maintenance of a stable internal environment
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Osmoregulation is the regulation of levels of what?
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water
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Thermoregulation is an example of what kind of feedback?
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negative
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Why is osmoregulation important?
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water is needed for substances to dissolve in and for chemical reactions to take place inside cells.
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How does the body loose water?
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breath, sweat and urine
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What can too much water lead too?
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swellings and high blood pressure
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Why is thermoregulation important?
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37C is the optimum temperature for enzymes that help reactions to take place quickly
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What part of the brain constantly monitors temperature?
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the hypothalamus
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What is the role of nerve endings in the dermis in thermoregulation
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they alert the hypothalamus of outside temperatures
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Explain how the body reacts if body temperature dips below 37C
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Vasoconstriction (reduce blood flow close to the skin), muscles shiver (release heat), erector muscles contract (has little effect, produces an insulation layer in other mammals)
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How does sweat reduce body temperature?
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as sweat evaporates it transfers heat energy from the skin into the surroundings
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What is the role of vasodilation in cooling the body?
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blood vessels close to the skin dilate allowing more blood to flow through them. This makes it easier for blood to loose heat to the air
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What does the central nervous system consist of?
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the brain and spinal chord
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What is a stimulus?
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anything that your body is sensitive to
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What types of cells do specifically sense organs contain?
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receptor cells
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How is information passed between the brain and receptor cells?
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electrical impulses
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Through what do electrical impulses travel?
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neurones
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Describe a nerve cell
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neurones have a cell body, with extensions to carry the impulses. They have dendrons at the end that have branches called dendrites, which receive impulses. Impulses travel past the cell body though the axon, which is insulated by the myelin sheath
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What are nerves formed of?
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bundles of neurones
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What effect does the thickness of the neurone have on impulse speed?
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impulse speed increases with neurone diameter
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Which neurones receive impulses from receptor cells?
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sensory neurones
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Which part of the reflex arc carries our a response to the stimuli?
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effectors
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Compare the jobs of sensory, motor and relay neurones
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sensory neurones- receive impulses from receptor cells, motor neurones- take impulses to effectors, relay neurones- link motor and sensor neurones
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How do sensory neurones differ from motor neurones?
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sensory neurones have a long dendron and axon, compared to motor neurones have no dendron as the dendrites are located in the cell body
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Which short neurones make up the brain, and are also found in the spinal chord?
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relay neurones
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Explain the role of the myelin sheath
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the myelin sheath insulates the axon allowing electrical impulses to travel faster
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How are impulses passed across the synapse?
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using chemical substances called neurotransmitters
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State a benefit and a drawback of having a synapse
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benefit- ensures impulses only travel in one direction, drawback- slows impulses down
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What is a reflex?
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A response to a stimulus that does not require processing by the brain
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Describe the reflex arc
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A sensory neurone detects the stimulus, and passes an impulse to a motor neurone often through a relay neurone directing the effector to initiate a response
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Where are hormones produced?
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endocrine glands
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What is a target organ?
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an organ that responds to a specific hormone
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Which two hormones are released by the pancreas?
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insulin and glucagon
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Explain how blood glucose levels are lowered when they are too high
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When high blood glucose levels are detected the pancreas releases insulin, which leads the liver to convert glucose to glycogen and store it.
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What follows the release of glucagon when blood glucose levels are low?
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the liver converts stored glycogen into glucose, raising blood glucose levels.
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Recall the causes of type 1 and type 2 diabetes
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type 1 is congenital and is caused by a lack of insulin, whereas type 2 is as a result of lifestyle and is caused by a resistance to diabetes
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Compare the methods of control of type 1 and 2 diabetes
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in order to control type 1 the sufferer usually injects insulin into the subcutaneous fat (as it absorbs insulin well) after meals. They may also need to increase the amount of exercise they do as factors that raise blood glucose levels must be balanced with those that lower it. Sufferers of type 2 diabetes can often be controlled by changing the persons diet and increasing the amount of exercise they do.
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What are the main risk factors for type 2 diabetes?
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high fat diets, lack of exercise, age, obesity
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What is the minimum BMI to be classified as obese?
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30
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How is BMI calculated?
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kg/m2
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What are the uses of plant hormones?
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selective weed killers, rooting powder, seedless fruit, ripening fruit
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Why is artificial auxin effective as a weed killer?
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Auxin is useful as it can be used to kill broad leaved plants such as dandelions, but leave narrow leaved plants such as wheat unharmed
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How is rooting powder made of synthetic auxins used?
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cuttings of plants are dipped in rooting powder which makes them develop roots quickly, meaning that large numbers of the same plants can be produced much faster than by seed
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Describe how seedless fruits are created
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flowers are sprayed with hormones that mean that the fruit develops but not the seeds, naturally seedless small fruits are sprayed with gibberellins so that they grow bigger
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What gas is used to ripen bananas?
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ethene or ethylene
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Explain the ways that artificial plant hormones are used in fruit ripening
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stops fruit from falling (prevent damage, grow larger), speed up ripening (can be picked in one go if it ripens together), ripen unripe fruit once it reaches its destination
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Define tropism
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responding to a stimulus by growing towards or away from it
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Phototropism is caused by light, whereas gravi (or geo) tropism is caused by ....
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gravity
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What is a negative tropism? Give an example in regards to plants
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negative tropisms are tropisms away from a stimulus. Plant roots are negatively phototrophic
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What do auxins do?
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promote cell elongation
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There is a shady side and a sunny side of the plant, where will the auxins travel to?
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The shady side
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Where are auxins found?
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root and shoot tips
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How is gravitropism beneficial to the plant?
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by promoting growth in the direction of gravity it allows the root to grow downwards, accessing moisture and anchoring the plant.
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What effect do gibberellins have?
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they cause starch stores in a seed to be turned into sugars, which the seed then uses to grow. Other uses include stimulating flower or fruit production in some species.
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What effects do cigarettes have on the body?
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nicotine is addictive, tar is carcinogenic, carbon monoxide in smoke reduces oxygen carrying ability of blood
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How does carbon monoxide in cigarette smoke effect the body?
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carbon monoxide bonds with haemoglobin in the blood but unlike oxygen does no let go and travel to the muscles, instead it stays attached meaning that oxygen can no longer bond with the red blood cell. Slowly less red blood cells can carry oxygen, muscles that don't get enough oxygen become painful, carbon monoxide also narrows blood vessels therefore areas supplied by said vessels get even less oxygen, causing the tissue to die. Dead tissue may become infected and if the heart receives too little oxygen it will lead to a heart attack. Carbon monoxide can also cause other respiratory diseases such as bronchitis and emphysema.
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How many deaths does smoking cause overall per year in the UK?
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102000
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Define drug
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a chemical substance that alters the way in which our body works, including our behaviour
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What are the 5 groups drugs are classified under? Give an example of each
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narcotics (heroin), painkillers (morphine), hallucinogens (LSD), stimulants (Caffeine), depressants (alcohol)
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Explain how depressants make us feel relaxed
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they slow down the activity of neurones in the brain
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Which type of drug changes the way the brain perceives the world?
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hallucinogens
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How are reaction times sped up by stimulants?
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stimulants increase the speed of neurotransmission across synapses .
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How do we feel pain? How do painkillers stop this?
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we feel pain when electrical impulses from a swollen or damaged area are sent via neurones from the brain; painkillers block some of these nerve impulses
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What are some of the criteria when doctors are deciding who will get an organ ?
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have similar tissue, similar ages, geographically close, how ill the patient is
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What restrictions do some hospitals put in place on alcoholics getting liver transplants?
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some hospitals may only give a live transplant to an alcoholic who can prove that they can stay off alcohol for 6 months
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Why may hospitals not perform a heart transplant on a clinically obese person?
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obesity makes operations more risky, they may have to prove they can stick to a weight loss diet first
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Describe some ethical issues related to organ donation?
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whether people who have damaged themselves through their choices should receive organs; whether people can choose who to give their organs too; whether people should be able to sell their own or a relatives organs
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What are the long and short term effects of drinking alcohol?
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short term- blurred vision, lowered inhibitions, slowed reactions, nausea, unconsciousness, poor coordination; long term- brain damage (inc. learning difficulties and clots), liver cirrhosis
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How much of the money spent on health in the UK is used to treat people who have been drinking excessively?
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5%
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What is the estimated and reported numbers of deaths related to alcohol consumption per year in the UK?
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9000, 40000
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What are infectious diseases caused by?
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pathogens
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Pathogens are microorganisms, what are the different types?
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bacteria, viruses, fungi and protoctists
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What pathogen is malaria caused by?
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a protoctist called protozoan
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Give examples of diseases caused by bacteria, viruses and fungi
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bacteria- cholera, salmonella, dysentery, TB; viruses- influenza, mumps, measles, AIDS; fungi- athletes foot
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How can diseases be transferred via vectors?
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houseflies may carry dysentery from human faeces to food; biting insects such as anopheles mosquitos can pass pathogens into human blood from one person to another
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Other than vectors, how can pathogens spread? Give examples of each
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water (cholera), airborne (influenza, TB), food (salmonella), contact (athletes foot), body fluid (HIV)
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What physical and chemical barriers does the human body have against pathogens?
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physical- skin, cilia, mucus, blood clots, skin; chemical- hydrochloric acid in the stomach, lyozymes in tears, sweat
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Define antiseptics
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chemical substances that kill microorganisms outside the body
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What do plants produce to prevent themselves from attack?
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antibacterials
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How do humans use plant antibacterials?
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mint toothpaste, aftershave
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How can antiseptics be used to prevent the spread of infections?
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cleaning areas where fresh meat is prepared, protecting open wounds, disinfecting dirty areas such as toilets
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What are antibiotics?
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antibiotics are chemical that kill or prevent the growth of bacteria and some fungi but not human cells
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Give an example of an antifungal and an antibacterial
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antifungal- nystatin; antibacterial- penicillin
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Which microorganisms can antibiotics not kill?
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viruses
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Describe how microorganisms such as MRSA may become resistant to antibiotics
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naturally less resistant pathogens will be killed off first, leaving the patient feeling better, however this leaves the more resistant bacteria to reproduce and spread to other people if the patient decides to stop taking the antibiotics , causing an infection of now antibiotic resistant microorganisms that cannot be treated
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How can overuse of antibiotics leads to antibiotic resistance?
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each antibiotic kills many types of microorganism, not just those it is being used against, therefore resistant pathogens of many types will be left behind after a course of antibiotics has been completed, to be spread to other people
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What are the levels producers and primary and secondary consumers examples of?
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trophic levels
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Define interdependence
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organisms depending on eachother for food
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What is the difference between a food chain and a food web?
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a food web contains many food chains
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At each trophic level, how is some energy transferred to less useful forms, limiting the length of the food chain?
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energy can be lost through respiration, excretion of faeces, as thermal energy, movement
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What is the shape of a pyramid of biomass determined by?
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energy transferred at each level
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Define parasitism
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a feeding relationship in which two organisms live together with one feeding off the other, the host must be harmed
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Give 4 examples of parasites
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fleas, headlice, tapeworms, mistletoe
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Define mutualism
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organism that live in close relationships where both organisms benefit
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Explain how the relationship between oxpeckers and wild cows, or cleaner fish and sharks, is mutualistic
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the oxpeckers/cleaner fish rely on the wild cows/sharks for nutrition and protection while the sharks/wild cows have parasitic insects and dead skin removed from them
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How do both the legumes and nitrogen-fixing bacteria benefit from their mutualistic relationship?
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legumes receive the nitrogen compounds from the bacteria which they need to grow, while the bacteria are protected from the environment and obtain chemical substances from the plant which they use as food
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With what to chemosynthetic bacteria enjoy a mutualistic relationship? How does each organism contribute?
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tubeworms; they gather chemical substances that the bacteria needs for chemosynthesis, the bacteria provides substances for the tubeworms to feed on
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How does human population growth lead to pollution?
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humans need food, therefore fertilisers are used to help make food grow better; this can wash off into water sources polluting them with sulpher and phosphates (eutrophication). Sulpher dioxide released in burning fossil fuels pollutes the air.
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What are the problems associated with eutrophication?
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high nitrate and phosphate concentrations encourage rapid plant and algae growth, surface plants block sunlight so deeper plants stop photosynthesising (stop producing oxygen), bacteria that breaks down dead materials increase in numbers and use up more oxygen, oxygen concentrations in water decrease, animals such as fish die from lack of oxygen
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What are indicator species?
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species that are so sensitive to pollution that their presence or absence can be used to measure pollution
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What does blackspot fungus on roses indicate?
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clean air, it cannot survive with high levels of sulpher dioxide
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What can different lichen species indicate?
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air quality
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What are some indicators of clean water?
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freshwater shrimp, stonefly larvae
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State 2 organisms that can survive in polluted water
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bloodworms, sludgeworms
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What are the benefits of recycling?
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landfill fills up space, materials can be reused, removes some risk of pollution, we are running out of raw materials, helps to keep up with demand
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Which process removes carbon dioxide from the air?
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photosynthesis
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How do carbon toms pass along a food chain?
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when an animal eats a plant all of the carbon compounds that make up fats, proteins and carbohydrates are absorbed or expelled as faeces. Some of the absorbed compounds will make up further animal biomass, or will be used in respiration. If it is eaten by a predator, the process will repeat. If it dies decomposers or detritus feeders start the process of decay. Carbon compounds will be used in respiration or to build more complex compounds in their bodies.
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How is carbon dioxide released into the atmosphere?
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during respiration, from decomposers, combustion of fossil fuels
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Explain the roles of nitrifying and denitrifying bacteria in the nitrogen cycle
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nitrifying bacteria oxidises ammonia turning it into nitrates; denitrifying bacteria turns nitrates into nitrogen gas
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Where are decomposers found in the nitrogen cycle?
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decomposers break down dead animals and plants urea and proteins into ammonia
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How can nitrogen gas be turned into nitrates?
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lightning; nitrogen fixing bacteria living in root nodules or the soil
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Why do plants need nitrates?
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it is used to make proteins, nitrogen gas doesn't work
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