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| Question | Answer |
|---|---|
| What is health? | it is a state of physical and mental well-being |
| What is a communicable disease? | a disease that can be passed from one person to another |
| Name two communicable diseases. | tuberculosis, diarrhoea and flu |
| What causes communicable diseases? | pathogens mainly bacteria and viruses |
| What is a non-communicable disease? | a disease that cannot be passed from one person to another |
| Name two non-communicable diseases. | heart disease and arthritis |
| Name 3 factors that affect health. | diet, stress, and life situation |
| How can diet affect health? |
• not enough to eat can cause starvation, weakness, even death • not getting the right nutrients can lead to a wide range of illnesses from anaemia to rickets • too much food can lead to obesity, some cancers or type 2 diabetes |
| How can stress affect health? | too much stress has been linked to diseases such as heart disease and mental health problems |
| What is included in life situations? |
• where the person lives • gender • finanicial status • ethnic group • access to health care • number of children • local sewage and rubbish disposal • and many more |
| Can different diseases and health conditons be treated in isolation? | no because different diseases and health conditions interact, they must all be considered in treatment |
| Can viruses be linked to cancers? | viruses living in cells can cause changes that lead to cancer e.g. the human papilloma virus (HPV) can cause cervical or throat cancer |
| Name some causes of an impaired immune system? | genes, poor nutrition, HIV/AIDS |
| What is the impact on health of an impaired immune system? | it will make a person more susceptible to disease and the impact of disease more serious |
| Is there a relationship between physical and mental health problems? | there is often a close relationship with one causing the other |
| What health problems can result from malnutrition? | kwashiorkor, blindness, cancer, cardiovascular disease, type 2 diabetes |
| Question | Answer |
|---|---|
| What is another name for a communicable disease? | an infectious disease |
| What is a microorganism? | an organism that can only be seen under a microscope? |
| What is a microorganism called that causes disease? | a pathogen |
| Which microorganisms include pathogens? | bacteria, viruses, protists, and fungi |
| How does a pathogen cause disease? | directly or as a result of toxins produced by the pathogen |
| Name 2 relatively mild communicable diseases. | the common cold and tonsillits |
| Name 3 communicable diseases that can be fatal. | influenza, HIV/AIDS, and tetanus |
| State two examples of diseases being passed between different species. |
• dogs and bats can pass rabies to people • badgers can pass tuberculosis to cows, and cows can pass tuberculosis to people |
| Which pathogens cause the majority of communicable diseases in people? | bacteria and viruses |
| Which pathogens cause the majority of communicable diseases in plants? | viruses and fungi |
| What are bacteria? | bacteria are single-celled living organisms that are smaller than plant and animal cells |
| List three uses of bacteria. |
• to make food • to treat sewage • to make medicine |
| Name two foods made using baceria. | cheese and yoghurt |
| Name an important role played by bacteria in the environment. | as decomposers |
| Are helpful or harmful bacteria the minority? | pathogenic bacteria are the minority |
| Which is larger out of bacteria and viruses? | bacteria are larger |
| Which organisms are affected by viruses? | viruses cause disease in every type of living organism |
| What is the first response of bacteria and viruses on entering a person? | most start by reproducing rapidly |
| How do bacteria reproduce? | they divide by splitting in two, a process called binary fission |
| How do bacteria cause disease? |
• some bacteria produce toxins which affect the body • some bacteria damage cells in the body |
| How do viruses cause disease? | they take over the cell to reproduce and damage or destroy cells in the process |
| Name 3 common disease symptoms. | high temperature, headaches, and rashes |
| How do the symptoms of disease arise? | they are due to the reponse of the body to the cell damage and/or toxins produced by the pathogens |
| Name 3 ways that pathogens are spread. |
• by air • through direct contact • by water |
| Describe how flu is spread by air. | when a sick person speaks, coughs or sneezes, she expels tiny droplets full of pathogens which other people breathe in |
| What is a disease vector? | an organism that carries a pathogen between from one individual to another |
| Give an example of a disease spread by a vector. | malaria is spread by mosquitoes (the vector) from one human to another human without the mosquitoes becoming infected |
| Name three diseases spread by direct contact. |
• syphilis and chlamydia are spread by direct skin contact • HIV/AIDS and hepatitis is spread through blood exchange due to scratches, abrasions, cuts, and needle punctures |
| Name 3 human diseases spread by water | cholera, diarrhoea, and salmonellosis |
| How does lifestyle affect the spread of disease? | lifestyle can make dieases spread quickly so for example, when people live in crowded conditions with no sewage, an infectious disease like diarrhoea is spread very quickly |
| Question | Answer |
|---|---|
| Why do scientists cultivate bacteria in the laboratory? | to understand them better especially the chemicals they need to grow or the ones that kill them |
| What is the scientific phrase for growing bacteria? | to culture bacteria |
| What is a group of bacteria called? | a colony of bacteria |
| Which are the most cultured microorganisms? | bacteria |
| How do bacteria reproduce? | by simple cell division known as binary fission |
| What is a culture medium? | a liquid or gel containing the nutrients needed to culture bacteria |
| What does a culture medium contain? |
• carbohydrates for energy • a nitrogen source for making proteins • various minerals • other essential chemicals |
| What do bacteria need to grow and reproduce? |
• oxygen • warmth • carbohydrates, minerals, and other chemicals |
| Describe the process of growing a culture of bacteria. |
• sterilise the petri dishes • sterlise the nutrient agar • pour hot agar gel into the petri dish • let the agar gel set • sterilise the innoculating loop • leave the innoculating loop to cool • dip the innoculating loop in a suspension of the bacteria to be grown • zig zag the innoculating loop across the prepared agar gel • place the petri dish lid over the petri dish • seal the petri dish • place the petri dish upside down in an incubator • leave the bacteria to grow |
| What is the alternative to agar gel for culturing bacteria? | a flask of sterile nutrient broth solution |
| Name two groups of chemicals that culture media are tested on. |
• disinfectants • antibiotics |
| Why must bacteria cultures be uncontaminated? | to ensure that the recorded results are attributed to the correct bacteria |
| How can a culture become contaminated? |
contamination can come from • the skin, • the soil, • water, and • the air |
| Why is extreme care necessary when cultivating harmless bacteria? | there is a chance that a mutation will occur producing a new and dangerous pathogen |
| What is the purpose of sterilisation? | to kill off unwanted microorganisms |
| How xan glass dishes be sterilised? | by heating |
| Name the equipment used to sterlise by heating. | an autoclave |
| How does an autoclave work? | it uses steam at high pressure |
| Other than heat, how can equipment be sterilised? |
• UV light, or • gamma radiation |
| What does it mean to inoculate the sterile gel with bacteria? | it means to introduce or add the bacteria to the sterile gel |
| Why must newly innoculated agar be incubated? | because bacteria need warmth to grow |
| Why should petri dishes be stored upside down during incubation? | so condensation does not fall from the lid of the petri dish onto the agar |
| What tool is used to transfer bacteria to the sterile agar? | an innoculating loop |
| How is an innoculating loop sterilised? | by heating it in a bunsen burner until it is read hot |
| Can the innoculating loop be cooled by blowing on it? | no, as this may transfer microorganisms to it |
| Where should the innculating be left to cool | anywhere where it stands upright as any contact with the loop may contaminate it |
| Should the lid of the petri dish be sealed all the way round? | no, as bacteria need oxygen to grow |
| What will happen if oxygen is not allowed inside the petri dish? | harmful anaerobic bacteria may grow |
| What is the maximum temperature at which bacteria are cultivated in schools and colleges? | 25 ° C |
| Why are bacteria cultures never incubated at more than 27 °C in schools and colleges? | there is a risk of dangerous pathogens which thrive at 37 °C (the human body temperature) growing in the incubator and infecting people - temperatures of 25 °C reduces this risk |
| Why are bacteria grown at tempepratures much higher than 27 °C in industry? | to enable the microorganisms to grow more rapidly |
| Name a bacterium grown industrially? | insulin-producing genetically modified (GM) bacteria |
| Why are bacteria grown in hospital laboratories at 37 °C? | so they grow as fast as possible and can be identified as quickly as possible allowing medics to start treatment quickly if necessary |
| Question | Answer |
|---|---|
| How do bacteria reproduce? | by binary fision |
| How fast can bacteria divide under the right conditions? | every 20 minutes, or hours, months, possibly years for some bacteria |
| List the factors that affect the growth rate of bacteria. |
• temperature • nutrients • oxygen levels • pH |
| The mean division time for a bacterium is 20 minutes. How many bacteria does it produce within 8 hours? |
• number of times a bacterium reproduces every hour = 60/20 = 3 times • number of times a bacterium reproduces in 8 hours = 3 x 8 = 24 • number of bacteria at the end of the 8 hours = 224 = 16 777 216 • 1 bacterium becomes nearly 17 million bacteria in 8 hours! |
| Name 3 ways to prevent the growth of bacteria. |
• lower or raise the temperature • use chemicals like disinfectants, to stop them growing or kill them • antibiotics |
| What are disinfectants? | chemicals used to kill bacteria |
| What are antiseptics? | antiseptics are disinfectants that are safe to use on human skin |
| What are antibiotics? | chemicals used inside the body to kill bacteria or stop them growing |
| What equipment can be used to investigate the effect of disinfectants and antibiotics on bacteria? | bacterial growth in agar plates |
| What is the zone of inhibition? | the area where the bacteria cannot grow - the agar gel remains clear |
| Question | Answer |
|---|---|
| How long have people understood the real causes of diseases? | around 150 to 200 years |
| When did Ignaz Semmelweis live? | in the 1850s |
| What was the disease that came to his attention? | childbed fever |
| What happened with childbed fever? | days after giving birth, many women got childbed fever and died |
| What did Seimelweis notice? | women who were treated by medical students and doctors were more likely to die than those treated by mid-wives |
| What did medical students and doctors do that was not done by mid-wives? | medical students and doctors worked on dissecting dead bodies when they were not attending to women giving birth |
| What did Seimelweiss surmise was the reason that women treated by medical students and doctors were more likely to die than when treated by mid-wives? |
• medical students and doctors would go straight from dissecting bodies to delivering babies without washing their hands • the medical students and doctors were thus carrying the disease from the dead bodies to the mothers giving birth |
| Besides dying mothers, what else made Seimelweis think disease was coming from the dead bodies? | a doctor cut himself while working on a dead body and died of symptoms similar to childbed fever |
| What did Seimelweis conclude about childbed fever? | it was caused by some sort of agent that could be carried from one body to another |
| What did Seimelweis do after concluding that childbed fever was caused by an agent carried from the dead bodies to the mothers giving birth? | he made his students and doctors wash their hands before delivering any babies |
| What was the consequence of the students and medical doctors washing their hands? | immediately fewer mothers died |
| What was the response to Seimelweis' ideas? | other doctors were resistant, some completely dismissive as it was contrary to everything they believed about disease and its causes |
| Name two other people in the 19th century besides Seimelweis who contributed to an understanding of disease. | Louis Pasteur and Joseph Lister |
| What did Louis Pasteur show? | that microorganisms caused disease |
| What did Louis Pasteur develop? | vaccines against diseases like rabies and anthrax |
| What did Joseph Lister start? | he used antispetic chemicals to destroy pathogens in operating theatres before they caused disease |
| What piece of equipment helped to show that pathogens caused disease? | the microscope because people could see pathogens clearly |
| List the ways of preventing the spread of communicable diseases. |
• hygiene • isolating infected individuals • destroying or controlling vectors • vaccination |
| List some simple hygiene measures that can prevent the spread of pathogens. |
• hand washing • disinfectants • isolating raw meat • coughing or sneezing into a handkerchief • maintaining personal and machine hygiene |
| When does it make sense to wash hands? |
• after using the toilet • before cooking • after touching animals • after contact with a person with an infectious illness |
| Why are disinfectants used? | to reduce the number of pathogens on surfaces like kitchen counters, toilets etc |
| Why should raw meat be isolated? | to stop it spreading pathogens to food that is eaten uncooked |
| Why should one sneeze into a handkerchief? | to prevent spreading pathogens onto other people and surfaces |
| Why is it important to keep agricultural equipment scrupulously clean? | to prevent spreading plant diseases? |
| What role can isolation play in disease control? | isolating a person with a serious contagious disease like Ebola or Cholera, reduces the contact with healthy people and thus the chance of the disease being passed on |
| Give an example of a disease spread by a vector. | malaria (disease) is passed on by mosquitoes (vector) |
| Name 4 vectors. |
• mosquitoes carry malaria and dengue fever • houseflies can carry over 100 human diseases • rats acts as vectors of diseases • aphids transmit over 150 plant diseases • beetles can transmit fungal, viral and bacterial plant diseases |
| How can vectors be used to manage the spread of disease? | by destroying or controlling the vectors that carry the disease |
| What is the purpose of vaccination? | to protect a large number of people or animals against serious diseases |
| What is done with vaccination? |
• a small amount of a harmless form of a pathogen is introduced into the body • the immune system generates a defense against the disease • in the event of encountering the live disease, the person does not get sick because they are immune |
| Why can vaccination not be used in plants? | they do not have an immune system |
| Question | Answer |
|---|---|
| How serious are viral diseases? | the range from mild to deadly |
| Why is vaccination important in the fight against viral diseases? | because there are no medicines to treat viral diseases so the goal is to prevent them |
| List 3 viral diseases. |
• measles • HIV/AIDS • tobacco mosaic disease |
| What are the symptoms of malaria? | fever and a red skin rash |
| How is measles spread? | the inhalation of droplets from coughs and sneezes |
| Does measles pass easily? | it is highly infectious |
| What are the serious consequences of measles? | blindness, brain damage, or death |
| How many people died of measles in 2013? | 145 700 |
| What is the treament for measles? | there is no treatment so people are isolated to prevent spreading the disease |
| Why is measles now rare in the UK? | improved hygiene and vaccinations |
| Why is measles on the increase in the UK? | vaccination rates are falling |
| How many people globally are infected with HIV? | around 35 million |
| What is the link between HIV and AIDS? | HIV turns into AIDS |
| How many people died of HIV-related illnesses in 2013? | around 1.5 million people |
| Why do many people not know that they are infected? | intially there are very few symptoms, sometimes no more than a mild flu-like illness |
| What does HIV do? |
• it attacks the immune cells • causes a mild illness • then hides in the immune system sometimes for years • when the immune system is so badly damaged that it can no longer deal with infections and certain cances, it has become AIDS |
| What factors affect the time between infection with HIV and the onset of AIDS? |
• level of nutrition • overall health • access to retroviral drugs |
| How is HIV spread? |
• direct sexual contact • body fluids like blood • breast milk |
| When is HIV spread via blood? |
• blood transfusions with unscreened blood • shared needles by drug users |
| What is the cure for HIV/AIDS | there is no cure or vaccination for HIV/AIDS |
| How is the spread of HIV/AIDS being tackled? |
• condoms prevent the spread of the disease • not sharing needles prevents infected blood being shared • screening blood transfusions removes infected blood • bottle-feeding the children of HIV-infected mothers |
| How are people infected with HIV/AIDS treated? | with regular use of antiretroviral drugs which can prevent the development of the virus for many years allowing the person to live a normal life almost |
| Why are many people still dying from HIV/AIDS? | the majority of people that are infected with HIV live in Sub-Saharan Africa where it is hard to get antiretroviral drugs, mainly because of poverty |
| What distinction does tobacco mosaic virus (TMV) have? | it was the first virus to ever be isolated |
| What is TMV? | it is a plant virus that infects around 150 different species of plant including tomatoes and tobacco |
| How is TMV detected? | it creates a 'mosaic' pattern on leaves as the virus destroys the cells |
| How does TMV affect plants? | damaged leaves cannot photosynthesis so plant growth is affected |
| Why do farmers care about their crop getting TMV? | crop yield can be significantly reduced |
| How is TMV spread? |
• healthy plants making contact with infected plants • insects acting as vectors |
| How long can the virus remain in the soil? | for 50 years |
| What is the treatment? | there is no treatment |
| How do farmers deal with TMV? | they grow TMV resistant-resistant strains of many crops |
| How is the spread of TMV controlled? | good field hygiene and good pest control |
| Question | Answer |
|---|---|
| What organisms are affected by bacterial diseases? | plants and animals |
| What factors have had a major impact on the death rate of communicable diseases? |
• vaccinations • improved living standards • antibiotics |
| What do antibiotics do? | they kill bacteria or stop them growing so can stop diseases |
| What is the problem with antibiotics? | bacteria are becoming resistant resulting in more deaths as a result of bacterial diseases |
| Where do salmonella live in nature? | in the guts of many animals |
| Where in the food we eat is salmonella found? | raw meat, poultry, eggs, and egg products like mayonnaise |
| What does salmonella do to humans? | they disrupt the balance of the natural gut bacteria and can cause Salmonella food poisoning |
| How do people become infected? |
• eating undercooked food in which the bacteria are not killed by cooking • eating food prepared in unhygienic conditions where food is contaminated by Salmonella from raw meat |
| How long does it take for symptoms to develop from Salmonella? | 8 to 72 hours |
| What are the symptoms of Salmonella? |
• fever • abdominal cramps • vomiting • diarrhoea |
| What is the effect of Salmonella in the UK? |
• for most healthy people, the infection is unpleasant but nothing more • for the very young and elderly, it can be fatal often because of dehydration • for the malnourished, it can be fatal |
| How many people (according to the WHO) die from diarrhoea? | 2.2 million, mainly children under 5 years old |
| How is Salmonella controlled in the UK? | poultry are vaccinated against Salmonella |
| Name another bacterium that causes food poisoning. | campylobacter |
| How should raw chicken be treated to avoid causing food poisoning? |
• keep food that is eaten uncooked away from raw chicken • avoid washing raw chicken as this sprays the bacteria around • wash hands and surfaces well after handling raw chicken • cook chicken thoroughly |
| What is gonorrhoea? | a sexually transmitted disease (STD) |
| What is another name for a sexually transmitted disease? | a sexually transmitted infection (STI) |
| How is gonorrhoea spread? | it is spread by sexual contact with an infected person |
| What is the pattern with gonorrhoea? | it has symptoms in the early stages and then becomes relatively symptomless |
| What are the early symptoms of gonorrhoea? | a thick yellow or green discharge from the vagina or penis and pain on urination |
| Do all people infected with gonorrhoea have symptoms? | about 10% of men and 50% of women have no symptoms at all |
| What is the long term effect of gonorrhoea? | long-term pelvic pain, infertility, and ectopic pregnancies |
| What happens to babies born to infected mothers? | they have severe eye infections and even become blind |
| Can gonorrhoea be treated? | it is bacterial so it can be treated with antibiotics |
| What is the challenge with treating gonorrhoea with antibiotics? | originally it could be treated with penicillin but as antibiotic-resistant strains of gonorrhoea develop, treatment is getting more difficult |
| Other than antibiotics, how can the spread of gonorrhoea be prevented? |
• a barrier method such as condoms • reduced number of sexual partners |
| How common are bacterial diseases in plants? | there are relatively few bacterial diseases in plants and they are usually found in tropical and sub-tropical regions |
| Name a bacterial plant disease. | agrobacterium tumefaciens |
| What does agrobacterium tumefaciens cause? | it causes crown galls - a mass of undifferentiated cells that grow between the root and the shoot |
| What plants are affected by agrobacterium tumefaciens? | a large number of plants including fruit trees, vegetables, and garden flowering plants |
| How does agrobacterium tumefaciens affect plants? | the bacteria insert plasmids into the plant cells and cause a mass of new undifferentiated genetically modified cells to grow |
| Why do scientists study agrobacterium tumefaciens? | to learn to genetically modify plant cells |
| How do scientists use agrobacterium tumefaciens? | they manipulate the bacteria so they carry desirable genes into the cells that they infect |
| Question | Answer |
|---|---|
| How common are fungal diseases in humans? | there are relatively few fungal diseases that affect people |
| Name a fungal disease that affects people. | athlete's foot |
| What is athlete's foot? | a relatively minor fungal skin condition |
| Are any fungal diseases fatal for people? |
• a small number of fungal diseases can be fatal to humans who are already sick when they attack the lungs and the brain • damaged heart values can develop fatal fungal infections • both conditions are rare |
| How are fungal diseases treated? | using antifungal medication |
| How common are fungal diseases in plants? | fungal diseases are common in plants |
| What is the impact of fungal diseases on plants? | they can be devastating - every year huge areas of crops from cereals to bananas are lost as a result of fungal infections |
| Name a plant fungal disease? | stem rust |
| Name a plant fungal disease of roses? | rose black spot |
| What is the impact of rose black spot? |
• it causes purple or black spots to develop on the leaves • the leaves often turn yellow and fall off • the area of leaves for photosynthesis is reduced thus weakening the plant • the roses don't flower well defeating the purpose of the roses |
| How is rose black spot spread? |
• the spores of the fungus are carried by the wind • they are then spread over the plant by splashes of the rain • the spores stay dormant dormant over winter on leaves and stems |
| How do gardeners try to prevent the spread of rose black spot? | removing and burning old and infected leaves and stems |
| What other solutions are there to rose black spot? |
• chemical fungicides can limit the spread • growing types of roses that are relatively resistant to black spot |
| What is a protist? | a type of single-celled organism |
| How common are diseases caused by protists? | they are relatively rare but the ones that do occur are often very serious |
| How are diseases caused by protists usually transmitted? | via a vector |
| Name a disease caused by protists? | malaria |
| What type of organism is the protist that causes malaria? | it is a parasite |
| Where does the malaria protist life cycle take place? | time in the human body and time in the body of the female Anopheles mosquito |
| Where does the malaria protist reproduce? | it reproduces sexually in the mosquito and asexually in humans |
| What is the role of the mosquito in the spread of malaria |
• the mosquito is a vector in the spread of malaria • the female needs two blood meals before she can lay her eggs • each time she feeds she releases protists in the human |
| What do malaria protists do in the human body? |
• the protists travel around the human body in the circulatory system • the protists reproduce asexually in the human body • the protists affect the liver and damage red blood cells • they cause fever and shaking when they break out the blood cells • it weakens the person over time and can kill them |
| Can malaria be treated? | if detected quickly, it can be treated with a combination of drugs |
| What is the problem treating malaria with the existing drugs? | the protists have become resistant to many of the drugs |
| Name four ways in which the spread of malaria is controlled. |
• using insecticide-impregnated insect nets to prevent mosquitoes biting humans and passing on the disease • using insecticide to kill mosquitoes in homes in offices • prevent vectors from breeding by removing standing water to prevent the vectors breeding and spraying water with insecticides to kill larvae • antimalarial drugs kill the parasites in the blood if they are bitten by an infected mosquito |
| Question | Answer |
|---|---|
| What colour is the nasal mucus when you have a cold? | green |
| Why does nasal mucus turn green when you have a cold? | because of the defence system of the body |
| How do pathogens enter the human body? | every body opening such as a break in the skin provide pathogens with a way in |
| What is the role of the skin in the defence system of the body? |
• it covers the body to act as a barrier to prevent pathogens like viruses and bacteria reaching the tissues beneath the skin • it produces antimicrobial secretions to destroy pathogenic bacteria • healthy skin is covered in microorganisms that present an additional barrier to pathogens |
| What happens when the skin is damaged or cut? |
• a cut or damage in the skin provides entry to pathogens • the platelets in the blood help to form a clot that dries as a scab • the scab forms a seal that prevents pathogens getting into the body |
| Why is the respiratory system a weak link for body defences? | each time you breath in, you draw pathogens into the lungs |
| Why is the digestive system a weak link in the defences of the body? | each time you eat or drink you can take pathogens into the body |
| How does the respiratory system protect itself against pathogens? |
• the nose if full of hairs and produces mucus • the hairs and mucus trap particles in the air that may contain pathogens • the trachea and bronchi produce mucus that traps pathogens • the lining of the tubes are covered in tiny hair-like projections called cilla • the cilla carry the mucus up to the back of the throat where the mucus is swallowed • stomach acid destroys the microorganisms in the swallowed mucus and food taken in through the mouth |
| Why does the body need a second line of defence? | because some pathogens will make it into the body through the body's defence mechanisms |
| What is the second line of defence? | the white blood cells of the immune system |
| How do white blood cells destroy pathogens? |
• ingesting microorganisms • producing antibodies • producing antitoxins |
| How does ingesting microorganisms protect against pathogens? | some white blood cells ingest pathogens to digest and destroy them |
| What are antibodies? | special chemicals produced by white blood cells |
| How do antibodies work? | antibodies target specific viruses and bacteria, disabling or collecting them before a white blood cells can destroy them |
| What is the advantage of antibodies in the fight against disease? |
• antibodies are specific to each type of pathogen • the first time white blood cells produce antibodies is slow • antibodies can be made very quickly each subsequent time protecting the body about getting the disease again |
| How do white blood cells fight toxins? | some white blood cells can produce antitoxins which disable toxins |
| How does mucus become green when fighting a cold? |
• the white blood cells that destroy the viruses of the cold contain green coloured enzymes • the dead white blood cells are removed in the mucus making it look green |
| Question | Answer |
|---|---|
| What is the global loss of food crops to plant pathogens? | 15 to 40% each year |
| Why is it important to understand the causes and prevent the spread of plant diseases? | to secure the food supply |
| What are plants vulnerable to? |
• bacteria • viruses • fungi • pests |
| What do insect pests do to plants? | they can destroy plants directly or acts as vectors for disease |
| How do aphids directly affect plants? |
• they have sharp mouthparts that penetrate into the phloem vessels of the plant so they can feed on on the sugar-rich phloem sap • they occur in huge numbers • they seriously weaken and damage plants by depriving the plants of the food and nutrition they need |
| What else can aphids do to plants? | they can act as vectors transferring viruses, bacteria, and fungi from diseased to healthy plants |
| How can aphids be destroyed? |
• chemical pesticides • biological pest control in enclosed spaces |
| Describe a means of biological pest control for aphids. | aphid-eating ladybirds and their larvae control aphids |
| List other plant pests and how they damage plants. | tiny nematode worms and many insect larvae that live in the soil, feed on plant roots, damaging them so they cannot absorb water and minerals effectively |
| What is a non-communicable disease in plants? | they are not passed from one plant to another |
| Name a cause of non-communicable diseases in plants. | mineral deficiency |
| Describe an example of the impact of mineral deficiency. |
• plants need a good supply of nitrate ions to convert sugars to proteins • if there is a shortage of nitrate ions in the soil, protein growth will be limited • the plants will be stunted and not produce a good crop |
| Why do plants need magnesium? | plants need magnesium to make chlorophyll |
| What happens if the level of magnesium ions in the soil is low? |
• the plant cannot make enough chlorophyll • the leaves become yellow • the plant cannot photosynthesise fully • growth slows down |
| What is the yellowing of leaves due to lack of mangnesium ions known as? | chlorosis |
| How can mineral deficiency be treated in plants? | if the missing mineral ions are provided quickly by for example using an appropriate fertiliser, the plant will recover and normal growth will resume |
| Why is it important to detect disease early? |
• the sooner a disease is detected, the more likely treatment is to be successful • fast detection helps prevent the spread of disease |
| List the symptons of disease in plants. |
• stunted growth • spots on leaves • areas of decay and rotting • growths • malformed stems and leaves • discoloration • presence of visible pests |
|
State a cause of each sympton • stunted growth • spots on leaves • areas of decay and rotting • growths • malformed stems and leaves • discoloration • presence of visible pests |
A cause of each sympton • nitrate deficiency; stunted growth • black spot fungus on roses; spots on leaves • black spot on roses, blight on potatoes; areas of decay and rotting • crown galls caused by bacterial infection; growths • aphid or nematode infestation; malformed stems and leaves • yellowing or chlorosis in magnesium deficiency, mosaic patterns from TMV; discoloration • aphids, caterpillars; presence of visible pests |
| What makes detecting plant disease difficult? | many plant diseases have similar symptoms |
| List some possible treatments of plant diseases. |
• pesticides • antifungal treatments • fertilizers • remove diseased plants • destroy diseased plants, stems or leaves |
| What can be used to identify plant diseases? |
• a gardening manual, paper or online • expert observation • DNA analysis on diseased specimens • testing kits containing monoclonal antibodies |
| Name a disease that can be identified using monoclonal antibodies. | the fungal pathogen Botrytis |
| Question | Answer |
|---|---|
| What kind of barriers can plants erect against pathogens? |
• chemical • physical |
| List the physical barriers that reduce the invasion of pathogens. |
• the cellulose cell wall • the tough waxy cuticle on the surface of leaves • bark on trees, and a layer of dead cells on the outside of stems • leaf fall |
| What is the purpose of the cell wall? |
• to strengthen plant cells • to resist invasion by pathogens |
| How do aphids allow other pathogens to threaten the health of plants? | aphids breach the physical barrier that the cell wall provides allowing pathogens a route into the plant |
| How do leaves protect themselves from pathogens? | a tough, waxy cuticle on the surface of leaves prevents pathogens entering the leaf |
| What is the only way that pathogens can enter leaves? | via the stomata which remain open to let air in and out |
| How do bark and dead cells protect plants? | they both provide a barrier to to pathogens and when they fall off, take attached pathogens with them |
| How does leaf fall protect plants against pathogens? | when leaves fall off plants they take infections and pathogens away with them |
| What chemical barriers can be found in plants? |
• many plants produce antibacterial chemicals which are very effective at preventing bacterial infections • some plants contain poisonous chemicals that make animals feel unwell and can sometimes kill |
| Name some plants that use poisons to deter animals eating them? |
• foxgloves • deadly nightshade • yew |
| Why are antibacterial chemicals being investigated by scientists? | as current antibiotics become less effective, antibacterial chemicals produced by plants are being investigated to see if they might be used as alternatives |
| Which plants are used as mild antiseptics? | mint and witch hazel |
| Name three plants that have promising antibiotic properties. |
• pines • cypress • euphorbias |
| Do plants only protect themselves against microorganisms? | they also protect themselves against small and large animals that want to eat them |
| Why would a plant protect itself against being eaten? | because it can then not flower and reproduce |
| What are the potential consequences of plants being attacked by small herbivores like aphids, beetles, or caterpillars? | the plant can be damaged and the damage provides access to pathogens plus the insects can act as vectors |
| List mechanical barriers found in plants |
• thorns to make it painful or unpleasant to eat them • hairy stems and leaves to deter insects and other animals from eating them or laying their eggs on them • drooping or curling leaves when touched • mimicry to appear sick |
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