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Flashcards by harvi lewars, updated more than 1 year ago
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Created by harvi lewars
about 8 years ago
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| Question | Answer |
| B2: understanding our environment | classification energy flow adaptations to cold,hot,dry environments evolution carbon cycle + nitrogen cycle Human impact on environment endangered species sustainable development |
| Classification | living things are divided into: kingdoms phylum class order family genus species. Natural classification systems: based on evolutionary relationships Artificial classification systems: based on appearance. |
| Classification systems | As scientists discover new species they have to adapt classification systems: - Newly discovered species might not fit into any category (e.g. archaeopterx fossil= bird and reptile features. - DNA sequencing shows genetic differences that don't support the groups already used. |
| Evolutionary Trees | - They show how closely related different species are to each other |
| Species - A group of organisms that can interbreed to produce fertile offspring. | Problems with classification: - Living things are at different stages of evolution and new species are being formed (difficult to put in distinct groups). - Bacteria produce asexually (not classified as species). - Hybrids are infertile, so can't be classified as a species. (Mule = donkey+horse). |
| Binomial system | - Species are given a 2 part name. Part 1= genus, Part 2= species E.g. Humans= Homosapiens - The binomial system is important as it avoids language confusion as all countries/languages use it. |
| Pyramids of Biomass | - Each bar shows the mass of living material. - Always pyramid shaped. - can be difficult because organisms have to be killed (unethical). - can be difficult because some organisms feed off more than one trophic level. |
| Pyramids of Numbers | - Each bar shows the number of organisms at the stage in the food chain. - Not always pyramid shaped. |
| Energy Transfer | - Energy enters food chains when plants absorb sunlight (producers trap energy by photosynthesis and convert it to chemical energy). - This energy is passed along the food chain as each organism eats another organism. -Energy is lost through: RESPIRATION BODY HEAT LOSS EGESTION EXCRETION. |
| Energy Flow | - To work out how much energy is lost at a level by taking away the energy available from the energy at the previous level. - Efficiency: how good it is at passing energy on from one level to the next. Efficiency= (energy available/energy at previous level)*100 |
| Competition between organisms | -Organisms need to compete for resources ECOLOGICAL NICHE- how species fit into their ecosystem. INTERSPECIFIC-where organisms compete for resources against another species. INTRASPECIFIC- where organisms compete for resources against the same species. Intraspecific competition has a bigger impact on organisms because the individuals have the same needs. |
| Predator- prey Relationships | -Population of species usually limited by food available. -When prey population increases, predator increases. -When predator number increases, prey number decreases. - Predator-prey cycles are always out of phase because it takes a while for a response from predator/prey. |
| Parasitic relationships | Parasites live off a host without giving anything back (win-lose situation). ¬ Tapeworms absorb nutrients from host causing malnutrition. |
| Mutualistic Relationships | - A relationship where both organisms benefits. ¬ Oxpeckers live on buffalo's, they eat pests and alert the buffalo to predators. |
| Adaptations | - FEATURES THAT ORGANISMS HAVE THAT MAKE THEM BETTER SUITED TO THEIR ENVIRONMENT. - Better adapted organisms are able to compete better and more likely to survive and reproduce. |
| Specialists and Generalists | SPECIALISTS- organisms that are highly adapted to a specific habitat. (giant pandas eat just bamboo). GENERALISTS- organisms that are adapted to live in a range of habitats. (black rats survive in forests, cities and farmland) |
| Extremophiles | -ORGANISMS THAT ARE ADAPTED TO LIVE IN EXTREME CONDITIONS (NEAR VOLCANOES) Example: organisms that live in very cold conditions sometimes have special antifreeze proteins- interfere with the formation and growth of ice crystals in the cells to stop ice damaging the cells. |
| Adaptations to cold environments | Anatomical adaptations: - thick coat or layer of blubber (to insulate body). - large size and compact body shape to give a small surface area to volume ratio. Behavioral adaptations: - Many species migrate to warmer climates. - Some species hibernate in winter to save energy and stay warm. - Species e.g. penguins, huddle together to keep warm. |
| Counter - current heat exchange system | - Present in penguins. The blood vessels going to and from the feet in opposite directions are close together, which allows heat to transfer between them. Warm blood flowing in arteries to the feet heats the cold blood in the veins going to the body. Feet stay cold but it prevents the cold blood cooling down the rest of the body. |
| Adaptations to hot environments | Anatomical adaptations: - Small body to give large surface area to volume ratio. - Large thin ears allow blood to flow near the surface of skin. - Fat in only one place to prevent whole body being insulated (e.g. Camel's hump). Behavioural adaptations: - Animals spend their day in the shade/underground to minimise how much heat is gained by the body. - Animals are sometimes active at night when it is cooler to reduce heat gain. - Animals bathe in water, as water evaporates and transfers heat to the surroundings. |
| Adaptations to dry environments (plants) | Some plants: 1) Have a rounded shape to give a small surface area to volume ratio (reduces water loss from surface). 2) Have a cuticle (thick waxy layer) and spines to reduce water loss. 3) Store water in their stems so they can survive in extreme droughts. 4) Shallow and extensive roots to absorb water over a large area. |
| Adaptations to dry environments (animals) | Some animals: 1) Have specialised kidneys that produce urine with low water content. 2) Have no sweat glands, so water can't be lost through sweat. 3) Spend time underground where air has more moisture. |
| Evolution: Natural Selection | 'Survival of the fittest': - Organisms that are the best adapted are more successful competitors and are more likely to survive. - The organisms that survive are more likely to reproduce and pass on their adaptations. - Which means over time the less adapted organisms will die out due to not being able to reproduce. - As successful adaptions become more common the species will change (it evolves). |
| Development of natural selection from new discoveries | - There was no explanation as to why adaptations were passed on to offspring because DNA wasn't discovered until 50 years after. |
| Speciation | - SPECIATION IS THE DEVELOPMENT OF A NEW SPECIES. - It happens when populations of the same species change enough to become reproductively isolated (can't produce fertile offspring). Reproductive isolation is caused by geographical isolation: - A physical barrier divides a population of species. - Mutations create different features in the groups of organisms. - Natural selection occurs and since the conditions are different on each side, the features will be different for each group. - They will not be able to produce fertile offspring and become reproductively isolated. |
| Controversial natural selection | 1) The theory went against the religious beliefs and the churches. 2) Darwin couldn't explain his theory properly (how useful characteristics appeared and how they were inherited). 3) Some scientists believed there wasn't enough evidence. |
| Natural selection is accepted... | 1) Many scientists have tested the theory and haven't proved it wrong 2) The theory is plausible as it supports observations of plants and animals. |
| Lamarck's theory | - He argued that if a characteristic was used a lot by an animal then it would become more developed. - He believed these characteristics could be passed on to the offspring. - Theory was rejected because people concluded the acquired characteristics were not genetic so couldn't be passed on. |
| The Carbon Cycle | -Plants remove carbon dioxide from the air by photosynthesis. -Feeding passes carbon compounds along a food chain or web. -Plants and animals release carbon dioxide into the air, as a product of respiration. -Burning fossil fuels (combustion) releases carbon dioxide. -Soil bacteria and fungi, acting as decomposers, release carbon dioxide into the air. |
| Carbon in the sea | -- Carbon gets locked up in the sea by organisms and is also dissolved in the oceans. -- Microscopic plants use CO2 in photosynthesis. -- Marine organisms use carbon to make shells. -- When the organisms die the shells sink to the sea bed and get compressed into limestone rock. -- The carbon returns to the air by weathering or volcanic activity as carbon dioxide. |
| The Nitrogen Cycle (1) | 1. Nitrogen fixing bacteria in the soil turn nitrogen in the soil into nitrate. 2. Nitrogen fixing bacteria on some plant root nodules turn nitrogen into nitrate. Plants that have these kinds of root nodules include peas, beans and clover. 3. Compounds containing ammonia occur in animal excretion and in dead animals. The ammonia turns into nitrite and there are nitrifying bacteria in the soil that turn nitrite (NO2) into nitrate (NO3). They are called nitrifying bacteria because they increase the amount of nitrate in the soil. 4. Lightning can cause chemical reactions in the atmosphere that make nitrogen react with oxygen producing nitrous oxides. Nitrous oxides are also made from petrol engine pollution. The nitrous oxides can react with more oxygen and dissolve in rain water to make dilute nitric acid (HNO3(aq)) (see acid rain). HNO3 contains nitrate and so rain water containing HNO3 increases the amount of nitrate in the soil. |
| The Nitrogen Cycle (2) | Most of the fixing of nitrogen occurs through the natural processes described above. The Haber process for making fertilisers accounts for about 30% of nitrogen fixing. Nitrate in the soil is essential for plant growth. There are denitrifying bacteria in the soil that turn nitrate (NO3) into nitrogen gas (N2) and the nitrogen gas goes back into the atmosphere. They are called denitrifying bacteria because they decrease the amount of nitrate in the soil. |
| Human impact on the Environment | -- The world's human population is rising exponentially which means it's increasing rapidly. -- The rapidly increasing population is putting pressure on the environment- more resources are being used up and more pollution is being produced. -- The higher standard of living among more developed countries demands even more resources, and although these developed countries have only a small proportion of the world's population, they cause a large proportion of pollution. |
| Global Warming | 1) Fossil fuels are coal, oil and natural gas. 2) When they're burned, they release lots of carbon dioxide, which is a greenhouse gas. Greenhouse gasses trap heat in the atmosphere which causes global temperature to rise. This is called global warming. 3) Scientists have predicted that, if global temperature continues to go up, sea levels will rise, weather systems will become less predictable and agricultural output will fall. |
| Acid Rain | 1) When fossil fuels and waste materials are burned they release a gas called sulfur dioxide. 2) Sulfur dioxide reacts with water in the atmosphere to form sulfuric acid which falls as acid rain. 3) Acid rain damages soils and can kill trees. 4) Acid rain can cause lakes to become more acidic. This has a severe effect on the lake's ecosystems. Organisms that are are sensitive to changes in pH can't survive in more acidic conditions. This ends up killing many plants and animals. 5) Acid rain damages limestone, ruining buildings and stone statues. |
| Ozone Depletion | 1) CFCs (chlorofluorocarbons) used to be used in aerosols, fridges, air-conditioning units and polystyrene foam. 2) They break down ozone in the upper atmosphere. 3) This allows more harmful UV rays to reach the Earth's surface. 4) Being exposed to more UV rays increases the risk of skin cancer. Australia has high levels of skin cancer because it is under an ozone hole. 5) The increase in UV rays might also kill plankton in the sea- this could have a massive effect on the sea ecosystem (because plankton are at the bottom of the food chain). Scientists that fish levels will drop (this could mean we get less food) |
| Indicator Species of Pollution | 1) Some species can only survive in unpolluted conditions, so if you find lots of them, you know it's a clean area. Lichens are used to monitor air quality- they're damaged by pollution. The cleaner the air, the greater the diversity of lichens that survive. Mayfly larvae used to monitor water quality- they can't survive in polluted water. 2) Other species have adapted to live in polluted conditions- so if you see a lot of them you know there's a problem. Water lice, rat- tailed maggots and sludgeworms all indicate polluted water. But out of these rat- tailed maggots and sludgeworms indicate a very high level of pollution. |
| Measuring Pollution with indicator species | 1) See if a species is present or absent from an area. This is quick, but is not good for telling how polluted an area is. 2) Count the number of indicator species in an area allowing measurements from different areas to be compared so you can see how polluted an area is... You can measure pollution directly by using: 1) Senstive instruments can measure the concentrations of chemical pollutants, e.g. carbon dioxide or sulfur dioxide in samples of air or water. 2) Satellite data to indicate pollutant level e.g. satellites can show where the ozone layer is thin or absent, which is linked to the CFC level. |
| Advantages and disadvantages of methods to measure pollution. | |
| Factors that lead to endangered species | 1) The number of habitats- it's hard for organisms to find food, shelter and other resources so there are not enough suitable habitats. 2) The number of individuals- if there are only a few individual species left it'll be hard to find mates. It means there will not be much genetic variation in the population. 3) Genetic variation- this is the number of different alleles in a population. If genetic variation is low, then a species is less likely to be able to adapt to changes in the environment or survive the appearance of a new disease. |
| Evaluating Conservation programmes | Conservation Programmes are designed to help save endangered plants and animals. They involve things like protecting habitats, creating artificial environments and captive breeding. 1) GENETIC VARIATION- the species being conserved should have enough genetic varation to survive the apperance of new diseases and to cope with environmental change. 2) VIABLILTY OF POPULATIONS- populations should be able to reproduce- so they must contain both males and females of reproductive age. They should also be large enough to prevent related individuals having to breed together- this is called inbreeding and reduces genetic variation. 3) AVAILABLE HABITATS- there should be plenty of suitable habitats to live in. The right type of habitat is especially important if the organisms being conserved are specialists. 4) INTERACTION BETWEEN SPECIES- it's important that species interact with each other as they would in their natural environment. |
| Benefits to Wildlife and Humans from conservation programmes | 1) PROTECTING HUMAN FOOD SUPPLY- over fishing has greatly reduced fish stocks in the oceans. Conservation programmes ensure that future generations will have fish to eat. 2) ENSURING MINIMAL DAMAGE TO FOOD CHAINS- if one species becomes extinct it will affect all the organisms that feed on and are eaten by that species, so the whole food chain will be affected. 3) PROVIDING FUTURE MEDICINES- many of the medicines we use today come from plants. Undiscovered plant species may contain new medicine chemicals. If these plants are allowed to become extinct, perhaps through rainforest destruction we could miss out on the cure to cancer or asperger's syndrome. 4) CULTURAL ASPECTS- individual species may be important in a nation's or an area's heritage. E.g. the bald eagle in America is being conserved in the USA as it is regarded as the national symbol. |
| Sustainable Development | SUSTAINABLE DEVELOPMENT-- PROVIDING FOR THE NEEDS OF THE INCREASING POPULATION WITHOUT HARMING THE ENVIRONMENT. |
| Examples of sustainable development | 1) Fishing quotas have been introduced to prevent some types of fish, such as cod, from becoming extinct in certain areas.This means that they will still be around for the future generations to enjoy. 2) To make the production of wood and paper sustainable there are laws insisting logging companies plant new trees to replace those they've cut down. |
| Case study; Whales (endangered) | -- They have a commercial value and make money. -- They are a tourist attraction. -- Their oil and meat can be used and cosmetics can be made from their material. -- Captive breeding programmes let whales breed and then be released. |
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