GSCE Biology B2

  • Created by: Ruqayya11
  • Created on: 14-04-17 20:03
What are the groups that organisms are classified into?
Kingdom, Phylum, Class, Order, Family, Genus, Species
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What is an Artificial System?
An artificial system is based on one or two characteristics that make identification easier
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What is a Natural System?
A natural system is based on evolutionary relationships
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What has sequencing the bases in DNA allowed scientists to do?
This has allowed scientists to know much more about how closely related organisms are, and has often meant that organisms can be reclassified
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What is a species?
A species is a group of organisms that can interbreed to produce fertile offspring
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How does the binomial system work?
There are two parts to the name, the first is the genus and the second is the species
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Why is it difficult to place organisms into distinct groups?
It is difficult as living things are at different stages of evolution, and new ones are being discovered all the times
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What problems does bacteria present with classification?
Bacteria do not interbreed, they reproduce asexually, so they cannot be classified into different species using the 'fertile offspring' idea
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What problems do hybrids present with classification?
A hybrid is produced when two members of two species interbreed. Hybrids are infertile, so cannot be classed as a species
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What does it mean if organisms are ecologically related?
They live in the same habitat
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What do pyramids of biomass show?
They show the dry mass of living material at each stage of a food chain
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Why may a pyramid of biomass look different to a pyramid of numbers?
Producers are very large and small parasites live on large animals
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Why are pyramids of biomass hard to construct?
This is because some organisms feed on organisms from different trophic levels and also measuring dry mass is difficult as it involves removing all the water from an organism, which will kill it
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How is energy lost at each trophic level?
It is lost through heat from respiration, egestion and excretion
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How is carbon dioxide removed from the air?
It is removed through photosynthesis in plants
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How are carbon compounds passed along a food chain?
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How is carbon dioxide released into the air?
By plants and animals respiring. Soil bacteria and fungi acting as decomposers. The burning of fossil fuels
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How is carbon dioxide absorbed from the air?
By oceans. Marine organisms make shells made of carbonate, which become limestone rocks
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How can carbon from limestone return to air as carbon dioxide?
During volcanic eruptions or weathering
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How do plants take in nitrogen?
They take in nitrogen as nitrates form the soil to make protein for growth
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How is nitrogen passed along a food chain?
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How are nitrogen compounds in dead plants and animals broken down?
They are broken down by decomposers and returned to the soil
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What microorganisms are responsible for the recycling of nitrogen?
Decomposers are soil bacteria and fungi and they convert proteins and urea into ammonia. Nitrifying bacteria convert the ammonia to nitrates. Denitrifying convert nitrates to nitrogen gas. Nitrogen-fixing bacteria living in root nodules fix nitrogen
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Why is decay slower in waterlogged soil?
It is slower as there is less oxygen (acidic conditions also slow down decay)
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What do organisms in the same habitat compete for?
They compete for resources, such as food
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What do organisms of the same species compete for?
They compete with each other for mates do they can breed
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What is meant by an ecological niche?
The habitat that an organism lives in and also its role in the habitat
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What is meant by interspecific competition?
Interspecific competition is between organisms of different species
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What is meant by intraspecific competition?
Intraspecific is between organisms of the same species and is likely to be more significant as the organisms need the same resources
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Describe the cyclical changes between predator-prey relationships?
When there are lots of prey, more predators survive and their numbers increase. This means more predators eat more prey, so prey numbers drop. More predators therefore stave and so there numbers drop
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What is meant by parasitism?
Parasites feed on another organism called the host. The host suffers as a result of the relationship.
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Examples of parasitism?
Fleas are parasites living on a host. Tapeworms are also parasites feeding in the digestive system of various animals
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What is meant by mutualism?
This is when both organisms benefit as a result of their relationship
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Examples of mutualism?
The nodules in pea plants contain nitrogen-fixing bacteria. The bacteria turn nitrogen into nitrogen-containing chemicals and give some to the pea. The pea plant gives the bacteria some sugars that have been produced by photosynthesis
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Examples of anatomical adaptation to help reduced heat loss?
Insulation to cut down heat loss. Some animals are very large, with small ears- this helps to decrease heat loss by decreasing the surface area to volume ratio
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Examples of behavioural changes to reduce heat loss?
Some animals migrate long distances to warmer areas. Others slow down all body processes and hibernate
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Explain what is meant by a penguin having a counter-current heat exchange mechanism?
This helps reduce heat loss. The warm blood entering the flippers warms up the cold blood leaving, to stop it cooling the body
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What biochemical helps organisms that live in cold climates?
Antifreeze proteins
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Examples of anatomical adaptations to increase heat loss?
Having very little hair on the underside of their bodies. Animals that live in hot areas are usually smaller and have large ears- this gives them a larger surface area to volume ratio, so they can lose more heat
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Examples of behavioural changes to increase heat loss?
Panting and licking their fur. Also seeking shade during the hotter hours during the day
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Examples of adaptations to cope with dry conditions?
Camels can survive with very little water because they can produce very concentrated urine. Cacti reduce water loss because their leaves have been reduced to spines. They also have deep roots and can store water in the stem
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Explain what is mean by an extremophile?
An organism that can survive in hot conditions. Some bacteria can live in hot springs as they have enzymes that do not denature at temperature as high as 100*C
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Explain what is meant by organisms being specialist?
Specialists are very well adapted to living in specific habitats. They would struggle to live elsewhere
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Explain what is meant by organisms being generalists?
They can live in several habitats. However, they would lose to specialists in certain habitats
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Explain the theory of natural selection?
Within any species there is variation. Organism produce far more young than will survive, so there is competition for limited resources. Only the best adapted will survive (survival of the fittest.) Those that survive pass on successful adaptations
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Explain how over time natural selection can result in new species?
Organisms may be prevented from mating because they live in different areas (geographical isolation), or because of behavioural isolation. If each group evolves differently they may become different enough to be classified as separate species
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Examples of natural selection?
More and more bacteria are developing resistance to antibiotics. Peppered moths are dark or pale in colour. Dark moths are better camouflaged in polluted ares, so more of them survive
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Explain why some people initially disagreed with Darwin's theory?
Some people though he did not have enough evidence to back up his theory. Many people also disagreed because they though God had created all species
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Explain why Darwin's theory is now more widely accepted?
It explains lots of observations. It has been discussed and tested by a wide range of scientists
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Explain Lamarck's theory on evolution?
The law of acquired characteristics. For example, giraffes acquired long necks to feed, and this characteristic was passed on
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Identify the types of pollution that have caused concern?
Carbon dioxide- from burning fossil fuels, which may increase global warming. CFCs- from aerosols, which destroy the ozone layer. Sulfur dioxide- from burning fossil fuels, which causes acid rain
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Explain what is meant by exponential growth?
The human population of the world is growing at an ever-increasing rate
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Explain what is meant by the 'carbon footprint'?
The amount of pollution caused per person or organisation. This measures the total greenhouse gas given off by a person within a certain time
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What do direct methods of measuring pollution include?
Oxygen probes attached to computers that can measure the exact levels of oxygen in a pond. Special chemicals can be used to indicate levels of nitrate pollution from fertilisers
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Identify methods of measuring pollution using indicator organisms?
The mayfly larva is an insect that can only live in clean water. The water louse, bloodworm and mussels live in polluted water. Lichen grows on tree only when the air is clean- wouldn't be found in cities as it is killed from pollution
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Identify the advantages of the different methods of measuring pollution?
Using indicator organisms is cheaper, does not need equipment that can go wrong. Using direct methods can give more accurate results at a specific time
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Explain what is meant by conservation?
Conservation involves trying to preserve the variety of plants and animals and the habitats that they live in
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Explain why conservation is important?
It protects our food supply. It prevents damage to food chains, which can be hard to predict. It protects plants and animals that might be useful fro medical uses. It protects organisms that people enjoy to study
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Identify the factors to bear in mind when trying conserve species?
The size of the population. The number of suitable habitats that are available for the organism to live in. How much competition there is from other species
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Why do some people object to whales being kept in captivity?
They believe that whales lose their freedom
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What is meant by sustainable development?
Sustainable development means taking enough resources from the environment for current needs, while leaving enough for the future and preventing permanent damage
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Examples of sustainable development?
We need to supply increasing amount of food for growing problems without destroying large areas of natural habitats. Large amounts waste products must be disposed of so as to prevent pollution
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Card 2


What is an Artificial System?


An artificial system is based on one or two characteristics that make identification easier

Card 3


What is a Natural System?


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Card 4


What has sequencing the bases in DNA allowed scientists to do?


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Card 5


What is a species?


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