B2- Understanding our Environment Flashcards
What are the 7 levels of classification?
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
What is artificial system?
Based on one or two characteristics that make identification easier (appearance)
What is natural system?
Based on evolutionary relationships and genetic similarities between organisms
Define genus
A group of closely-related species that can interbreed to produce **fertile **offspring
What is the binomial system?
- genus (Capital letter)
- species (lower case letter)
Why was it difficult to put the Archaeopteryx in a group?
- It had feathers like a bird
- It had teeth and a long, bony tail, like a reptile
How does bacteria go against the definition of ‘species’?
They reproduce **asexually **and do not interbreed
What are hybrids?
The **infertile **offspring produced when two animals of different species breed
Name some examples of hybrids
- mules (donkey and horse)
- lyger (lion and tiger)
- zedonk (zebra and donkey)
What does ecologically related mean?
Organisms with similarities due to the fact that they live in the same habitat, for example dolphins and fish (although dolphins are mammals)
How are dolphins and bats similar and different?
They both evolved to live in different habitats (dolphins in sea, bats in roosts), but both are mammals as they are related through evolution
What do pyramids of biomass / numbers represent?
The feeding relationships between organisms in a food chain or web
What does a pyramid of biomass show?
The dry mass of living material at each stage of a food chain
How could a pyramid of biomass look different to a pyramid of numbers?
Pyramids of biomass always have a triangular shape
Why are pyramids of biomass usually pyramid-shaped?
This is because biomass is a measure of the amount of food available. If there is less biomass in the lower level, then it would mean there is not enough food for the consumers
What are trophic levels?
The stages in a food chain
How could pyramids of biomass be difficult to construct?
- some organisms feed on organisms from different trophic levels
- measuring dry mass is difficult as it involved removing all the water from an organism, which will kill it
What is energy transferred into as it flows along a food chain?
- growth
- heat from respiration
- egestion (e.g. poop)
- excretion (e.g. urine)
What is the difference between egestion and excretion?
Egestion is expulsion of solid waste (e.g. poop) and excretion is the process of getting rid of waste from the body (e.g. urine, sweat)
How is the material lost at each stage of the food chain not wasted?
Decomposers use the waste to start another food chain
Why does a food chain eventually end?
Because each trophic level ‘loses’ about 90% of the energy, so by the end of the food chain, there is not much energy left
How could you calculate the efficiency of energy transfer in the food chain?
energy used for growth / energy input = energy efficiency
What element is found in living organisms?
Carbon
How is carbon dioxide removed from the air?
By photosynthesis
How is carbon dioxide released into the air?
- plants and animals respiring
- soil bacteria and fungi acting as decomposers
- burning of fossil fuels (combustion)
What occurs in the ocean when carbon dioxide is absorbed?
Marine organisms make shells made of carbonate, which become limestone rocks
How can the carbon in limestone return to air?
Volcanic eruptions of weathering of limestone can return it into the air as carbon dioxide
What process is used to show the recycling of carbon dioxide in the air?
Carbon cycle
What is nitrogen useful for?
To make proteins for growth
What do decomposers do to nitrogen compounds in dead organisms?
Break it down and return into the soil
Which organisms are involved in the nitrogen cycle?
- decomposers (convert proteins and urea into ammonia)
- nitrifying bacteria (ammonia to nitrates)
- denitrifying bacteria (nitrates to nitrogen gas)
- nitrogen-fixing bacteria, living in root nodules (fix nitrogen gas)
How does pH and oxygen affect decomposers?
- decay will be slower in waterlogged soil as there is less oxygen
- acidic conditions will slow down decay
What is intErspEcific competition?
Between organisms of diffErEnt species?
What is intrAspecific competition?
Between organisms of sAme species
How do organisms in the same habitat/ species compete with each other?
- habitat - resources e.g. food
- species - resources and mates
What is an ecological niche?
The habitat the organism lives in and also its role in the habitat. For example, ladybirds live on trees such as sycamore and eat greenfly
Why do predator and prey show cylical changes?
- lots of prey = more predators survive = increase in numbers
- more predators = eat more prey = prey numbers drop
- more predators starve = predator numbers drop
Why do the predators peak after the prey peaks?
It takes a while for the increased supply of food to allow more predators to survive and reproduce
What is a parasite?
- Feed on or in another living organism
- The host suffers
- Parasites benefit
What is a mutualistic relationship?
Both organisms benefit as a result of their relationship
For example, insects visit flowers and transfer pollen, allowing pollination to occur, and the insects get sugary nectar
How do legumes and nitrogen-fixing bacteria benefit from mutualism?
- bacteria turn nitrogen into nitrogen-containing chemicals and gives to pea
- pea plant gives bacteria sugars that has been produced from photosynthesis
What anatomical adaptations do animals have to living in cold conditions?
- insulation to cut down heat loss (arctic fox has thick fur that traps air for insulation)
- quite large, with small ears (decrease heat loss by decreasing surface area to volume ratio)
What behavioural adaptations do animals have to living in cold conditions?
- migrate long distances to warmer areas
- slow down all body processes and hibernate
What do penguins have to help reduce heat loss?
Counter-current heat exchange
warm blood entering flippers warms up cold blood leaving, to stop it cooling the body
What biochemical adaptations do some organisms have to live in cold climates?
antifreeze proteins in their cells
What anatomical adaptations do animals have to living in hot conditions?
- very little hair
- smaller and have larger ears (larger surface area to volume ratio so they lose more heat)
What behavioural adaptations do animals have to living in hot conditions?
- seek shade during the hotter hours
- bathe in cold water
How are organisms adapted to living in dry conditions?
- camels can survive with little water as they produce concentrated urine
- cacti reduce water loss because their leaves have been reduced to spines
- deep roots and can store water in stem
What are extremophiles?
Organisms that can survive in hot conditions, such as bacteria that can live in hot springs (containing enzymes that do not denature at 100°C)
What are specialists?
Very well adapted to living in specific habitats and would struggle to live elsewhere
e.g. polar bears
What are generalists?
Organisms that can live in several habitats and would lose to specialists in certain habitats
Who wrote the theory of natural selection over 150 years ago?
Charles Darwin
What is the idea of natural selection?
- within any species there is variation
- organims produce far more young than will survive, so there is competition for limited resources
- only best adapted will survive (survival of the fittest)
- those that survive pass on successful adaptations to the next generation in their genes
Why might the changes produced by natural selection result in a new species?
- if the different groups of organisms cannot mate for a long time
- geographical isolation
- if each group evolves differently
What is geographical isolation?
If organisms live in different areas and are prevented from mating
What are some examples of natural selection?
- antibiotic resistant bacteria e.g. MRSA
- peppered moths (dark vs light)
Why did people disagree with Darwin’s ideas?
- thought he did not have enough evidence to back up his theory
- thought God created all species
Why is Darwin’s theory now accepted?
- it explains a lot of observations
- has been discussed and tested by scientists
What was Lamarck’s theory of ‘the law of use and disuse’ and ‘the law of acquired characteristics’?
- characteristic which is used more and more by an organism becomes bigger and stronger
- one that is not used disappears eventually
- characteristic is improved through use and passed to its offspring
e.g. giraffes acquired long necks to feed and this characteristic was passed on
Why is Lamarck’s theory wrong?
- It does not have a genetic basis
- Cannot account for all the observations made of life on Earth
Which 3 pollutants cause most concern?
- carbon dioxide (burning fossil fuels = increase greenhouse effect and global warming)
- CFCs (aerosols = destroy ozone layer)
- sulfur dioxide (burning fossil fuels = acid rain)
What is exponential growth?
Ever-increasing growth of human population
(Birth rate exceeding death rate)
Where are the greatest rise of world population?
In under-developed land masses
e.g. Africa and India
Which countries use more fossil fuels?
Developing land masses
e.g. USA and Europe
What is a carbon footprint?
Amount of pollution caused per person or organisation
What can pollution in water or air be measured using?
Direct methods or indicator organisms
What are examples of direct methods?
- oxygen probes attached to computers to measure oxygen levels in pond
- special chemicals to indicate levels of nitrate pollution from fertilisers
What does the presence of an indicator species show?
The estimate levels of pollution
What are examples of indicator species?
- mayfly larva is an insect that can only live in clean water
- water louse, bloodworm and mussels can live in polluted water
- lichen grows on trees and rocks only when air is clean
What are advantages of both methods of measuring pollution?
indicator organisms:
- cheaper, does not need equipment that can go wrong and monitors pollution levels over long periods of time
direct methods:
- more accurate results at any specific time
What does conservation do?
Preserve the variety of plants and animals and the habitats they live in
Why do people think conservation is important?
- protect food supply
- prevent damage to food chains
- protect plants and animals that might be useful for medical uses
- protect organism and habitats people enjoy to visit and study
What factors do you need to consider when trying to conserve species?
- size of population (if below critical level, it is unlikely to have genetic variation in population to enable it to survive)
- number of suitable habitats available to live in
- amount of competition
Why are whales hunted?
- body parts to make food, clothes and other products
- live whales for tourist trade
Why do some people disagree with captive breeding of whales?
Whales lose freedom
Why do scientists believe that killing whales is useful?
- to find out more about how whales survive
Could study whales without killing them
- migration patterns
- whale communication could only be investigated when animal is alive
What is sustainable development?
Taking resources from the environment for current needs, while leaving enough for the future and preventing permanent damage
What are examples of sustainable development?
- fishing quotas
- woods are replanted to keep up supply of trees
Why is it crucial to carry out sustainable development?
- fossil fuels will run out, so we must manage alternative fuels, such as wood
- need to supply food for growing populations without destroying large areas of natural habitats
- waste products must be disposed of to minimise pollution
