Life on earth Flashcards
What is the definition of a species?
A group of organisms that can breed together to produce fertile offspring
What are the changes that enable a species to cope with a specific niche called?
Adaptations.
What is the niche?
The role within an ecosystem
Give examples of adaptations.
eg Cactus storing water; squirrel can turn paws round; camel’s hump
What is the word for the environment in which a species lives?
Habitat
What do animals compete for?
Food, mate, living space/territory
What do plants compete for?
Light, nutrients, water, space
How would you show the feeding relationships of organisms?
Food web
What is the name for the way species rely on each other?
Interdependence
What happens if you change something for one species in a food web?
All the species are likely to be affected
What happens if a species cannot adapt quickly enough to a change in the environment?
Extinction
What happens to a species if the human activity removes the habitat?
Extinction is likely - eg Siberian tiger, Orangutan, mountain gorilla
What happens if a new species is introduced into an area?
Extinction is possible if the species is a competitor, predator, or causes disease. (eg cane toad in Australia)
What happens to other species in the food web if one species is extinct?
They may face extinction.
What is the source of energy for almost all species on earth?
The sun
What proportion of the energy of the sunlight do plants use?
A small amount (under 10%)
How do plants store the energy of the sun?
As chemical energy
How do organisms that can’t photosynthesise get their energy?
Mostly by eating green plants.
What does almost every food chain begin with?
A green plant
What proportion of the food eaten remains in the organism?
A small amount
Why is energy lost at each level of the food chain?
Some parts of the organism can’t be eaten/digested; respiration; waste products still contain energy
Why is the length of food chains limited?
Energy is lost at each stage
What is percentage efficiency of energy transfer
energy in tissue/energy in food eaten x 100
What happens to the energy contained in an organism after the organism dies?
It is transferred to the decomposers (fungi/bacteria). Also used by scavengers and predators.
What is partly decayed material called?
Detritus
What feeds on detritus?
Detritivores, eg earthworms, woodlice
What is the key element of the chemicals that make up living things
Carbon
What is the name for the process whereby carbon is reused on earth?
Carbon cycle
How does carbon enter the carbon cycle?
As carbon dioxide from the air
What do plants do to the carbon to make it accessible to living things?
Carbon is fixed via the process of carbon dioxide
How does carbon return to the air?
respiration; decomposition; combustion
How is nitrogen recycled?
Via the nitrogen cycle
How do plants take in nitrogen?
Nitrogen compounds in the soil are absorbed through the roots
What are the nitrates made into by the plant?
Protein (via amino acids)
What happens to the proteins in plants?
It passes along the food chain
How do nitrates return to the soil?
Animals excrete waste, and are decomposed
How does nitrogen enter the nitrogen cycle?
Nitrogen in the air split by lightening,combines with oxygen to form nitrates, washed into the soil by rain; nitrogen fixing bacteria, found in soil and in roots of some plants (beans, peas, clover)
How does nitrogen leave the nitrogen cycle?
Denitrifying bacteria in the soil convert nitrates to nitrogen gas
How can you measure environmental change?
Non-living indicators, eg CO2 levels ; living indicators eg phytoplankton
What information can living indicators give us?
Precise measurement of pollution/climate change.
What is the name given to measuring environmental change using living indicators?
Biotic scale
Name an organism used for measuring pollution
The mayfly as mayfly larvae need high levels of oxygen in the water they are sensitive to pollution
Why would you use non-living indicators?
They can give trends over a period of time.
Where could you find historical levels of CO2?
Trapped in bubbles in ice
When did life on earth begin?
3500 million years ago
What was the first life form like
Very simple
What is the process of change in living things called?
Evolution
What is the best explanation we have for the change in living things?
The theory of evolution
How can you date a fossil?
By the rock it is found in, also other similar fossils.
How can you date a rock?
By the fossils found in it, rock layers
What is the name for a change in the genetic information in the cell?
Mutation
When are mutations most likely to occur?
When the DNA is being copied prior to cell division (transcription errors). Vast majority are corrected!
What happens to an organism with a detrimental mutation?
It is less likely to have offspring
What happens if the organism has an advantageous mutation?
It is more likely to have offspring
What happens over time to the gene pool of an organism?
The alleles present will change
What evidence is there to support the theory of evolution?
Fossil record; observation of living species; selective breeding of domestic animals; similarities between species
What is natural selection?
The theory that the fittest organism is the most likely to pass on the genes that it has.
How can a new breed of cat be produced?
Selective breeding of individuals who are closest to having the wanted features… eg a very long nose and blunt claws, with a mane, over many generations.
Name a process of natural selection that is happening in our lifetime
Bacterial resistance is spreading in the gene pool of the bacteria. Eventually that allele will become the common one.
How are organisms classified?
By putting similar organisms into groups
How were similarities determined for the classification of animals?
Looking at them, eg teeth, body structure, etc
How are similar organisms chosen now?
DNA testing shows which animals are closely related.
How can DNA tell you which animals are related?
Their base sequences will be similar
Who proposed the theory of evolution?
Darwin and Wallace
What gave Darwin the idea of evolution?
Observing species on Galapagos. They are volcanic islands, so a few animals came from the mainland.
What was Lamarck’s theory?
Lamarck suggested that animals acquired characteristics that were passed on to offspring
What evidence was found for Lamarck’s theory?
None. However, some evidence now being found that whether genes are switched on or off can change in the life of an animal and can be passed on.
What is biodiversity?
The variety of life on earth
What is another name for the variation within a species?
Genetic diversity
What is a kingdom?
A large group with many organisms with few characteristics in common
What is the species?
The lowest level of classification.
What is sustainability?
Meeting today’s needs without stopping future generations from meeting theirs.
What do we need to do to achieve sustainability?
limit our impact on wildlife, habitats and the environment; actively support populations and ecosystems.
How is biodiversity related to sustainability?
Biodiversity is essential to achieve sustainability, as removable of a single species can have such a devastating impact on the rest of the ecosystem
How do our farms maximise crop yield?
They use a system called intensive monoculture crop production; fertilisers and pesticides, massive fields, no hedges, just one species
Is intensive monoculture crop production sustainable?
Probably not; for instance, the over-use of pesticides is killing the bees that mankind relies on to fertilise our crops.
How can we increase sustainability in product manufacture?
Use little energy and packaging; limiting transport and using local products; creating as little pollution as possible
How is the environmental impact of a product tracked?
Life cycle assessment
What are the stages of the life cycle assessment?
raw materials; manufacture; transport; use; disposal
What can packaging be to be more sustainable?
Biodegradable
Why is it better to use no packaging at all?
Even biodegradable packaging takes space in landfill and takes a long time to degrade. It can also produce methane.
