B7 Flashcards
Define population
All the organisms of one species living in a habitat
What is a habitat?
A place where an organism lives
Define community
The populations of different species living in a habitat
Define ecosystem
The interaction of a community of living organisms (biotic) with non-living (abiotic) parts of their environment
Why do organisms compete?
Organisms compete with organisms from different and their own species for the same resources. Being successful at competition increases the chance of survival.
What do plants compete for?
Plants compete for light, space, water and mineral ions from the soil
e.g. weeds compete with crop plants for light and minerals in the soil
What do animals compete for?
Animals compete for food, mates and territory
e.g. male peacocks compete for mates, lions and hyenas compete for food and water.
What is interdependence?
A community where each species depend on other species (for food, shelter, pollination, seed dispersal etc.) If one species is removed it can affect the whole community
What is a stable community?
One where all the species and environmental factors are in balance so that population sizes remain fairly constant.
What is an abiotic factor?
non-living factors of the environment that can affect organisms
Give examples of abiotic factors
- light intensity
- wind intensity and direction
- pH of soil
- moisture level
- temperature
- CO2 concentartion
- mineral content
- CO2 levels for plants
- oxygen levels for aquatic animals
What is a biotic factor?
a living factor of the environment that affects another organism.
Give examples of biotic factors
- arrival of new predators
- competition; one species outcompeting another so the numbers are no longer sufficient to breed.
- pathogens
- parasites
- food availabilty
- decomposers
What are extremophiles?
Organisms that live in environments that are very extreme, such as high temperatures, pressures or salt concentration
Give an example of extremophiles
bacteria living in deep sea vents
What are the three categories of adaptions?
- structural - features of an organism’s body structure (e.g. shape or colour)
- behavioural- the ways that organisms behave
- functional- things that go on the inside an organism’s body that can be related to processes like reproduction and metabolism
Give examples of structural adaptations
- artic fox=white fur- camouflaged against the snow (helps avoid predators & sneak up on prey)
- polar bears=thick fur- withstand the cold conditions
- seals=rounded shape- store of fat, low surface area: volume ratio (conserves body heat) brown colour- camouflage from predators
Give examples of behavioural adaptations
- elephants- flap their ears, spray themselves with water- (cool them down) to combat the hot environment
- swallows- migrate to warmer climates during the winter- to avoid living in cold conditions
Give examples of functional adaptations
- desert animals(e.g. camels)- conserve water by producing very little sweat and small amounts of concentrates urine. Fat(in hump) that can be broken down into water
- brown bears- hibernate during winter- lower their metabolism which conserves energy- no need to hunt when there is limited food available
What is a food chain?
A food chain shows what is eaten by what in an ecosystem.
What do all food chains start with?
a producer e.g. algae, green plants
What happens in a stable community?
The numbers of predators and prey rise and fall in cycles
Explain the relationship between prey and predators
(the population of a species is limited by the food availability)
- if the population of the prey increases, so will the population of predators
- as the population of predators increases, the number of prey will decrease
- fewer prey= fewer predators
- the number of prey is able to rise again
Why are predator-prey cycles always out of phase with each other?
It takes a while for one population to respond to changes in the other population
True or false: All materials in the living world are recycled to provide the building blocks for future organisms.
True
What does the carbon cycle do?
The carbon cycle returns carbon from organisms to the atmosphere as co2 to be used by plants in photosynthesis
What is the water cycle?
The water cycle provides fresh water for plants and animals on land before draining into the seas
- water is continuously evaporated and precipitated
What is compost used as?
A natural fertiliser for growing garden plants or crops
What does anaerobic decay produce?
methane gas
What is the function of a biogas generator?
produces methane gas as a fuel
What environmental changes affect the distribution of species in an ecosystem?
- temperature
- water availability
- composition of atmospheric gases
What is biodiversity?
Biodiversity is the variety of all the different species of organisms on Earth, or within an ecosystem
How does a great biodiversity ensure the stability of an ecosystem?
By reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment.
What is rapid growth in the human population and an increase standard of living result in?
more resources are used and more waste is produced
Give three ways pollution can occur
- in water, from sewage, fertiliser or toxic chemicals
- in air, from smoke and acidic gases
- on land, from landfill and toxic chemicals
What does pollution do?
It kills plants and animals which can reduce biodiversity
How do humans reduce the amount of land available for other animals and plants?
by building, quarrying, farming and dumping waste
What does the destruction of peat bogs do?
reduces the area of this habitat and thus the variety of different plant, animal and microorganism species that live there.
What does the decay or burning of the peat release?
carbon dioxide into the atmosphere
Why has large-scale deforestation occurred in tropical areas?
- to provide land for cattle and rice fields
- grow crops for biofuels
What is contributing to ‘global warming’?
the increasing levels of carbon dioxide and methane in the atmosphere
Give examples of methods used to tackle the problems caused by human impacts on the environment
- breeding programmes for endangered species
- protection and regeneration of rare habitats
- reintroduction of field margins and hedgerows
- reduction of deforestation and carbon dioxide emissions
- recycling resources rather than dumping in landfill
What are the trophic levels?
- producers- photosynthetic organisms
- primary consumers- herbivores
- secondary consumers- carnivores that eat herbivores
- tertiary consumers- carnivores that eat other carnivores
- apex predators- carnivores with no predators
Explain the role of decomposers
Decomposers break down dead plants and animal matter by secreting enzymes into the environment. Small soluble food molecules then diffuse into the microorganism
What does the pyramid of biomass represent?
the relative amount of biomass in each level of a food chain
level 1- producers
level 2- primary consumers
level 3- secondary consumers
level 4- carnivores
How much of the biomass from each trophic level is transferred to the level above it?
10%
Why is some biomass lost?
- not all the ingested material is absorbed, some is egested as faeces
- some absorbed material is lost as waste, such as carbon dioxide and water in respiration, water and urea in urine
What is food security?
Having enough food to feed a population
List biological factors which threaten food security
- increasing birth rates
- changing diets in developed countries → scarce food resources are transported around the world
- new pests and pathogens that affect farming
- environmental changes, e.g widespread famine is rains fail
- conflicts that affect the availability of water or food
How can the efficiency of food production be improved?
By restricting energy transfer from food animals to the environment, which can be done by limiting their movement and by controlling the temperature of their surroundings
What are some animals fed to increase growth?
high protein foods
Why is it important to maintain fish stocks at a level where breeding continues?
to prevent certain species from disappearing altogether in some areas
What measures are put in place to combat the declining fish stocks?
- control of net size
- introduction of fishing quotas
What do modern biotechnology techniques enable?
Large quantities of microorganisms to be cultured for food
What is mycoprotein?
a protein-rich food suitable for vegetarians
What is the name of the fungus which is useful for producing mycoprotein?
Fusarium- the fungus is grown on glucose syrup in aerobic conditions and the biomass is harvested and purified
What would a genetically modified bacterium that produces insulin be used for?
treating people with diabetes
What can genetically modified crops do?
provide more food or food with an improved nutritional value e.g. golden rice
