Life on earth Flashcards
Definition of species
A group of organisms that are able to interbreed to produce fertile offspring of a similar type
Definition of biodiversity
the variety and abundance of living organism found in a particular area
Definition of population
the number of individuals of one species found in an area
Definition of producers
green plants that can produce food by the process of photosynthesis
Definition of consumer
consumers eat other organisms to obtain energy
definition of herbivore
A consumer that only eats plants to obtain energy
Definition of carnivore
only eat other animals to obtain energy
Definition of omnivore
consumers that eat both animals and plants to obtain energy
Definition of predator
consumers that kill other animals to eat
Definition of prey
Species that ate killed by other consumers
Definition of food chain
a sequence of organisms through which energy flows when one organism eats another
Definition of food web
Shows the numerous paths that energy can take as it flows through the species in an ecosystem
What is an ecosystem
An ecosystem consists of all the organisms living in a particular habitat and the non living components which these organism interact
What does a food web show
The feeding interactions within a food web using arrows to show the direction of energy flow which indicates which species are feeding on which as the energy moves from prey to predators
What do food webs also reveal
Competitive interactions within a food web
What is the effect on a food web if a prey species is removed
It’s predators will decline in population
What is the effect on a food web if a predator species is removed
It’s prey species will become more common
What is a niche
A role that an organism plays within a community
What does a niche relate to
the resources an organism requires in its ecosystem, such as light and nutrient availability, and its interactions with other organisms in the community
What does niche involve
competition and predation and the conditions an organism can tolerate, such as temperature
When does competition in ecosystems occur
When resources are in short supply
Does interspecific competition occur between the same species or different species
Different
Does intraspecific competition occur between the same species or different species
Same
What is more intense interspecific competition or intraspecific competition
Intraspecific
Where is the majority of energy lost in transfer from one level to the next on a food chain
as heat, movement or undigested materials
Definition of a pyramid of numbers
Pyramid of numbers show the total number of individual organisms at each level in the food chain of an ecosystem
Definition of a pyramid of energy
A pyramid of energy shows the total quantity of available energy stored in the organisms at each level in the food chain of an ecosystem per year
What are true pyramids of energy
Irregular shapes of pyramids of numbers based on different body sizes
What does the increasing human population require
Increasing food yield
What can this involve
The use of fertilisers or pesticides
What do fertilisers do
provide chemicals such as nitrates, which increase crop yield
What do pesticides do
Kill plants or animals that reduce crop yield
What are nitrates that are absorbed into soil water also absorbed into
Plants
What are nitrates used for
produce amino acids which are synthesised into plant proteins
Why do animals consume plants or other animals
To obtain amino acids for protein synthesis
What do fertilisers do when added to soil
Increase the nitrate rate
What do fertilisers do if they leach into fresh water
Add extra unwanted nitrates
What do these nitrates increase
Algal population which can cause algae blooms
What do alga, blooms do
reduce light levels, killing aquatic plants
What does these dead plants become
Food for bacteria which greatly increase in number
What does this bacteria use up
large quantities of oxygen, reducing the oxygen availability for other organisms
What can be used to reduce the use of fertilisers
Genetically modified crops
When pesticides are sprayed onto crops what can happen
They can accumulate in to bodies of plants over time
What is bioaccumulation
The build-up of toxic substances in living organisms
What happens when pesticides are passed along food chains
toxicity increases and can reach lethal levels
What can be used as alternatives to pesticides
Biological control and genetically modified crops
What is a mutation
A random change in genetic material
Are mutations only a disadvantage to survival
Now they can be an advantage and neutral as well
What are mutations the only source of
New alleles
What can increase the rate of mutation
Environmental factors such as radiation and some chemicals
What can new alleles result in
Plants and animals being better adapted to their environment
What does variation in a population make possible
a population to evolve over time in response to changing environmental conditions
What is an adaption
an inherited characteristic that makes an organism well suited to survival in its environment/niche
When does natural selection occur
When there are selection pressures
What type of individuals survive natural selection
The best adapted
What do these surviving individuals do
Reproduce sending on favourable alleles that confer the advantage
What do these alleles do
Increase in frequency in the population
When does speciation occur
after part of a population becomes isolated by an isolation barrier, which can be geographical, ecological or behavioural
How does natural selection work
selects for different mutations in each group, due to different selection pressures
What are the two stages of photosynthesis
Light reactions and carbon fixation
What is the light reaction
The light energy from the sun is trapped by chlorophyll in the chloroplasts and is converted into chemical energy which is used to generate ATP. Water is split to produce hyrdrogen and oxygen. oxygen diffuses from the cell. The hydrogen and ATP are required for the next stage of carbon photosynthesis.
What is carbon fixation
A series of enzyme-controlled reactions, which use hydrogen and ATP (produced by the light reactions) with carbon dioxide to produce sugar.
What is the sugar that is produced by photosynthesis used for
Respiration, stored as starch and to make carbohydrate cellulose
What are the limit g factors of photosynthesis
Carbon dioxide concentration, light intensity and temperature
What is the carbon dioxide concentration impact on photosynthesis
Carbon dioxide is required during the carbon fixation stage of photosynthesis to make sugar
What is the light intensity impact on photosynthesis
Light is required to provide energy for the light reactions - without these there will be no ATP or hydrogen to pass to carbon fixation.
What is the temperatures impact on photosynthesis
the temperature affects the rate that the enzymes that are responsible for catalysing the reactions in both stages can occur.
What are biotic factors
Competition for resources, disease, food availability
What are abiotic factors
Light intensity, moisture, Ph and temperature
What measures light intensity
Light meter
What measures temperature
thermometer
What measures soil ph
soil ph meter
What measures soil moisture
soil moisture meter
What can cause error with light intensity and how do you minimise it
Casting shadows by accident over the meter ensure that you do not stand near it
What can cause error with temperature and how do you minimise it
Refrain from touching then end of the thermometer as this will effect the reading
what can cause error with soil ph and how do you minimise it
The meter must be wiped clean between each measurement otherwise the ph might be similar to the before measurement
What can cause error with soil moisture and how do you minimise it
same as soil ph
What are indicator species
Species that by their presence/absence indicate environmental quality/levels of pollution
