Life on earth Flashcards
Revision
Herbivore
Organism that eats plants only
Carnivore
Organism that eats animal material only
Omnivore
Organism that eats a mix of plants and animals
Producer
A green plant that makes its own energy using sunlight
Consumer
An organism that eats another organism
Predator
An animal that hunts and kills other animals for food
Prey
An animal which is hunted and killed for food by the predator
Ecosystem
All the living and non living organisms (community) living in a habitat
Food chain
A diagram which shows the transfer of energy between organisms
Habitat
The place where an organism lives
Food web
A diagram which shows inter connected food chains
Species
A group of organisms that can interbreed to create fertile offspring
Biodiversity
The number, variety and abundance of species
Community
All the plants, animals and microorganisms living in a habitat
Population
All the members of one species living in a habitat n
Biome
Large ecological of the earth with its own characteristics climate and community adapted to survive their
Niche
The role an organism within a community
Competition
when organisms require the same or similar resource(s) that are in
short supply.
Interspecific competition
different species for one or
a few of the resources they require.
Intraspecific competition
Intraspecific competition occurs amongst individuals of the same species and is for
all resources required.
Abiotic
Non biological factors that can affect a species
Biotic
Biological factors that can affect a species
Abiotic examples
Ph, temperature, soil moisture or humidity, rainfall, light intensity
Biotic examples
Grazing, predation, food availability, disease, competition
Pitfall traps
sample organisms that live on the surface of the soil.
Quadrats
Quadrats can be used to sample plants or slow moving organisms such as limpets on
a rock shore.
How to measure temperature
Thermometer or
temperature probe
Insert into soil or pond until reading Has stabilised
How to measure pH
pH meter or chemical
test (pH indicator)
Insert pH probe into soil and read From scale
How to measure light intensity
Light meter
Hold light sensitive panel towards light
to be measured and read result from
scale. Make sure that you are not
casting a shadow over the light Sensitive panel
How to measure soil moisture
Moisture meter
Insert probe into soil and read level
from scale. Make sure to wipe the
probe to ensure that moisture from a
previous reading does not affect the Results
Photo synthesis word equation
Carbon dioxide + water - light energy + chlorophyll = glucose + oxegyn
The light reaction stage
Light energy is trapped by chlorophyll, splits water molecules into hydrogen and oxygen molecules. Chemical energy is
also produced .The
hydrogen and ATP are passed on to the next stage of photosynthesis and the excess oxygen diffuses from the cell
Carbon fixation stage
This stage is controlled by enzymes. Carbon dioxide combines with hydrogen from the light reactions stage to
produce sugar (chemical energy). ATP from the light reactions provides the energy
for this process to take place.
Uses of sugar
Respiration, cellulose or to store starch
LIMITING FACTORS
Light intensity, carbon dioxide concentration, temperature
How is energy lost in the food chain
- Heat
- Movement
- Undigested waste.
What is a pyramid of numbers
A pyramid of numbers shows the total number of organisms at each stage in a
food chain.
Pyramids of energy
A pyramid of energy shows the energy available at each stage in a food chain.
How to increase food yield
Use of pesticides to kill plants and animals which would reduce crop yield, Use of fertilisers to stop land being leached of minerals,Growing monocultures over large areas, introducing GM crops
Fertilisers
Fertilisers are added to land to increase the levels of essential plant nutrients that are used up by
the growing plants/crops So farmers add nitrogen to the soil in the form of synthetic fertiliser, manure or compost.
The nitrogen cycle
Animals make urine and faeces which is absorbed by decomposers, they change the waste into nitrates and release them into the soil, Plants absorb the nitrates through their roots.
Plants convert the nitrates into plant protein. Animals eat the plants. They convert the plant protein into animal protein.
Leaching
The fertiliser added can leach off into a body of water nearby. This increases the nitrate levels and the algae already present in the water can
now multiply rapidly causing a huge population increase known as an algal bloom
What is algal bloom
Algal blooms
reduce light levels, killing aquatic plants. When the water can’t sustain all the algae they die which gives bacteria food source so they start to multiply and the bacteria use up all of the oxygen which reduces oxygen for other organisms causing them to die decreasing biodiversity .
Pesticides
Pesticides are sprayed on to crops to prevent pest species (both plant and animal) from reducing
crop yield by damaging the crop or competing for resources with the crops
Bioaccumulation
Some pesticides are not biodegradable and as a result they will remain in soil/rivers/lochs for long
periods of time and will accumulate in the body of organisms over time. The build-up of toxic
substances in living organisms is known as bioaccumulation. These toxins are passed along food
chains when one organism eats another causing an increase in toxicity which can reach lethal levels.
Alternative methods
Biological control, GM crops,
Mutation
Variation, the differences between individuals of the same
species
What affects mutation
Environmental factors such as radiation (UV light, X Rays) or
chemicals (mustard gas) can increase the rate of mutation, these are known as
mutagenic agents.
Natural selection
New alleles produced by mutation can result in plants and animals becoming better
adapted to their environment. Variation allows
a population to evolve over time in response to changing environmental conditions
therefore increasing the long term survival chance of the species.
Different types of adaptation
Changes in structure, changes in behaviour and physiological changes
Learned Behaviour
Behaviour can be learned by watching and listening to others, and by experience. For
example people learn to walk, talk, swim, make choices and behave appropriately
Isolating mechanisms
The isolating mechanisms or barriers that split a population can be geographical (oceans,
mountains, deserts), behavioural (differences in courtship rituals such as breeding calls
or mating dances) or ecological (different habitats, pH or salinity).
