Life on Earth Flashcards
habitat
the place where an organism lives
population
all the members of one species living in a habitat
community
all the plants, animals and micro-organisms living in a habitat
species
a group of organisms that can interbreed to produce fertile offspring
producer
a green plant that makes its own energy (food) using sunlight
consumer
an animal that eats another organism (plants or animals)
herbivore
an organism that eats plant material only
omnivore
an organism that eats a mixture of both plant and animal material
carnivore
an organism that eats animal material only
predator
an animal which hunts and kills other animals for food
prey
an animal which is hunted and killed for food by the predator
biodiversity
the number and abundance of species
food chain
a diagram which shows the transfer of energy between organisms
food web
a diagram which shows inter-connected food chains
ecosystem
all the organisms living in a particular habitat and the non-living parts which the organisms interact with
organism
any individual living thing
predation
a relationship between 2 organisms in which one hunts, kills and eats the other
niche
the role that an organism plays within a community
parasitism
a relationship between 2 organisms in which one benefits or lives off of the other- with a certain amount of disadvantage to the host
sampling
studying part of an area rather than the whole thing, making sure that you study a representative portion
indicator species
species that by their presence or absence indicate environmental quality/ levels of pollution
pitfall traps
a method of sampling non-flying invertebrates in an area by placing concealed pits for them to fall into
abiotic factors
examples
non-living factors
eg pH, temperature, light intensity and soil moisture
light intensity
a measure of how much light energy falls on an area in any given time
quadrat
equipment used to sample plants or very slow moving animals, usually a large square split into smaller squares
light meter
equipment used to measure light intensity
biotic factors
examples 5
living factors- they come from the activity of a living thing
eg competition for resources, disease, food availabilty, grazing and predation
pH
a measure of whether a solution such as the soil water is acidic, alkaline or neutral
soil thermometer
equipment used to meaure the soil temperature
grazing
an example of a biotic factor that can affect the distribution of organisms
light intensity- possible sources of error and the solution
- the observer may stand in the way of the light casting a shadow on the light sensitive panel.- ensure that observers are standing to one side of the light meter
-light intensity may change from one moment to another due to clouds making comparisons between areas invalid- take all measurements as near as possible during periods of similar light intensities i.e samples taken at the same time of day if study is over some time.
temperature- source of error and the solution
probe not inserted deep enough into the soil- insert probe into soil to half its depth
soil moisture- sources if error and solutions
-soil from previous sample may still be on the surface of the probe- clean probe before and after each reading with a paper towel
-samples are taken at different depths- place a marker around the probe to ensure it is pushed to the same depth for readings.
soil pH source of error and solution
soil from a previous sample may still be on the surface of the probe- clean probe before and after each reading with a paper towel
how is light intensity measured
the switch on the meter is set at the light meter position. The meter is held so that the light sensitive panel is directed towards the light source to be measured
how is temperature measured
thermometer is placed in the soil or air until temperature is constant
how is soil moisture measured
the switch in the meter is set at the moisture meter position. The moisture probe is pushed into the soil and the reading is taken from the scale once the pointer has stopped moving.
how is soil pH measured
pH meter probe is placed into the soil and the needle is allowed to stabilise
what is the energy transfer in photosynthesis
light energy–> chemical energy
what is the word equation for photosynthesis
light
carbon dioxide + water –> glucose + oxygen
chlorophyll
raw materials products
what are the 3 uses for glucose produced in photosynthesis
- some is immediately used for RESPIRATION to provide the energy required by the plant
-some is converted into the STRUCTURAL carbohydrate CELLULOSE to build cell walls - some is converted into the STORAGE carbohydrate STARCH. this is stored by the plant in the leaves and can be converted back into glucose when required for respiration
what is the structure of starch
long chain of glucose molecules which coil uo to form a starch grain
what is the structure of cellulose
bundles of chains of glucose units are branched to form fibres
properties of starch
large in size so cannot diffuse of the cell
insoluble in water
properties of cellulose
insoluble
freey permeable
what are the 2 stages of photosynthesis called
stage 1- light reactions
stage 2- carbon fixation
what does stage 1 look like
light energy
|
chlorophyll
|
ADP+Pi ) chemical energy ( water
ATP ) ( hydrogen+oxgygen
| | |
passed onto passed onto diffuses out
second stage second stage of cell
description of light reactions
the light energy from the sun is trapped by chlorophyll in the chloroplasts and is converted into chemical enery which is used to generate ATP. water is split to produce hydrogen and oxygen. Oxygen diffuses out of the cell
what does stage 2- carbin fixation look like
hydrogen ATP ADP + Pi
\ \ /
————————————–glucose
/
carbon dioxide
(from the air)
enzyme controlled reaction
description of carbon fixation
the ATP and hydrogen from stage one are combined with carbon dioxide from the air to produce glucose. These reactions are enzyme controlled
What are the 3 ways in which photosynthesis is measured
Production of oxygen over a set period of time
Uptake of carbon dioxide over a set period of time
Production of glucose over a set period of time
What is a limiting factor
A limiting factor slows down or decreases the rate of a process because it is in short supply.
What are the 3 main limiting factors
Temperature
Carbon dioxide concentration
Light intensity
Why does light intensity effect photosynthesis
The first stage will be altered as it is light dependant
How does temperature effect photosynthesis
Temperature will alter stage 2 as it depends on enzymes for it to work
How does carbon dioxide concentration effect photosynthesis
It will alter the second stage as it is a raw material required in the second stage.
How can the rate of photosynthesis be measured
By counting the number of oxygen bubble produced from a green aquatic plant based on the light intensity
How can carbon dioxide concentration be shown
Can be shown by the colour of the hydrogen carbonate (bicarbonate) indicator in the tube
Yellow is very high concentration
Red is medium concentration
Purple is very low concentration.
How do you find out the limiting factor on the slope
Look at the label on the x-axis
What is carbon fixation
The second stage of photosynthesis where glucose is synthesised
What is chlorophyll
Traps light energy from the sunn
What are enzymes
Controls the series of photosynthesis reactions
What energy is found in ATP
Chemical energy
What is the limiting factor on a sunny day in winter
Temperature
What is light reactions
The first stage of photosynthesis in which water is split
What is ATP
An energy rich molecule synthesised during the light reaction
What is the limiting factor in a cloudy day
Light intensity
What carbohydrate is used to make cell walls
Cellulose
What byproduct of water splitting diffuses out of the leaf
Oxygen
What is a chloroplast
A leaf organelle which is the site of photosynthesis
When is growth maximum
When there are no limiting factors
What is produced by water splitting and combines with carbon dioxide to produce glucose
Hydrogen
What is growth
The increase in biomass of living things which can provide food for other organisms
What are resources
All the things needed by an organism or population to survive e.g food water shelter, nutrients etc.
What is a pyramid of numbers
A diagram with the width of each bar representing the number of organisms at that trophic (feeding) level
What is all the energy in living things eventually converted into
Heat
How can energy be lost in a food chain
Heat, movement, undigested waste
What is the form of energy in food
Chemical
What is intraspecific competition
When individuals from the same species compete for all required resources
It is more intense
What is interspecific competition
Competition between individuals of different species for one or a few resources required
What is a pyramid of energy
A diagram with the width of each bar representing the total energy contained in the organism at that trophic (feeding) level
What are 2 reasons why the human population continues to increase rapidly
Humans have no natural predators
Healthcare has greatly improved
What is competition
The interaction between organisms of the same species when both require the same limited resource
What are nitrates
Used to produce amino acids which are synthesised into plant proteins
Animals consume plants or other animals obtain amino acids for protein synthesis.
Describe the nitrogen cycle
Nitrates are used to synthesise amino acids
Plant protein is synthesised
Animals consume plants or other animals to obtain amino acids for protein synthesis
The animals die and decomposes elf bacteria or fungi break it down.
Describe eutrophication
Fertilisers are added to soil and leach into fresh water
Algal blooms form due to increase in nutrients
Algal blooms stop sunlight from reaching the plants below the water
The plants are killed as they cannot photosynthesise. Algal blooms also die as they run out of nutrients
Bacteria use the dead algae and plants as food, this causes the bacteria to increase in number.
The bacteria use up MOST of the oxygen. This reduces the oxygen that is available for the other organisms
With little oxygen available, the animals int he fresh water die
Why are fertilisers used
To increase levels of essential plant nutrients that aren’t replaced naturally
What is bioaccumulation
The build up of toxic substances e.g pesticides in living organisms.
How did DDT effect bird populations
Birds eggs were too thin because it was difficult for the birds to absorb calcium due to the use of the insecticide. The chicks were then hatching prematurely leading to a premature death.
3 advantages of GM crops
They are more productive, therefore creating a larger yield.
Could provide more flavour and nutrition
Foods are more pest resistant and stay ripe for longer, so they can be shipped longer distances and kept on shop shelves for longer
3 arguments against GM crops
Herbicide and pesticide resistant crops could give rise to super weeds and pests, that would lead to newer stringer chemicals needing to be used.
They could cross-pollinate with non-gm crops which could cause ecological problems. If this were to happen to crops containing vaccines, antibiotics etc it could cause a human health nightmare.
Scientists can choose the gene to manipulate but don’t know where in the DNA to insert it, which could lead to drastic changes with unpredictable results.
4 advantages of biological control
There are no problems of chemicals contaminating the environment or food chain.
Predator is specific to pest, meaning biodiversity may not be reduced
After initial set up cost, it may be much cheaper
Most pests do not become resistant to the treatment so can be used year after year
4 disadvantages of Biological Control
Some of the introduced predators have become pests themselves, e,g the cane toad
It doesn’t work well in large unconfined spaces, as the predators can leave the environment
It can be initially very expensive due to high developmental costs
Not all the pests will be killed, some will remain and still cause damage, meaning pesticides may still need to be used.
what are algal blooms
sudden excessive growth of microscopic algae due to the increased nutrient levels
what are GM crops
genetically modified plants which have had their genetic material altered to give them desirable qualities or remove undesirable ones
what is nitrogen
an element which is the most abundant gas on the planet and is an important part of every protein
what is biological control
the use of natural predators or parasites to limit the population of a pest species
what is leaching
when soluble substances in the soil dissolve and are gradually washed into fresh water e.g rivers and lochs, by the rain
what are nitrates
a chemical containing nitrogen and oxygen which is soluble in water and easily taken up by plant roots to use in making proteins
what are pesticides
a chemical used to kill pests, they are often insecticides (to kill insects) or herbicides (weed killers)
what is mutation
a random change to genetic material. it can be a change to the DNA or the whole chromosome
how can the rate of mutation be increased
the rate of mutation can be increased by mutagenic agents
what are the 2 different mutagenic agents and their examples
radiation- gamma rays, x-rays, UV light
chemicals- colchicine, mustard gas, agent orange, benzene
what 3 things can Mutations do
confer an advantage
confer a disadvantage
have no effect- neutral
what is produced from mutation and what do they do
new alleles, which can result in animals and plants being better adapted to their evironment
what does variation do
variation within a population makes it possible for a population to evolve over time in response to changing environmental conditions
what is an adaptation
an inherited characteristic that makes an organism well suited to survival in its environment/ niche
these adaptations can be structural or behavioural
what are the kangaroo rats behavioural adaptations
-active at night because the temperatures are cooler
-remains in underground burrow and is inactive during the day
what are the structural adaptations of the desert plant
-thick, waxy cuticles to reduce water loss
-water stored in succulent tissues
-leaves reduced to spines to reduce leaf surface area and decreasing water loss
-long roots to reach deep water
-superficial roots which grow parallel to the soil to absorb maximum water
what are the structural adaptations of darwins finches
different shape and sizes of beaks so that the birds can eat different foods
small pointed beaks to pick insects out of tree bark
big, blunt beaks to break open the coatings and shells of nuts and seeds
what is natural selections
the survival of the organisms that are best adapted to their environment. those with a favourable characteristic will have a selective advantage and survive.
describe natural selection
- sexual reproductions produces many offspring
- inherited variation means that organisms are different from each other
- struggle for survival- due to disease, inability to compete for scarce food or other resources, predation, abiotic environmental conditions
- survival of the fittest
- mating and offspring produced favoured forms of genes- alleles passed on
- offspring struggle for survival again
- survival of the fittest to pass on characteristics (alleles) to next generation
why does survival of the fittest happen
because species produce more offspring than the environment can sustain
when does natural selection occur
when there are selection pressures
what happens to alleles during natural selection
they increase in frequency within the population
what is speciation
the formation of new species, due to mutations and natural selection
describe speciation
- large freely interbreeding population of one species
- isolation by barrier, could geographical, ecological or behavioural
subpopulation A barrier Subpopulation B - mutations arise in both populations (some of these confer selective advantage)
- natural selection over a very long time
- barrier removed
- not interbreeding to produce viable offspring occurs between members of 2 populations- because 2 different species have arisen i.e speciation has occured
what is the order of mutation, natural selection and isolation
isolation
mutation
natural selection
examples of geographical barriers
river, desert, sea, mountain range
examples of ecological barriers
difference in temperature, humidity, pH
example of behavioural barrier
different mating dances
what does it mean when an organism is isolated
when 2 groups are seperated so that they cannot exchange genetic material between the groups- they cannot breed with eachother
how is energy passed on in a food chain
growth
