Life On Earth test Flashcards
Abiotic factors
(Non - living factors) -ph, temperature, soil moisture, humidity, rainfall, light intensity
Biotic factors
(Factors linked to living things) -grazing, predation, food availability, disease, competition
Direction of energy flow
Producer (plant) ➡️ primary consumer (herbivore) ➡️ secondary consumer (omnivore/carnivore) ➡️ tertiary consumer (top carnivore)
Niche
A niche is the role that an organism plays within a community
Interspecific competition
Interspecific competition occurs amongst individuals of different species for one or a few resources they require
Intraspecific competition
Intraspecific competition occurs amongst individuals of the same species and is for all resources required. It is therefore more intense competition than Interspecific
Photosynthesis word equation
Carbon dioxide + water, arrow with light energy above arrow and chlorophyll bellow arrow, then glucose + water
Stages of photosynthesis
Stage 1 photolysis OR KNOWN AS light reactions
Stage 2 carbon fixations
Stage 1 photosynthesis diagram
Draw on whiteboard
Stage 2 photosynthesis diagram
Draw on whiteboard
Uses of sugar in photosynthesis
- Respiration
- Structural carbohydrate (used for cell walls) = cellulose
- Converted into storage carbohydrate = starch
Limiting factors
- Light intensity
- Carbon dioxide concentration
- Temperature
Limiting factor graphs
Do some examples
Paired statement key
Do some examples
How is energy lost in food chains
- Heat
- Movement
- Un digested waste
Pyramid of numbers
Shows total number of organisms at each stage in a food chain
- Draw one for grass, rabbit, fox
- isn’t always a pyramid shape
- eg draw oak tree, greenfly, ladybird, small bird.
Pyramid of energy
Shows energy available at each stage of food chain
- always pyramid shaped
- goes produces, primary consumer, secondary consumer
Food yield
An increased food yield is required due to the increased human population
Pesticides
The use of pesticides to kill plants and animals deciding crop yield
- some pesticides are not biodegradable and result in remaining in soil/rivers/lochs for a long time and will build up in body’s of organisms over time. These toxins are passed along food chains so when one organism eats an intoxiniated animal it will increase there toxicity. This is called bioaccumulation
- ddt is a lethal example of bioaccumulation
The nitrogen cycle
Draw this
Leaching
The fertiliser added to an area can run off in nearby body’s of water. This increases nitrate levels and algsl bloom forms, blocking light and killing any green plants. When the water cannot sustain such a large algae population it dies. The dead algae provides a huge food dource for bacteria. The bacteria reduces huge amounts of oxygen killing any left over organisms
Fertilisers
Fertilisers are added to land to increase the levels of essential plant nutrients that are used up by the growing plants/crops and not replaced by natural nutrient cycling due to the removal of the crop. So farmers ass nitrogen to the soil in the form of synthetic fertiliser, manure or compost.
Biological control
Biological control can be used as an alternative method to pesticide. This involves the introduction of a predator to prey on a pest species. An example of a biological control is using ladybirds to control greenfly populations.
Gm crops
Genetically modified crops are crops which have had their genome altered. This change can enable the crop to produce a chemical that is harmful to the pest but should not be harmful to humans, there has however been some controversy over the use of gm crops
Mutation
Mutations are caused by a random change to an organisms genetic material.
Environmental factor such as radiation or chemicals can increase mutation rate
Natural selection
New alleles produced by mutation can result in plants and animals becoming better adapted to their environment. As the environment changes constantly variation allows a population to evolve over time in response to the change.
This is also known as survival of the fittest
Speciation
-population to interbreed freely
-barrier placed
-different mutations occur in each sub population
- natural selection occurs within the sub populations
-each sub population evolves until even the barrier is removed, the sub populations can no longer breed to produce fertile offspring - speciation has occurred
Isolating mechanisms
The isolating mechanisms or barriers that split a population can be geographical (mountains/rivers) THE EXAMPLE TO USE IN EXAM IS GEOGRAPHICAL, behavioural (differences in rituals ie breeding calls or mating dances) or ecological (different habitats, PH or salinity
