Unit 3 Flashcards
What is a niche?
The role an organism plays within a community
What are the factors that determines an organisms niche?
Habitat, feeding level, when active, interaction with other organisms
What are biotic factors?
Factors related to living things
What are abiotic factors?
Non-living or physical factors
Give an example of a biotic factor
Competition for food, space, mates. Number of predators. Disease. Grazing
Give an example of abiotic factors
Temperature, humidity, pH, light intensity, rainfall, wind
What could over grazing lead to?
Plant species being destroyed
What is predation?
The eating of one organism from another
What do predators keep down the numbers of?
Their prey
What is biomes?
The different regions of our planet as distinguished by their similar climate, fauna and flora
What can biomes be influenced by?
Temperature and rainfall
How can energy be lost in an ecosystem?
Heat movement, trapped in waste
In a food chain how much of the energy is lost between each animal?
90%
When an animal or plant dies what breaks it down?
Decomposers
What is a pyramid of biomass?
Represents the mass of each feeding level in a food chain
Which type of pyramid is the most accurate?
Pyramid of energy
Why do living things need nitrogen?
To form proteins
What can farmers do if the soil is low in nitrates?
They add it in the form of fertilisers
What is nitrification?
Bacteria converting ammonium compounds into nitrites then nitrates
What is denitrification?
Bacteria deprived soil of nitrogen by releasing gas into the air
What is nitrogen fixation?
Bacteria absorb and ‘fix’ nitrogen into nitrates for plants to absorb
What is intra specific competition?
Competition between members of the same species
What is the definition of a community?
All living things in an ecosystem
What is inter specific competition?
Competition between members of different species
What does competition help prevent?
Population of animal and plants becoming too large
What can competition be for?
Space, mates, food, water, light, shelter
What would plant in a large forest compete for?
Light, water, CO2, nutrients
Name two sampling techniques for biotic factors
Quadrat and pitfall trap
How does a quadrat work?
Laid out randomly on ground, plants and animals are counted
How does a pitfall trap work?
Animals fall into container
What is a pitfall trap for?
Sampling surface living animals
Why must samples be completely random?
To avoid any bias. Truly representative of the whole area being studied
How could you make your sampling technique more accurate?
Use better apparatus
How could you make your sampling technique more reliable?
Take more samples
What could be used to measure light intensity?
A light meter
A combined meter is used to measure what?
The water content and pH of soil
What do you have to do when using a combined meter?
Push probe to same depth and always clean between readings
What is a limitation of a pitfall trap?
Sample obtained may not be representative of the whole area
How could you prevent animals eating each other in a pitfall trap?
Don’t leave traps fro long periods of time before emptying
What are mutations?
Changes which alter the amount or structure of the genetic material in an organism
Do environmental factors increase or decrease the rate at which mutations occur?
Increase
What are environmental factors affecting mutations called?
Mutagenic agents
What can mutations result in for the organism?
An advantage or disadvantage (usually a disadvantage)
What type of mutation has no effect on an organism?
A neutral mutation
All members of a population shows what?
Variation
Without variation what would not be possible?
Evolution
What is adaption
A variation that makes an organism more likely to survive in its niche
When does natural selection occur?
When there are more animals than the environment can sustain
What is a species?
Organisms that can interbreed and produce fertile offspring
What is speciation?
The formation of a new species
What are the three types of isolation barriers?
Geographical, ecological, reproductive
What is being used to increase food yield?
Intensive farming
What are some of the things used in intensive farming?
Chemical fertilisers and pesticides, animals kept inside, competing plants removed
What is the definition of monoculture farming?
Growing a single crop over a large area
What are some advantages of monoculture?
Allows for more than one harvest per year, reduced labour costs
What are some disadvantages of monoculture?
Higher risk of disease, requires lots of fertilisers, biodiversity decreases
What are chemical fertilisers?
Chemicals added to soil to improve plant growth
What minerals are important to plant growth?
Nitrates and magnesium
What forms when fertilisers leach into fresh water?
Algal blooms
What are some of the impacts of algal blooms in fresh water?
Less light reaches plants, plant unable to photosynthesis, therefore reduction in oxygen levels in water
What are pesticides?
Chemicals sprayed onto crops to reduce completion from other organisms
What are the four types of pesticides?
Herbicides, fungicides, insecticides and bactericides
Why do pesticides have a negative effect on biodiversity?
Pesticides can accumulate in the bodies of organisms over time
What is bioaccumulation?
As you get higher up the food chai, the level of pesticides increases
As pesticides go up the food chain what increases?
Toxicity
What is biological control?
When a natural predator in introduced and it feeds on the pest
What is an alternative to using pesticides?
Biological control
Why is biodiversity a good alternative to using pesticides?
It is a cheaper method, natural and biodiversity is not reduced
What can cause harm to an ecosystem?
Pollution
What is an indicator species?
By its presence, absence or abundance shows the environmental conditions
What does the indicator species ‘fresh water invertebrates’ show?
Levels of pollution in fresh water
What does the indicator species ‘lichen’ show?
Levels of air pollution
