The Organism in the Environment Flashcards
All 23 cards in this deck
What is a population?
All the organisms of one species living in a habitat at one time.
What is a community?
All the populations of different species living together in a habitat.
List the levels of organisation in ecology, from lowest to highest.
Individual organism → population → community → ecosystem.
What is a habitat?
The place where an organism lives.
What is an abiotic factor? Give two examples.
A non-living factor in an ecosystem, e.g. temperature and light intensity.
What is a biotic factor? Give two examples.
A living factor in an ecosystem, e.g. competition and predation.
True or false? Predation is an abiotic factor.
False. Predation involves living organisms, so it is a biotic factor.
Name the instrument used to measure light intensity in field-work, and its units.
A light meter (lux meter); light intensity is measured in lux.
What is interdependence in a community?
Species depend on each other for things such as food, shelter, pollination and seed dispersal, so a change in one population affects others.
Hedgehogs eat slugs and earthworms. If slug pellets kill the slugs, what happens to the earthworm population and why?
It decreases, because more earthworms will be eaten by hedgehogs (hedgehogs have only one food source left).
Slugs and caterpillars both eat lettuce. Why does the number of caterpillars increase when slug numbers fall?
There is more food (lettuce) for the caterpillars to eat because fewer slugs are eating it.
True or false? If the number of prey falls, the predator population will usually fall too.
True. There is less food for the predators, so fewer survive.
What is parasitism?
A relationship where the parasite lives in or on its host and feeds off the host, benefiting while the host is harmed.
When a tick burrows into human skin, the tick benefits and the human is harmed. What is the tick classed as?
A parasite.
What is mutualism?
A relationship between two species in which both organisms benefit.
An oxpecker eats ticks living on a zebra. Name this type of relationship and state the benefit to each organism.
Mutualism: the oxpecker gets food (ticks) and the zebra has its parasites removed.
What is the equation for the mean number of organisms per quadrat?
mean number per quadrat = total number of organisms counted ÷ number of quadrats
How do you estimate the total population of an organism in an area from quadrat data?
Multiply the mean number of organisms per quadrat by the total area in .
What are the steps to use a belt transect to investigate how light intensity affects plant growth?
e.g. stinging nettles at the edge of a wood
- Lay a tape measure in a line at 90° from the edge of the wood.
- Place a quadrat against the line and measure light intensity with a light meter.
- Record the growth of the nettles (e.g. height or number of plants) in the quadrat, then move along the line and repeat at different distances.
Give two ways to improve the quality of data from a quadrat sampling investigation.
Use more (or larger) quadrats and sample other areas of the habitat; also repeat on different dates and calculate a mean.
True or false? Quadrats should be placed where you can see the most organisms.
False. Quadrats must be placed randomly so the sample is representative and unbiased.
What is an ecosystem?
All the organisms living in an area (the community) together with the abiotic (non-living) parts of their environment.
What is a belt transect used to investigate?
How the distribution or abundance of a species changes across a habitat along a gradient in an abiotic factor, e.g. light intensity from shade into full sun.