7. Ecology Flashcards
Define habitat
The habitat is the environment in which an organism lives in
Define population
A population is the total number of individual organisms of the same species living in the same geographical area
What is a community?
A community is made up of the populations of all the different species that live in the same habitat interdependently
e.g. the african grassland contains lots of species such as giraffes, zebras gazelles, as well as fungi and bacteria
Define the biotic part of the environment
The biotic part of the environment is the living part of the environment - the community
Define the abiotic parts of the environment
The abiotic part of the environment is the non-living parts of the environment
(e.g. amount of water, minerals in the soil)
Is the community the biotic or abiotic part of the environment?
The community contains all of the living organisms in an environment, therefore it is the biotic part of the environment
Define ecosystem
An ecosystem is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment
Describe the different levels of organisation in an ecosystem
- Individual Organism
- Population
- Community
- Ecosystem
Why do organisms need resources from both abiotic and biotic parts of an ecosystem?
In order to survive and reproduce
Why do organisms compete for resources?
Because the resources are finite and in short-supply - and all organisms need them in order to survive and reproduce
Give 4 resources that plants compete for
- Light
- Space
- Water
- Mineral ions in the soil
Give 3 resources that animals compete for
- Food
- Mates
- Territory
Describe interdependence
Interdependence is when different species depends on other species. For example: for food, shelter, pollination, seed dispersal etc.
If one species is removed it can affect the whole community.
Give 4 examples of things that species may depend on each other for?
- Food (e.g. Animals eat other species like other animals or plants)
- Shelter (e.g. Trees)
- Pollination (e.g. Bees to spread polllen)
- Seed Dispersal
Describe what a stable community is
A stable community is one where all the species and environmental factors are in balance so that population sizes remain fairly constant
List the 7 abiotic factors that can affect a community
- light intensity
- temperature
- moisture levels
- soil pH and mineral content
- wind intensity and direction
- carbon dioxide levels for plants
- oxygen levels for aquatic animals
Explain how light intensity is an abiotic factor that can affect a community
- Plants need light in order to carry out photosynthesis
- The light intensity affects the rate at which photosynthesis is carried out, which affects the rate of the growth of a plant
- This affects the food supply for animals and other species in a community as many rely on plants as a food source
If the light intensity is high:
- It increases the rate of photosynthesis, which means that plants and algae grow faster
- This means there is more of a supply of food to animals
If the light intensity is low:
- The rate of photosynthesis falls, which means that plants and algae grow slowly
- This means there may not be enough food supply for animals
Explain how temperature is an abiotic factor that can affect a community
- Different species of plants have different optimum temperatures for growth and survival and have different adaptations for temperature, so changes in the temperature of an environment could the distribution of species to change
- It is a limiting factor of photosynthesis, which means that it can affect the rate of photosynthesis, hence the rate of growth of a plant, and therefore the food supply for animals
- Also affects enzyme activity
Explain how temperature is an abiotic factor that can affect a community
- Different species of plants have different optimum temperatures for growth and survival and have different adaptations for temperature, so changes in the temperature of an environment could the distribution of species to change
- It is a limiting factor of photosynthesis, which means that it can affect the rate of photosynthesis, hence the rate of growth of a plant, and therefore the food supply for animals
- Also affects enzyme activity
Explain how moisture levels is an abiotic factor that can affect a community
- Plants and animals need water to survive, as without water there is no life
- Moisture is also required for decay in the soil to occur. Decay releases mineral ions in the soil, which plants can absorb
Explain how soil pH and mineral content is an abiotic factor that can affect a community
- Different plant species are adapted to different pHs, so the soil pH has a major effect on what plants can grow in the soil. (also as many plants cannot grow on soil that is too acidic or alkaline)
- A low soil pH also inhibits decay, which reduces the mineral ions in the soil which plants can absorb
- Different species of plants thrive in different nutrient concentration levels
Explain how wind intensity and direction is an abiotic factor that can affect a community
- It can affect the rate of transpiration in plants
- This can limit the distribution of plant species
Explain how carbon dioxide levels for plants is an abiotic factor that can affect a community
- Carbon Dioxide is needed for plants to photosynthesise, it is a limitng factor of photosynthesis
- This affects the growth of plants, which affects animal food supply
Explain how oxygen levels for aquatic animals is an abiotic factor that can affect a community
- Oxygen in the air is constant, but the level of oxygen in the water varies
- If the oxygen level in the water is too low, it can kill or harm aquatic animals that live in the water
List 4 biotic factors that might affect a community
- availability of food
- new predators arriving
- new pathogens
- one species outcompeting another so the numbers are no longer sufficient to breed