Unit 19 - Organisms and their environment Flashcards
Forms of energy passing through organisms
Light energy from sun –> chemical energy
Energy lost in flow
heat energy + activities and processes e.g. growth
Process which energy is transferred by
Ingestion
Food chain
Shows the direction of energy from one organism to the next
Consumers
Organisms that get their energy by feeding on other organisms
Producer
An organism that makes its own organic nutrients usually from sunlight
Herbivores
Animals that get their energy by eating plants
Carnivores
Animals that get their energy by eating other animals
Decomposers
Organisms that get their energy from dead or waste organic material
Types of consumers
- Primary
- Secondary
- Tertiary …
- Depending on place in the food chain
Food web
A network of interconnected food chains to show multiple pathways of energy flow through an ecosystem
Overharvesting
Harvesting something excessively to a point that it gets depleted
Foreign species
A species not found naturally in an ecosystem
Trophic levels
Represent levels of energy transfer
Biomass of an organism
The total mass of an organism’s living material
Unit for biomass
g/m^2
Reasons why only 10% of available energy is transferred
- Not all the plant is eaten
- Energy is used to make inedible tissue
- Energy is lost as heat during respiration
- Energy lost as heat
- Energy lost as excretory products
- Energy used for biological activities
How carbon dioxide is removed from air
Photosynthesis - carbon dioxide becomes carbohydrates
Carbon in feeding
- Carbon is passed in compounds when feeding
- Proof is fossil fuels
How carbon dioxide returns into air
- Respiration
- Combustion
Four main carbon reservoirs
- Atmosphere
- Oceans
- Land biomass
- Fossil fuels
Processes involved in the carbon cycle
- Change to ecosystems - cutting down forests adds carbon dioxide to the air
- Fossil fuels - burning of fossil fuels adds carbon dioxide to the air
- Ocean/atmosphere - more carbon dioxide gas dissolves in the ocean than that that escapes into the air
- Respiration/photosynthesis - takes more carbon dioxide out of the air than that released by respiration & decomposition
- Rocks - Manufacturing of cement changes carbon in rocks to carbon dioxide
Uses of nitrogen
- Air
- Liquid nitrogen
- Amino acids & proteins
- Substances that organisms can use e.g. nitrate ions
Nitrogen fixation
Converting atmospheric nitrogen into substances that plants can absorb e.g. nitrates
Two methods of nitrogen fixation
- Lightning - nitrogen gas molecules combine with oxygen gas in the air to make nitrogen oxides that dissolve in rainwater and are washed into the soil
- Bacteria - bacteria live freely in soil and convert nitrogen gas in the air to ammonia
Denitrification
Converting nitrate ions into atmospheric nitrogen
Nitrification
Ammonium ions in the soil are converted to nitrate ions
- NH^4+ –> NO2 –> NO3
How nitrogen is returned to the environment from animals and plants
- Deamination in animals - nitrogen containing part of amino acids comes urea and is excreted
- Decomposition - decomposers break down plant and animal proteins and waste to make ammonium ions
Population
A group of organisms of one species, living in the same area, at the same time
Community
Consists of all of the populations of different species in an ecosystem
Ecosystem
A unit containing the community of organisms and their environment, interacting together
Factors that affect population size
- Food supply - increase food leads to increase, lack leads to decrease
- Predation - if predation is faster than breeding population decreases, fewer prey leads to less predators
- Disease - Reduce population sizes quickly
- Competition -
Four factors that determine how size of population changes
- Number of births
- Immigration
- Number of deaths
- Emigration
Stages of the sigmoid curve of population growth
- Lag phase - slow increase in population size when introduced to new environment
- Exponential (log) phase - resources are relatively plentiful - individuals reproduce at a high rate - exponential increase
- Stationary phase - resources are limited, population is at the carrying capacity of the environment, competition for resources
- Death phase - Rapid decrease in population caused by a change in the environment
Limiting factor / environmental resistance factors
Something that keeps a population from increasing in size
Carrying capacity
The maximum number of organisms that an ecosystem can support
