Ch 19 - (Organisms and the environment) Flashcards
What is the main principal source of energy?
The sun
how does energy flow through organisms?
- Light energy from sun and chemical energy in organisms
- energy is transferred to the environment as heat
what does a food chain?
Transfer of energy from om organism to organism
What do arrows in the food chain show?
Transfer of energy from one trophic level to another
How is energy transferred from one organism to another?
Ingestion
define producers
- organisms that produce their own organic nutrients usually using energy from sunlight
Define herbivore
animal that gets its energy from eating plants
Define carnivore
an animal that gets its energy by eating other animals
Define primary consumers
herbivore - they feed on producers (plants)
Define secondary consumers
predators that feed on primary consumers
Define tertiary consumers
predators that feed on secondary consumers
Define decomposers
Bacteria and fungi that get their energy from feeding off dead and decaying organisms and undigested waste
What is a food web?
Network of interconnected food chain
What does a food Web show?
- Show connections between organisms
- animals rarely exist on just one type of food source
- show interdependence on how a specie affects another
Why do most change in populations happen?
- human impact
- overharvesting of food species
- introduction of foreign species to a habitat
What do change in population do die to interdependence?
Long lasting knock on effects
What does a pyramid of numbers show?
How many organism there are are
What does the width of a box show in a pyramid?
Number of organisms
Why may some pyramids not be pyramid shaped?
Size of organism is also important
What are the rule to remember when drawing a pyramid of numbers
- You cannot change trophic levels of organisms
- Larger an individual organism is, the less of them there are
What does pyramid of biomass show?
how much mass the creatures at each level would have without including all the water that is in the organisms
How are biomass pyramids like, and why?
- ALWAYS pyramid shaped
- cuz mass of an organism has to decrease as you go up a food chain
- provide better idea of quantity
How is energy passed on?
Has to be consumed (eaten)
What happens to energy in energy of pyramids?
- not all of the energy grass plants receive goes into making
- only the energy that is made into new cells remains with the organism to be passed on
Is the energy that is made into new cells consumed?
- No
- energy is stored in these parts and so it does not get passed on
What is majority of energy in an organism used?
- making waste products
- as movement
- as heat
- as undigested waste
How is the human energy transfer in food chain?
- omnivore
- choice of what we eat
- impact on what we grow
What nutrients does the carbon cycle involve?
Carbon and nitrogen
- recycled
What happens to carbon in the cycle?
- Carbon is taken out of the atmosphere in form of CO2 for plants to be sued in photosynthesis
- passed onto organisms by feeding
- returned as CO2 thru respiration
- decomposed dead organisms form fossil fuels
- burnt fossil fuels releases CO2
What are the main issues causing an increase in CO2?
- increased use of fossil fuels
- mass deforestation by reducing the amount of procedures
What is nitrogen?
An element required to make proteins
Why can’t plants or animals absorb N2?
- very stable
- cannot be broken down
what are 2 ways that nitrogen can be converted into a usable form?
- Nitrogen fixing bacteria - lives in the soil
- Lightening - splits the bonds between N and turns into nitrous oxide
Explain how nitrogen is transferred?
- plants absorb nitrogen in form of nitrates from soil
- animals eat plants, so it is passed up by food chain
- waste send nitrogen out of the body
- waste and dead species decay and nitrogen group is broken into ammonia
- plants can’t absorb ammonium compounds so nitrifying bacteria concerts it to nitrites then nitrates
What does denitrifying bacteria do?
- takes nitrates out of soil
- reduces soil fertility
Define population.
A group of organisms of one species living in the same area at the same time
Define a community
All of the populations of different species in an ecosystem
Define an ecosystem.
a unit containing the community of organisms and the environment interacting together
What do all living organisms compete with each other for?
Flood, water and living space.
What are the 3factors required for population growth?
- Food supply
- Predation
- Disease
What are the 4 stages of a population growth curve?
- Lag phase
- Log phase (exponential phase)
- Stationary phase
- Death phase
What happens in lag phase?
- organism adapting to the environment
-
What happens in log phase or exponential phase?
- food supply is abundant
- birth rate is rapid
- death date is low
- growth is exponential
What happens in stationary phase?
- populations level out
- due to nutrient factor in environment
- birthrate becomes limited
What happens in death phase?
- population decrease
- food supply is short
- metabolic waste produced by population builds up to toxic levels
What are organisms in a natural environment unlikely to show rapid growth unlike sigmoid growth curve?
Other factors
What’s re the factors that’s effect population growth
- changing temperature or light
- predators
- disease
- immigration (individuals moving into area)
-emigration (individuals moving out of area)
