19) Ecology (4.5) Flashcards
1.1. What is the principal source of energy input to biological systems?
The Sun
1.2. Describe the flow of energy through living
organisms
Light energy from the Sun flows to the first trophic level
Producers convert it to chemical energy, which flows from one consumer to the next
Eventually all energy is transferred to the environment; some energy is used and lost at each stage
Non-cyclical process; once energy gets to the top of the food chain/web, it is not recycled but “lost” to the environment
2.1 Describe a food chain
It shows the transfer of energy from one organism to the next, beginning with a producer
2.3 Describe a food web
A network of interconnected food chains and interpret food webs
2.4 Describe a producer
An organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis
2.5 Describe a consumer
An organism that gets its energy by feeding on other organisms
2.6. How may consumers be classed according to their position in the food chain?
Primary, secondary, tertiary and quaternary
2.7. Describe a herbivore
An animal that gets its energy by eating plants
2.8. Describe a carnivore
An animal that gets its energy by eating other animals
2.9. Describe a decomposer
An organism that gets its energy from dead or waste organic material
2.12 Discuss the advantages of using a pyramid of biomass rather than a pyramid of numbers to represent a food chain
2.13. Describe a trophic level
The position of an organism in a food chain, food web or ecological pyramid
2.16. Discuss the advantages of using a pyramid of energy rather than pyramids of numbers or biomass to represent a food chain
2.17. Explain why the transfer of energy from one trophic level to another is often not efficient
2.18. Explain, in terms of energy loss, why food chains usually have fewer than five trophic levels
2.19. Explain why it is more energy efficient for humans to eat crop plants than to eat livestock that have been fed on crop plants
3.1. Describe the carbon cycle
Photosynthesis:
Respiration:
Feeding:
Decomposition:
Formation of fossil fuels:
Combustion:
3.2. Describe the nitrogen cycle
Decomposition of plant and animal protein to
ammonium ions:
Nitrification:
Nitrogen fixation by lightning and bacteria:
Absorption of nitrate ions by plants:
Production of amino acids and proteins:
Feeding and digestion of proteins:
Deamination:
Denitrification:
3.3. State the roles of microorganisms in the nitrogen cycle
Decomposition:
Nitrification:
Nitrogen fixation:
Denitrification:
4.1. Describe a population
A group of organisms of one species, living in the same area, at the same time
4.2. Describe a community
All of the populations of different species in an ecosystem
4.3. Describe an ecosystem
A unit containing the community of organisms and their environment, interacting together
4.4. Identify and state the factors affecting the rate of population growth for a population of an organism
Food supply
Competition
Predation
Disease
4.5. Identify the lag, exponential (log), stationary and death phases in the sigmoid curve of population growth for a population growing in an environment with limited resources
4.7 Explain the factors that lead to each phase in the sigmoid curve of population growth, making reference, where appropriate, to the role of limiting factors
Lag: organisms adapt to the environment before they are able to reproduce. There are few organisms so reproduction is not producing larger numbers of offspring
Log (exponential): food supply is abundant, birth rate is rapid, death rate is low. Growth is exponential and only limited by the number of new individuals that can be produced
Stationary: population levels out due to a factor, such as a nutrient, becoming limited as it is not being replenished. Birth and death rates are equal until the nutrient is replenished or severely limited
Death: population decreases as death rate is now greater than birth rate, usually because food supply is short or metabolic wastes produced have built up to toxic levels
