Man and his environment Part 1 Flashcards
Population
A group of organisms of the
same species living together
in a particular habitat.
Community
A group of populations
that live and interact
with one another in a
particular habitat.
Ecosystem
A community of organisms interacting with one another and with the abiotic environment.
Habitat
The place
where an organism lives
What do organisms need to survive
• All organisms require energy and nutrients for growth,
maintenance, reproduction and locomotion.
Whats a food chain
A linear network of links in which
organisms transfer energy by eating and being eaten.
Food web
All possible feeding relationships in a community.
• Made up of a network of food chains in an ecosystem.
Describe relationship between Predator and prey
• Population of prey is high → A lot food for predators →
Predator population ↑.
• Population of predator is high → Prey are killed faster
than they can reproduce → Prey population ↓
• Less food (prey) is available → Predator population ↓.
• Predator population is low → Prey population recovers
and ↑ again.
• Predator now have more food (prey), predator
population ↑ again.
Describe Parasite-Host relationship
• An organism (parasite) depends on another
organism (host) for food, harming it and possibly
causing death.
• The parasite lives on or in the body of the host.
Producer-Consumer relationship
Producers/Autotrophs use sunlight or chemical
energy to manufacture complex organic materials
from simple inorganic molecules.
Consumers/Heterotrophs cannot make their own
food, thus feed on plants and animals for food.
What do decomposers do and are they consumers
Decomposers are consumers. They break down organic materials
externally into simple molecules and absorbed e.g.
fungi, bacteria
What do consumers get from eating other organisms and how are they used
By eating other organisms, consumers gain a source of
energy (ATP from cellular respiration) and biomolecules
from the food ingested.
• The energy is used to carry out cellular processes.
• The biomolecules are used to build new biomass of the
consumers, resulting in growth.
How does energy flow in a food chain
Energy flows in one direction in a food chain. It is
linear or non-cyclic.
How is energy lost in food chain
Organisms use energy for life processes e.g. cell division,
photosynthesis, cellular respiration, active transport.
• Exothermic chemical reactions release energy as heat
How much energy is passed on to next trophic lvl
10%
Why are food chains short?
• As you move up a food chain, both the energy
available and biomass decrease.
• As less energy becomes available to the higher
trophic levels, they can sustain a smaller population
of individuals (hence smaller biomass).
Biomass
The total amount of organic matter in
living organisms in a given area or ecosystem.
Whats an ecological pyramid
a diagram that shows the relative
amount of energy or biomass or organisms contained
within each trophic level of a food chain or web
How can the pyramid of no. be inverted
Pyramid may be inverted if
• Consumer is parasitic
• Producer is a single large organism
Advantages of Pyramid of no.
Data easy and fast to collect
using sampling counts.
Good for comparing changes
in ecosystem at different
times of the year
Disadvantages of pyramid of no. (3)
Numbers may be too large
to measure accurately.
Producers may vary in size. Pyramid may be inverted if consumer is parasitic, or producer is a single large organism.
Does not take into account
juvenile or immature forms.
Pyramid of biomass
show the total mass of organisms at each trophic level at a
particular time.
It takes into account the size of the organism
How find biomass
There are 1000 rabbits in a given area at one time.
• Anaesthetise 10 rabbits, then kill them.
• Dry the dead rabbits in an oven at 100°C until a
constant mass is obtained (to remove water).
• Multiply the mass by 100
How explain inverted pyramid of biomass of phytoplankton as producer
Pyramid of biomass does not take into account the rate of
reproduction (productivity) and rate of consumption of organisms.
• Phytoplankton reproduce quickly enough to replace the individuals
consumed by zooplankton.
