Mod 3: Effects of the environment on the organism Flashcards
define ecosystem
the combination of organisms (biotic factors) living in an area that interact with each other and the abiotic factors in which they live in
What are environmental pressures?
a change in the environment that often results in some resources becoming limited, and individuals have to compete for the limited resources
how are quadrats used to measure plant abundance? (provide formula)
it is a sampling technique
total number of individuals counted
——————————————————— X total area
area of quadrats x number of quadrats
What are the advantages and disadvantages of the quadrat method?
advantages:
-easy and cheap
- minimal disturbance to the environment
- quadrats can also be used for determining the distribution of species along a transect
disadvantages:
- only suited for plants and slow moving animals
how is the captured-recaptured technique use dot measure animal abundance? (provide formula)
animals are captured and then tagged before getting released back into their environment.
recapture animals to look at proportion of animals marked from the first capture
insert values into formula:
no.captured x no.recaptured/no.marked in recapture
what happens to organisms if environmental pressures in a habitat change?
individuals with the characteristics best suited to the changed natural pressure will survive and reproduce offspring with the characteristic/s that helped them survive in the new environment
individuals without the characteristic will eventually die out
What are the types of adaptations?
structural, behavioural, physiological
What is a structural adaptation?
(provide an example)
it is a physical feature of an organism that helps it survive in its environment
eg. camel humps store water and fat (energy)
What is a behavioural adaptation?
(provide example)
It is the way an organism behaves due to their environment for their survival
eg. desert animals are usually nocturnal so they conserve energy
What is a physiological adaptation?
The function of a organism that helps them survive in their environment
eg. some animals survive hot summers by reducing their metabolic rate
Explain how Darwin related adaptations and natural selection through finches
Darwin analysed the finches in the Galapagos Islands and observed that the shape of the finches’ beaks depended on what their environment was like and what food was accessible for them.
He proposed that there were originally a few finches with variation on the islands and as time passed on, they dispersed. Finches with the favourable adaptation for their environment would survive and reproduce. Those without adaptation would die out.
Define genetic diversity
total no. of genetic characteristics in the genetic make-up of a specie
Define species diversity
measure of the diversity of different species in an ecological community
Define ecosystem diversity
the variation of different ecosystems found in a region
What is the importance of genetic diversity?
Populations with more genetic diversity have a smaller risk of getting wiped out by one threat.
Due to the high diversity, what may kill some organisms may not be affective when killing other organisms with varied genetics
Define speciation
the formation of a new and distinct species
define palaeontology
the scientific study of fossils
List the physical and chemical abiotic factors of an environment
Physical: temp, availability of water, light, wind, slop, slides
Chemical: gases (O2, CO2), pH levels, concentration of other chemicals (salts and metals)
define macroevolution
evolution over very long periods of time - over millions of years where new species are formed (allegedly)
define microevolution
evolution that takes place over shorter periods of time and results in changes WITHIN POPULATIONS (not producing new species).
define convergent evolution
distantly related species form similarities due to experiencing the same environmental pressures
define divergent evolution
closely related species become different due to experiencing different environmental pressures.
define gradualism
population slowly diverge by accumulating changed in characteristics due to different environmental pressures which suggests that transitional forms (fossils) should exist
define punctuated equilibrium
proposes the idea that evolution happens in short bursts of rapid change, followed by longer periods of stability (no change)
