Ecology Flashcards
Outline what is meant by the trophic level of an organism with three examples from one named habitat.
(4 max)
- feeding level for an organism in a food chain
- naming of habitat
- naming three trophic levels correctly
- three examples forming a food chain from the named habitat
Compare the ways in which autotrophic, heterotrophic and saprotrophic organisms obtain energy.
(6 max)
autotrophs use an external / non-organic energy source
(reject statements suggestion that energy is made)
(some) autotrophs use light / (some) autotrophs use photosynthesis
(some) autotrophs use inorganic chemical reactions / (some) autotrophs use chemosynthesis
heterotrophs obtain energy from other organisms
heterotrophs (usually) ingest food / consume food
saprotrophs obtain energy from non-living matter / dead organisms
saprotrophs digest organic matter extracellularly
Draw a labelled sigmoid population growth curve.
4 marks
x-axis (time) and y-axis (number in population/of individuals) correctly labelled; (do not accept growth on y-axis)
S curve correctly drawn;
lag phase;
exponential/log phase;
population growth slowing down / transitional phase / environmental resistance;
plateau phase;
Apply the concept of carrying capacity to the struggle for survival resulting from overproduction of offspring.
(5 max)
- the environment can only support a certain maximum population
- this population is sometimes exceeded (due to overproduction of offspring)
- food / space / resources are insufficient / competition for resources
- some individuals fail to obtain enough
- deaths / failure to reproduce / survival of the fittest
- population falls to carrying capacity
- reference to evolution by natural selection
Outline the international system used for naming species of living organisms.
(4 max)
binomial system
devised by Linnaeus
the first name is the genus name
the second name is the species name
genus name can be abbreviated
genus consists of a group of (closely related) species
upper case for first letter of genus name and the rest of the binomial is lower case
Citrus sinesis / other example
first published name is the correct one
local / colloquial names can be very confusing / helps international communication
Discuss the definition of the term species.
(8 max)
a species is a group of organisms
a species shares a common gene pool
showing similar morphology / characteristics
capable of interbreeding
and producing fertile offspring
but dissimilar organisms sometimes interbreed
mule formed by crossing horse and donkey / other example of interspecific hybridisation
interspecific hybrids are sometimes fertile
sometimes organisms that are very similar will not interbreed
Drosophila pseudoobscura and persimilis / other example of sibling species
reference to the problem of defining fossil species
reference to the problem of species that only reproduce asexually
reference to the problem of isolated populations gradually diverging
Name the levels and the specific taxa in the hierachy of classification using humans as an example.
(2 marks)
(Kingdom) Animalia
(Phylum) Chordata
(Sub-phylum) Vertebrata
(Class) Mammalia
(Order) Primata
(Family) Hominidae
(Genus) Homo
(Species) sapiens
Describe the relationship between the rise in the concentration of atmospheric carbon dioxide and the enhanced greenhouse effect.
5 marks
CO2 is a greenhouse gas;
increases in CO2 increase/enhance the greenhouse effect;
greenhouse effect is a natural phenomenon but not its increase;
Earth receives short wave radiation from the sun;
reradiated from Earth as longer wave radiation/infra red/heat;
CO2 /greenhouse gases trap/absorb longer wave radiation/infra red/heat;
global warming happened during same time/period as CO2 rise;
CO2 concentration correlated (positively) with global temperature / global temperature
increases as CO2 concentration increases;
(causal) link accepted by most scientists;
no proof that man-made increases in CO2 have caused global warming;
Outline the consequences of a global temperature rise on arctic ecosystems.
melting of permafrost;
disturbance to food chains/webs/trophic levels;
increased detritus decomposition;
expansion of temperate species / reduced range for arctic species;
changes in distribution of prey species affecting higher trophic levels
increased success of pest species, including pathogens
rise in sea levels;
change in climatic patterns;
loss of ice habitat;
Outline the structural differences which characterize bryophytes, filicinophytes, coniferophytes and angiospermophytes.
9 marks
bryophytes
small plants
no true stems or leaves
rhizoids only
dominant plant is haploid / is the gametophyte
spores produced in a capsule
non-vascular / lack of xylem and phloem
filicinophytes
seedless
vascular tissues / xylem and phloem
roots
leaves and stems
spores produced in clusters / spores usually produced under the leaves
prothallus / small gametophyte / gametophyte grows independently
coniferophyta
seeds not enclosed in ovary / pericarp / fruit
pollen and ovules
cones
often have narrow leaves / thick waxy cuticle
vascular tissue / xylem and phloem
angiospermophytes
flowers / flowering plants
ovules / seed are enclosed
fruits
xylem vessels
Briefly explain Darwin`s theory of evolution.
4 marks
parents produce more offspring than survive
there is competition among members of a species for survival/struggle for existence
species show variation
certain variations will give a selective advantage/survival of fittest
depending on environment
these variations will be passed on to the next generation
leading to change in allele frequency
Outline five types of evidence which support the theory of evolution by natural selection.
6 marks
geographic distribution
ring species/other evidence from geographical distribution
biochemistry
cytochrome c/other biochemical evidence
fossils/paleontological
fossilized horse ancestors/other evidence
homologous structures
pentadactyl limb/vertebrate embryos/other
recent observed evolution
resistance to antibiotics/insecticides/heavy metal tolerance/other recent example
Outline one modern example of observed evolution by natural selection.
2 marks
named example
selective pressure
result
example
beaks of Galapagos finches
competition for food
change in numbers/proportion of birds with different sized beaks
Explain the evidence from homologous anatomical structures that supports the theory of evolution.
6 marks
homologous structures are various different structures of the same basic plan
derived from a similar embryonic origin
variations on the basic structure allow different functions
permitting exploitation of differnt ways of life/adaptive radiation
the suggests divergence from a common ancestor
named example of a homologous structure (e.g. pentadactyl limb, flower, birds` beaks)
description of basic structure of this example
variation related to different functions of this example
Outline how antibiotic resistance in bacteria can arise in response to environmental change.
5 marks
antibiotic resistance can be inherited;
alleles for resistance can be passed from one cell to another by exchange of
plasmids/conjugation;
some varieties are more resistant than others;
bacteria reproduce very rapidly and have high mutation rate;
evolution can occur rapidly;
increased exposure to antibiotics is the environmental change that selects for resistant varieties;
for example, in hospitals / animal feed / inappropriate prescriptions / not finishing prescriptions;
bacteria without resistance die / resistant bacteria survive and pass on genes to next generation;
results in change in genetic makeup of population;
