Topic 5 - Ecology and evolution Flashcards
What is a species?
A group of organisms that can interbreed and produce fertile offspring
What is a habitat?
The environment in which a species normally lives or the location of a living organism
What is a population?
A group of organisms of the same species who live in the same area at the same time
What is a community?
A group of populations living and interacting with each other in an area
What is an ecosystem?
A community and its abiotic environment
What is ecology?
The study of the relationships between living organisms and between organisms and their environment
What is an autotroph?
An organism that synthesises its organic molecules from simple inorganic substances
What is a heterotroph?
An organism that obtains organic molecules from other organisms
What is a consumer?
An organism that ingests other organic matter that is living or recently killed
What is a detritivore?
An organism that ingests non-living organic matter
What is a saprotroph?
An organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion
What is a food chain?
A sequence of trophic relationship, where each member in the sequence feeds on the previous one
Give three examples of food chains
- passionflower → heliconius butterly → tegu lizard → jaguar
- carrot plant → carrot fly → flycatcher → sparrowhawk → goshawk
- sea lettuce → marine iguana → galapagos snake → galapagos hawk
What is a food web?
A diagram that shows all the feeding relationships in a community.
What is a trophic level?
The position of an organism in the food chain
(producer → primary consumer → secondary consumer → etc)
What is the initial energy source for almost all communities?
Light
Describe the energy flow in a food chain
Are energy transformations ever 100% efficient?
No
What is a pyramid of energy?
A pyramid that shows the flow of energy from one trophic level to the next in a community
Why is the pyramid of energy pyramidal?
Because energy is lost at each trophic level and less energy remains for the next level
While energy enters and leaves ecosystems, what happens to nutrients?
They must be recycled
What organisms recycle nutrients?
Saprotrophic bacteria and fungi
Draw and label a diagram of the carbon cycle
What has happened to the concentration of atmospheric carbon dioxide?
It has gradually increased
What is meant by the enhanced greenhouse effect?
- Short wavelengths come from the Sun and pass through the atmosphere
- Sunlight warms up the surface of the Earth which emits long-wave radiation
- Greenhouse gases in the atmosphere trap some of the long-wave radiation, causing the earth to be warmer than if the radiation escaped
What have greenhouse gases done to the enhanced greenhouse effect?
They have increased its effect
Is the greenhouse effect a natural phenomenon?
Yes
What is the precautionary principle?
An idea of a policy, in which people planning to do something must prove that it will not do harm to the atmosphere before actually doing it
Is the precautionary principle qualified?
The risks are so great that yeah it should be followed.
Is there solid proof for greenhouse gases causing global warming?
Nope
What are the consequences of global warming on Arctic ecosystems?
- Glaciers will melt and polar ice sheets will break up into icebergs
- Permafrost will melt, increasing the rates of decomposition of trapped organic matter, which release CO2
- Species adapted to temperate conditions will spread north
- Marine species of animal in Arctic waters may become extinct because the water becomes too warm
- Polar bears and other animals will lose their ice habitat
- Pests and diseases may become more prevalent
- Sea levels will rise
- Extreme weather conditions
How is population size affected by natality, immigration, mortality and emigration?
Increase = natality and immigration
Decrease = mortality and emigration
What are the stages of an S-shaped population curve?
- Exponential growth phase
- the no. of individuals increases exponentially - Transitional phase
- growth rate slows down consistently - Plateau phase
- the no. of individuals is stabilised
Explain the reasons for exponential growth, transitional, and plateau phases in the population curve
Exponential phase
- Ideal conditions → population can double on a regular basis
- Plentiful resources (food, space, light)
- Little or no competition
- Favourable abiotic factors
- Little or no predation or diseas
Transitional phase
- With increasing population there is competition for resources
- Preadators start to move to the area (attracted by growing food supply)
- Diseases spread easily in a large population
Plateau phase
- Limited supply of food
- mortality + emigration = natality + immigration
Define carrying capacity, K
The maximum number of individuals that a particular habitat can support
List three factors that can limit population increase
- Availability of resources
- Predation
- Disease
Define evolution
The cumulative change in the heritable characteristics of a population.
Outline the evidence for evolution provided by fossil record
- Life which existed back then was very different from life today
- Even though Earth has had oceans for a long time, fish fossils have only been found 500 million years old or younger
- Today’s predators have not existed at the time of the dinosaurs or before
- Many organisms today have no identical form in the fossil record
Outline the evidence for evolution provided by selective breeding
By conducting selective breeding, certain varieties of animals show unique combinations of characteristics that have not existed in the earlier generations
Outline the evidence for evolution provided by homologous structures
- Anatomical structures which are similar in form and function have been found in dissimilar species
- E.g. five-fingered limb (pentadactyl limb) found in humans, whales, and bats
- Although functions may vary, the general format is the same in these structures
Do populations tend to produce more offspring than the environment can support?
Yes
What is the consequence of overproduction in populations?
Struggle for resources and survival (survival of the fittest)
How does cuckoo compete for resources?
It lays its eggs in other species’ nests and the newly hatched cuckoo chick pushes the other eggs down to get more to eat
Do members of a species show variation?
Yes
How does sexual reproduction promote variation?
Genes of the parents are mixed twice, first in random distribution in meiosis and secondly in fertilisation. Each egg and each sperm have different combinations of genes. Offspring have 50% of the father’s genes and 50% of the mother’s, which makes it even more mixed.
Outline the stages in natural selection
- Overproduction in offspring creates natural variation due to genetic differences
- Individuals that are poorly adapted to the environment are less successful and are likely to die
- Individuals that are well adapted tend to be more successful
- The successful organisms survive to adulthood and get to reproduce and pass on their genes
- Over many generations the changes in the characteristics result in evolution
Explain the response to environmental change in bacteria and antibiotics
- A person gets sick from a bacterial infection
- Doctor gives an antibiotic to kill the bacteria
- Bacteria are largely destroyed
- Due to genetic variation, one bacterium is resistant (not immune) to the antibiotic and survives
- The survived bacterium reproduces in the body and makes the person sick again
- Doctor gives the same antibiotic again
- The antibiotic doesn’t work and a different antibiotic must be used
How do bacterial genes generally evolve?
By mutations and plasmid transfer
Explain the response to environmental change in rats and pesticides
- Pesticides are applied to fields and kills most of the rats
- Due to natural variation, a few rats are slightly different and aren’t affected by the poison
- The resistant rats survive and reproduce
- Pesticide is applied again but it doesn’t work this time
- A new pesticide must be used
What are the rules for using binomial nomenclature?
- Two names
- First name is capitalised and refers to the genus
- Second name is not capitalised and refers to the species
- Both are written in italics when typed or underlined when written by hand
What are the reasons for using binomial nomenclature?
- Trying to make sense of the biosphere
- Showing evolutionary links
- Predicting characteristics shared by members of a group
List the seven levels in the hierarchy of taxa
Species → Genus → Family → Order → Class → Phylum → Kingdom
List the five kingdoms
- Plantae (plants)
- Animalia (animals)
- Fungi (fungi and moulds)
- Protoctista (protozoa and algae)
- Prokaryotae (bacteria)
Give two examples of complete classification for a species
Give examples of bryophyta
Plants of very short stature such as mosses
Give examples of filicinophyta
Plants such as ferns and horsetails etc.
Give examples of coniferophyta
Conifers: cedar, juniper, fir, and pine trees
Give examples of angiospermophyta
Any flowering plant that has its seeds surrounded by a fruit
How can plant phyla be distinguished?
By examining vegetative characteristics (leaves and stems) and reproductive characteristics
Give examples of porifera
All sponges
Give examples of cnidaria
Jellyfish and coral polyps
Give an example of platyhelminthes
Flatworms
Give an example of annelida
Segmented worms
Give examples of mollusca
Snails, clams, and octopi
Give examples of arthropoda
Insects, spiders, and crustaceans
