Ecology and Evolution Flashcards
Define species.
a group of organisms that can interbreed and produce fertile offspring.
Define habitat.
the environment in which a species normally lives or the location of a living organism.
Define population.
a group of organisms of one species that live in the same area at the same time.
Define community.
a group of all of the living organisms that live in the same area, interacting with each other
Define ecosystem.
a community and its abiotic environment.
Define ecology.
the study of relationships between living organisms and between organisms and their environment.
What is an autotroph?
Autotrophs are organisms that synthesize their organic molecules from simple inorganic substances.
What is an heterotroph?
Heterotrophs are organisms that obtain organic molecules from other organisms.
What are consumers?
an organism that ingests other organic matter that is living or recently killed.
What are detritivores?
an organism that ingests non-living organic matter.
What are saprotrophs?
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 food chain shows the linear feeding relationships between species in a community
The arrows represent the transfer of energy and matter as one organism is eaten by another (arrows point in the direction of energy flow)
The first organism in the sequence is the producer, followed by consumers (1°, 2°, 3°, etc.)
Give three examples of food chains.
!!!
Define food web.
A food web is a diagram that shows how food chains are linked together into more complex feeding relationships within a community
There can be more than one producer in a food web, and consumers can occupy multiple positions (trophic levels)
What is the initial energy source for all communities?
Light
Define trophic level.
the trophic level of an organism is its position in the food chain. Producers, primary consumers, secondary consumers and tertiary consumers are examples of trophic levels.
Explain the energy flow in a food chain.
Energy flows from producers to primary consumers, to secondary consumers, to tertiary consumers…
Energy is lost between trophic levels in the form of heat through cell respiration, faeces, tissue loss and death.
Some of this lost energy is used by detritivores and saprotrophs. These in turn also lose energy in the form of heat through cell respiration.
How efficient are energy transfers?
Never 100% efficient
~10% efficient
Explain reasons for the shape of pyramids of energy.
Pyramids of energy will never appear inverted as some of the energy stored in one source is always lost when transferred to the next source
Each level of the pyramid of energy should be approximately one tenth the size of the level preceding it, as energy transformations are ~10% efficient
Explain how energy and nutrients enter, move through, and exit a food chain in an ecosystem.
Energy enters from sunlight which is captured by chloroplasts in plants, and other producers. Energy flows through the trophic levels, only about 10% of the energy is passed on. Heat energy is lost through cell respiration, and is lost from the food chain. Energy is lost due to material that is excreted, this energy passes to decomposers in dead organic matter.
Nutrients are recycled within an ecosystem.Nutrients are absorbed from the soil by producers, they move through the food chain by the digestion of other organisms. The nutrients are then recycled from the decomposition of dead organisms.
What recycles nutrients?
Saprotrophic bacteria and fungi (decomposers) recycle nutrients.
Draw and label a diagram of the carbon cycle to show the processes involved.
Include:
plants taking in CO2 in photosynthesis;
animals eating plants;
animals/plants giving off CO2 by cell respiration;
decomposers/microorganisms giving off CO2 by cell respiration;
fossilization of animal parts, causing them to store carbon as fossil fuels;
factories/cars giving off CO2 through combustion of fossil fuels.
Explain the relationship between rises in carbon dioxide, methane and oxides of nitrogen and the enhanced greenhouse effect.
The incoming radiation from the sun is short wave ultraviolet and visible radiation.
Some of this radiation is absorbed by the earths atmosphere.
Some of the radiation is reflected back into space by the earths surface.
The radiation which is reflected back into space is infrared radiation and has a longer wavelength.
The greenhouse gases in the atmosphere absorbe some of this infrared radiation and re-reflect it back towards the earth.
This causes the green house effect and results in an increase in average mean temperatures on earth.
A rise in greenhouse gases results in an increase of the green house effect which can be disastrous for the planet.
Describe the causes and effects of the increased greenhouse effect.
Causes:
- fossil fuel burning
- deforestation
- methane production (from cows)
- production of nitrogen oxides
Effects:
- increasing CO2 concentration
- increasing temperature
- increase in photosynthesis
- changing climate
- extinction of species
- glaciers melt/increase in sea levels - flooding
Outline the potential harmful effects of increased carbon dioxide concentration on the ecosystem and state one measure that could be taken to reduce the amount of carbon dioxide in the atmosphere.
Effects:
- global warming
- rising sea levels affects coastal ecosystems
- melting ice caps leads to changes in currents
- changes in weather patterns
- rapid ecological change favours emergent pest species
Measure:
- carbon dioxide absorption by photosynthesis must be encouraged, by reducing deforestation
- burning of fossil fuels must be reduced by using solar energy
Outline the precautionary principle.
The precautionary principle holds that, if the effects of a human-induced change would be very large, perhaps catastrophic, those responsible for the change must prove that it will not do harm before proceeding. Those opposing the change do not have to prove that there will be harm. This is the reverse of the normal situation, where those who are concerned about the change would have to prove that it will do harm in order to prevent such changes going ahead.
For example. proving that a GMO will not harm unintended species before widespread use.
Outline the consequences of an increased greenhouse effect on arctic ecosystem.
- melting of permafrost
- increased detritus decomposition
- expansion of temperate species
- rise in sea levels
- change in climatic patterns
- loss of ice habitat
- more pests/pathogens
- disturbance to food webs
How is population size affected by natality, immigration, mortality, and emigration?
Natality: increases population size as offspring are added to the population.
Immigration: increases population size as individuals have moved into the area from somewhere else and so this adds to the population.
Mortality: decreases the population as some individuals get eaten, die of old age or get sick.
Emigration: decreases the population as individuals have moved out of the area to go live somewhere else.
Draw and label a graph showing a sigmoid (S-shaped) population growth curve.
Include:
- Clear ruled axes, labelled time on the x-axis and the population size on the y-axis
- exponential phase annotated to indicate rapid population growth because of abundant resources
- transitional phase annotated to indicate a developing shortage of resources and increase competition between members of the population
- plateau phase annotated to indicate a population now constrained by resource availability.
Explain the reasons for the exponential growth phase, the plateau phases and the transitional phase of the sigmois population growth curve.
Exponential phase: Rapid increase in population growth. Natality rate exceeds mortality rate. Abundant resources available. (food, water, shelter) Diseases and predators are rare.
Traditional phase:
Natality rate starts to fall and/or mortality rate starts to rise.
There is a decrease in the number of resources.
An increase in the number of predators and diseases.
Population still increasing but at a slower rate.
Plateau phase:
No more population growth, population size is constant.
Natality rate is equal to mortality rate.
The population has reached the carrying capacity of the environment.
The limited resources and the common predators and diseases keep the population numbers constant.
List three factors that set limits to population increase.
- Shortage of food
- Increase in predators
- Availability of shelter
Define evolution
Evolution is the cumulative change in the heritable characteristics of a population.
Outline the evidence for evolution provided by homologous structures.
- homologous structures are those that are similar in shape in different types of organisms
- comparative anatomy of groups of animals or plants shows certain structural features are similar
- structural similarities imply a common ancestry
- e.g. pentadactyl limb in vertebrates illustrates adaptive radiation since basic plan adapted to different niches
- the more exclusive the shared homolgies, the closer the two organisms are related
- certain homologous structures in some species with no apparent function such as the human appendix
Outline the evidence for evolution provided by the fossil record.
The fossil record reveals that, over time, changes have occurred in features of organisms living on the planet (evolution)
Moreover, different kinds of organisms do not occur randomly but are found in rocks of particular ages in a consistent order (law of fossil succession)
This suggests that changes to an ancestral species was likely responsible for the appearance of subsequent species (speciation via evolution)
Furthermore, the occurrence of transitional fossils demonstrate the intermediary forms that occurred over the evolutionary pathway taken within a single genus
Outline the evidence for evolution provided by selective breeding of domesticated animals.
Selective breeding of domesticated animals is an example of artificial selection, which occurs when man directly intervenes in the breeding of animals to produce desired traits in offspring
As a result of many generations of selective breeding, domesticated breeds can show significant variation compared to the wild counterparts, demonstrating evolutionary changes in a much shorter time frame than might have occurred naturally
Examples of selective breeding include:
Breeding horses for speed (race horses) versus strength and endurance (draft horses)
What is natural selection?
The mechanism that increases the chance of certain individuals reproducing
State that populations tend to produce…
more offspring than their environment can support.
What is the consequence of the potential overproduction of offspring?
As more offspring are produced, there will be less resources available to other members of the population. If there is an over production of offspring this will result in a struggle for survival within the species as the resources become scarce and individuals in the population will start to compete for these. This results in an increase in mortality rate as the weaker individuals in the population will lose out on these vital resources that are essential for their survival.
What factors could be important for a species to evolve by natural selection?
Environmental change and variation within a species
How does sexual reproduction promote variation within a species?
Sexual reproduction is important for promoting variation as even though mutations form new genes or alleles, sexual reproduction forms a new combination of alleles. There are two stages in sexual reproduction that promote variation in a species. The first one is during meiosis during which a large variety of genetically different gametes are produced by each individual. The second stage is fertilisation. Here, alleles from two different individuals are brought together to form one new individual.
Discuss the theory of evolution by natural selection.
- Theory put forward by Darwin.
- Overproduction of offspring leads to a struggle for survival
- variation within a species exists, and some varieties are better adapted than others and the best adapted survive
- The best adapted survive and reproduce and pass on beneficial characteristics
- These beneficial characteristics will then be passed on to the next generation and the species will evolve to continually show beneficial characteristics
- evidence that species has evolved in the fossil record
- competing theory is that organisms have not changed since they were created by God
Outline the binomial system of nomenclature.
Each species is given two names. The first is the genus name and is given an upper case first letter. The second is the species name and is given a lower case first letter. If the name is printed, italics are used. If on the other hand the name is hand-written, it is underlined.
List the seven levels of hierarchy of taxa.
Kingdom Phylum Class Order Family Genus Species
Give two examples of the seven levels of hierachy of taxo, from two different kingdoms
Human: Animalia Chordata Mammalia Primates Hominidae Homo sapiens
Buttercup: Plantae Angiospermophyta Dicotyledoneae Ranales Ranunculacae Ranunculus acris
What are the external recognition features of the plant bryophyta?
No roots, instead they have structures similar to root hairs called rhizoids. Mosses with simple leaf like structure. Maximun height: 0.5m
Reproductive structures:
spores produced in capsule which develops at the end of a stalk.
What are the external recognition features of the plant filicinophytes?
Have roots, leaves and short non-woody stems. Leaves are usually pinnate (divided into leaflets) and curled up in a bud.
Maximum height: 15m
Reproductive Structure:
Spores are produced in sporangia, usually on the underside of the leaves.
What are the external recognition features of the plant coniferophytes?
Evergreen woody plant. Shrubs or trees with roots, leaves and woody stems. Leaves are usually narrow with thick waxy cuticle.
Maximum height: 100m
Reproductive structures: Seeds are produced from ovules on the surface of the scales of female cones. Male cones produce pollen.
What are the external recognition features of the plant angiospermophytes?
Many different characteristics but usually have roots, leaves and stems. Stems of flowering plants that develop into shrubs and trees are woody.
Maximum height: 100m
Reproductive structures: Seeds are produced from ovules inside the ovaries. The ovaries are part of the flower. The fruits then develop from the ovaries and disperse the seeds.
What are the external recognition features of the animal porifera?
- no clear symmetry
- attached to a surface
- pores through body
- no mouth or anus
- example: sponges
What are the external recognition features of the animal Cnidaria?
- radially symmetric
- tentacles
- stinging cells
- mouth but no anus
- example: jellyfish
What are the external recognition features of the animal Platyhelminths?
- bilaterally symmetrical
- flat bodies
- unsegmented
- mouth but no anus
- example: tapeworm
What are the external recognition features of the animal Annelida?
- bilaterally symmetrical
- bristles often present
- segmented
- mouth and anus
- example: earthworm
What are the external recognition features of the animal Mollusca?
- muscular foot and mantle
- shell may be present
- segmentation not visible
- mouth and anus
- example: slugs and snails
What are the external recognition features of the animal Arthropoda?
- bilaterally symmetric
- exoskeleton
- segmented
- jointed appendages
- example: spiders and insects
Outline the evidence for evolution provided by homologous structures.
- homologous structures are those that are similar in shape in different types of organisms
- comparative anatomy of groups of animals or plants shows certain structural features are similar
- structural similarities imply a common ancestry
- e.g. pentadactyl limb in vertebrates illustrates adaptive radiation since basic plan adapted to different niches
- the more exclusive the shared homolgies, the closer the two organisms are related
- certain homologous structures in some species with no apparent function such as the human appendix
