Topic 5 - Ecology and Evolution Flashcards
5.1.1 Define Species
A group of organisms that can interbreed and produce fertile, viable offspring
5.1.1 Define Habitat
The environment in which a species normally lives of the location of a living organism
5.1.1 Define Population
A group organisms of the same species who live in the same area at the same time
5.1.1 Define Community
A group of populations living and interacting with each other in an area
5.1.1 Define Ecosystem
A community and its abiotic envrionment
5.1.1 Define Ecology
The study of relationships between living organisms and between organisms and their environment
5.1.2 Distinguish between autotroph and heterotroph
Autotroph:
An organism that synthesises its organic molecules from simple inorgance substances - autotrophs are producers
Heterotroph:
An organism that obtains organic molecules from other organisms - heterotrophs are consumers
5.1.3 Define ‘consumer’
An organism that ingests other organic matter that is living or recently killed
5.1.3 Define Detritivore
An organism that ingests non-living organic matter
5.1.3 Define Saprotroph
An organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion
5.1.4 Decribe what is meant by a food chain
A food chain shows the linear feeding relationships between species in a community,
The arrows represent the transder of energy and matter as one organism is eaten by another.
The first organism in the sequence is the producer, followed by consumers
5.1.5 Describe what is meant by a 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
5.1.6 Define Trophic Level
An organism’s trophic level refers to the position it occupies in a food chain.
Producers always occupy the first trophic level, while saprotrophs would generally occupy the ultimate trophic level of a given food chain or food web/
Level 1 : Producer
Level 2: Primary Consumer
Level 3: Secondary Consumer
Level 4: Tertiary Consumer
5.1.7 How can you determine the trophic level of organisms in food webs and chains?
Counting the number of feeding relationships preceding it and adding one
Trophic Level: Number of arrows (in sequence) before organism +1
In food webs, a single organism may occupy multiple trophic levels
5.1.9 What is the initial source of energy for most communities?
Light.
All green plants, and some bacteria are photo-autotrophic - they use light as a source of energy for synthesising organic molecules
5.1.10 Explain the energy flow in a food chain
Energy enters most communities as light, where it is absorbed by autotrophs, and converted into chemical energy via photosynthesis.
Energy then gets passed to the primary consumer (herbivore) when they eat the plan, and then gets passed to successive consumers (carnivores) as they are eaten in turn
Only ~10% of energy is passed from one trophic level to the next, the rest is lost.
Because ~90% of energy is lost between trophic levels, the number of trophic levels are limited as energy flow is reduced at higher levels
5.1.11 Are energy transformations every 100& efficient?
Typically energy transformations in living thigns are ~10% efficient, with about 90% of the energy lost between trophic levels. This energy may be lost as heat, be used up during cellular respiration, be excreted in faeces or remain unconsumed as the uneaten part of the food.
5.1.12 Explain the reason for the shape of pyramids of energy
A pyramid of energy is a graphical representation of the amount of energy of each trophic level in a food chain
They are expressed in units of energy per area per time (e.g. kJ m2 year -1).
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
This is an application of the second law of thermodynamics
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
5.1.13 Explain that energy enters and leaves ecosystems, but nutrients must be recycled
The movement of energy and matter through ecosystems are related because both occur by the transfer of substances through feeding relationships.
However, energy cannot be recycled and an ecosystem must be powered by a continuous influx of new energy from an external source
Nutrients refer to material required by an organism, and are constantly being recycled within an ecosystem as food
The autotrophic activities of producers produce organic materials from inorganic sources, which are then fed on by the consumers.
When heterotrophic organisms die, these inorganic nutrients are returned to the soil to be reused by the plants
Thus energy flows through ecosystems, while nutrients cycle within them
5.1.14 State that saprotrophic bacteria and fungi (decomposers) recycle nutrients
Certain bacteria and fungi ensure a continual supply of raw materials for the producers, by freeing inorganic materials from the dead bodies and waste products of organisms.
Thus saprotrophic bacteria and fungi play a vital role in recycling nutrients within an ecosystem.
5.2.1 What are the four main ‘pools’ of carbon in our environment?
Atmosphere, Biosphere, Sediments, Ocean
5.2.1 Name the processes by which carbon can be cycled between the carbon ‘pools’
PHOTOSYNTHESIS
Atmospheric carbon dioxide is removed and fixed as organic compounds
FEEDING
In which organic carbon is moved from one trophic level to the next in a food chain
RESPIRATION
All organisms metabolise organic compounds for energy, releasing carbon dioxide as a by-product
FOSSILIZATION
In which carbon from partially decomposed dead organisms becomes trapped in sediment as coal, oil and gas
COMBUSTION
During the burning of fossil fuels and biomass. In oceans, carbon can be reversibly trapped and stored as limestone.
5.2.2 Analyse the changes in concentration of atmospheric carbon dioxide using historical records
RECENT
- Atmospheric carbon dioxide concentrations have been measured across a number of locations globally, the data shows there is an annual cycle in carbon dioxide concentrations, which may be as a result of seasonal factors, but when data from two hemispheres is incoperated it suggests that atmospheric carbon dioxide levels have steadily risen over the last 30 years.
LONG TERM
- Carbon dioxide concentration changed over a long period of time, which would have been due to a variety of sources, including analysing the gases trapped in ice
- Data taken from Antartica shows that fluctuating cycles of carbon dioxide concentrations over thousands of years appear to correlate with global warm ages and ice ages
- It is compelling to note that carbon dioxide levels appear to be currently higher than at any time in the last 400,000 years
5.2.3 Explain the relationship between the rises in concentrations of atmospheric carbon dioxide, methane and oxides of nitrogen and the enhanced greenhouse effect
The greenhouse effect is a natural process, whereby the earth’s atmosphere behaves like a greenhouse to create moderate temperatures to which life on earth has adapted.
The incoming radiation from the sun is short-wave ultraviolet and visible radiation. Some of this radiation is reflected by the earth’s surface back into space as long-wave infrared radiation.
Greenhouse gases absorb this infrared radiation and re-reflect it back to the earth as heat, resulting in increased temperatures (greenhouse effect).
The enhanced greenhouse effect refers to the suggested link between the increase in greenhouse gas emissions by man and changed in global temperatures and climate conditions.
The main greenhouse gases are water vapour, carbon dioxide, methane and oxides of nitrogen. Whilst these gases occur naturally, man is increasing greenhouse gas emissions by a number of processes, including deforestation, industrialization, increased farming/agriculture. With increases in greenhouse gas emissions, it is thought that the atmospheric temperature may increase and threaten the viability of certain ecosystems, although this link is still being debated.
5.2.4 Outline the precautionary principle
When a human-induced activity raises a significant threat of harm to the environment or human health, then precautionary measures should be taken, even if there is no scientific consensus regarding cause and effect.
Because the global climate is a complex phenomena with many emergent properties, and is based on time frames well beyond human lifespans, it is arguably impossible to provide appropriate scientific evidence for enhanced global warming before consequences escalate to potentially dire levels.
According to the precautionary principle, the onus falls on those contributing to the enhanced greenhouse effect, to either reduce their input or remonstrate their actions do not cause them - making it the responsibility of governments, industries, communities and even the individual.
The precautionary principle is the reverse of previous historical practices whereby the burden of proof was on the individual advocating action.
5.2.5 Evaluate arguments for the precautionary principle as justification for strong action in response to threats posed by the enhanced greenhouse effect
Risks of inaction are potentially severe, including increased frequency of severe weather conditions and rising sea levels.
Higher temperatures will increase the spread of vector-borne diseases.
Loss of habitat will result in the extinction of some species, resulting in a loss of biodiversity.
Changes in global temperature may affect food production, resulting in famine in certain regions.
The effects of increased temperatures could destroy certain industries which countries rely on, leading to poverty.
All of these consequences could place a far greater economic burden on countries than if action were taken now.
These factors would increase competition for available resources, potentially leading to increased international tensions.
5.2.5 Evaluate arguments against the use of the precautionary principle as justification for strong action in response to threats posed by the enhanced greenhouse effect
Cutting greenhouse gas emissions may delay economic growth in developing countries, increasing poverty in these regions.
Very difficult to police - what could be considered sufficient on a global scale without a scientific consensus?
International tensions could develop and economies of countries could be negatively effected if there were boycotts of non-compliant countries.
No guarantee that human intervention will be sufficient to alter global climate patterns.
Money and industrial practices that may be used to develop future technologies may be lost due to restrictions imposed by carbon reduction schemes.
Carbon reduction schemes will likely result in significant job losses from key industries, retraining workers will require significant time and money.
5.2.6 Outlien the consequences of global temperature rise on arctic ecosystems
CREDIBLE
- Changes in arctic conditions (reduced permafrost, diminished sea ice cover, loss of tundra to coniferous forests)
- Rising sea levels
- Expansion of temperate species increasing competition with native species (e.g. red and arctic fox)
- Decomposition of detritus previously trapped in ice will have a significant impact on greenhouse gas levels, with the potential to exacerbate temperature changes.
- Increased spread of pest species and pathogens
- Behavioural changes in native species
- Loss of habitat
- Extinction and resultant loss of biodiversity as food chains are disrupted
5.3.1 How is population size affected?
Natality - increases population size through reproduction
Immigration - increases to population size from external populations.
Mortality - Decreases to population size as a result of death
Emigration - Decreases population size as a result of loss to external populations.
5.3.3 Explain reasons for the exponential growth phase in a graph showing population growth
There is a rapid increase in population size/growth as the natality rate exceeds the mortality rate
This is because there is abundant resources and limited environmental resistance.
5.3.3 Explain reasons for the transitional phase in a graph showing population growth
As the population continues to grow, eventually competition increases as availability of resources are reduced.
Natality starts to fall and morality starts to rise, leading to a slower rate of population increase
5.3.3 Explain reasons for the plateau phase in a graph showing population growth
Eventually the increasing mortality rate equals the natality rate and population size becomes constant.
The population has reached the carrying capacity (K) of the environment.
Limited resources, predation and disease all contribute to keeping the population size balanced.
While the population size at this point may not be static, it will oscillate around the carrying capacity to remain relatively even (i.e with no net growth)
5.3.4 List three factors that sets limits to increase in population size
AFFECTED BY POPULATION DENSITY Predation and parasites Availability of shelter and water Nutrient supply Disease Accumulation of wastes
UNRELATED TO POPULATION DENSITY
Climate and weather conditions
Availability of light, carbon dioxide and oxygen
Natural disasters
5.4.1 Define evolution
The cumulative change in the heritable characteristics of a population
5.4.2 Outline the evidence for evolution provided by the fossil record
Fossil evidence may either be direct (bones, teeth, shells, leaves) or indirect (footprints, tooth marks, tracks, burrows)
The totality of fossils (discovered and undiscovered) is known as the fossil record.
This record reveals that, over time, changes have occurred in features of organisms living on the planet, moreover, different kinds of organisms do not occur randomly but are found in rocks of particular ages in a consistent order. This suggests that changes to an ancestral species was likely responsible for the appearance of subsequent species. Furthermore, the occurrence of transitional fossils demonstrate the intermediary forms that occurred over the evolutionary pathway taken with a single genus.
However, it is important to remember that the fossil record is incomplete, as it requires an unusual combination of specific circumstances to occur and only the hard parts of an organism are preserved, and often only fragments of fossilized remains are discovered.
5.4.2 Outline the evidence for evolution provided by selective breeding
This is a type of artificial selection. 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: breeding horses for speed vs. strength and endurance. Breeding dogs for herding, hunting or racing. Breeding cattle for increased meat production or milk.
5.4.2 Outline the evidence for evolution provided by homologous structures
A common ancestry is implied within comparative anatomy groups of animals or plants as they show certain structural features.
Homologous structures are those that are similar in shape in different types of organisms, despite being used in different ways.
An example being the pentadactyl limb structure in vertebrates, whereby many animals show a common bone composition, despite the limb being used for different forms of locomotion.
This illustrates adaptive radiation, as a similar basic plan has been adapted to suit various environmental niches.
The more similar the homologous structures between the two species are, the more closely related they are likely to be.
5.4.4 Explain the consequences of potential overproduction of offspring
When there is an abundance of resources, a population can achieve a J-curve maximum growth rate. However, with more offspring there will be less resources available to other members of the population. This will lead to competition for available resources and a struggle for survival. Intraspecific competition occurs when members of the same species compete for the same resources in an ecosystem. It is density dependent, as the available resources must be shared among members of the species. Competition that occurs between different species for resources is interspecific.
The result of this competition will be an increase in the mortality rate, leading to an S-curve growth rate as the population approaches the carrying capacity.
5.4.5 How might members of a species show variation?
DISCONTINUOUS
Variation usually controlled by a single gene, leading to distinct classes (e.g. ABO blood groups in humans).
CONTINUOUS
Controlled by many genes, leading to a range of characteristics (e.g. skin pigmentation in humans)
5.4.5 What are the three primary sources of variation within a given population
Gene mutations (permanent change to the genetic composition of an individual) Gene flow (movement of genes from one population to another via immigration and emigration) Sexual reproduction (combination of genetic materials from two parental sources)
5.4.7 Explain how natural selection leads to evolution
There is genetic variation within a population and there is competition for survival. Environmental selective pressures lead to differential reproduction. Organisms with beneficial adaptations will be more suited to their environment and more likely to survive to reproduce and pass on their genes. Over generations there will be a change in allele frequency within a population (evolution)
5.4.8 Explain an example of evolution in response to environmental change with reference to antibiotic resistance in bacteria
Staphylococcus aureus
VARIATION: antibiotic resistance
ENVIRONMENTAL CHANGE: exposure to antibiotic
RESPONSE: Methicilling-susceptible S. aureus (MSSA) die, whereas methicillin-resistant S. aureus (MRSA) survive and can pass on their genes.
EVOLUTION: Over time, the frequency of antibiotic resistance in the population increases (drug-resistant gene can also be transferred by conjugation).
5.4.8 Explain an example of evolution in response to environmental change (MOTH)
Peppered Moth
VARIATION: Colouration
ENVIRONMENTAL CHANGE: Pollution from industrial activities caused trees to blacken with soot during the industrial revolution.
RESPONSE: Light coloured moths died from predation, whereas melanic moths were camouflaged and survived to pass on their genes.
EVOLUTION: Over time, the frequency of the melanic form increased
5.5.1 Outline the binomial system of nomenclature
The binomial system of nomenclature - devised by Linnaeus - demonstrates evolutionary relationships between organisms.
- Genus is written first and is capitalised. (Homo)
- Species follows and is written in lower case (Homo sapiens)
- Some species may also have a sub-species designation (Homo sapiens sapiens)
- Handwritten - UNDERLINED
- Typed - ITALICS
5.5.2 List the seven levels in the hierarchy of taxa
Kingdom Phylum Class Order Family Genus Species
5.5.2 Give two examples of a kingdom
Animalia
Plantae
5.5.2 Give two examples of a Phylum
Chordata
Angiospermophyta
5.5.2 Give two examples of a class
Mammalia
Dicotyledoneae
5.5.2 Give two examples of an order
Primates
Ranales
5.5.2 Give two examples of a family
Hominidae
Ranunculacae
5.5.2 Give two examples of a Genus
Homo
Ranunculacae
5.5.2 Give two examples of a species
sapiens
5.5.3 How would you recognise a ‘bryophyta’?
No ‘true’ leaves or roots.
Spores produced in a capsule at end of stalk.
Anchored by rhiziod’s.
e.g. Mosses and liverworts.
5.5.3 How would you recognise a ‘filicinophyta’?
Have leaves, roots and non-woody stems.
Spores in sporangia on underside of leaf.
Have large leaves (fronds) that are divided into leaflets.
e.g. ferns
5.5.3 How would you recognise a ‘coniferophyta’?
Have leaves, roots and woody stems.
Seeds found in cones.
Leaves usually narrow with a thick waxy cuticle.
e.g. Conifers and pines
5.5.3 How would you distinguish a ‘angiospermophyta’?
Have leaves, roots and stems (woody or non-woody).
Seeds found in fruits.
Have flowers.
e.g. Flowering plants and grasses
5.5.4 How would you distinguish a porifera?
Asymmetrical
No mouth or anus
Pores through body
e.g. sponges
5.5.4 How would you distinguish a cnidaria?
Radial
Mouth but no anus
May have tentacles with stinging cells
e.g. Jellyfish and anemones
5.5.4 How would you distinguish a Platyhelminthes?
Bilateral
Mouth but no anus
Flat, softened body
e.g. flatworms and tapeworms
5.5.4 How would you distinguish an annelida?
Bilateral
Mouth and anus
Segmented body
e.g. earthworms and leeches
5.5.4 How would you distinguish a mollusca?
Bilateral
Mouth and anus
Muscular foot and mantle, may have a shell.
e.g. squids, slugs and snails
5.5.4 How would you distinguish a arthropoda?
Bilateral
Mouth and anus
Jointed appendages
Exoskeleton
e.g. spiders, insects and crustceans
