C10/11 Flashcards
Homologous structure
A structure that appears superficially different (and may preform different functions) in different organisms but has same underlying structure.
Homologous structure example
The pentadactyl limb of vertebrates (many different functions but basic structure very similar)
How does the presence of homologous structures provide evidence for evolution
Evidence for divergent evolution (describes how from common ancestor, different species have evolved, each with different set of adaptive features). This type evolution occurs when adapt new habitat (loss or migrate).
Convergent evolution example
Marsupial and Placental Mole
Both burrow through soft soil to find worms and grubs
Both have streamlined body shape and modified forelimbs for digging
Both have velvety fur (allows for smooth movement through soil)
Differ in fur colour (marsupial orangish, placental grey).
Human influence on Biodiversity (explanation):
Human population growing dramatic rate
To create enough space for housing, industry and farming, humans severely disrupting the ecology of many areas
Deforestation (definition):
Permanent removal of large areas of forest (provide wood for buildings and fuel, and create space for roads, buildings and agriculture)
Agriculture (definition)
Increasing amount land has to be farmed in order feed increasing population. Result large amounts land cleared and in many causes planted with a single crop (monoculture).
Climate change (definition)
Evidence that the release of carbon dioxide and other pollutants into atmosphere from burning fossil fuels increasing global temperature.
Deforestation affects on Biodiversity (4)
Occurs naturally, however most deliberately from human actions.
- Directly decreases the number trees in area
- If only specific tree type is felled, the species diversity is reduced
- It reduces number of animal species, destroying their habitat
- Animals forced to migrate (may increase the biodiversity of neighbouring areas).
Aesthetic reasons for maintaining biodiversity (3)
- Different plants and animals in environments enriches our lives
- Natural world provides inspiration for people (musicians, writers) in turn provide pleasure to others.
- patients recover more rapidly from stress and injury when supported by plants and relatively natural environment.
Economic reasons maintain biodiversity (8)
If biodiversity in an ecosystem is maintained, levels of long-term productivity are higher.
- soil erosion and desertification may occur due to deforestation (reduce ability to grow crops).
- need to conserve all organisms that we use to make things (furniture), result in collapse ,any industries.
- species with potential economic importances may become extinct before even discovered (I.e chemical/ medical uses).
- Continuous monoculture results in soil depletion (reduction diversity of soil nutrients).
- Promotes tourism
- High biodiversity provides protection against abiotic stresses and disease (if not maintained change in conditions or disease can destroy entire crops).
- Plant varieties needed for cross breeding
- Higher the chance of producing different products in the future (medicines).
Ecological reasons for maintaining biodiversity (2)
- All organisms independent on others to survive. Removal of one species may have significant effect on others.
- Some species play a key role in maintaining the structure of an ecological community (“keystone species”).
Agriculture affect on biodiversity
Deforestation Removal of hedgerows Pesticides Herbicides (kill weeds, unwanted plants) Monoculture
Climate change affects biodiversity
- Melting of polar ice caps (extinction of animals and plants)
- Rising of sea levels (melting ice caps and thermal expansion of oceans, flooding low-lying land (salt water will also flow up rivers and contaminate fresh waters).
- Higher temperature and less rainfall (plant species falling to survive effects animals).
- Insect life cycle and populations will change.
If climate change is slow species may have time to adapt. New food source or migrate.
What creates genetic biodiversity
All members of species share same genes, but may have different variations of these genes (alleles ).
What determines how genetically biodiverse a population is
The more alleles present in population, the more genetically biodiverse the population is.
Species that contain greater biodiversity are more likely to…
Adapt (not become extinct), some organisms carry an advantage allele, allows them to survive in the altered conditions.
Factors effecting (an increase in) genetic biodiversity
For it to increase, the number of possible alleles in a population most also increase;
- Mutations
- Interbreeding between different populations
Factors that decrease genetic biodiversity (7)
Selective breeding ( artificial selection)
Captive breeding programmes in zoos and conservation centres
Artificial cloning (asexual reproduction)
Natural selection
Genetic bottlenecks (where few individuals survive an event or change, narrowing gene pool)
The founder effect (small number of individuals create new colony)
Genetic drift (due to random nature of alleles being passed on from parents to their offspring, the frequency of occurrence of an allele varies).
How do we measure genetic biodiversity
By measuring polymorphism (polymorphic genes have more than one allele). Most genes are monomorphic (ensuring the basic structure of individuals in a species remains consistent).
What does the locus/loci of a gene refer to
The position of the gene on a chromosome. The greater the proportion of polymorphic gene loci, the greater the genetic biodiversity within the population.
Equation for the proportion of polymorphic genes loci
Number of polymorphic gene loci/ total number of loci
What is Student T-test used for?
This is used to compare the means of data values of two populations
What are the 2 types of student T-tests
Unpaired T-test: is there a difference between 2 groups (different groups)
Paired T-test: is there a difference in a group between two points in time (variable). One group, the same group being tested.
What is Simpsons index of diversity used for
It’s a measure of biodiversity, that takes into account both species richness and species evenness.
Use the formula to calculate biodiversity.
Spearman’s rank
A method of testing the strength and direction (positive/ negative) of the correlation between two variables
Identify if there’s any relationship between two sets of data
Standard deviation
It’s a measure of how spread out the data is. The greater the standard deviation is, the greater the spread of data.
Conservation
Name given to presevation and careful management of environment and natural resources
What are the two main categories in maintaining biodiversity
In situ conservation (within the natural habitat)
Ex situ conservation (out off the natural habitat)
In situ conservation
Takes place inside an organism’s natural habitat. Maintains not only genetic biodiversity. Generally cheaper than ex situ conservation.
Wildlife reserves
Active management techniques may include: (7)
Controlled gazing Restricting human access Controlling poaching Feeding animals Reintroduction of species Culling (removal of invasive species) Halting successions
Marine conservation zones
Vital preserving species richness area (I e coral reefs being devastated by non sustainable fishing methods). They create an area of refuge within which populations can build up and repopulate adjacent areas. Lundy island only marine reservation in England.
Ex situ conservation
Involves removal of organisms from their natural habitat
Botanic Gardens
Plant species can be grown successfully in botanic gardens. Here species are actively managed to provide them with the best resources to grow (nutrients, watering, no pests).
Seed banks
An example of a gene bank (a store of genetic material).
Seeds carefully stored so that new plants can be grown in future (dried and stored at -20⁰C) so they don’t loose their viability, by slowing down rate they loose ability to germinate ( doesn’t work for all plants, tropical rainforest tree seeds).
Captive breeding programmes
Produce offspring of spices in a human controlled environment. Usually run and managed by zoos and aquatic centres
Aim of captive breeding programmes
Aim to create a stable, healthy population of a species, then reintroduce gradually back into natural habitat.
Reasons why introducing organisms born in captivity into natural habitats are hard (4)
Diseases
Behaviour
Genetic races
Habitat
Conservation agreements
To conserve biodiversity successfully local and international cooperation required for habitat and species preservation (animals migrate, and cross border protection should be offered).
What is biodiversity?
The variety of living organisms. It can be measured in terms of species diversity (number of species in a community), habitat diversity (range of different habitats) and genetic diversity (variety of alleles within a species)
Difference between species richness and evenness
Species richness: The number of species in an area Species evenness: The number of individuals within a species.
What are the different types of sampling
Random - no particular system, however aim is still to be representative. Opportunistic - Those that are encountered first are chosen. Stratified - Population divided into strata based on characteristics, then sampled. Systematic - Follows a particular pattern.
Why is sampling important
We cannot study the whole population as it is impractical. Using a representative sample instead allows us to investigate the population easily.
Describe how Simpsons index of biodiversity is used
- A measurement of the total number for organisms compared to the total number of organisms of each species. - A high index of diversity means several different species are equally abundant, whereas a low index means one or two species dominate over others.
How can we access generic biodiversity
Proportion of polymorphic gene loci = number of polymorphic gene loci ÷ total number of loci
Give factors that effect biodiversity
Population growth - Deforestation for agriculture - Climate change affecting habitats.
Give some agreements made with the aim of protecting species and habitats
Convention on International Trade in Endangered Species (CITES) - Rio Convention on Biological Diversity (CBD) - Countryside Stewardship Scheme (CSS)
What are the two components to a binomial naming system
Generic name = The genus the organism belongs to. Two closely related species will share the same genus. Specific name = The species the organism belongs to.
What are the advantages of using a binomial naming system
It is universal; an organism’s binomial name is the same everywhere in the world
How were organisms classified into kingdoms
Based on similarities in observable characteristics.
How was the domain system of classification developed?
By analysing molecular differences between organisms to determine their evolutionary relationships (phylogeny).
What’s the difference between classification and phylogeny
Classification is simply sorting organisms into groups. Phylogeny investigates the evolutionary relationships between organisms.
Explain how natural selection results in evolution
- Random mutations result in new alleles. - Some alleles provide an advantage against a selection pressure, making an individual more likely to survive and reproduce. - Their offspring recieve the new allele, and are said to have evolved a new characteristic.
Give evidence for the theory of evolution
Natural selection (Darwin and Wallace) Fossils = Allows us to compare extinct organisms to today's organisms. Genomic DNA = sequencing of genomes have shown how closely related we are to primates. Molecular = Proteins are composed of the same 20 amino acids in all organisms."
What’s the 2 types of variation
Genetic = mutations, random fertilisation etc. Environmental = climate, diet, culture etc.
Differentiate between intraspecific and interspecific variation.
Intraspecific = varitation within the same species. Interspecific = variation between different species.
Differentiate between continuous and discontinuous variation.
Continuous = variation exists as gradual changes over a range e.g. habitat, root length. Discontinuous = variation exists as distinct categories e.g. blood groups, bacteria shape.
“Why might we calculate a Spearman’s rank correlation coefficient?”
To measure correlation between two variables, i.e. the extent to which changing one variable affects the other variable.
What are the three different types of adaptation (give examples)
Anatomical adaptation, where an organisms has a change to their body structure - Oily fur. Physiological adaptation, where an organism has a change to its bodily processes - venom production. Behvaioural adaptation, where an organism has a change its actions - hibernation.
Why might organisms from different taxonomic groups show similar features
Marsupial moles and placental moles live in different continents, but share similar anatomical features as they have adapted to similar selection pressures.
Give some implications of evolution for humans
Bacterial antibiotic resistance means infections are harder to treat. - Pecticide resistance means entire crops could be destroyed.
Prokaryote
General features
- Unicellular
- No nucleus or membrane bound organelles (ring naked DNA), small ribosomes
- No visible feeding mechanism
Protoctista
General features
- (Mainly) unicellular
- Nucleus and other membrane bound organelles (some have chloroplast)
- Some are sessile, but others move by cillia, flagella or by amoeboid mechanisms
- nutients by photosynthesis (autotrophic feeders), ingestion of other organisms (heterotrophic feeders) or both.
Fungi
- Uni or multicellular
- nucleus, membrane bound organelles and cell wall (chitin), no chloroplast
- Most have a body or mycelium made of threads or hyphae
- Nutrients acquired by absorption (decaying material, saprotrophic feeders), most store food as glycogen
Animalia
General features
Multicellular
Nucleus and other membrane bound organelles (no cell wall or chloroplast)
Move with aid cilia, flagella or contractile proteins
Nutrients by ingestion (heterotrophic feeders), stored as glycogen
Plantae
General features
Multicellular
Nucleus, other membrane bound organelles (chloroplast and cell wall, cellulose mainly) all contain chlorophyll
Most don’t move, although gametes of some move via cilia or flagella
Nutrients (via photosynthesis), autotrophic feeders (organisms that make own food), stored as starch
