⭐️Genetic Info, Variation And Relationships: Biodiversity Flashcards
What is the definition of a species?
Organisms that share a large number of common characteristics and so can interbreed and produce fertile offspring
What is the binomial system
The system that uses two names to identify organisms through genus and species
What are the rules of using the binomial system in scientific writing?
- The names are typed in italics or underlined when handwritten
- the first letter of the genus is capital and the first letter of the species is lowercase
- if the species isn’t known it can be written after the genus as sp
Why don’t members of two different species reproduce?
Because the offspring being the hybrid will end up sterile because they would have an odd number of chromosomes so they wouldn’t pair up during meiosis. This means the offspring of two different species is a waste of energy because it can’t go on to pass down its genes to the next generation.
What do sign stimuli allow for organisms?
To make sure they have recognised their own species and chosen the organism with the best characteristics for sexual reproduction
Why are courtship and mating essential?
In order for the species to survive so that their DNA can be passed on to through the reproductive process to the next generation
Give 5 ways courtship ensures successful mating
By allowing members of a species to:
- recognise members of their own species to make sure mating only takes place between members of the same species to produce fertile offspring
- to identify a mate that’s capable of breeding as both partners need to be sexually mature, fertile and receptive to mating
- to form a pair bond that will lead to successful mating and raising of offspring
- to synchronise mating so it takes place when there’s the maximum possibility of sperm and egg cell fusing
- to become able to breed by bringing a member of the opposite sex into a phycological state that allows breeding to occur
How do males use courtship behaviour?
To determine wether the female is in the window where they are receptive to mating
What is classification?
Grouping of organisms
What is a hierarchy?
Where the groups are within groups and the groups don’t overlap
What is taxonomy?
The theory and practise of biological classification
What are the two types of biological classification?
Phylogenetic classification and artificial classification
What is each group of the classification system called?
A taxon
List all the taxa in the classification system
Domain Kingdom Phylum Class Order Family Genus Species
What is artificial classification based on?
- not based on evolutionary relationships
- groups of organisms are instead based on analogous characteristics (characteristics with the same function but different evolutionary origin e.g. the wings of butterflies and birds are both used for flight but originated in different ways)
What is phylogenetic classification? What is it based on?
- groups of species using shared features derived from common ancestors e.g. the pentadactyl limb and arranges groups on a hierarchy where there is no overlap between them
- based on evolutionary relationships
What are the three domains?
Bacteria, archaea (a group of prokaryotes ) and eukarya
State what bacteria are and give five features they possess
A group of single celled prokaryotes
- lack membrane bound organelles e.g. nuclei/ mitochondria
- they are unicellular although may occur in chains/ clusters
- they have smaller 70s ribosomes (eukaryotic cells have 80s)
- the cell walls are present but made of murein (never chitin or cellulose)
- they contain a single loop of naked dna with NO HISTONES
State what archaea are and 4 features they possess
- their genes and protein synthesis are more similar to eukaryotes
- their membranes contain fatty acid chains attached to glycerol by ether linkages
- there is no murein in their cell walls
- they have a more complex form of RNA polymerase
State what are eukarya and 4 features they possess
They are a group of organisms made up of one or more eukaryotic cells
- their cells have membrane bound organelles like mitochondria or chloroplasts
- they have membranes containing fatty acid chains attached to glycerol by ester linkages
- not all have cells with a cell wall but where they do it doesn’t contain murein
- the ribosomes are 80s so are larger than in bacteria and archaea
What are the four divisions of the eukarya domain?
Proctista, fungi, plantae and animalia
What is phylogeny?
The evolutionary relationship between organisms and can be represented as a phylogenetic tree
What are the three components of biodiversity that allow it to relate to a range of habitats from and what do they each refer to?
- species diversity = the number of different species and the number of individuals of each species within any one community
- genetic diversity = the variety of genes possessed by the individuals that make up a population of a species
- ecosystem diversity = the range of different habitats from a small local habitat to the whole earth
Give the two measures of species diversity and state what they each are.
- Species richness and is the number of different species in a particular area at a given time ( so number of species in a community)
- species evenness which is the relative abundance of different species in a given area
How can you measure the species diversity?
Using an index that’s calculated (check biology camera roll for the index and how to use it)
Define ecosystem
A community and its abiotic environment
Define community
The biotic component of an ecosystem
Define population
The number of individuals of a particular species in a given area at a given time
What does a high index value suggest?
What does a low index value suggest?
- a high index value suggests a stable site with many different niches and low competition (so high richness and evenness)
- a low index value suggests a site with few potential niches where only a few species dominate ( so low richness and evenness)
How are agricultural ecosystems different to natural ecosystems?
With time natural ecosystems develop a high index of diversity where as agricultural ecosystems are controlled by humans where farmers select species for certain qualities and reduce the variety of alleles that they possesses.
What are the two reasons the index of species diversity is low in agricultural ecosystems? What does this reduce overall?
-due to the genetic variety of alleles in the species being reduced, most of the area is taken up by one species and so there is a smaller area for other species and they will have to compete for the little space and resources that are available causing many to not survive as only few will adapt hence reducing the population of the species.
-use of pesticides excludes species as they compete for light, water, mineral ions and food required by the farmed species
Overall, these techniques of agricultural farming reduce biodiversity
What 4 practises have directly removed habitats and reduced species diversity?
- removal of hedgerows and grubbing out woodland
- creating monocultures e.g. replacing natural meadows with cereal crops or grass for silage
- filling in ponds and draining marsh and other wetland
- over grazing of land e.g. upland areas by sheep, thereby preventing regeneration of woodland
What practices have indirectly removed habitats and reduced species diversity?
- use of pesticides and inorganic fertilisers
- escape of effluent from silage stores and slurry tanks into water courses
- absence of crop rotation and lack of intercropping or under sowing
What is the reason there are ways to balance intrusive food production and conservation?
To increase the species and habitat diversity without unduly raising food costs or lowering yields
Give 7 examples of techniques used to balance conservation and farming
- plant hedges instead of erect fences as field boundaries
- to leave wet corners of the field instead of drain them
- to plant native trees on land with a low species diversity rather than in species rich areas
- to reduce the use of pesticides and use biological control or gm organisms that are resistant to pests
- use intercropping rather than herbicides to control weeds and other pests
- leave the cutting of verged and field edges until after flowering and when the seeds have dispersed
- introduce conservation headlands (areas at the edges of fields where pesticides are used restrictively so wild flowers and insects can breed
How can you decide how closely related two species are?
By looking at the degree of similarity in the amino acid sequence of the same protein in the two species
What has inferring DNA differences from observable characteristics been replaced by?
Directly observing DNA sequences themselves through the advances in gene technology