Genetic Diversity and Classification Flashcards
What is genetic diversity?
the number of different alleles within a population
What is an allele?
different version of a gene
Why does genetic diversity lead to variation?
different combinations of alleles mean different proteins are produced, resulting in different characteristics.
How does genetic diversity influence natural selection?
- change in environment causes a selection pressure
- random mutations produce genetic diversity
- some alleles provide an advantage to gaining resources
- those individuals with the alleles survive and reproduce
- advantageous alleles are passed on
- the frequency of advantageous alleles in the population increases
- frequency of trait increases
What is the mnemonic for how genetic diversity influences natural selection?
Some- selection pressure
Really- random
Massive- mutations
Goats- genetic diversity
Ate- advantage
Some- survive
Raw- reproduce
Premium- pass on alleles
Fish- frequency of alleles increases
Fingers- frequency of trait increases
Which factors decide what is advantageous?
The environment or nature (genetics)
What is a modern example of natural selection?
antibiotic resistant bacterium
What is selection pressure?
an environmental change that leads to selection
What are the two types of variation?
continuous- a characteristic that can have a wide range of values
discontinuous- a characteristic with few possible values
What are most characteristics controlled by?
multiple genes/ alleles (polygenic) so show more variation
Are polygenic or monogenic traits influenced more by the environment?
polygenic
What are the 2 effects selection can have on a population?
- favouring individuals that vary from the mean (directional selection)
- favouring the average individuals (stabilising selection)
What can be said about phenotypes in directional selection?
phenotypes are selected for. genotypes are indirectly selected
What can be said about phenotypes in stabilising selection?
phenotypes at the extremes are selected against
Why are mutations not a result of natural selection?
-they do not occur because of selection pressure
-they are random and rare
-a mutation leading to an advantage is a result of chance
What do the graphs for directional and stabilising selection look like?
Exam technique: stabilising selection
- occurs in an unchanging environment
- selection against extremes
- range is reduced
- increasing proportion of populations become well adapted to the environment
What do organisms need to do to ensure they survive over time?
Reproduce.
The females of most species produce eggs at specific times. This places a selection pressure on courtship behaviours.
What do courtship behaviours allow individuals to do? (5 points)
- Recognise members of the same species
- Identify a sexually mature mate
- Form a pair bond that will lead to successful mating and raising of offspring
- Synchronise mating so that it takes place at a time where egg and sperm are most likely to meet
- Become able to breed by bringing a member of the opposite sex into a state that allows breeding to occur
What is classification?
grouping species
What is the scientific word for a group? What is the study of a group called?
Group - taxon
Stay of group- taxonomy
What does classifying organisms allow scientists to do?
-Identify new species.
-Study evolutionary relationships.
-Understand shared traits and adaptations.
-Share research globally to identify links with organisms on other continents
What is Artificial Classification?
Grouping organisms based on features that are useful at the time e.g colour, wings. The evolutionary origin of these features may not be taken into account
What is Phylogenetic Classification?
-based on evolutionary relationships
-based on shared ‘homologous’ features derived from their evolutionary ancestors
-arranges organisms into groups called hierarchies
What are hierarchies?
Groups within groups that do not overlap
What is the mnemonic for the taxonomic ranks?
Domain (Divine)
Kingdom (Kings)
Phylum (Play
Class (Chess)
Order (On)
Family (Fat)
Genus (Green)
Species (Stools)
What are the 3 domains organisms are classified into?
-Bacteria
-Archaea
-Eukarya
What are the 4 Kingdoms included in Eukarya?
-Plantae (plants)
-Animalia (animals)
-Protoctista (unicellular eukaryotes)
-Fungi (such as yeasts)
What does the 2 part binomial naming system consist of?
- Genus
- Species
e.g humans are Homo Sapiens
