Species and taxonomy Flashcards
What is a species?
A group of organisms that can (interbreed to) produce fertile offspring
Suggest why 2 different species are unable to produce fertile offspring
● Different species have different chromosome numbers → offspring may have odd chromosome number
● So homologous pairs cannot form → meiosis cannot occur to produce gametes
Explain why courtship behaviour is a necessary precursor to successful
mating
● Allows recognition of members of same species → so fertile offspring produced
● Allows recognition / attraction of opposite sex
● Stimulates / synchronises mating / production / release of gametes
● Indicates sexual maturity / fertility
● Establishes a pair bond to raise young
Describe a phylogenetic classification system
● Species (attempted to be) arranged into groups, called taxa, based
on their evolutionary origins (common ancestors) and relationships
● Uses a hierarchy:
○ Smaller groups are placed within larger groups
○ No overlap between groups
Name the taxa in the hierarchy of classification
- Domain (largest / broadest)
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
How is each species universally identified?
A binomial consisting of the name of its genus and species, eg. Homo sapiens
Suggest an advantage of binomial naming
Universal so no confusion as many organisms have more than one common name
How can phylogenetic trees be interpreted?
● Branch point = common ancestor
● Branch = evolutionary path
● If two species have a more recent common
ancestor, they are more closely related (eg. C & D)
Describe two advances that have helped to clarify evolutionary
relationships between organisms
- Advances in genome
sequencing → allowing
comparison of DNA
base sequences:
● More differences in DNA base sequences → more distantly related /
earlier common ancestor
● As mutations (change in DNA base sequences) build up over time - Advances in
immunology → allowing
comparison of protein
tertiary structure (eg.
albumin):
● Higher amount of protein from one species binds to antibody against
the same protein from another species → more closely related / more
recent common ancestor
● As indicates a similar amino acid sequence and tertiary structure
● So less time for mutations to build up
What is biodiversity?
● Variety of living organisms (species, genetic and ecosystem diversity)
● Can relate to a range of habitats, from a small local habitat to the Earth
What is a community?
All populations of different species that live in an area
What is species richness?
A measure of the number of different species in a community
What does an index of diversity do?
Describes the relationship between:
1. The number of species in a community (species richness)
The number of individuals in each species (population size
Suggest why index of diversity is more useful than species richness
● Also takes into account number of individuals in each species
● So takes into account that some species may be present in small or high numbers
What is the formula for index of diversity?
d = N (N - 1)/Σ n (n -1)
N = total number of organisms of all species
n = total number of organisms of each species, Σ = the sum of
Describe how index of diversity values can be interpreted
● High → many species present (high species richness) and species evenly represented
● Low → habitat dominated by one / a few specie
Explain how some farming techniques reduce biodiversity
Farming technique:
Removal of woodland and hedgerows Monoculture (growing one type of crop)
Use of herbicides to kill weeds
—
Explanation
● Reduces variety of plant species
● So fewer habitats and niches
● And less variety of food sources
Farming techniques:
Use of pesticides to kill pests
Explanation
Predator population of pest decreases
Explain the balance between conservation and farming
● Conservation required to increase biodiversity
● But when implemented on farms, yields can be reduced, reducing profit / income for farmers
○ Eg. by reducing land area for crop growth, increasing competition, increasing pest population
● To offset loss, financial incentives / grants are offered
Give examples of how biodiversity can be increased in areas of agriculture
● Reintroduction of field margins and hedgerows (where farmers only grow one type of crop)
● Reduce use of pesticides
● Growing different crops in the same area (intercropping)
● Using crop rotation of nitrogen fixing crops instead of fertilisers
