biodiversity Flashcards
define species richness
the number of different species in a community
define biodiversity
the variety of living organisms within a habitat
define species diversity
the number of individuals of each species and the number of different species in community
how to obtain a more precise value for the index of diversity
- take more samples and find mean
- random sampling
what is conservation
protection and management of earths resources and species and habitats
give 3 examples of conservation
- using organic fertilisers
- not using pesticides
- not removing hedgerows
give an advantage and disadvantage of maintaining hedgerows for farmers
:) increases species diversity so more predators for pests
:( less space for crop growth
define population
a group of individuals of same species that live in the same habitat
define community
all the different species that live in one area and interact with each other
difference between biotic and abiotic
biotic- living factors e.g. predation, competition
abiotic- non living factors e.g. temperature, light
give the equation for estimated population size using the mark-release-recapture technique
number of 1st captured x number of 2nd captured
/
number of marked recaptured in 2nd
what is meant by a dynamic ecosystem
-populations rise and fall
- any small change may have a big impact
- biotic and abiotic factors may alter conditions of the ecosystem
how does speciation happen (5)
- geographical isolation
- reproductive separation
- different selection pressures
- variation due to mutation in one population
- advantageous allele passed on to offspring
- different species cannot interbreed to form fertile living offspring
suggest 1 precaution to take when marking animals
non toxic
how would you estimate the size of a population of sundews in a meadow (5)
- create a grid with 2 tape measures
- use random generator to generate co-ordinate
- place quadrat at co-ordinate and count number of sundew in quadrat
- repeat 10 times and find mean
- multiply by total number of quadrats
suggest and explain how digesting insects helps the sundew grow in soil with low nutrients (2)
- insects contain proteins
- proteins break down into amino acids
- sundew uses amino acids to form proteins for growth
explain how succession happens (5)
- pioneer species
- they provide food
- they increase then decrease in population as they are outcompeted by other species
- other species colonise
- overall there is an increase in species richness
give two features of a climax community (2)
- same species present
- abiotic factors constant
how should student use data from plot 1 to estimate total number of beetles in the meadow (4)
- calculate the area of the plot
- calculate area of the meadow
- divide area of meadow by area of plot
- multiply by number of beetles
explain why it is more useful to calculate index of diversity rather than species richness
- index of diversity measures abundance of each species
- useful as they may be many of the same species
what do the students need to collect to calculate index of diversity
total number of individuals of each species
what are the 3 components of biodiversity
- species diversity
- genetic diversity
- ecosystem diversity
define species diversity
number of different species and individuals of each species in a community
define genetic diversity
number of different genes of a species in a population
define ecosystem diversity
range of different habitats, from a small local habitat to the the whole Earth
explain why it is more useful to calculate species diversity rather than just record number of species present
measures both number of species and number of individuals of each species
takes into account species that are present in small numbers
give 4 examples of conservation techniques
- maintain hedgerows
- use biological control instead of pesticides
- don’t fill in ponds
- use organic fertilisers
explain how agriculture has reduced species diversity
species with desired features are selected and grown
other species are excluded
small space left for other species
they compete for limited resources
they compete with the desired species for light,food,water
farmers remove other species with pesticides
number of different species decreases
explain why species diversity decreases when forest is replaced by grassland for grazing sheep
forests have many layers
have many habitats with different species
grasslands have a single layer, fewer habitats, fewer species, and fewer species diversity
suggest why draining of ponds on agricultural land might have a greater effect on biodiversity than removing a hedgerow
ponds provide a habitat for aquatic species which are unlikely to find alternative habitats
ponds are source of food and water for terrestrial organisms which may not be able to survive without them
hedgerow species are likely to find alternative habitats as most of the area around is terrestrial with other sources of food- fewer species are likely to be lost
