topic 4 - the annoying bs

why use biomass instead of counting number of individuals

Less time consuming

Individual organisms could not be identified/separated

Too small to count

How to standardise sampling

Same sample size area

Same day/time of day samples are taken

Same sampling time

investigating diversity w DNA

Compare DNA base sequences/banding on computerised systems

More similar genes/DNA = more closely related species

what do we aim for in investigating

• Aim to have representative sample

• Avoid sampling bias

• Account for chance anomalies

sd

spread of the data values about the mean - higher spread of data around the mean = more variability

what is species richness and what is index of diversity

species richness - number of different species in a community (particular area at given time)

index of diversity - relationship between number of diff species and number of individuals within each species in a community

index of diversity equation

how does farming reduce biodiversity

• Remove habitats

• Use monocultures which reduce species richness

• Use pesticides and herbicides

• Overuse of fertilisers which can lead to eutrophication and damage aquatic ecosystems

what happens if less plant species present

fewer habitats and fewer food sources

balancing conservation and farming

Better conservation = higher species richness, biomass and more carbon stored

Higher species richness and biomass = more organisms for food webs

More carbon stored = less CO₂ in atmosphere

Lower yield so less food profit

what is hierarchy/phylogeny

smaller groups within bigger groups with no overlap btw groups at same taxonomic level

what causes smaller population

• Inbreeding

• Population may have started with very few individuals/one pregnant female/founder effect

• Population might have been small/genetic bottleneck

why is courtship behaviour done

• Recognise members of their own species of the opposite sex

• Identify a mate that is capable of breeding because both partners need to be sexually mature, fertile and receptive to mating

  • Ensure successful reproduction

• Form a pair bond that will lead to successful mating and raising of offspring

• Synchronise mating so it takes place when there is the maximum probability of the sperm and egg meeting

what is genetic diversity

number of different alleles of genes in population

for selection

Directional/stabilising selection

Change in environmental conditions/constant conditions

Random mutation

Result in new allele of gene

Selective advantage

More likely to survive and reproduce

Pass on advantageous alleles

Frequency of allele increases

One extreme selected for/Standard deviation decreases

what is gene mutation

change in the base sequence of DNA in chromosomes

how meiosis works

DNA replication occurs in late interphase

Two divisions

In first - homologous chromosomes are separated

In second - sister chromatids are separated from centromere splitting

Produces 4 haploid cells

what are the two ways of variation in meiosis

independent segregation of homologous chromosomes - during metaphase, lining up on equator is random

crossing over during prophase - form bivalent, chiasmata form, equal portions of alleles are swapped, new combination of alleles

what is gene

sequence of DNA bases that codes for amino acid sequence of polypeptide or functional RNA (rRNA or tRNA) - occupies specific locus

what is genome and what is proteome

genome - complete set of genes in cell

proteome - full range of proteins that cell is able to produce