unit 2

• Symbosis?

  ?co- evolved initmate relationships between members of two different species
• sexual dimorphism?


  two Sexes of the same species exhibit different characteristics beyond the differences in their sexual organs
• Sexual selection is the non random selection of alleles that increase the individuals chances of mating and producing offspring
• Sexual selection may be due to;

  • male/ male rivalry ( large size/ weapon art increased access to females Through conflict)
  • female choice ( females assessing the males fitness)
• define fitness in evolution?

  fitness is a measure of the tendency if some organisms to produce more surviving offspring than competing members of the same species
• evolution?

  evolution is the change, over successive generations, in the proportion of individuals in a population differing in one or more inherited traits.

  populations produce more offspring than the environment can support

  individuals with variations better suited to the environment tend to survive longer and produce more offspring. they breed more and pass on advantageous alleles to the next generation
• Define genetic drift?

  the random change in how frequently a particular allele occurs within a population
• Genetic drift has a more significant impact in small populations because alleles are more likely to be lost from the gene pool
• Define Virulence?

  The potential of a parasite to cause harm to a host
• Asexual reproduction is when an individual produces genetically identical offspring without fertilisation
• define Sexual dimorphism?

  Describes animals where there is a physical difference between the males and females of the same species
• Outcome of host- parasite co-evolution?

  hosts are able to resist parasites more easily, parasites can reproduce more easily in host
• Effects of genetic drift?

  can lead to loss of genetic variation in populations and can cause harmful alleles to become fixed
• Link between transmisson and virulence?

  a higher rate of transmission is linked to higher virulence
• Asexual reproduction in plants?

  vegetative cloning e.g. In bulbs
• Definitive host?


  the organism on or in which the parasit reaches sexual maturity
• Founder effect?


  loss of genetic variation that occurs when a new population is established by a small number of individuals from a larger population. the founders gene pool with not be representative of the original populations can result in the loss of alleles from a gene pool
• define ethology?

  study of animal behaviour
• Who has greater parental investment?

  females
• Hazards of fieldwork?

  terrain, weather conditions, isolation and tidal changes
• Gene flow?

  gene flow is the gain or loss of alleles from a population by movement of individuals gametes in or out of a population
• Benefits of asexual reproduction?

  Production of offspring can be rapid metabolic costs are lower
• What sampling techniques can be used for mobile species?

  capture techniques such as mark and recapture
• Define courtship?

  specialised behaviour in animals that attracts a member of the opposite sex and leads to mating
• How does crossing over increase genetic variation l?

  results in the recombination of alleles which produces different combinations of alleles which increases genetic variation
• Realised niches?


  is the niche that the organism occupies when there is competition from another species
• Fixed pattern action?

  is a fixed behaviour sequence that involves a series of sign stimulus by responses
• Parasitism is an examples of what type of relationship?

  harmful symbotic relationship
• Parasite?


  a parasite is an organism that lives on or in a host. parasites benefit from their hosts in terms of shelter and nutrients
• Benefits of improved parasite control to human populations?

  reduction in child mortality

  body used more resources for growth/ development
• Explain what is meant by a lekking species?

  males compete in communal area to allow female choice
• Costs and benefits of sexual reproduction (5)?

  ?only females able to produce offspring

  only half of each parents genome is passed to offspring

  disrupts successful genomes

  increases genetic variation

  genetic variation allows evolution in response to changing envro
• Discuss asexual reproduction as a successful reproduction strategy?

  ?successful genome passed on

  in narrow stable niches

  vegetative cloning in plants

  pathogensis in animals

  pathogensis where parasite burden is low

  in organisms using asexual reproductio, horizontal gene transfer allows exchange of genetic material
• State why the cell culture medium in which the neurons were cultured contains serum?

  serum provides growth factors
• State one disadvantage of cell counts performed using the haemocytometer?

  dead cells are not distinguished from live cells
• State a type of biological material using bright field microscopy?

  parts of organism
• Advantage of a trail carrie doubt in vivo?

  allows side effects to be seen
• Explain why a placebo group was included?

  shows drug was responsible for effect
• State one factor that can increase the rate of evolution?

  higher mutation rate
• State one feature of a representative sample?

  ?same mean as population as a whole