U2 definitions Flashcards
arthropods
joint-legged invertebrate that are identified by their segmented body, typically with pared appendages eg fruit fly,. wasps
sodium-potassium ATPase?
the enzyme that acts as the sodium-potassium pump bringing three sodium ions into the cell and taking two potassium ions out of the cell during the cycle of action.
chordates
sea squirts and vertebrates eg birds, mammals, reptiles, amphibians, fish
nematodes
also called roundworms
unsegmented thread-like body
many are parasitic living inside their hosts eg.flukes and tapeworm
why are carriers less likely to be affected by deleterious mutations on one of their X chromosomes?
because of random X chromosome inactivation
what does the SRY gene on the Y chromosome do?
encodes testes- determining factor (TDF) and determines the development of male characteristics.
what can sex be determined by?
- sex chromosomes (In most mammals)
- environmental temperature of egg incubation (in some reptiles ie. Mississippi aligators)
- size
- competition
- parasitic infection
- resource avaliability
why do the benefits of sexual reproduction outweigh the costs?
due to an increase in genetic variation in the populations
parthenogenesis
reproduction from a female gamete without fertilisation
more common in colder environments which are disadvantageous to parasites, or regions of low parasite density or diversity
example of horizontal gene transfer
plasmids between bacteria and yeasts
why may co-evolutionary interactions between parasites and host select for sexually reproducing hosts?
- hosts better able to resist and tolerate parasitism have greater fitness.
- if hosts reproduce sexually, the genetic variability of the offspring reduces the chances that all will be susceptible to infection by parasites.
- the genetic variation in their offspring increases the chances that some of the offspring will have improved ability to exploit their hosts.
why may co-evolutionary interactions between parasites and hosts select for sexually reproducing hosts?
hosts better able to resist and tolerate parasitism have greater fitness
using external fertilisation
allows very large numbers of offspring to be produced
many gametes are predated and not fertilised
there’s little to no parental care
few offspring survive
using internal fertilisation
increases the chances of successful fertilisation
fewer eggs needed
retained internally for protection and or development
higher offspring survival rate
the disadvantage of internal fertilisation
energy is required to find a mate and required the difficult direct transfer of gametes from one partner to another
independent assortment
the order in which chromosomes line up at the equator of the cell during meiosis I. This is random and irrespective of their paternal origin.
biotic selection pressures
competition
predation
disease
parasitism
abiotic selection pressures
temperatures pH light intensity salinity ALL SELECTION PRESSURES INCREASE THE RATE OF EVOLUTION
conditions for HW
no mutation no gene flow no natural selection large population size RANDOM MATING
fitness is an indication of?
a measure of?
refers to?
- an indication of an individual’s ability to be successful at surviving and reproducing.
- a measure of the tendency of some organisms to produce more surviving offspring than competing members of the same species
- the contribution made to the gene pool of the next generation by individual genotypes
commensalism
is a symbiotic relationship in which only one of the species substantially benefits and the other is neutral
if the absolute fitness is 1?
if greater than 1?
less than 1?
then the frequency of that genotype is stable
an increase in genotype frequency
a decrease in the frequency of genotype
what is classic taxonomy based on?
morphology
examples of taxonomic groups (3)
nematodes
arthropods
chordates
what does the mark and capture technique assume?
- all individuals have an equal chance of capture
- no immigration or immigration
- all that are marked and released can mix fully and randomly with the total population
What’s an ethogram?
a list of species-specific behaviours shown by a species in a wild context that allows the construction of time budgets
what is meant by fitness?
a measure of the tendency of some organisms to produce more surviving offspring than competing members of the same species
advantages of horizontal gene transfer?
- rapid
- more variation as more rapid so more mutations
- no need for mating
- whole genomes are transferred and left undisturbed.
vegetative cloning is asexual and gives very little variability in offspring.
Explain how enough variation is produced to allow evolutionary processes such as natural selection to occur.
mutations can still occur.
some mutations may be advantageous to the individual and so they are selected for.
Explain why resource availability can change the sex ratio of offspring in some species.
- When the competition is high, lemurs will produce male offspring. This is because male offspring will leave the nest sooner than female offspring and so this will reduce the competition for resources for the mother.
If a display during lekking provides honest signals, explain the benefit that may be obtained by females receiving these signals.
- they will be around to help feed and raise the offspring
this will make the female more likely to mate with them as they will share some of the burdens of raising the offspring. - this also suggests they will have a low parasite count and so females will be more likely to mate.
What is sexual selection?
selection for characteristics which have little survival benefit for the individual, but increase their chances of mating.
red deer are also a moorland species, they have an annual rut in which male stags fight for mating rights with female hinds. Explain how this differs from a lek.
a rut is an example of male-male rivalry. when this happens males fight for the right to mate, females do not get a choice.
in a lek, males display their best characteristics and female choice occurs.
what happens if hosts reproduce sexually? (RQH)
- The genetic variability in their offspring will reduce the chance that all will be susceptible to infection by parasites.
- the genetic variation in their offspring increases the chances that some of the offspring will have improved ability to exploit their hosts.
what is virulence?
the parasites ability to cause damage to the host
what does increased virulence allow the parasite to do?
better able to feed
reproduce
find new hosts
what must be true for a valid investigation using the mark and capture technique?
- all individuals have an equal chance of being captured
- immigration and emigration occur at equal rates
- the sampling methods used are kept the same
genetic drift
- random
- occurs when chance events cause unpredictable fluctuations in allele frequencies from one generation to the next.
why is genetic drift more important in small populations?
because alleles are more likely to be lost from the gene pool and any changes to allele frequency is more likely to be significant to the population as a whole.
why may some alleles be underrepresented or overrepresented following genetic drift?
the new population carries only a random sample of the original populations alleles.
what is the bottleneck effect?
a type of genetic drift in which the population size is significantly reduced so the variation in allele frequency is much less.
what is coevolution ?
the process by which two or more species evolve in response to selection pressures imposed by eachother
what is the irreversible development process which occurs in birds and may influence their mate choice later in life called?
imprinting
what is a species-specific sign stimulus?
a feature or action that indicates intent, often to start courtship
what causes type 1 diabetes?
insufficient insulin production
Explain that monitoring populations can provide important information for assessing the environmental impact.
the presence of indicator species can tell us about the environmental qualities such as the presence of a pollutant eg. sulfur dioxide or a desired human resource eg. oil or copper.
how are linked genes used to map chromosomes?
linked genes are those that are found on the same chromosome. separating linked genes through crossing over leads to recombinants. scientists can then use this frequency of recombination to map chromosomes, working out the location of the genes on the chromosome in relation to each other.
what are courtship behaviours?
behaviours in animals which result in mating eventual reproduction eg. leks, sneaking, honest signals for females.
what does the construction of time budget allow?
Recording the duration of each of the behaviours in an ethogram, together with the total time of observation allows the proportion of time spent on each behaviour to be calculated as a time budget.
in which niches is asexual reproduction likely to be a successful reproductive strategy?
narrow and stable niches
example of a species in the UK that takes part in a lek?
Black grouse
describe satellites
satellite birds are subordinates and juveniles who occupy the fringes of a lek.
describe the benefit of satellite birds
the satellite benefit from the presence of females attracted by the dominant male and will attempt secretive mating with some of them, often successfully
in some species, territorial males benefit from the presence of the satellite birds since their presence seems to attract additional females to the lek.
The black grouse male is larger and more brightly coloured than the female and competes
with other males at leks. What kind of mating system allows this?
polygamy
schistosomiasis in humans is caused by an
endoparasitic platyheliminth
red queen hypothesis
in a co-evolved relationship, the change in traits of one species can act as a selection pressure on another species. this means that species must adapt to avoid extinction.
structure of a virus
- contains either RNA or DNA
- the outer surface contains antigens which are proteins that the host cell may or may not be able to detect as forgein.
- some have a phospholipid coat made up of the host cell materials
compare the sizes of the fundemental niche and the realised niche?
the realises niche is narrower than that of the fundemental inch
