UNIT 2 Flashcards
Organism & Evolution
All practical work involves identification of …………..
All practical work involves identification of risks and hazards.
Risk assessment
A document that identifies potential hazards, asses the likelihood of them occurring and describes the steps taken to minimize their occurrence, reducing the probability of injury or loss .
Hazards and risks associated with fieldwork
- Terrain
- Weather conditions
- Isolation
- Tidal Changes
Transect Studies
A line along which different samples can be taken. Often set up along an area where terrain or abiotic factors are changeable
Point count
Counts are carried out. useful for sampling bird populations
Remote Detection
uses camera traps that are triggered when wildlife is present. Useful for elusive species.
Scat sampling
sampling animal droppings providing information about abundance and diet.
Random sampling
Individuals selected from the larger population must be chosen completely by chance.
Stratified sampling
Individuals are randomly selected form sub-groups within a population.
Systematic intervals
Samples are taken at regular/pre-set intervals
Identification of a sample can be made using:
- expertise
- classification guides
- keys
- laboratory analysis of DNA
Life is classified into 3 domains:
- Archea
- Bacteria
- Eukaryotes
Monitoring populations is essential in understanding………….
Monitoring populations is essential in understanding environmental conditions
________ ______ _________ is a method used to estimate population size
Mark and recapture is a method used to estimate population size.
The Marking technique in mark and re-capture must have a minimal impact on the species being studied so that…………
The Marking technique in mark and re-capture must have a minimal impact on the species being studied so that it does not interfere with its normal behaviour or make it more conspicuous to predators.
Methods of marking in mark and recapture include:
- hair clipping
- banding
- tagging
- painting
- surgical implantation
Ethology
Study of animal behaviour
An ________ is a study of all the observed behaviours shown by a species over a period of time.
An ethogram is a study of all the observed behaviours shown by a species over a period of time.
Evolution-
the change, over successive generations, in the proportion of individuals in a population differing in one or more inherited traits.
Evolution can occur through:
- Genetic Drift
- Natural selection
- Sexual Selection
Genetic drift is __________ whereas Natural selection and sexual selection is _____________
genetic drift is random whereas natural selection and sexual selection is non-random.
Genetic drift-
Random change in how frequently a particular allele appears in a particular population.
Natural selection and sexual selection are non-random because…………..
Natural selection and sexual selection are non-random because certain alleles offer a selective advantage.
Fitness can be measured in……………….
Fitness can be measured in absolute or relative terms.
Absolute fitness-
ratio of frequencies of a particular genotype from one generation to the next.
Relative fitness
The ratio of surviving offspring of the genotype compared to other genotypes.
When selection pressures are high, the rate of ___________ can be rapid.
When selection pressures are high, the rate of evolution can be rapid.
- Shorter generation times
- Warmer enviroments
- sharing DNA sequences
increase rate of evolution
Co-evolution
where a change in the traits of one species acts as a selection pressure on another species with which it frequently interacts.
Symbiosis
An inter-relationship between different species whereby at least one organism benefits.
Mutualism
Symbiotic relationship where both organisms benefit.
Parasitic relationship
Symbiotic relationship where one species is harmed
commensalism
symbiotic relationship where one benefits and one benefits and one neither benefits or is harmed.
When compared to assexual reproduction, sexual reproduction appears to have 2 main disadvantages:
- Half of the population (males) are unable to produce offspring
- Each parent is only able to pass on half of their genetic material rather than the full 100%
advantages to sexual reproduction
greater genetic variation within sexually reproducing organisms
when niches are narrow and stable, ___________ __________ can be a successful reproductive strategy.
when niches are narrow and stable,assexual and stable can be a successful reproductive strategy.
_____________ reproduction is usually faster when recolonising habitats as it is usually faster.
assexual reproduction is usually faster when recolonising habitats as it is usually faster.
Examples of assexual reproduction in eukaryotes:
- Vegetative propogation/ cloning
- parthenogenesis
Meiosis is the process by which……….
Meiosis is the process by which gametes are produced in the reproductive organs. One diploid mother cell provides 4 haploid daughter sex cells.
______________ has 2 divisions and results in variable gametes.
Meiosis has 2 divisions and results in variable gametes.
Genes on the same chromosome are said to be _________
Genes on the same chromosome are said to be linked.
separating linked genes during crossing over creates……………
separating linked genes during crossing over creates recombinants
many organisms, usually invertebrates, are……….
many organisms, usually invertebrates, are hermaphroditic (an organism with both male and female sexual organs)
simultaneous hermaphrodites have………….
simultaneous hermaphrodites have both reproductive organs
sequential hermaphrodites can…………
sequential hermaphrodites can change gender at some point during their life.
sometimes sex determination is under _________ rather than _________ control
sometimes sex determination is under environmental rather than genetic control
sex can change as a result of…………..
sex can change as a result of size competition or parasitic infection
autosome-
a chromosome that is not a sex chromosome
In mammals, males tend to be heterogametic. This means that sex linked traits are more common in males than in females.
In mammals, males tend to be heterogametic. This means that sex linked traits are more common in males than in females.
females can be carriers of a recessive sex linked train yet show no _____________ effects. The reason for this is that
females can be carriers of a recessive sex linked train yet show no deleterious effects. The reason for this is that one x chromosome in each cell in randomly deactivated.
lekking
males display for females in a communal display area, then females choose a mate.
sexual dimorphism
physical differences between males and females of a species
polygamy-
usually where one male has access to mate with several females
monogamy-
where species from breeding pairs, this one male to one female
K-selected species
larger organisms, lower numbers of offspring, extensive parental care, longer life span.
R-selected species
smaller organisms, larger number of offspring, little to no parental care, shorter lifespans.
all species, produce………..
all species produce more offspring than survive to reproduce
external fertillisation
fusion of gametes occurs outside the female
Internal fertillisation
fusion of gametes occurs inside the female
sessile organisms
fixed to a surface and therefore cannot move
__________ are always more numerous than eggs
sperm are always more numerous than eggs
due to the presence of an energy store, _____ are much larger and fewer in number.
due to the presence of an energy store, eggs are much larger and fewer in number.
At least 5% of all species are classed as _____________
At least 5% of all species are classed as parasites
all free living species are thought to………….
all free living species are thought to host parasites to some extent.
an ecological niche is………….
an ecological niche is a complex outline of tolerances and requirements of a species.
parasites tend to have a very narrow niche due to……………..
parasites tend to have a very narrow niche due to high host specificity.
many parasites are ___________ (lacking in structures and organs found in other organisms)
many parasites are degenerate (lacking in structures and organs found in other organisms)
ectoparasite
niche on the surface of the host
endoparasite
niche inside the host
definitive (primary) parasite host
this is where the parasite reaches sexual maturity
intermediate (secondary) parasite host
the parasite might require this in order to complete its lifecycle, perhaps carrying out assexual reproduction to greatly increase its numbers or as a means of transmission (spread), thus making the intermediate host a vector
vectors are responsible for-
vectors are responsible for transmitting the parasite from one host to another. Vectors can also be hosts of a parasite.
Fundamental niche
the niche that the organism occupies when there are no other species present competing for space or resources
realised niche
niche the organism occupies when there is competition from other species.
competitive exclusion princilple
when 2 species are in competition with each other, thus the niches occupied by each is very similar and the weaker of the 2 species will likely die out.
Resource partioning
where 2 species occupy different realised niches, allowing them to co-exist by compromising over resources.
virulence
the deleterious effect the parasite has on a host.
The _______ the transmission rate, the _____________ the virulence.
The higher the transmission rate, the higher the virulence.
transmission rates of parasites are greatest when:
- overcrowding of hosts
- a means of transmission
extended phenotype
a theory whereby the parasite modifies the host organisms behaviour to increase its own transmission
phagocytes
white blood cell in specific defence involved in engulfing and destroying foreign antigens.
natural killer cells
lymphocytes responsible for killing abnormal cells.
phagocytosis
non-specific defence where phagocytes engulf foreign antigens and digest them using digestive enzymes present in lysomes
B cells
white blood cells (lymphocytes) that produce specific anti-bodies in response to specific antigens.
T cells
white blood cells (lymphocytes) that destroy specific infected or damaged cells by bring about apoptosis
apoptosis
cell death
antigens
proteins found on the surface of cells
clonal selection
lymphocytes become amplified, with some clones used in immediate defence and other clones acting as memory cells.
memory cells
cloned lymphocytes that remain in the body to respond faster if the individual is exposed to the antigen a second time.
antigenetic variation
where parasites show great variety amongst different different strains
epidemiology
the study of outbreak and spread of infectious diseases.
herd immunity
protection offered to non-immune members of a population by sufficient numbers of immune individuals.
herd immunity threshold
density of resistant individuals required in the population to prevent an epidemic.
ectoparasites are transmitted by …………….
ectoparasites are transmitted by direct contact
endoparasites of the body cavities are transmitted via
endoparasites of the body cavities are transmitted via vectors
viruses are composed of………..
viruses are composed of nucleic acid enclosed inside a protein coat.
the outer surface of a virus contains _______ that a host may or may not be able to detect as foreign.
the outer surface of a virus contains antigens that a host may or may not be able to detect as foreign.
retroviruses are virus that contain ___ instead of ____. HIV is an example of a retrovirus.
retroviruses are virus that contain RNA instead of DNA. HIV is an example of a retrovirus.
rapid parasite __________ change makes designing vaccines very difficult.
rapid parasite antigen change makes designing vaccines very difficult.
