Unit 2 AOS 2 test Flashcards
Asexual reproduction
the production of offspring from a single parent organism
characteristics of asexual reproduction
- offspring are genetically identical to the parent organism
- efficient way to reproduce
- disadvantage in a changing environment due to lack of genetic variation
Fission
- type of asexual reproduction
- DNA replicates then cytoplasm separates
- single parent cell divides into two approximately equal daughter cells
- unicellular eukaryotes (protists) reproduce using fission (accept yeast)
Fragmentation
- type of asexual reproduction
- regeneration of a new organism from a part of another
- flatworms
- marine worms
- starfish and sponges
Regeneration
- growing back a lost body part
Budding
- type of asexual reproduction
- an outgrowth from the parent body pinches off to produce a small individual
- daughter organisms are identical accept for the unequal division of cytoplasm
- occurs in hydra, sponges, yeast cells and cacti
Spore formation
- type of asexual reproduction
- spores are single celled haploid reproductive units
- do not need to fuse with another cell to divide into a new organism
- produced by meiosis
- have a tough outer shell
- released from the parent organism and develop into a new organism in favourable conditions
- occurs in moulds, mosses and ferns
Vegetative reproduction
- occurs in plants
- does not involve seeds or spores
- new plants develop form the roots, leaves or stems of the parent plant
Somatic cell nuclear transfer (SCNT)
- type of cloning
1. the diploid nucleus of a mammary gland cell is removed
2. the nucleus of an ovum form another organism is discarded and replaced with the diploid nucleus from the mammary cell
3. a cell with 46 chromosomes is made and acts as a fertilised cell - the resulting organism is genetically identical to the mammary gland organism
Cuttings
- type of cloning
- a new plant grows from the roots, stems or leaves of another
Grafts
- type of cloning
- the leaf system of one plant is attached into the root system of another plant
Tissue culture
- fragments or cells from a parent organism are selected to grow into clones
- produces large numbers very quickly
Embryo splitting
- type of cloning
- can occur naturally
embryo splits and grows into two identical organisms - embryo can be split and then planted into surrogate mothers
Natural selection
- where mutation and selection pressures drive the evolution of species such that only the organisms that are able to adapt survive
Genetic drift
- random change in the frequency of alleles from generation to generation due to chance alone
- effects are most pronounced in small populations
bottle neck effect
- type of genetic drift
- a catastrophic event wipes out particular alleles
- the gene pool is no longer representative of the parent genepool
- usually effects small populations the most
Founder effect
- type of genetic drift
- a small number of individuals migrate or become separated from the original population
- different alleles and environments create potential for different evolutionary patterns
downfalls of low genetic diversity
- increased risk of extinction and lack of evolutionary potential
- susceptible to disease
- inbreeding depression and increased homozygosity (especially of recessive alleles)
abiotic factors
the non-living factors that impact on the survival of an organism in its environment
biotic factors
the living factors that impact on the survival of an organism in its environment
structural (morphological or anatomical) adaptations
evolved modification of an organism’s physical anatomy
physiological (functional) adaptations
evolved modifications of an organism’s internal function or metabolic process
adaptation
a heritable characteristic of an organism that enables it to survive and to reproduce in its habitat
behavioural adaptations
evolved modifications to an organism’s actions
biosphere
the region of the earth that all living things are found in
biomes
largest geographically based biotic communities, can be aquatic or terrestrial
ecosystem
- self sustaining unit
comprised of - all populations of organisms
- physical surroundings
- biotic and abiotic factors
community
several interacting populations of different species that live together in a particular place at a particular time
population
a group of organisms of the same species living in a defined area
can interbreed and compete for resources
organism
the lowest level of organisation
any unicellular or multicellular form exhibiting all of the characteristics of life
habitat
the physical place that an organism lives in
microhabitat
the precise location within a habitat where a species is normally found
ecological niche
the way in which a species interacts with its environment and alters the conditions of the environment
competitive exclusion principle
no two species can occupy the same niche in the same habitat at the same time
intraspecific interactions
relationships between members of the same species
interspecific interactions
relationships between members of different species
symbiosis
a time of close, long term interaction between individuals of two or more different species where at least one species benefits
types of symbiosis
mutualism
commensalism
parasitism
organisms in these relationships are referred to as symbionts
mutualism
where both species benefit
obligate mutualism
each species is completely dependant on the other and cannot live without the other
EG ruminants and gut bacteria
facultative mutualism
each species benefits from the other but can survive without the other
EG gazelle and oxpecker
commensalism
the commensal benefits while the host is unaffected
EG epiphytes and trees
parasitism
non-mutual symbiotic relationship where the parasite benefits at the expense of the host
ectoparasites
live externally on the host
EG tick
endoparasite
live within the host body
EG tapeworm
amensalism
not symbiotic
when one species is harmed but to no benefit to the other
EG elephants and ants
Predation
not symbiotic
when a predator hunts and kills prey for food
EG lions hunting zebra
food chain
a series of organisms each dependant on the next as a source of food
food web
a combination of food chains in an ecosystem that shows feeding interactions between food chains
trophic levels
producers
primary consumers (herbivores)
secondary consumers
tertiary consumers
top order consumers (apex predators)
keystone species
organisms that play a unique and crucial role in maintaining the structure of an ecological community
population density
the result of processes that add and remove individuals form a population
population size is affected by
- natality
- mortality
- immigration
- emegration
growth factors (biotic potential)
things that help a population grow
biotic
- generalized niche
abiotic
- favourable light
decrease factors (environmental resistance)
things that decrease the population size
biotic
- specialized niche
abiotic
- too much or too little light
carrying capacity (of a species)
the maximum population of the species that the environment can sustain indefinitely
trophic cascade
the ecological phenomenon that describes the direct and indirect effects of removing an apex or top order predator down through the trophic levels and food chain
tropism
- physiological adaptations
- a physiological directional growth response to an environmental stimulus due to the action of hormones
positive tropism
growth towards a stimulus
negative tropism
growth away from a stimulus
light stimulus tropism
phototropism
gravity stimulus tropism
geotropism
water stimulus tropism
hydrotropism
touch stimulus tropism
thigmotropism
chemical stimulus tropism
chemotropism
nastic movement
- a type of physiological adaptation
- a movement in response to an environmental stimulus but is independent of the direction of the stimulus
photonasty
movement in response to change in light intensity
eg opening and closing of flowers
thigmonasty
movement in response to touch
eg venus fly trap
thermonasty
movement in response to changes in temperature
torpor
- a physiological sate where metabolic activity is lowered to save energy and survive difficult conditions
hibernation
a long period of torpor in winter where body temperature drops dramatically
aestivation
is a long period of torpor in summer, enabling high temperatures and water scarcity to be tolerated
parthenogenesis
when a female organism produces gametes that develop directly into offspring without fertilisation
eg Lizards
rhizomes
underground stems that grow form nodes and grow into new plants
form of vegetative reproduction
niche partitioning
when a species changes niches
stolon
above ground stems that grow into a new plant
form of vegetative reproduction
tuber
stems that rise from the plant underground and shoot into a new plant
vegetative reproduction
bulbs and corms
bodies that grow on parent organisms that split off to form new plants
vegetative reproduction
