evolution and variation (ch12) Flashcards
what does the theory of evolution state
that all species evolved from simple life forms that developed 3 billion years ago
what was lamarcks theory
inheritance (genetically passing on) of acquired characteristics and characteristics that arent used eventually disappear
why is lamarcks theory false
implies that all organisms gradually become more complex and simple organisms disappear
what is darwins theory
genetic variation -> too many organisms need to compete for food and water -> natural selection (those who are best adapted survive)-> animals best adapted for environment have the most competitive environments -> more likely to survive and pass on allele
what is mutation
a change in genetic material
what is natural selection
process by which evolution takes place and only those who are most fitted to the environment survive (peppered moth example)
what is variation
any difference between individuals in a species
how do you answer a 6 mark natural selection question
1)start with mutation
2) competitive advantage (state what it is and how it helps them)
3)more likely to survive and reproduce to pass on allele
4)specify answer to example
define species
a group of organisms with similar characteristics and interbreed to produce fertile offspring (donkey+horse are infertile since theyre seperate species)
how do species change
-when small populations become isolated to a different environment by:
1) geographical isolation (ex: island formation or mountain ranges)
2)deforestation
3) construction of new roads
how does speciation occur
1) small population becomes geographically isolated
2) different environmental conditions they must adapt to
3) mutation -> variation in new population
4)new population can no longer interbreed with the old one and produce a fertile offspring
how do animals adapt in cold climates
larger than usual to have a small SA:V and reduce energy transfer
very insulated blubber from the inside and thick fur coat on the outside
huddle to reduce exposed surface area
how do animals benifit from camouflage
-predators avoid being seen by prey and prey hide from predators
how do animals adapt in hot and dry climates
-large SA:V to transfer as much energy to environment as possible
-dont sweat often to reduce water loss
-thin fur and little body fat to make it easier to transfer energy and cool down
what happens if plants are in hot and dry conditions
photosynthesis and respiration take place too rapidly and the plant looses water
how do plants change their surface area to adapt to environments
-broad leaves with large surface area collect dew
- most animals in dry areas have a small sa:v ratio and curled leaves to cut down on water loss
how do cuticles help plants adapt to their environment
they have a waxy layer coating the leaf that stops water from evaporating
how are cacti adapted to suit their environment
leaves are reduced to spikes that discourage animals from eating them and they have a large spine full of water storage tissue
how do plants collect water
they often have a large root sytem to absorb as much water as possible from the soil
what happens if organisms loose to their competitors
they either die , migrate or find a new stratigy
what are the 4 main things animals compete for
water
food (prey compete not to be eaten and predators compete for prey)
why is it a problem when animals only have 1 food source
all animals in the same species need to compete for it (intraspecific)
why do animals need their own territory
so they can have more space to breed and increase their species
what is meant by intraspecific
when animals from the same species compete for resources
what is meant by interspecific
when different species need to compete for territory
what do plants need to compete for
-water to keep tissue supported and rigid
-light for photosynthesis
-space to grow
-nutrients for chemicals needed to support cells
what do parasites feed on
hosts. parasite is benifited while host is harmed
what is the parasite that causes malaria
plasmodium
what types of parasites live inside hosts and what parasites live outside
inside; tapeworms
outside; hair lice
how are fleas adapted against hosts
they release a chemical that stops blood clotting so they can get constant blood flow
sharp teeth to pierce skin and not fall off easily when scratched
long legs to jump quickly from host to host
what do tapeworms do
attach themselves to the hosts small intestine and absorb nutrients which causes vomiting and weightloss
how are tapeworms adapted to feed on hosts
-multiply asexually very quick
hooks to hold onto small intestine
very long to increase surface area so more efficient absorption of nutrients
thick cuticle acts as protection from digestive enzymes
how is malaria transmitted
by mosquitos
explain the plasmodium life cycle
1) mosquito bites malaria-infected host
2) An infected mosquito bites another human and injects infected blood into them
3)plasmodium infects liver cells and then multiplies
4) infection reaches red blood cells till they burst
what happens if you have a hetrozygous sickle cell anemia gene (carrier)
-competitive advantage since youre immune1 to malaria
-survive and reproduce
-then pass on sickle cell anemia gene to offspring
why were moths being marked under their wings instead of above
so their camouflage isnt changed
why did rails disappear from their previous inhabited islands
- too many competitors
-new diseases
-new preditors
describe 3 ways fossils can be made
-bones are preserved
-lack of oxygen causes decay
-organism is replaced with debris as they decay
suggest a reason why sheep decreased in size over 25 years
- mutataion or variation in gene
-warmer and dryer now
-smaller lambs survive
-smaller sheeps breed and pass on the allele to offspring
