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Flashcards in Evolution Deck (33):
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Inheritance of acquired characteristics (lamark's theory)

-characteristics of individuals change during their own lifetime
-the changed (acquired) characteristics are passed onto the next generation

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Evidence for Lamarck

Changes in individuals can be acquired over time

2

Evidence against Lamarck

Acquired characteristics are not passed on

3

Natural selection (darwin's theory)

The mechanism if evolution
-the environment 'selects' from already existing variations the ones that are the best suited for a particular environment (=selection pressure)
-these survive and breed and pass on their genes
-more offspring with these characteristics are produced
-not forced by environment

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Give examples of selection pressures

Predators
Food
Disease
Climate
Mate finding

5

Why do rabbits have very long ears in the desert

As longer ears mean more SA/V therefore heat loss is more likely to occur at a larger and quicker rate

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Why are stick insects adapted so well for their environment

To disguise themselves from predators

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Why do peacocks have brightly coloured feathers

To attract a mate

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Why do giraffes have long necks

To reach leaves off tall trees in scarce food supply

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Microevolution

Small scale changes within species leading to new subspecies

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Macroevolution

Large scale changes leading to a new species as explanation for origin of life and species

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Darwin's theory of evolution

All species have evolved from simple life forms which first developed more than 3 billion years ago through the process of natural selection

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Name three types of recent evolution

-peppered and dark moths
-bacteria resistant to antibiotics
-sickle cell anaemia spreading in Africa as resistant to malaria

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Selective breeding

Breeding only those individuals with desirable characteristics (AKA artificial selection) not due to climate disease etc

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Natural selection causes

-predators, climate, disease etc
-only organisms with favourable traits survive and breed

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Artificial selection causes

-mutations
-variation
-selection pressure (human choice)
-survival and reproduction
-only organisms with desirable traits are chosen to breed

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What traits do farmers select for in plants

-high yield
-disease resistance
-pesticide resistance
-hardier
-flavour
-growth rate

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What traits do people select for in animals

-speed
-looks
-obedience

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What traits do farmers select for in animals

-more meat/milk/eggs
-more/better quality fur
-more offspring
-disease resistance

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Cloning

Any procedure that produces genetically identical offspring

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Cuttings

Take a small piece of plant, dip in rooting powder, plant in compost, keep in warm humid environment ie greenhouse to speed up growth

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Micropropagation

Take a few cells/small parts from the plant (explants), put into culture medium (agar gel), plantlets will begin to grow

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What does agar gel contain

Vitamins
Minerals
Nutrients
Water
Glucose
Growth promoters

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What are the advantages of micropropagation

Quick
Large number of genetically identical plants
Any time of year
No variation
Genetic modification can be introduced along the way
Puts small farms out of business as cant keep up with production rates

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Reproductive cloning

Transfer of a nucleus from a somatic cells of a donor A to an egg cell from B that has no nucleus in order to form a diploid zygote with A's DNA, the developing embryo is implanted into the uterus of a foster mother (C) to develop and give rise to a clone of A

25

What are the issues with reproductive cloning

-not reliable
Birth defects and abnormalities
May lead to human cloning
Could help end world hunger

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Fossils

Mineralised or otherwise preserved remains of animals, plants and other organisms

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3 ways fossils are formed

-harder parts of animal/plant are replaced by minerals over a long period of time
-animal/plant locked in ice, amber tar pits and so didnt decay (rare)
-casts or impressions can be found (footprints)

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What can fossils tell us

-carbon dating tells us when something lived
-can help build evolutionary timeline of how plants or animals have or havent changed
-extinct animals that could be ancestors

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What cant fossils tell us

-whole construction
-some missing links in evolutionary timeline if fossils not found
-colour etc exact appearance

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Extinction

The permanent loss of all the members of a species from the earth

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Mass extinction

Loss of a number of species at the same time

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Causes of extinction

-environmental: climate change, meteorites, volcanoes
-new predators
-new diseases
-competition