T6 genetics and evolution Flashcards Preview

aqa gcse biology free > T6 genetics and evolution > Flashcards

Flashcards in T6 genetics and evolution Deck (21)
Loading flashcards...
1
Q

outline the theory of evolution by natural selection

A

individuals of a species show a wide range of variation for a characteristic

those with the characteristic most suited to the environment will survive, breed most successfully

the desirable characteristic that has enabled the individuals to survive are passed onto their offspring

2
Q

why was Darwin’s theory of evolution not accepted initially

A

most people believed in creationism

insufficient evidence to prove the theory

mechanism of variation and inheritance was not known at the time

3
Q

Jean-Baptiste Lamarck’s theory of inheritance

A

that changes during the lifetime of an organism can be inherited

4
Q

what is speciation

A

formation of a new species, when 2 populations become so varied that they cannot interbreed to produce fertile offspring

5
Q

definition of a species

A

groups of organisms with similar characteristics which are able to interbreed to produce fertile offspring

6
Q

outline the process of speciation through geographic isolation

A

2 populations of the same species are separated geographically

geographic isolation prevents interbreeding and mixing of genes between the populations

due to different selection pressures, different mutations occur producing different phenotypes in each population

over time, the 2 populations may evolve so that they can’t interbreed

7
Q

why is genetic variation important in speciation

A

produces phenotypic variation, some of which are better suited to the environment and are selected for

8
Q

how did Mendel study inheritance

A

through carry breeding experiments on plants and analysing the ratio of characteristics in offspring

9
Q

why was Mendel’s work not recognised until after his death

A

couldn’t explain mechanism of inheritance as chromosomes were discovered after

not communicated well to other scientists and not published in a reputable scientific journal

10
Q

2 kinds of evidence used to show evolution

A

fossils

antibiotic resistance in bacteria

11
Q

how are fossils formed

A

parts of organisms that haven’t decayed due to conditions needed for decay being absent

parts of organisms that have been replaced by minerals as they decayed

traces of organisms are preserved, covered in sediment and becoming rock

12
Q

why are there few traces of early life-forms left behind

A

mostly soft-bodied

13
Q

how do fossils act as evidence for evolution

A

scientists can identify the ages of the fossils and use them to show how organisms change over time

14
Q

what do branches in evolutionary trees indicate

A

where speciation has occurred

15
Q

factors that may lead to extinctions

A
new disease
predation
competition
changes to the environment
catastrophic events
16
Q

what enables bacteria to evolve quickly

A

fast rate of their reproduction

17
Q

outline the process of antibiotic resistance bacteria evolving

A

mutations occur in bacteria producing GV

certain strains are resistant and are not killed when antibiotic is applied

resistant strains survive and reproduce

over time, population of the resistant strains increase

18
Q

why are resistant strains of bacteria dangerous

A

no immunity and no effective treatment

19
Q

example of a resistant strain of bacteria

A

MRSA

20
Q

what can be done to reduce the rate of development of antibiotic resistant bacteria

A

refrain from inappropriately prescribing antibiotics

complete prescribed course

restrict agricultural uses of antibiotics

21
Q

why is it difficult to keep up with emerging resistant strains

A

developing antibiotics have a high cost and take a long time to develop