a4.1 evolution and speciation

Question 1

what allows different variations in a species

Answer 1

mutation of genes inside organisms over a period of time

Question 2

theory of evolution

Answer 2

natural selection

Question 3

evolution

Answer 3

cumulative change in the heritable characteristics of a population

Question 4

what is not regarded as evolution

Answer 4

acquired characteristics that are not genetic in origin
eg. language

Question 5

explanation for natural selection

Answer 5

1. organisms with more favourable characteristics within the environment will survive
2. higher chance to pass on their genes onto the next generation

Question 6

what does “the fittest” mean

Answer 6

organisms that can adapt to the current environment

Question 7

what happens if no organisms in a species can adapt to the new environment

Answer 7

become extinct

Question 8

word for gaining species

Answer 8

speciation

Question 9

steps for selective breeding [4]

Answer 9

1. humans choose the individual animals or plants with the desired characteristics
2. then they breed them together to produce offsprings
3. then they choose the offsprings carrying the desired characteristics and have them breed with each other
4. repeat these steps for several generations, eventually the desired characteristics will be present in more of the offsprings

Question 10

analogous structures

Answer 10

same function but different evolutionary origins

Question 11

homologous structures

Answer 11

might look different as the species evolved and perform different functions

Question 12

eg for homologous structures

Answer 12

pentadactyl limbs

Question 13

eg of corn

Answer 13

wild ancestor- teosinte (grass)
domesticated- maize (corn)

Question 14

cons of artificial selection [3]

Answer 14

1. reduce variations in the species
2. may cause extinction if the environment changes
3. selectively bred organisms may not survive in the wild without human support

Question 15

how is dna base sequences used to support the theory of evolution

Answer 15

not just about gaining genes
also losing genes that are no longer fit for survival

Question 16

what might mutations in dna do to a species

Answer 16

more adaptive to their environment

Question 17

name for ‘dead gene’

Answer 17

pseudogene

Question 18

what leads to divergent evolution

Answer 18

adaptive radiation

Question 19

why are analogous structures not evidence for evolution

Answer 19

• did not come from the same origin
• species evolved and body parts served a similar function

Question 20

what is analogous structure a product of

Answer 20

convergent evolution

Question 21

how to promote speciation

Answer 21

reproductive isolation- their gene pools can no longer mix

Question 22

eg for speciation

Answer 22

bonobos and chimpanzees

conditions of diff parts of the jungle
south (bonobos)- make friends, less likely to be eaten by predators and can mate
north- presence of gorillas so chimpanzees evolved to be violent and aggressive

Question 23

differential selection

Answer 23

when theres a selection pressure on a certain type of mates

Question 24

allopatric speciation

Answer 24

caused by geographical isolation

Question 25

sympatric speciation

Answer 25

anything BUT geographical

Question 26

temporal isolation

Answer 26

sympatric speciation diff time of flowering or in heat

Question 27

behavioural isolation

Answer 27

sympatric speciation diff bird songs

Question 28

adaptive radiation eg

Answer 28

galapagos finches - adapted on diff islands based on diff food sources - diff species meet again- diff songs and appearance stops them from mating

Question 29

why are hybrids rare

Answer 29

zygotes often die during embryo development

Question 30

are hybrids efficient

Answer 30

no - genes are not passed onot the next generation

Question 31

ways to prevent hybridisation [3]

Answer 31

1. very specific courtship behaviour 2. sterility of interspecific hybrids (odd number of chromosomes so cant be evenly divided and cant make gametes, meiosis cant happen) 3. geographical isolation

Question 32

result if hybrids can produce offsprings

Answer 32

abrupt speciation

Question 33

factors that cause abrupt speciation [2]

Answer 33

1. offspirngs of hybrids 2. polyploidy

Question 34

what is polyploidy

Answer 34

more than 2 sets of homologous chromosomes

Question 35

why can polyploidy occur

Answer 35

- eg. meiosis did not occur after S phase and a diploid gamete fused with a haploid gamete - can be due to error in meiosis or hybrid between 2 species

Question 36

polyploid

Answer 36

cant reproduce with original species but if they can produce fertile offsprings, then u have a new species

Question 37

4 sets of chromosomes

Answer 37

tetraploid

Question 38

autotetraploid

Answer 38

4 sets of chromosomes that came from the same organism

Question 39

why is polyploidy more common in plant cells

Answer 39

pluripotent (stem cells)

Question 40

triploid

Answer 40

meiosis in an autotetraploid individual produces diploid cells

Question 41

allotetraploid

Answer 41

- involved hybridisation - can interbreed with other allotetraploids but not w either of the diploid parent species

Question 42

how to create new species w polyploidy

Answer 42

2 homologous pairs w AB - can do meiosis normally