A4.1

Question 1

Darwinism theory of evolution (4)

Answer 1

in nature - tendency to produce more offspring than supported by nature

individuals in population exhibit variation

natural selection - individuals with variations help them adapt better to environment survive + produce offspring

more favorable variations = greater proportion of population

Question 2

Lamarkism’s theory of evolution (4)

Answer 2

Change in environment leads to use of certain organs

organs used more would increase in size over the lifetime of the organisms

organs not used over the lifetime of the organism would shrink.

changes over the lifetime of an individual would be passed on to offspring

Question 3

Define molecular phylogeny (2)

Answer 3

determining the closeness of relation for different species

through analysis of bases in DNA, RNA and amino acids

Question 4

Evidence for evolution (3)

Answer 4

molecular phylogeny

homologous structures

selective breeding

Question 5

Define homologous structures

Answer 5

similar physical features in different species suggesting that they share a common ancestor

Question 6

Define analagous structures (3)

Answer 6

body parts with same or similar function but with different structures

evolve by convergent evolution

e.g wings of birds, bats and insects

Question 7

Define convergent evolution

Answer 7

distantly related groups of organisms face similar environmental conditions + adapt in similar ways

Question 8

Define reproductive isolation

Answer 8

barriers that prevent populations of the same species from interbreeding

Question 9

Types of reproductive isolation (3)

Answer 9

geographical isolation

temporal isolation

behavioural isolation

Question 10

Define geographical isolation

Answer 10

separation of species by natural barriers

Question 11

Define temporal isolation

Answer 11

separation of species due to differences in timing of reproductive cycle (mating seasons) + gamete production

Question 12

Define behavioural isolation

Answer 12

differing mating rituals + mating calls prevent reproduction

Question 13

2 types of speciation (2)

Answer 13

allopatric speciation

sympatric speciation

Question 14

Define allopatric speciation

Answer 14

population split into 2 by a geographical barrier, preventing exchange of genetic material

Question 15

Define sympatric speciation

Answer 15

species formed in same location with isolating mechanisms

Question 16

Define prezygotic barriers

Answer 16

bariers that prevent formation of zygote (prevent fertilisation)

Question 17

Define postzygotic barriers

Answer 17

barriers after zygote is formed

Question 18

Define adaptive radiation (3)

Answer 18

evolution of single ancestral species into several species, adapting to environmental niches

closesly related species can coexist without competing

increases biodiversity in ecosystems with vacant niches

Question 19

Define hybrid inviability

Answer 19

offspring are produced but do not survive to become sexually mature adults

Question 20

Define hybrid infertility (2)

Answer 20

hybrid individuals are produced

not capable of producing functioning gametes (hybrid is sterile)

Question 21

Define hybrid breakdown (2)

Answer 21

first generation of hybrids capable of reproducing

offspring cannot reproduce

Question 22

Define polyploidy (2)

Answer 22

diploid cell/organism contains one or more additional sets of chromosomes

non-disjunction - error during meiosis