B15- Genetics and Evolution

Question 1

describe mendel’s discoveries

Answer 1

carried out breeding experiments on peas
he cross bred smooth, wrinkled, green and yellow
suggested there were separate units of inherited material and some characteristics were dominant over others so they never got mixed together

Question 2

when and why was mendel’s work accepted

Answer 2

16 years after his death (1884) as people then could see chromosomes under a microscope and observed cell division

Question 3

how was dna discovered

Answer 3

in the 1950s rosalind franklin and maurice wilkins observed dna by xray

Question 4

what is lamarck’s theory of evolution

Answer 4

the way organisms behaved affected the features of their body- if animals used something over a lifetime this feature would grow and develop, if a feature wsn’t use it would shrink and be lost

Question 5

what were problems with lamarck’s ideas

Answer 5

no proof

people didn’t like the idea of being descended from worms

Question 6

what is darwins theory

Answer 6

all living organisms have evolved from simpler life forms which has come about by a process of natural selection

Question 7

what were darwin’s main ideas

Answer 7

1. individual organisms in a species show a range of variation for a given characteristic
2. survival of the fittest as reproduction gives more offspring than the environment can support
3. when the ‘fittest’ survive they pass on the characteristics that have enabled them to survive

Question 8

why did darwin take so long to publish his ideas

Answer 8

he was conscious that he needed evidence so he spent years carrying out experiments but he was pushed to publish when he found out that alfred russell wallace had similar ideas

Question 9

why was darwin’s ‘origin of species’ only gradually accepted in some areas

Answer 9

challenged the religious view that was widely accepted
people felt there was not enough evidence
no way to explain how variety and inheritance happens as genes and genetics were not known of until 50 years after Darwin published

Question 10

how is alfred russel wallace

Answer 10

had similar ideas to darwin but darwin published before him so he focused on the idea of speciation and developed theories on the role of geographic isolation in the formation of species

Question 11

what is speciation

Answer 11

when a new species forms as a result of geographical isolation so alleles that allow the organism to survive in the new conditions are selected and variation increases because of natural selection. population changes until they can no longer interbreed with the old population and a new species is formed

Question 12

how do populations become isolated

Answer 12

new mountain range or river
earthquakes and volcanoes
climate change in only one area

Question 13

what is an endemic species

Answer 13

when a species evolves in isolation and is found in only one place in the world

Question 14

what is mineralisation

Answer 14

harder parts of the animal or plant are replaced by minerals

Question 15

how are animal and plant fossils formed

Answer 15

when an animal or plant does not decay because there is no oxygen or posionous gases kill bacteria needed for decay then animals/ plants are preserved almost intact

Question 16

what are examples of traces as fossils

Answer 16

footprints, burrows, eggs, droppings

Question 17

what are the reasons for the fossil record being incomplete

Answer 17

many of the earliest organisms were soft bodied so left little trace
many get destroyed by geological activity
many still to be found
many didn’t form fossils as the conditions for fossil formation were rare

Question 18

what are natural causes of extinction

Answer 18

change in temperature
new predators 
new diseases
more successful competition 
flooding
drought 
volcanic eruptions
asteroid collisions

Question 19

what causes mass extinction

Answer 19

often a single catastrophic event eg asteroid collision o volcanic eruption

Question 20

what caused dinosaur extinction

Answer 20

giant asteroid collision in mexico which would have casued fires, earthquakes, landslides and tsunamis. theory is that dust in the atmosphere amde everywhere dark, temp dropped and 50-70% of species died

Question 21

what is antibiotic resistance

Answer 21

when a bacteria that used to be killed by a drug has a natural mutation meaning they are no longer affected by it

Question 22

how can you prevent more resistant strains of bacteria forming

Answer 22

don’t overuse antibiotics- doctors cut down on prescriptions
finish course of medicine to ensure there are no bacteria surviving that could mutate and form resistant strains
restrict agricultural use of antibiotics to prevent spread of antibiotic resistance from plant to animal pathogens

Question 23

who is carl linnaeus and what did he do

Answer 23

swedish botanist born in 1707 who put forward a system of grouping living things based on physical similarities
he proposed diferent levels of oranisation where organisms share more characteristics

Question 24

what is a species

Answer 24

a group of organisms that can breed together and produce fertile offspring

Question 25

what is the binomial naming system

Answer 25

a scientific naming system intorduced by carl linnaeus in latin
the first name is the genus of the organism (upper case letter)
the second name is the species of the organism (lower case)
when hand written the 2 names are underlined and in italics if printed

Question 26

who is carl woese

Answer 26

american biologist born in 1928 who modernised linnaeus’ system to include different types of bacteria

Question 27

what is the archaea domain made up of

Answer 27

primitive forms of bacteria including extermophiles (organisms that can live in extreme environments) this domain contains one kingdom; the archaebacteria

Question 28

what is the bacteria domain made up of

Answer 28

bacteria and cyanobacteria that can photosynthesise

contains one kingdom; the eubacteria

Question 29

what is the eukaryota domain made up of

Answer 29

organisms that have cells that contain nuclei. contains 4 kingdoms; protista, fungi, plants, animals

Question 30

what are the 3 domains

Answer 30

archae, bacteria and eukaryota