B15 Genetics and Evolution

Question 1

how did Darwin develop his theory of evolution by natural selection?

Answer 1

he studied many fossils, animal specimines and plants
he then discussed and experimented and came up with his theory

Question 2

what is present within any species for any characteristic

Answer 2

wide range of genetic variation

Question 3

what does ‘survival of the fittest’ mean?

Answer 3

individuals with the characteristics most suited to the environment are more likely to survive and reproduce

Question 4

what happens to beneficial characteristics

Answer 4

they are passed on to the next generation

Question 5

why did many people disagree with Darwin’s theory?

Answer 5

• it challenged the belief that God made all the plants and animals on the earth
• many scientists felt that Darwin did not have enough evidence to back up his theory
• there was no understanding of how characteristics were inherited as genetics was not understood until 50 years after Darwin’s publication

Question 6

what was Lamarck’s theory?

Answer 6

he suggested that when a characteristic is regularly used, it becomes more developed
the strengthened characteristic is then passed on to the offspring

Question 7

what was the problem with Lamarck’s theory?

Answer 7

changes that occur in an organism’s lifetime, cannot be passed on to the offspring

Question 8

what is speciation?

Answer 8

the process by which two species evolve from a single original species by natural selection

Question 9

how does speciation occur?

Answer 9

• a geographical area contains a population of organisms which can all interbreed so a beneficial mutation is spread through the whole population
• a geographical barrier separates the one population into two separate groups
• no interbreeding now takes place between the two groups
• over time, natural selection will favour different alleles in each of the two groups
• mutations cannot be spread between the two groups as no interbreeding takes place . this means that the two populations will begin to change over many generations
• if the two populations mix again, their phenotypes are so different that they can no longer breed to produce fertile offspring

Question 10

what is a species?

Answer 10

a group of organisms which can breed together to produce fertile offspring

Question 11

what did Mendel investigate and study?

Answer 11

he looked at the different characteristics of pea plants and how they transferred from plant to plant

Question 12

what did Mendel discover?

Answer 12

He said that characteristics are determined by inherited units (genes) and the units are not changed when passed on to descendants
he also showed that characteristics could be masked and reappear in later generations (recessive alleles)

Question 13

What is are fossils?

Answer 13

Remains of organisms from millions of years ago that can be found in rocks, ice and other places

Question 14

How can fossils be formed?

Answer 14

• when an organism does not decay after it died
• mineralisation of the harder parts of the organism
• preserved traces

Question 15

Why is the fossil record incomplete?

Answer 15

• early life forms were soft bodied
• most organisms that died did not become fossilised
• many fossils are still to be found

Question 16

how does decay not happen when a fossil is formed?

Answer 16

the conditions for decay are absent

Question 17

what do fossils show?

Answer 17

large amount of species have become extinct

Question 18

what does extinct mean?

Answer 18

when there are no remaining members of a species alive

Question 19

what can cause a species to become extinct?

Answer 19

• catastrophic event
• when the environment changes
• new disease
• new predator
• new more successful competitor

Question 20

why can bacteria evolve rapidly?

Answer 20

because they reproduce at a very high rate

Question 21

what does antibiotic resistant mean?

Answer 21

when a bacteria is no longer killed by antibiotics

Question 22

how does antibiotic resistance occur in bacteria?

Answer 22

• in a population of bacteria, it is possible that a bacterium develops a mutation making it resistant to bacteria.
• the rest of the bacteria are killed by the antibiotic, leaving the resistant bacterium to reproduce without any competition.
• the population of the resistant bacteria increases and spreads rapidly as there is no treatment or immunity.

Question 23

what are the ways to reduce antibiotic resistance?

Answer 23

• not prescribe antibiotics inappropriately
• complete the course of antibiotics to kill all the bacteria so none can survive to mutate
• restrict the use of antibiotics in farming

Question 24

what is the problem with developing new antibiotics?

Answer 24

it takes a long time and is expensive

Question 25

what are the two kingdoms of Linneaus’ classification system?

Answer 25

plants
animals

Question 26

what are the categories of Linneaus’ classification system?

Answer 26

kingdom
Phylum
Class
Order
Family
Genus
Species
(King Phillip Came Over For Good Soup)

Question 27

where does an organism’s binomial name come from?

Answer 27

their genus and species

Question 28

what is Linneaus’ classification system based on?

Answer 28

characteristics that you can see

Question 29

what can be used to classify an organism?

Answer 29

physical features
biochemistry
internal structures
these are compared to other species for similarities

Question 30

what are archae?

Answer 30

another domain for classification which is a primitive type of bacteria

Question 31

what are the three domains for classification?

Answer 31

archae
true bacteria
eukaryota

Question 32

what types of organisms are eukaryota?

Answer 32

plants, animals, fungi and protists

Question 33

what data is used to make evolutionary trees?

Answer 33

classification data from living organisms
fossil records

Question 34

what is the problem with using fossils for evolutionary trees?

Answer 34

the fossil record is incomplete