5.1 Evolution Evidence

Question 1

what is biological evolution?

Answer 1

cumulative change that occurs within a population between one generation and the next

Question 2

how are heritable characteristics encoded?

Answer 2

by genes and may be transferred between generations as alleles

Question 3

what is a concise definition of biological evolution?

Answer 3

a change in the allele frequency of a population’s gene pool over successive generations

Question 4

what do fossil records provide?

Answer 4

evidence by revealing the features of an ancestor for comparison against living descendants

Question 5

what is a fossil?

Answer 5

preserved remains or traces of any organism from the remote past

Question 6

what two ways do fossils provide evidence for ancestral forms?

Answer 6

direct - bones, teeth, shells, leaves etc
indirect - footprints, tooth marks, burrows and faeces

Question 7

what is the fossil record?

Answer 7

the totality of fossils both discovered and undiscovered
(shows that over time changes have occurred in the features of living organisms)

Question 8

how can fossils be dated? (3)

Answer 8

• by determining the age of the rock layer which the fossil is found
• sedimentary rock layers develop in chronicle order, so low layers are older and newer strata from on top
• each strata represents a variable length of time that is classifieds according to geological time scale)

Question 9

In what order are different kinds of organisms found in rock layers? (3)

Answer 9

• prokaryotes before eukaryotes
• ferns before flowing plants
• invertebrates appear before vertebrates

Question 10

what is the law of fossil succession?

Answer 10

newer species likely evolved as a result of changes to ancestral species

Question 11

why is the fossil record incomplete? (2)

Answer 11

• fossilisation requires unusual set of specific circumstances in order to occur so very few organisms became fossils
• only the hard parts of an organism is typically preserved, so only fragments of remains are discovered

Question 12

what are transitional fossils?

Answer 12

they demonstrate the intermediary forms that occurred over the evolutionary pathway taken by a single genus

Question 13

how do transitional fossils work?

Answer 13

• they establish links between species by exhibiting traits common to both an ancestor and its predicted descendants

Question 14

what is an example of a transitional fossil?

Answer 14

• archaeopteryx, links the evolution of dinosaurs to birds

Question 15

what is an example of how fossils provide evidence? (3)

Answer 15

comparing hominin skeletons
- Australopithecus is an early hominin ancestor that first appeared in fossil record 4 million yrs ago
- comparing these fossils to bone structure of modern man demonstrates evolutionary change

Question 16

what is selective breeding?

Answer 16

form of artificial selection to produce desired traits in offspring

Question 17

how does artificial selection work? (3)

Answer 17

• by breeding members of a species with a desired trait
• the trait’s frequency becomes more common in successive generation
• selective breeding provides evidence of evolution as targeted variation in a short period

Question 18

what has selective breeding caused?

Answer 18

• allowed for the generation of new types of foods that has been bred to produce different foods by modifying plant sections through artificial selection
  (eg. broccoli, cabbage and kale)

Question 19

what are 2 examples of horse selective breeding?

Answer 19

• race horses - for speed and leaner, lighter, taller and quicker
• draft horses - for power and endurance and are sturdier and stokier

Question 20

what are 2 examples of cow breeding?

Answer 20

• improve milk production
• Belgium blue - produce more edible lean meat

Question 21

what are 4 examples of dog breeding?

Answer 21

• hunting dogs - smaller to enter fox holes
• herding dogs - heightened intelligence
• racing dogs - sleek and fast
• toy dogs - diminutive size

Question 22

what may the comparative anatomy of groups show? (3)

Answer 22

• certain structural features are similar implying common ancestry
• anatomical features are similar in basic structure despite being used in different ways (homologous structures)
• the more similar homologous structures the more likely the more closely related

Question 23

what do homologous structures show? (2)

Answer 23

adaptive radiation
- where several new species rapidly diversity from an ancestral source (with each species having a species niche)

Question 24

what is an example of a homologous structure?

Answer 24

pentadactyl limb in animal
(eg, mammals, birds, amphibians and reptiles)

Question 25

what despite possessing similar bone arrangements animal limbs are dissimilar in terms of use, state 4 examples of their adaptive use

Answer 25

• human hand - tool for manipulation (power/precision of grip)
• bird and bat wings -flying
• horse hooves - for galloping
• what and dolphin fins- for swimming

Question 26

what does continuous variation follow?

Answer 26

follow a normal distribution curve as the rate of change is gradual and cumulative

Question 27

what will occur if 2 populations of a species are geographically separated with different ecological conditions? 2

Answer 27

• over time the 2 populations will adapt to the different environmental conditions
• gradually diverge from one another

Question 28

what is the degree of divergence depend on when 2 populations are geographically separated? (3)

Answer 28

• extent of geographical separation and the amount of time since the separation occurred
• populations located in close proximity that separated recently will show less variation
• distance populations that separated a longer period of time ago will show more variation

Question 29

what will happen to the degree of divergence between geologically separated populations the longer they are separated?

Answer 29

it will increase

Question 30

what will occur as the degree of divergence increase the longer 2 populations are separated? (2)

Answer 30

• as the genetic divergence between the related populations increase, their genetic compatibility decreases
• eventually the 2 populations will diverge where they can no longer interbreed if returned to shared habitat

Question 31

what occurs when 2 populations can no longer interbreed and produce viable, fertile offspring?

Answer 31

• they are separate species

Question 32

what is the evolutionary process by which 2 related populations diverge in to separate species called?

Answer 32

speciation

Question 33

what is an example of evolution?

Answer 33

peppered moths that exist in 2 distinct polymorphic forms (light colouration and darker melanic variant)

Question 34

how does evolution of white and black peppered moths work?

Answer 34

• in an unpolluted environment the trees are covered by a pale-coloured lichen which provides camouflage
• in polluted environment sulphur dioxide kills the lichen, while soot blackens the break provides camouflage for the dark moth

Question 35

what is the frequency of the 2 different forms of peppered moth dependent on? (4) with example

Answer 35

the environment
- before industrial revolution the environment was unpolluted and lighter moths had survival advantage
- after industrial revolution it was heavily polluted and there was a survival advantage for the darker moth
- recent environmental policies reducing pollution, altering the frequency of 2 population once again