B5.2 Natural Selection And Evolution

Question 1

Non-coding DNA

Answer 1

Regions of DNA which do not encode protein sequences

Question 2

Cystic fibrosis

Answer 2

Caused by a mutation in a region of coding DNA
Extra mucus is produced in the body

Question 3

Evidence fossils provide

Answer 3

History of past life on earth

Question 4

Why fossils are a significant source of evidence

Answer 4

Show evolution within a species and evolution between one group of organisms
Can help to build a comprehensive history
Allow a picture to be built in terms of life upon Earth e.g. earliest fossils bacteria, then plants, then animal fossils

Question 5

How fossil evidence shows evolution has occurred

Answer 5

Systematic change through time
Different fossils found in different rock
Oldest layers of rock show oldest fossils

Question 6

What can be seen in the fossil record

Answer 6

Increase in complexity over time, simple organisms appeared first
Increase in diversity
Intermediate forms between groups - transitional fossils

Question 7

What can not be seen in the fossil record

Answer 7

Unable to show how life started on earth
Earliest fossils were soft bodied - difficult to fossilise

Question 8

Does evidence from fossils provide conclusive proof of change

Answer 8

No
Record is biased/incomplete
Very few individuals become fossils
Hard-bodied organisms often form fossils
Most fossils are aquatic animals

Question 9

Main fossil types found

Answer 9

Impressions - when footprints become covered in mud which hardens to rock

Moulds - when a dead organism gets buried in mud, which hardens to rock

Caste fossil - when mould fossils are filled with minerals that harden, taking the shape of the mould fossil

Preserved fossil - when animals have been covered in a natural preservative such as ice, tar, amber or peat

Question 10

How extinction provides evidence for evolution by natural selection

Answer 10

Species which are not adapted to / do not have advantageous characteristics for their environment die out

Question 11

Fossil

Answer 11

Remains of a plant or animal which have mineralised / changed to rock over millions of years

Question 12

Most likely ancestor of all living things

Answer 12

Unicellular aquatic organisms

Question 13

How organisms evovle

Answer 13

Process of natural selection

Question 14

Process of evolution by natural selection

Answer 14

Genetic variation within species caused by differences in genes
Organisms which have the most advantageous characteristics are the most likely to survive and reproduce
Genes from successful organisms are passed to offspring
Process is repeated many times and can lead to new species developing

Question 15

Survival of the fittest

Answer 15

Only organisms which have most advantageous characteristics are the most likely to survive and reproduce

Question 16

Why must scientist constantly develop new antibiotics

Answer 16

Bacteria reproduce quickly,
so any mutation which develops antibiotic resistance is quickly passed on to many offspring

Question 17

Examples of evolution that has happened in a short and observable time period

Answer 17

Peppered moth changing from pale to dark due to industrial revolution
Bacteria evolving resistance to antibiotics
Mosquitos evolving resistance to DDT
Rats evolving resistance to the rat poison warfarin

Question 18

During Darwin’s scientific expedition to the Galapagos Island, on which species did he make his famous observations

Answer 18

Finches

He wrote the book “The origin of species”

Question 19

Charles Lyell’s hypothesis about the origins of fossils

Answer 19

Gave Darwin inspiration for theory of evolution by natural selection

Question 20

The theory of spontaneous generation

Answer 20

Animals are produced from their surroundings or environment
e.g. sudden appearance of fish in a puddle of water

Question 21

Key ideas of Jean-Baptiste Lamarck

Answer 21

All organisms evolved through simple to more complex organisms
Use vs. Disuse

Organisms adapt during their lifetime - altered their behaviour in response to environmental change, which modifies their organs

Acquired traits are heritable - when giraffes stretch their necks to reach leaves high in trees, they would strengthen and gradually lengthen their necks. These giraffes would then have offspring with slightly longer necks

Continuous evolution towards ‘perfection’ - If an organism has to repent the same task everyday, their body would adapt for it to increase efficiency

Question 22

Alfred Wallace (1809-1882)

Answer 22

Independently proposed the theory of evolution by natural selection while working in Borneo

Key ideas:
Living things change over long periods of time
Fittest individuals survived and reproduced
Advantageous characteristics passed on to their offspring
Speciation by reproductive isolation – Wallace effect

Studied Beetles and butterflies

Question 23

Why did theory of evolution take time to be widely accepted

Answer 23

At the time of publication, most people believed God created all animals and plants
Darwin’s opposed this belief
Darwin was unable to explain how inheritance occurred
Darwin had no knowledge of genes, which meant it was hard to convince people that the theory was correct
It took time to collect further evidence to support the theory

Question 24

3 key scientists who provided evidence for the theory of evolution

Answer 24

Charles Lyell

Charles Darwin

Alfred Wallace

(Lamarck)

Question 25

Classification

Answer 25

Grouping of organisms into groups based on similarities and differences between them

Question 26

Linnaean classification system

Answer 26

Classification is the organisation of living things into groups according to their similarities in structure and characteristics

Closely related organisms are grouped together into groups called ‘taxa’:
Each taxa is arranged in a hierarchy, which divide into smaller more specific taxa

7 levels of the kingdom:
Kingdom - Phylum - Class - Order - Family - Genus - Species
Kittens Prodded Croupiers Once Freud Glided Shamefacedly

Question 27

Phylogeny and how has it advanced classification

Answer 27

Study of evolutionary relationships with the aid of modern techniques such as DNA and protein analysis
- Has led to the re-classification of some organisms
- Has led to devlopment of the 3-domain system and the new taxon ‘domain’

Question 28

3-domain system

Answer 28

Proposed by Carl Woese
Classifies based upon chemical analysis - DNA, RNA and protein comparison to show phylogenic links

Three domains:
Eukaryota – organism with complex subcellular structures (animals, plants, fungi, protist)
Bacteria – true bacteria
Archaea – primitive bacteria

Question 29

Artificial classification

Answer 29

Grouping by observable characteristics not phylogeny
Method led to inaccurate classification
Linnaeus’s method of classifying plants based on a limited number of their physical and sexual characteristics

Question 30

Speciation

Answer 30

When organisms evolve to become distinct species
Fertile offspring cannot be produced among the distinct species

Question 31

Extinction

Answer 31

When there are no remaining individuals of a species alive