Natural selection

Question 1

What is the struggle for survival?

Answer 1

when more animals are born than will survive to reproduce (natural selection)

Question 2

What is Darwin’s theory of evolution?

Answer 2

organisms best adapted to conditions will survive (survival of the fittest)

Question 3

What happened when Darwin proposed his theory?

Answer 3

The public was outraged and did not believe him.

Question 4

What are the steps (acronym) for natural selection?

Answer 4

Variation, Inheritance, Selection, Time, Adaptation (VISTA)

Question 5

What does variation refer to?

Answer 5

a variation must exist in populations of single species

Question 6

What does inheritance refer to in natural selection?

Answer 6

there is a variation due to genes inherited by parents

Question 7

What does selection refer to in VISTA?

Answer 7

only the ‘fittest’ organisms possess characteristics which allow them to survive.
- these characteristics are passed onto offspring via genes

Question 8

What does ‘survival of the fittest’ mean?

Answer 8

Organisms which adapt to changing environment survive, and are deemed ‘fit’, and those which do not adapt become extinct.

Question 9

What happens in artificial selection?

Answer 9

Humans speed up what happens in nature, humans select desirable traits.

Question 10

Who proposed speciation?

Answer 10

Charles Darwin

Question 11

What is speciation?

Answer 11

Species living in different conditions evolve in different directions. Over generations, populations vary and eventually a new species develops.

Question 12

How does natural selection apply in geographical regions?

Answer 12

Naturals selection is based on environmental conditions.

Question 13

When does speciation usually occur?

Answer 13

same species, different location, different pressures = new species
- generally occurs when populations are isolated.

Question 14

What are the evidences of evolution?

Answer 14

The fossil record, DNA hybridisation, comparing anatomy.

Question 15

What is the fossil record?

Answer 15

fossils which depict the timeline of evolution. Evolutionary changes can be observed in fossils.

Question 16

How do fossils form?

Answer 16

found in sedimentary rock when seas and lakes lay layers of sedimentary rick over millions of years. Occurs when not decomposed and conditions are right. Rock presses down and creates a mould, mould is filled and creates fossil.

Question 17

Where are the oldest fossils found?

Answer 17

In the lowest layers, younger fossils found in upper layers.

Question 18

How complex will organisms be on lower levels?

Answer 18

Simple organisms on lower levels, more complex on higher levels.

Question 19

How can fossil record be used to find a common ancestor?

Answer 19

If a new species evolves from ancestral species, fossil records could contain organism that have same features of both modern + ancestors.

Question 20

What is DNA hybridisation?

Answer 20

DNA is heated and separated, single strands are placed next to each other and bonded. If strands are similar, high amount of bonding will occur.

Question 21

What does homoduplex mean?

Answer 21

both strands from the same DNA

Question 22

What does heteroduplex mean?

Answer 22

DNA strands from different species.

Question 23

When does pairing take place in DNA hybridisation?

Answer 23

when complementary bases are found.

Question 24

When did mammals first appear?

Answer 24

~200mybp, evolved from reptile ancestors

Question 25

what would you see in mammals related by evolution?

Answer 25

expected to see similar structures regardless of way of life

Question 26

What is an example of anatomical similarities in mammals?

Answer 26

forelimb of all mammals very similar in number and structure of bones present.

Question 27

what is an example of a homoogous structure?

Answer 27

the Pentadactyl limb

Question 28

What is a homologous structure?

Answer 28

structure that is similar in closely related organisms, changed slightly due to different selection pressures in different environments.

Question 29

What is an analogous structure?

Answer 29

arise in unrelated organisms due to action of different selection pressures.

Question 30

Analogous structures illustrate concept of convergent evolution. What is convergent evolution?

Answer 30

an unrelated group of organisms develop similar characteristics. e,g insect wing and bird wing.

Question 31

What is divergent evolution?

Answer 31

organisms develop structural differences over time, speciation occurs due to different selection pressures.