7.1- Evolution

Question 1

Define evolution

Answer 1

the cumulative change in the heritable characteristics of a population

Question 2

How are the changes in evolution transferred between populations

Answer 2

controlled by GENES, transferred between generations as alleles

Question 3

What are the four main evidence for evolution

Answer 3

1.comparing genomes
2. fossil record
3. artificial selection
4. comparative anatomy showing homologous structures

Question 4

Define fossil

Answer 4

the preserved remains or traces of any organism from the past

Question 5

Direct evidence

Answer 5

bones, teeth, shells, leaves

Question 6

Indirect evidence

Answer 6

bite marks, burrows, faeces, footprints

Question 7

Why are there gaps in the fossil record

Answer 7

the fossil record includes all discovered and undiscovered fossils.

• therefore there are gaps due to fossilisation being a rare event.
• only hard parts of the remains are preserved
• fossils are damaged during to predation, erosion, human impact

Question 8

Explain relative dating

Answer 8

Fossils can be dated by determining the age of the rock layer in which the fossil is found

Fossils can be stuck in sediments as the rock forms. Sedimentary rock is laid down chronologically in layers called strata.

The age of the fossil is then estimated relative to the rock it is found in or other fossils that have been dated in the same rock layer

Question 9

What is strata

Answer 9

Sedimentary rock laid down in chronological layers

Question 10

Explain absolute dating

Answer 10

unstable radioactive elements decay over time, forming different elements as they do
- carbon 14 decays to nitrogen 14

this time is known as the half life.

as atmospheric carbon is fixed during photosynthesis and passed through the food web, the amount of carbon-14 remaining in fossils can be used to establish the age of a fossil.

Question 11

What did scientists learn from the fossil record

Answer 11

prokaryotes before eukaryotes
ferns before angiosperms
inveterbrates before vertebrates.

Question 12

How are fossils used to infer evolutionary relationship between species

Answer 12

through comparative anatomy

Question 13

Compare and contrast homologous structures and analogous structures

Answer 13

Homologous structures
- similar in anatomy
- dissimilar in function
- developed from common ancestor
- develop in a related species
- developed as adaptations to different environments
- divergent evolution
ex. Pentadacyl limb in most veterbrates.

Analogous structures
- disimilar in anatomy
- similar in function
- no common ancestor
- unrelated species
- adaptations to same environments
- convergenet evolution
ex. wings of insects and birds, tails of fish and whales

Question 14

Define speciation

Answer 14

accumulation of differences between related populations that lead to the formation of two species

Question 15

What is speciation caused by

Answer 15

reproductive isolation between two populations of a pre-existing species

Question 16

Four types of reproductive isolation

Answer 16

geographical
mechanical
temporal
behavioural

Question 17

Describe reproductive isolation

Answer 17

separation of two populations that prevents interbreeding

restricts gene flow between the two populations

two populations experience different selection pressures, the changes accumulate over time.

speciation occurs when the two populations cannot produce fertile offspring

Question 18

What is geographical isolation

Answer 18

physical barriers preventing two populations from interbreeding.

clearings, rivers, mountains, roads, dams

Question 19

Example of speciation in Bonobos and Chimpanzees in the DRC

Answer 19

separated geographically by the congo river.
- different selection pressures -> different adaptations.

Chimps
- aggressive, territorial
- patriarchy
- use tools to fish
- only copulate for procreation
- kill each other/infants

Bonobos
- peaceful, nomadic
- matriarchal
- will copulate when female is not in estrus
- work togheter

Question 20

What does extinction result from

Answer 20

last remaining individuals in a phylogenetic tree NOT possessing adaptations to help them survive in their environment

Question 21

Where does evidence for evolution come from

Answer 21

base sequences in DNA/RNA

amino acid sequences in proteins

Question 22

How is selective breeding evidence for evolution

Answer 22

demonstrates that the heritable traits of a species can change over time

evolution can happen rapidly