Evolution 2

Question 1

What is evolution

Answer 1

Process of change in something, over
time

Question 2

What is biological evolution

Answer 2

Process whereby populations change over time in response to changes in their environment

Question 3

What is a belief

Answer 3

an explanation for a phenomenon that is based on religious or cultural values that cannot be proved or disproved
using scientific evidence.

Question 4

What is a hypothesis

Answer 4

a possible explanation of a phenomenon, that can be tested using observations and / or experiments.

Question 5

What is a theory

Answer 5

a widely held explanation of a phenomenon that is supported by numerous observations, experiments & scientific evidence.

Question 6

Using combination of sources of info evolutionary scientists…

Answer 6

developed detailed histories of the evolution of life forms
* demonstrate the evolutionary relationships among
organisms that are currently alive

Question 7

Fossils

Answer 7

• Paleontology is the study of fossils
• Fossils are the remains or traces of
  organisms that once lived on earth
  -By recording the positions of fossils in geological strata, paleontologists deduce that: Fossils of organisms found in the deeper rock strata lived much longer ago than those species fossilized in the younger strata.

Question 8

What is the driving force / mechanism by which evolution occurs

Answer 8

Natural selection

Question 9

EVOLUTION ‘theory’ proposes:

Answer 9

When natural selection happens enough times to change the gene pool within a population, then
evolution has occurred.

Question 10

Criteria for evolution by NS

Answer 10

• THERE IS NATURAL GENETIC VARIATION IN POPULATIONS.
• More offspring ARE PRODUCED THAN REQUIRED.
• THERE MUST BE COMPETITION FOR RESOURCES
• ENVIRONMENTAL CHANGE .
• THERE MUST BE Survival of the fittest (most suited).

Question 11

Outcome of NS

Answer 11

• Organisms of pop better adapted to environment over time
• Causes gene pool of pop to change over time
• If gene pool changes a lot ­ individuals from the new population can no longer breed and produce fertile offspring with the individuals from the ancestral population ( SPECIATION )

Question 12

Artificial selection

Answer 12

HUMANS selecting and breeding organisms with desirable characteristics

• to produce offspring with those characteristics that will be of some use to humans, eg horticulture, “garden” agriculture, transport, companionship and leisure.
• Only those organisms with the desired trait are allowed to reproduce

Question 13

What are the differences between artificial and natural selection?

Answer 13

The selection force is
- HUMANS ­ decide which characteristic
are DESIRABLE
- NATURE / ENVIRONMENT ­
determines which characteristics will
SURVIVE

Selection is in response to:

• Satisfying human needs
• Suitability/adaptation to the environment

Occurs
-Within one or more different species
- Within a single species

Question 14

Artificial selection in crop plants

Answer 14

• Deliberate interbreeding of closely or distantly related individuals of a species
• to produce new crop varieties with desirable characteristics.
• Native Americans selectively interbred
  a wild grass, “teosinte”
  with a sub­species, Zea mays into MAIZE (large cobs) skillful breeding

Question 15

What is speciation

Answer 15

The process whereby a new species evolves

Question 16

What is a species

Answer 16

A group of organisms which have the same characteristics and are able to breed amongst themselves and produce viable offspring

Question 17

What is a population

Answer 17

Group of organisms of the same species living in the same area and are able to interbreed

Question 18

What are the 2 methods whereby speciation occurs

Answer 18

• Geographic isolation
• Reproductive isolation

Question 19

Explain Geographic isolation

Answer 19

• When a new species is formed as a result of geographic isolation (barriers) from the ancestral species. (Most common form of speciation in animals but not in plants)
• If a population of a single species pg 10
• becomes separated by a geographical barrier (ocean, river, mountains),
• then the population splits into two populations.
• There is now no gene flow between the two
  populations.
• Since each population may be exposed to different
  environmental conditions,
• natural selection occurs independently in each of the
  two populations
• such that the individuals of the 2 populations differ
  from each other both genotypically & phenotypically.
• Even if the 2 populations were to mix again,
• they will not be able to interbreed.
• They have become different species.

Question 20

Explain Reproductive isolation

Answer 20

• A mechanism that prevents two or more species from exchanging genes, (i.e. interbreeding) and producing viable, fertile hybrids even though they are not geographically separated
• When one species gives rise to two new species, the two species cannot reproduce with each other even if they do mix. They remain separate due to mechanisms that restrict gene flow between them
• Mechanisms of
  reproductive isolation
  
  • Breeding at different times of the year
  • Species­specific courtship behaviour
  • Adaptation to different pollinators (plants)
• Infertile offspring in cross species hybrids
• Prevention of fertilization