Evolution

Question 1

Define evolution

Answer 1

evolution is the cumulative change in the heritable characteristics of a population

Question 2

Outline the evidence for evolution provided by the fossil record, selective breeding of domesticated animals and homologous structures

Answer 2

Fossil records:

• fossilization is an extremely rare, chance event.
• most fossils remain buried
• exposed fossils are mostly overlooked and destroyed
• fossils may be dated using C14 or K40 radiocarbon dating

Fossil forms

• Petrification-organic matter is replaced by mineral ions
• Mould-organic matter decays, the space left works as mould and is filled by mineral matter
• trace-impression of a form is preserved in layers that harden ex.footprint
• preservation - intact of whole organism, ex. in amber

Question 3

Selective breeding of domesticated animals

Answer 3

Selective breeding of domesticated animals is used to ‘‘create’’ all the plants and animals used by humans from wild ancestor organisms. The most useful varieties of organisms in one generation. The result is deliberate genetic change in the population by repeating the human controlled selection process for generations

Question 4

Homologous structures

Answer 4

• Groups of related organisms often show similar underlying organization, ex. limb skeleton, although they have adapted to different habitats or life styles. The most likely explanation is a common ancestor.

Question 5

Explain that the consequences of the potential overproduction of offspring is a struggle for survival

Answer 5

In a stable population, only one breeding pair may result from each breeding event, all other offspring are casualties of the ‘‘struggle’’ to survive.

Population size is naturally limited by environmental factors: space, light, availability of food, diseases.

Never-ending competition for resources results in the majority of organisms failing to survive and reproduce

Question 6

Explain how natural selection leads to evolution

Answer 6

Natural selection operates to determine the survivors and the genes that are passed on to the next generation. This may eventually lead to the formation of new varietis and ultimately new species. This may be summarized in ‘‘survival of the fittest’’

Question 7

Explain one example of evolution in response to environmental change

Answer 7

Charles Darwin…..
He reasoned that these birds most likely shared a common ancestor.
Geographical separation and different food choices had turned one ancestor into several species with different beak shapes over generations. This is what evolution is.