Human Evolution Session 24

Question 1

What were the four stages of origin of life development ?

Answer 1

• Small organic molecules : simple organic molecules , called monomers , evolved from inorganic compounds.
• Macromolecules : organic monomers joined into larger macromolecules (polymers)
• Protocells (protobionts) : first cell precursors ; polymers became enclosed in a membrane
• Living cells : protobionts acquired the ability to self replicate

Question 2

Describe the stage of small organic molecules :
What was the earth atmosphere like ?

Answer 2

• Atmosphere was formed by gases escaping from volcanoes
• had little , if any, free oxygen
• was extremely hot
• water was only a gas and formed dense clouds

Question 3

Describe what the Stanley miller experiment was in 1953?

Answer 3

• it was to stimulate the earth’s early environment and he heated materials believed to have been present and circulated it past an electrical spark and after a week the solution contained amino acids and organic compounds

Question 4

What were the two hypotheses that explain how small organic molecules joined into larger polymers ?

Answer 4

• RNA first hypothesis : only RNA was needed to form the first cell
• Protein first hypothesis : amino acids join together when exposed to dry heat

Question 5

According to the RNA- first hypothesis , how was the first true cell formed?

Answer 5

• The first cell had RNA genes that could have specified protein synthesis (including enzymes)
• One of these enzymes could use RNA as a template to form DNA

Question 6

According to the Protein- first hypothesis , how was the first true cell formed?

Answer 6

• Some of the proteins in the protocol were able to synthesize DNA and RNA from nucleotides in the ocean.

Question 7

What were the first true cells known as ?

Answer 7

• Prokaryotes

Question 8

What were the three main parts of natural selection ?

Answer 8

• Variation : individuals vary in physical characteristics that can passed on
• Competition for limited resources : even though individuals produce many offspring , the overall population size stays the same due to limited resources , which create competition
• Adaptation : Members of a population with advantageous traits capture more resources and are more likely to reproduce

Question 9

What are the different evidence of evolutions ?

Answer 9

• Fossil evidence
• Biogeographical evidence
• Anatomical evidence
• Biochemical evidence