1.1 - What is life?

Question 1

What characterises living organisms (2)

Answer 1

• Use energy to grow + reproduce (metabolise)
• Uses energy to increase local order (reduce entropy)

Question 2

Name the molecular characteristics of life (5)

Answer 2

1. Self replication
2. Self assembly
3. Autocatalysis
4. Cell membranes
5. Evolutionary competition + selection

Question 3

Name the 2 theories for the origin of life

Answer 3

1. RNA
2. Metabolism

Question 4

Describe the RNA theory for the origin of life

Answer 4

• RNA nucleotides emerged by funnelling prebiotic chemical soup to macromolecules via reactions that lead to:
  1. Reduced diversity of synthetic products
  2. Amplification of small initial differences in abundance
  3. Stability of biopolymers and self-assembled structures

Question 5

Describe the Metabolism theory for the origin of life

Answer 5

• Proposes life started at white smoker hydrothermal vents using chemical energy as interface alkaline emissions from seafloor and acidic seawater
• All living organisms use nitric acid cycle (oxidise acetate + produce CO2) , many anaerobic prokaryotes run cycle reverse (incorporate CO2 in organic molecules by exploring reducing potential of geologically produced molecules eg. H2)