Biology 2.1

Question 1

Formation of seas and atmosphere of early earth

Answer 1

volcanic outgassing of the molten interior of the earth, gases cool the earth which leads to condensation and rainfall that forms oceans

Question 2

Atmosphere of early earth

Answer 2

reducing atmosphere has very little oxygen, composed of CO, CO2, H2, N2, H2O, HS, CH4, NH3

Question 3

Oparin-Haldane Hypothesis

Answer 3

the reducing atmosphere of early earth allowed for reactions to transform simple molecules to a primordial soup of complex organic monomers upon exposure to UV light, lightning, radioactivity, heat

Question 4

Miller-Urey Experiment

Answer 4

Tested the oparin-haldane hypothesis by simulating early atmosphere conditions and providing electric current energy, proved that some complex organic molecules such as NH3, H2O, H2 and CH4 can be made from simple inorganic molecules

Question 5

Proteinoids

Answer 5

abiotic polypeptides formed through the heating of amino acids

Question 6

Two theories for the earliest form of self-replicating life

Answer 6

RNA World (Naked Gene) Hypothesis and Metabolism-first Hypothesis

Question 7

RNA World (Naked Gene) Hypothesis

Answer 7

Self-replicating genetic material like RNA was the earliest life form that eventually became self-sustaining through addition of metabolic networks

Question 8

Metabolism-first Hypothesis

Answer 8

Isolated environments allowed for formation of metabolic networks that eventually become the earliest life form

Question 9

Protobionts

Answer 9

primitive cells that form an isolated environment for chemical reactions to occur, contenders for protobionts include coacervates (self-organized lipid spheres) and proteinoid microspheres (self-organized polypeptide spheres)

Question 10

Heterotrophs

Answer 10

Get energy from eating other substances

Question 11

Primitive heterotrophs

Answer 11

consumed organic molecules in the primordial soup. However, there became an increase in population and competition for the molecules which created selective pressure for the evolution of autotrophs

Question 12

Autotrophs

Answer 12

make their own complex molecules by harvesting light or chemical energy

Question 13

Cyanobacteria

Answer 13

earliest autotrophs that release O2 as byproduct, leading to formation of ozone layer which absorbs UV light making it so that natural synthesis of organic compounds in primordial soup could not happen, thus heterotrophs could not rely on primordial soup and needed to consume autotrophs to get complex molecules

Question 14

Endosymbiotic Theory

Answer 14

Theory for origin of eukaryotes, states that engulfment of one prokaryote by another led to a mutually beneficial association, causing formation of eukaryotic cell

Question 15

Evidence for endosymbiotic theory

Answer 15

Mitochondria and chloroplast were independent prokaryotes: organellar DNA, ribosomes, independent reproduction, double membranes, thylakoid membranes

Question 16

Organellar DNA

Answer 16

both mitochondria and chloroplast contain their own circular DNA that lack protein (similar to plasmids). Also, mitochondrial DNA comes from mother

Question 17

Ribosomes

Answer 17

both mitochondria and chloroplast have ribosomes resembling prokaryotes

Question 18

Independent reproduction

Answer 18

both mitochondria and chloroplast reproduce independently of eukaryotic cell under a process similar to binary fusion in bacteria

Question 19

Double membranes

Answer 19

Cells engulf materials by endocytosis. The presence of double membranes in mitochondria and chloroplasts suggest they may have been engulfed via endocytosis as vesicles

Question 20

Thylakoid membranes

Answer 20

thylakoid membranes of mitochondria and chloroplasts are similar to the photosynthetic membranes found in cyanobacteria