A2.1 Origin of cells

Question 1

A2.1.1 Conditions on early Earth

Answer 1

Lack of oxygen and therefore ozone, higher concentrations of CO2 and CH4, resulting in higher temperatures and ultraviolet light penetration

Question 2

A2.1.1 Conditions on early Earth may have caused a variety of _____ compounds to form spontaneously by chemical processes that do not now occur

Answer 2

Carbon

Question 3

A2.1.2 Differences between living and non-living

Question 4

A2.1.2 Reasons why viruses are considered non-living

Question 5

A2.1.3 Cells are highly complex structures that can currently only be produced by _____

Answer 5

Division of pre-existing cells

Question 6

A2.1.3 Necessary requirements for the evolution of the first cells

Answer 6

Catalysis, self-replication of molecules, self-assembly, and emergence of compartmentalization

Question 7

A2.1.3 NOS: Claims in science, including hypotheses and theories, must be testable. In some cases, scientists have to struggle with hypotheses that are difficult to test. Explain with the example of the conditions on pre-biotic Earth

Answer 7

Exact conditions on pre-biotic Earth cannot be replicated and the first protocells did not fossilize

Question 8

A2.1.4 Evaluate the Miller-Urey experiment

Question 9

A2.1.5 Formation of a _____ is needed to allow internal chemistry to become different from that outside the compartment

Answer 9

Membrane-bound compartment

Question 10

A2.1.6 RNA can be _____ and has some _____ activity, so it may have acted initially as both the _____ and the _____ of the earliest cells

Answer 10

Replicated, catalytic, genetic material, enzymes

Question 11

A2.1.6 _____ in the ribosome are still used to catalyze _____ bond formation during protein synthesis

Answer 11

Ribozymes, peptide

Question 12

A2.1.7 Evidence for a last universal common ancestor

Answer 12

Universal genetic code and shared genes across all organisms

Question 13

A2.1.7 It is likely that other forms of life have evolved but became extinct due to competition from the _____ and _____

Answer 13

Last universal ancestor (LUCA) and descendants of LUCA

Question 14

A2.1.8 Life has been evolving on Earth for an _____ length of time

Answer 14

Immense

Question 15

A2.1.9 Evidence for the evolution of the last universal common ancestor in the vicinity of hydrothermal vents

Answer 15

Fossilized evidence of life from ancient seafloor hydrothermal vent precipitates, conserved sequences from genomic analysis

Question 16

A2.1 Guiding Q: What plausible hypothesis could account for the origin of life?

Question 17

A2.1 Guiding Q: What intermediate stages could there have been between non-living matter and the first living cells?

Question 18

A2.1 Linking Q: For what reasons is heredity an essential feature of living things?

Question 19

A2.1 Linking Q: What is needed for structures to be able to evolve by natural selection?