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What were conditions like on early Earth?
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What were conditions like on early Earth?
The conditions on early Earth included:
A lack of free oxygen and presence of ozone,
Higher concentrations of carbon dioxide and methane, resulting in...
Higher temperatures
Ultraviolet light penetration
There are other conditions that may have been present on early Earth, but these are specific conditions you are required to learn.
True or False?
The conditions on early Earth led to the spontaneous formation of a variety of hydrogen compounds.
False.
The conditions on early Earth led to the spontaneous formation of a variety of carbon compounds.
The Miller-Urey experiments attempted to demonstrate conditions on early Earth. What was used as the energy source instead of UV light in the Miller-Urey experiments?
Electrical discharge was used as the energy source instead of UV light in the Miller-Urey experiments.
True or False?
The Miller-Urey experiments attempted to demonstrate conditions on early Earth.
A source of error in the experiment was that methane was used in low concentrations instead of high concentrations.
False.
A source of error in the experiment was that methane was used in high concentrations instead of low concentrations.
The Miller-Urey experiments attempted to demonstrate conditions on early Earth. What error was generated by using a 'primordial soup?'
The error generated using a primordial soup was that amino acids tend to remain as monomers in a solution, rather than forming complex proteins. This negates the idea that complex molecules could have formed in this environment.
What two features do all cells have in common?
Two features all cells have in common are:
They are enclosed by a membrane which separates the cell contents from the outside
They store genetic information in DNA molecules which is expressed during protein synthesis
What are the seven processes required for an organism to be considered living?
The seven processes required for life are:
Metabolic reactions, e.g. respiration
The need for nutrition
The production of metabolic waste which must be excreted
The ability to reproduce and to pass genetic information on to offspring
The ability to receive and respond to stimuli
The ability to grow
The ability to move
What is the only way in which new cells can be produced?
New cells can only be produced by the division of pre-existing cells.
Name two processes required for the evolution of the first cells.
Processes required for the evolution of the first cells are:
Catalysis
Self-replication of molecules
Self-assembly
Compartmentalisation
Why are hypotheses on the evolution of the first cells difficult to test? (NOS)
Hypotheses on the evolution of the first cells are difficult to test because the conditions of early Earth are difficult to reproduce and the first protocells did not fossilise, so there is a lack of evidence.
Why is compartmentalisation necessary within cells?
Compartmentalisation is necessary because it allows the internal chemistry (of an organelle) to become different from that outside the compartment.
Define coalescence in terms of membrane formation.
Coalescence occurs during membrane formation when hydrophobic tails of fatty acids combine/come together to avoid contact with a polar solution.
Which properties of RNA give evidence that it may have acted as the genetic material and the enzymes of the earliest cells?
The properties of RNA which give evidence that it may have acted as the genetic material and the enzymes of the earliest cells are that RNA can be replicated and that it has some catalytic activity.
True or False?
RNA can be replicated.
True.
RNA can be replicated.
What are ribozymes in the ribosome used for during protein synthesis?
Ribozymes in the ribosome are used to catalyse peptide bond formation during protein synthesis.
What is meant by the term LUCA?
LUCA is the Last Universal Common Ancestor. All life on Earth is thought to have evolved from LUCA.
What is the evidence for LUCA?
Evidence for LUCA is:
Universal genetic code
The same shared amino acids form protein molecules in organisms
The same biochemistry in all organisms
Name two methods for estimating dates of the first living cells and the last universal common ancestor.
Methods for estimating the dates of the first living cells and the last universal common ancestor include:
Carbon dating
Radiometric dating
Analysing its genome
What evidence exists for the existence of LUCA in hydrothermal vents?
Fossilised evidence (small tubes made of haematite) from ancient seafloor hydrothermal vent precipitates exists as evidence for the existence of LUCA.