The Devlopment Of Life On Earth Flashcards
What was the purpose of the Miller-Urey experiment?
The Miller-Urey experiment aimed to test if simple organic compounds, like amino acids, could form naturally under early Earth conditions, providing evidence for the theory of abiogenesis (life arising from non-living matter).
How did the Miller-Urey experiment simulate early Earth conditions?
The experiment used a closed system with water, methane, ammonia, and hydrogen, which were heated and exposed to electric sparks (mimicking lightning) to simulate early Earth’s atmosphere.
What were the key findings of the Miller-Urey experiment?
The experiment resulted in the formation of several amino acids, showing that essential organic molecules could be generated under prebiotic conditions.
What are complex prebiotic molecules?
They are building blocks of life (organic compounds), like amino acids, nucleotides, and simple sugars, that form naturally without any living organisms.
Why are complex prebiotic molecules important for life?
They are essential for making proteins, DNA/RNA, and providing energy, forming the basic structures needed for living organisms.
How much oxygen was in Earth’s early atmosphere?
Earth’s early atmosphere had almost no oxygen.
What keeps oxygen levels stable in Earth’s atmosphere today?
The constant production of oxygen by living organisms (plants) maintains its level in the atmosphere.
What would happen to atmospheric oxygen without replenishment?
Oxygen would disappear in about 2 million years due to reactions with minerals and nitrogen.
How did early photosynthetic bacteria produce carbohydrates?
They used hydrogen sulfide (H₂S), carbon dioxide (CO₂), and sunlight to produce carbohydrates, which was relatively easy chemically.
What is the main photosynthesis process used today?
Modern photosynthesis uses water (H₂O), carbon dioxide (CO₂), and sunlight to produce carbohydrates and oxygen (O₂), which is more efficient but chemically more complex.
How did life start?
Essential materials were already on Earth: CO₂, CH₄, NH₃, water, H₂, N₂.
Extra materials may have arrived on comets/meteorites.
Formation of amino acids from simpler molecules
Big Steps to Life:
Formation of specific organic molecules (like amino acids, nucleotides).
Creation of proteins and nucleic acids.
Formation of cell-like droplets with unique chemical properties.
Development of replication and heredity (RNA & DNA).
What did the Earth’s early atmosphere contain?
Earth’s early atmosphere composed of:
Gases from Volcanic Eruptions:
Volcanic activity released gases into the atmosphere, including:
Carbon dioxide (CO₂)
Nitrogen (N₂)
Water vapor (H₂O)
Small amounts of methane (CH₄) and ammonia (NH₃)
Hydrogen sulfide (H₂S), giving it a “rotten egg” smell
Earth’s early atmosphere may have had a reddish or hazy appearance. This color likely came from:
Why is Earth considered a “water planet”?
Crust Dynamics:
Ocean crust subducts (sinks) into the mantle.
Continental crust floats and grows over time.
Water Content: Only 0.1% of Earth’s mass is water (Europa may have 20%).
Surface Variation:
Height varies from 8 km above to 5 km below sea level.
Average ocean depth is 4 km.
If Earth had 0.2% water mass, oceans would cover all land.
How are single-celled organisms different from today?
Early cells were complex, containing DNA and various components. However, the very first cells were likely much simpler, with basic cytoplasm enclosed within a membrane.
What is the Cambrian Explosion?
A significant event in Earth’s history, approximately 541 million years ago, marked by a rapid diversification of life forms.
