bio: A2.1.1 Flashcards
When did life on Earth originate?
3.5 - 3.9 Billion years ago
What were early Earth conditions like?
Surface temperatures ranged from 75°C to 95°C.
The Earth was covered in a single global ocean, with no solid land masses.
What was Earth’s early atmosphere comprised of?
The early Earth’s atmosphere was primarily composed of methane, ammonia, water vapor (H₂O), and higher concentrations of carbon dioxide (CO₂).
What did early Earth bombardments bring?
Water and other compounds to the planet.
What gases were released?
Methane (CH₄) and ammonia (NH₃) gases were released during collisions and volcanic eruptions.
Did early Earth have oxygen?
The early Earth’s atmosphere lacked free oxygen, so there was no ozone layer.
Early Earth core status?
The inner core of early Earth was much hotter and liquid, unlike the solid inner core of today
What was the effect of increased motion within Earth’s liquid core in the past?
It resulted in a weaker protective magnetic field compared to today.
How did a weaker magnetic field affect early Earth?
It exposed early Earth to higher levels of cosmic and solar radiation.
What type of extreme weather events were common on early Earth?
Electrical storms and other extreme weather events were frequent.
What was a necessary precursor to the origins of life?
The formation of simple carbon-based compounds.
Why did early Earth have a reducing atmosphere?
Due to the lack of oxygen and the presence of reducing gases like methane and ammonia.
How did reducing gases contribute to the formation of complex carbon compounds?
They donated electrons, enabling chemical reactions that formed amino acids and hydrocarbons.
What biological building blocks did complex carbon compounds eventually form?
Proteins, lipids, and nucleic acids.
How did some complex carbon compounds lead to the formation of cells?
They developed the ability to self-replicate and became packaged into membranes.
Why is the spontaneous formation of biological molecules not possible today?
Modern Earth lacks the extreme conditions necessary for spontaneous biological molecule formation.
