Life on Earth: A Brief History

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Questions and Answers

What is one of the essential organic materials that were already present on Earth during the early development of life?

Helium

Carbon dioxide (CO2) (correct)

Methanol

Oxygen

Which process was NOT part of the sequence of steps leading to the start of life on Earth?

Spontaneous combustion of gases (correct)

Replication via RNA and DNA

Joining of large molecules into proteins

Formation of specific organic molecules

What was a characteristic of Earth's early atmosphere?

Completely dry with no water vapor

Clear and breathable

Dominated by CO2 and thick with gases (correct)

Rich in oxygen

Which of the following was NOT a factor affecting Earth's early environment?

Stable solar illumination Signup and view all the answers

How did comets and meteorites contribute to the early development of life on Earth?

They brought ready-made complex organic molecules Signup and view all the answers

What structure is formed when lipid molecules arrange themselves in a bilayer?

Vesicle Signup and view all the answers

What percentage of Earth's total mass is composed of water?

0.1% Signup and view all the answers

Which step is NOT part of the sequence leading to the formation of pre-cells?

Natural selection among DNA molecules Signup and view all the answers

What was the approximate depth of the average ocean during Earth's early development?

4 km Signup and view all the answers

Which gas was NOT part of Earth's early atmosphere?

Ozone (O3) Signup and view all the answers

What phenomenon occurs when a mixture of lipids and water is shaken?

Development of micelles Signup and view all the answers

How do external conditions like salinity affect lipid molecules?

They cause structural changes in membranes Signup and view all the answers

What is a characteristic behavior of micelles in solutions?

They behave like complex cells Signup and view all the answers

What is the primary reason oxygen would disappear from Earth's atmosphere in about 2 million years?

It would react with minerals through oxidization. Signup and view all the answers

Which gases were primarily utilized by the first photosynthesizing bacteria?

Hydrogen sulfide and carbon dioxide. Signup and view all the answers

In the current photosynthesis process, what is produced alongside carbohydrates?

Oxygen. Signup and view all the answers

What makes the current type of photosynthesis more efficient compared to the first type?

It utilizes more readily available water. Signup and view all the answers

What is the significance of LUCA in the context of the tree of life?

It is the last common ancestor of all living organisms. Signup and view all the answers

Which early idea about the origin of life is no longer widely accepted due to scientific advancements?

Pungent ponds of tidal water full of organic substances. Signup and view all the answers

Which gases were part of the atmosphere used in the Miller-Urey experiment?

Methane, Ammonia, Hydrogen Signup and view all the answers

What was one of the criticisms of the 'primordial soup' theory of life's origin?

It lacked chemical disequilibrium. Signup and view all the answers

What percentage of Earth's mass would represent double the current amount of water?

0.4% Signup and view all the answers

What notable outcome did the Miller-Urey experiment achieve after a week of testing?

Production of several amino acids. Signup and view all the answers

In what type of environment is it theorized that life may have originated according to more recent studies?

Deep-ocean hydrothermal fields. Signup and view all the answers

What aspect of the original atmosphere proposed in the Miller-Urey experiment is considered unrealistic today?

Composition of gases used. Signup and view all the answers

What limitation does a uniform 'primordial soup' pose for chemical reactions?

It creates chemical dis-equilibrium. Signup and view all the answers

What role do lipids play in relation to water molecules?

They have ends that sense the electric asymmetry of water. Signup and view all the answers

What can be inferred about prokaryotic cells compared to simple organic molecules?

Prokaryotic cells are much more complex than just ensembles of organic molecules. Signup and view all the answers

What is a key feature of the structures formed by hydrothermal deposits?

They contain minerals that can act as catalysts. Signup and view all the answers

Which element is likely involved in the dis-equilibrium mentioned in hydrothermal deposits?

Hydrogen Signup and view all the answers

How does the cytoplasm relate to the structure of a prokaryotic cell?

It is confined within a membrane. Signup and view all the answers

Which statement about the first cells is accurate?

They were much simpler than current prokaryotic cells. Signup and view all the answers

What is one of the characteristics of the formations at hydrothermal deposits?

They concentrate chemicals in small crevices. Signup and view all the answers

What is the significance of the steady stream of chemicals from hydrothermal deposits?

It results in dis-equilibrium in the local ecosystem. Signup and view all the answers

Study Notes

### Life on Earth: A Brief History

The early Earth's atmosphere was dominated by CO2 and other gases like nitrogen, hydrogen sulfide, steam, and methane, with minimal oxygen.
Early Earth was subjected to frequent impacts from comets and meteorites that deposited heat and water.
The early Sun was less luminous and more variable compared to today, leading to rapid changes in solar illumination.
The Miller-Urey experiments demonstrated the generation of amino acids from a simulated early Earth atmosphere containing methane, ammonia, and hydrogen.
Deep-ocean hydrothermal fields are considered a promising location for the origin of life.
Lost City is an example of such a field with structures formed due to chemical percolation.
Complex organic molecules like lipids can self-assemble into micelles and bilayer structures that mimic simple cells.
The early stages of life are thought to have involved:
- Formation of organic molecules.
- Self-replicating RNA strands.
- Membranes enclosing pre-cells to trap organic molecules.
- Natural selection leading to increased complexity in RNA molecules.
- Evolution of DNA.
The Last Universal Common Ancestor (LUCA) is believed to be the ancestor of all life on Earth.
The evolution of photosynthesis by early bacteria was crucial for the production of oxygen in Earth’s atmosphere.
Oxygen reacts with atmospheric nitrogen to form nitric acid, a key component of acid rain.
The first photosynthetic bacteria utilized hydrogen sulfide and carbon dioxide to generate carbohydrates.
Modern photosynthesis uses water and is more efficient, although chemically more complex.
Earth's ocean crust subducts back into the mantle, while continental crust floats on top and grows.
The total water on Earth makes up 0.1% of its total mass, significantly less than water-rich bodies like Europa.

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Description

Explore the fascinating journey of life on early Earth, from the composition of the atmosphere to the impact of comets and meteorites. Discover groundbreaking experiments like the Miller-Urey experiment that shed light on the origins of life and the role of hydrothermal fields. This quiz will delve into the complex processes that shaped the planet and its early inhabitants.