Practice #1

Topic 8: The Tree of Life

• Life on Earth uses carbon (C), oxygen (O), hydrogen (H), and nitrogen (N) in organic molecules. These elements are highly abundant on Earth and in the atmosphere. Carbohydrates, proteins, fatty acids, and nucleic acids are primarily composed of these elements.
• Human body composition contains 96.3% oxygen, carbon, hydrogen, and nitrogen.
• The age of the universe is 13.8 billion years
• The age of the Earth is 4.6 billion years
• The first direct evidence of life is 3.5 billion years ago.
• Fossils are preserved remnants or impressions of organisms.
• Stromatolites are layered rocks formed by photosynthetic prokaryotes.
• The seven properties of life include: cellular organization, reproduction, metabolism, heredity and evolution, growth and development, regulation and homeostasis, and response to stimuli
• Viruses are not considered organisms because they lack cellular organization, internal metabolism, and growth.

Learning Outcomes (Topic 8)

• Describe 7 properties of life using an organism as an example.
• Justify the importance of C, H, N, and O in organic molecules.
• Explain how specific properties of life emerged during the formation of protocells.
• List advantages of ribonucleic acid molecules for the emergence of life.
• Explain how the fossil record provides evidence for the evolution of organisms.
• Compare two methods used to date fossils
• Describe how the Burgess Shale contributed to the understanding of evolution of animals
• Define mass extinction and give an example.
• Define adaptive radiation and give an example.
• Analyze graphical data to infer changes to taxonomy.
• List characteristics of LUCA (Last Universal Common Ancestor)
• Name characteristics for the 3 domains.
• Give examples of organisms from each domain of life.
• Explain the evolution of eukaryotes from endosymbiosis.
• Explain the evolution of multicellularity.

First Evidence of Life on Earth

• Age of the Universe: 13.8 billion years
• Age of Earth: 4.6 billion years
• First direct evidence of life: 3.5 billion years
• Fossilised Stromatolite: The earliest forms of life.
• Stromatolites are layered rocks.

From Organic Molecules to Protocells

• Four necessary steps for the evolution of life from abiotic molecules to protocells:
  1. Abiotic synthesis of small organic molecules (monomers)
  2. Polymerization of monomers into macromolecules
  3. Packaging of molecules into protocells
  4. Origin of inheritance through the transmission of self-replicating molecules

Stanley Miller's Experiment (1953)

• Created early Earth conditions (methane, ammonia, hydrogen) and lightning to synthesise organic molecules.
• Found amino acids and other organic molecules.

Formation of Macromolecules

• Polymers of amino acids and other nitrogenous bases can form spontaneously without enzymes or ribosomes.
• Precursor molecules, thermal energy (heat), and catalysts (Fe²⁺, Pb²⁺, Mg²⁺, etc.) are important components in the process.
• Clay is a mineral catalyst for polymerization of RNA.

Formation of Protocells

• Protocells are membrane-bound droplets that maintain an internal chemistry distinct from the external environment.
• Experiments have shown their spontaneous division, internal metabolism, and selective permeabilities
• Protocells are not living organisms.
• Properties of life can emerge from abiotic conditions.

Explore the fundamentals of life on Earth in this quiz, covering essential elements, human body composition, and the timeline of life. Understand the properties of life, fossils, and the distinction between living organisms and viruses. This informative quiz is perfect for students studying biology.