Practice #1

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Questions and Answers

What defining characteristic distinguishes eukaryotes from prokaryotes?

Eukaryotes are always unicellular.

Eukaryotes contain membrane-bound organelles. (correct)

Eukaryotes lack a plasma membrane.

Eukaryotes reproduce exclusively asexually.

What is the approximate size of typical eukaryotic cells?

1-5 mm

100-200 µm

1-10 µm

10-100 µm (correct)

What is meant by the term 'monophyletic group' regarding eukaryotes?

It contains the common ancestor and all of its descendants. (correct)

It includes both prokaryotes and eukaryotes.

It refers only to multicellular organisms.

It includes only modern descendants without their common ancestor.

Which process is thought to be responsible for the evolution of the first eukaryotic cells?

Endosymbiosis Signup and view all the answers

What do prokaryotes and eukaryotes differ in regarding cellular structures?

Eukaryotes have ribosomes that are larger. Signup and view all the answers

Which of the following is the correct first step in the origin of life on Earth?

The abiotic synthesis of small organic molecules. Signup and view all the answers

What is a protocell?

A droplet with membranes that maintains a distinct internal chemistry. Signup and view all the answers

Which experiment simulated early earth's atmosphere to create organic compounds?

Stanley Miller's experiment. Signup and view all the answers

What role did catalysts such as clay play in the origin of life?

They selectively increased the rate of polymerization reactions. Signup and view all the answers

What hypothesis describes the early conditions that could lead to the emergence of life?

Primordial soup hypothesis. Signup and view all the answers

What is the first necessary step in the origin of life as described in the process of life formation?

The abiotic synthesis of small organic molecules Signup and view all the answers

Which of the following substances was NOT synthesized during Stanley Miller's experiment?

Nucleic acids Signup and view all the answers

What distinguishes protocells from living organisms?

Protocells lack genetic material. Signup and view all the answers

What role did deep-sea vents play in the context of the origin of life?

They led to the synthesis of amino acids. Signup and view all the answers

Which of the following conditions was NOT a part of the primordial soup hypothesis?

Access to solar energy Signup and view all the answers

What process describes the decay of the isotope 14C into 14N?

Radioactive decay Signup and view all the answers

What is the half-life of Carbon-14?

5,730 years Signup and view all the answers

What factor contributes to the discontinuity in the fossil record?

Global extinction events Signup and view all the answers

Which of the following ranges does Carbon-14 dating cover?

100 - 60,000 years Signup and view all the answers

Which of the following does NOT contribute to the bias in the fossil record?

Environmental changes Signup and view all the answers

Study Notes

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.

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Description

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.