3B3 Evidence of Evolution and Origins of Life

Question 1

What is the field of paleontology?

Answer 1

The study of prehistoric life, including fossils, footprints, and past climatic events.

Question 2

How do fossils contribute to understanding evolution?

Answer 2

By providing a chronological record of evolutionary changes in organisms.

Question 3

What is radiometric dating used for in paleontology?

Answer 3

To determine the age of rocks and fossils.

Question 4

Define:

biogeography

Answer 4

The study of how species are distributed across Earth.

Question 5

What did Charles Darwin observe about animals on the Galapagos Islands?

Answer 5

They were very similar to animals on the South American mainland but dissimilar to animals on other islands with similar environments.

Question 6

What evidence supports the evolution of whales and dolphins from land animals?

Answer 6

The body structure of whales and dolphins, such as flippers and vestigial hind limbs.

Question 7

What is homology in comparative anatomy?

Answer 7

Traits inherited from a common ancestor that appear similar in different species.

Question 8

What is studied in embryology to compare evolutionary relationships?

Answer 8

Embryos, looking for shared structures during development.

Question 9

Why is molecular biology used to study the evolution of organisms that are very distantly related?

Answer 9

Because the relationship between such organisms can be difficult to link with anatomy.

Molecular biology examines DNA of organisms to see if there are any similarities that could point to those organisms being related.

Question 10

What does the degree of difference in DNA between organisms tell us?

Answer 10

The evolutionary distance between species.

Question 11

Define:

endosymbiosis

Answer 11

When one species lives inside another; in biology, it explains how mitochondria and chloroplasts originated from free-living prokaryotes engulfed by ancestral eukaryotic cells.

Question 12

Define:

endosymbiont

Answer 12

The species that lives inside another species.

Example: Nitrogen fixing bacteria in the roots of plants

Question 13

Define:

host in endosymbiosis

Answer 13

The species containing the endosymbiont.

Question 14

What is the Endosymbiotic Theory?

Answer 14

The theory that mitochondria and chloroplasts were once free-living prokaryotic cells that formed an endosymbiotic relationship with a proto-eukaryotic or eukaryotic host cell.

Question 15

What evidence supports the endosymbiotic theory?

Answer 15

Similarities in DNA, enzymes, and membrane structures between prokaryotes and organelles like mitochondria and plastids.

Question 16

What did the aerobic endosymbionts evolve into?

Answer 16

Present-day mitochondria

Question 17

What did the photosynthetic endosymbionts evolve into?

Answer 17

• Present-day chloroplasts
• Other plastids

Question 18

How do mitochondria and chloroplasts replicate?

Answer 18

Via a process called binary fission.

Similar to some bacterial cells.

Question 19

Define:

molecular clock

Answer 19

A method that estimates evolutionary time based on the rate of genetic mutations.

Question 20

When was the molecular clock discovered?

Answer 20

1962

Discovered by chemist Linus Pauling and biologist Emile Zuckerkandl during the exploration of protein sequences.

Question 21

How can one calculate the age of species divergence using the molecular clock?

Answer 21

By dividing the number of mutations between two related species by the mutation rate to determine the timeframe of divergence.

Question 22

What issue arises with the accuracy of dating back timescales using the Molecular Clock?

Answer 22

The presumption that genes mutate at a relatively constant rate for different lineages, which can vary between genes and organisms.

Question 23

What is a cladogram?

Answer 23

It displays the relationships between organisms based on their characteristics or ancestors.

The Greek root clados means branch, and gram means written.

Question 24

How are organisms sorted in a cladogram?

Answer 24

• Organisms are grouped based on shared derived characteristics (synapomorphies) that evolved in their most recent common ancestor.
• Each branching point (node) represents a common ancestor, and new traits are used to define each clade.

While traits like limb structure or bone orientation might be used in specific clades (e.g., dinosaurs), cladograms across biology typically use a broad range of traits including genetic, anatomical, or behavioral features.

Question 25

What is a **phylogenetic tree**?

Answer 25

A diagram showing the **evolutionary history and genetic relationships** among species, illustrating common ancestry and divergence over time.

Question 26

What information is used to **build** phylogenetic trees?

Answer 26

* DNA * Protein sequences * Behaviors * Biochemical pathways * Anatomy * Morphology

Question 27

What are the **3 main branches** of a phylogenetic tree?

Answer 27

1. bacteria 2. archaea 3. eukarya

Question 28

What is the **relationship** between cladograms and phylogenetic trees?

Answer 28

* **Cladograms** are based on characteristics. * **Phylogenetic trees** are based on genetics.

Question 29

What is the **difference** between a cladogram and a phylogenetic tree?

Answer 29

* **Cladogram** displays related characteristics. * **Phylogenetic tree** shows evolutionary and genetic distance.

Question 30

What is a **rooted tree**?

Answer 30

A tree that starts at the basal node or 'root' displaying the **common ancestor of all organisms listed**.

Question 31

What is the **limitation** of constructing phylogenetic trees?

Answer 31

It does not show the amount of time between each change.

Question 32

# Define: clade

Answer 32

A branch on a cladogram or phylogenetic tree starting with one common ancestor and including everything that comes off of that ancestor.

Question 33

How do you read a **cladogram**?

Answer 33

Every organism on the cladogram share a common trait. With each new branch, a new trait is used to differentiate the organisms.

Question 34

What does **abiotic synthesis** refer to in the scientific context?

Answer 34

The formation of organic molecules from inorganic substances under prebiotic conditions. ## Footnote Abiotic synthesis is the creation of organic molecules from non-organic molecules through complex chemical processes.

Question 35

# Define: organic molecule

Answer 35

A carbon-containing molecule typically produced by living organisms. ## Footnote Examples: * Carbohydrates * Nucleic acids * Proteins

Question 36

What did Stanley Miller and Harold Urey aim to prove with their 1953 experiment?

Answer 36

The **Oparin-Haldane hypothesis** by recreating the conditions on early Earth that would have led to abiotic synthesis.

Question 37

What organic molecules **were produced** in the Miller-Urey experiment?

Answer 37

* Amino acids * Nucleic acids * Sugars * Lipids

Question 38

What did the **Oparin-Haldane hypothesis** assert?

Answer 38

Life arose gradually and by chance from gases in the early Earth's atmosphere. ## Footnote The key to abiotic synthesis occurring during this time was the significant lack of oxygen in the atmosphere.

Question 39

What were the **components of early Earth's atmosphere** in the Miller-Urey experiment?

Answer 39

* Ammonia * Water vapor * Carbon dioxide * Methane * Hydrogen

Question 40

What did **Louis Pasteur's** 1859 experiment disprove?

Answer 40

Theory of Spontaneous Generation

Question 41

What is the **Theory of Biogenesis**?

Answer 41

States that living things can only come from other living things.

Question 42

What did researchers consider as a key condition of the primitive Earth for the synthesis of organic molecules?

Answer 42

Heat

Question 43

What did **Charles Darwin** suggest as the 'original spark of life'?

Answer 43

Generated in a warm pond containing chemical compounds, sunlight, and electric sparks that may have formed the first proteins.

Question 44

What came first: **DNA** or **RNA**?

Answer 44

RNA ## Footnote Single-stranded genetic molecules.

Question 45

Why is RNA **important** in the origin of life under abiotic conditions?

Answer 45

* RNA strands can be spontaneously synthesized from nucleotide monomers under abiotic conditions. * RNA can also store genetic information in its own sequence, making it a candidate for the earliest self-replicating molecules. ## Footnote RNA plays a crucial role in the formation of proteins.

Question 46

What **functional roles** does RNA play that support its importance in the origin of life?

Answer 46

* RNA is capable of catalyzing biochemical reactions (acting as a ribozyme), including the synthesis of other RNA molecules. * Artificially synthesized RNA can develop metabolic functions, and RNA is essential for the formation of proteins through translation.

Question 47

What are the characteristics of the **Last Universal Common Ancestor**? | (LUCA)

Answer 47

* It was probably a simple prokaryote separated from the external environment by a lipid membrane. * It stored self-replicating chemicals such as RNA. ## Footnote Lipids were essential for the emergence of the earliest cells.

Question 48

What is the **Theory of Spontaneous Generation**?

Answer 48

The theory that **living organisms could arise from nonliving matter**, later disproven by experiments such as those by Louis Pasteur.

Question 49

What is the **Panspermia Hypothesis**?

Answer 49

Life may have originated on Earth from bacterial spores that floated in outer space in a frozen state and fell to the surface of the planet attracted by gravity.

Question 50

# Define: abiogenesis

Answer 50

A scientific theory that explains the processes by which life arose on Earth from inorganic chemical compounds. ## Footnote Also known as biopoiesis.

Question 51

According to the **endosymbiotic theory**, what were mitochondria and chloroplasts before they became part of eukaryotic cells?

Answer 51

Free-living prokaryotic cells.

Question 52

What were the byproducts from **early volcanic eruptions** that were released into Earth’s early atmosphere over time?

Answer 52

* Carbon dioxide * Sulfur dioxide * Carbon monoxide * Methane * Ammonia * Water * Chlorine gas * Nitrogen gas

Question 53

Why was it easier for life to evolve in an **oxygen-poor** environment?

Answer 53

Oxygen is highly reactive and can damage organic molecules, making early life difficult.

Question 54

What happened to many of Earth's early organisms as atmospheric oxygen began to collect?

Answer 54

Many were unable to adapt and died out.

Question 55

How old is Earth?

Answer 55

About **4.6 billion** years old.

Question 56

What type of autotrophs contributed to **oxygen accumulation** in the atmosphere?

Answer 56

Cyanobacteria ## Footnote They were the first photosynthetic autotrophs to produce oxygen as a byproduct.