ILTS Science: Biology > Common Ancestry & Diversity > Flashcards

Common Ancestry & Diversity Flashcards

Understand the evidence for evolution, the mechanisms of natural selection and speciation, and factors affecting population genetics (e.g., drift, gene flow, Hardy–Weinberg). (85 cards)

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1
Q

What is the field of paleontology?

A

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

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2
Q

How do fossils contribute to understanding evolution?

A

By forming a biological timeline that shows historical changes in organisms.

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3
Q

What is radiometric dating used for in paleontology?

A

To determine the age of rocks and fossils.

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4
Q

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

A

The body structure of whales and dolphins, including flippers and small internal back limbs.

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5
Q

What is biogeography?

A

The study of how species are distributed across Earth.

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6
Q

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

A

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

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7
Q

What is homology in comparative anatomy?

A

Similar characteristics in organisms from a common ancestor.

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8
Q

What is studied in embryology to compare evolutionary relationships?

A

Embryos, looking for shared structures during development.

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9
Q

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

A

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.

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10
Q

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

A

How distant the ancestor is.

Fewer DNA differences mean a recent common ancestor, while more differences indicate an older divergence. This concept underlies molecular clocks and phylogenetic trees.

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11
Q

What is the definition of endosymbiosis?

A

The symbiosis where one species lives inside another species.

Endosymbionts often form mutualistic relationships, such as mitochondria and chloroplasts in eukaryotic cells, which are believed to have originated from ancient symbiotic bacteria.

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12
Q

What is the definition of endosymbiont?

A

The species that lives inside another species.

Example: Nitrogen fixing bacteria in the roots of plants

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13
Q

What is the definition of host in endosymbiosis?

A

The species containing the endosymbiont.

In endosymbiosis, the host provides shelter and resources for the endosymbiont. For example, eukaryotic cells are hosts to mitochondria and chloroplasts, which supply energy and carry out photosynthesis, respectively.

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14
Q

What is the Endosymbiotic Theory?

A

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.

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15
Q

What did the aerobic endosymbionts evolve into?

A

Present-day mitochondria.

Aerobic bacteria that were engulfed by ancestral eukaryotic cells evolved into mitochondria. These organelles supply energy through cellular respiration, making them essential for most eukaryotic life.

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16
Q

What did the photosynthetic endosymbionts evolve into?

A
  • Present-day chloroplasts
  • Other plastids
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17
Q

What evidence supports the endosymbiotic theory?

A

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

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18
Q

How do mitochondria and chloroplasts replicate?

A

Via a process called binary fission.

Similar to some bacterial cells.

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19
Q

What is a Molecular clock?

A

A clock that measures the constant rate of change in an organism’s genome (DNA or protein sequences of a specific gene) over time, representing species divergence and evolution.

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20
Q

When was the molecular clock discovered?

A

1962

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

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21
Q

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

A

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

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22
Q

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

A

The presumption that genes mutate at a relatively constant rate for different lineages, which may not always be the case.

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23
Q

What is a cladogram?

A

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

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

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24
Q

How are organisms sorted in a cladogram?

A
  1. Direction of the pubis bone.
  2. Number of legs they walk on.
  3. Presence of armor.
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25
What is a **phylogenetic tree**?
It is based on **genetic relationships** and shows how closely related organisms are in an evolutionary sense.
26
What information is used to **build** phylogenetic trees?
* DNA * Protein sequences * Behaviors * Biochemical pathways * Anatomy * Morphology
27
What is the relationship between cladograms and phylogenetic trees?
* **Cladograms** are based on characteristics. * **Phylogenetic trees** are based on genetics.
28
What is the **difference** between a cladogram and a phylogenetic tree?
* **Cladogram** displays related characteristics. * **Phylogenetic tree** shows evolutionary and genetic distance.
29
What is a **rooted tree**?
A tree that starts at the basal node or 'root' displaying the **common ancestor of all organisms listed**.
30
What is the **limitation** of constructing phylogenetic trees?
They do not show the amount of time **between evolutionary changes**. ## Footnote Phylogenetic trees illustrate relationships and branching patterns but usually lack precise information about when divergences occurred.
31
What is a **clade**?
A group of organisms that includes a **common ancestor and all of its descendants**. ## Footnote On a cladogram or phylogenetic tree, a clade appears as a single branch. Clades can be small (e.g., a single genus) or large (e.g., all mammals), depending on the ancestor chosen.
32
What are the **3 main branches** of a phylogenetic tree?
1. Bacteria 2. Archaea 3. Eukarya
33
How do you read a cladogram?
Every organism on the cladogram share a common trait. With each new branch, a new trait is used to differentiate the organisms.
34
What does **abiotic synthesis** refer to in the scientific context?
Creation of life from non-life. ## Footnote Abiotic synthesis is the creation of organic molecules from non-organic molecules through complex chemical processes.
35
What is the definition of an **organic molecule**?
A **carbon-containing molecule** produced by living cells. ## Footnote Organic molecules typically contain carbon–hydrogen bonds and include carbohydrates, lipids, proteins, and nucleic acids. They are the basis of life’s structure and function, distinguishing them from inorganic molecules. Examples: * Carbohydrates * Nucleic acids * Proteins
36
What did Stanley Miller and Harold Urey aim to prove with their 1953 experiment?
The **Oparin-Haldane hypothesis** by recreating the conditions on early Earth that would have led to abiotic synthesis.
37
What organic molecules **were produced** in the Miller-Urey experiment?
* Amino acids * Nucleic acids * Sugars * Lipids
38
What did the **Oparin-Haldane hypothesis** assert?
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.
39
What were the **components of early Earth's atmosphere** in the Miller-Urey experiment?
* Ammonia * Water vapor * Carbon dioxide
40
What did **Louis Pasteur's** 1859 experiment disprove?
The theory of spontaneous generation. ## Footnote Pasteur’s swan-neck flask experiment showed microbes came from existing life, not nonliving matter, supporting the principle of biogenesis.
41
What is the Theory of **Biogenesis**?
The principle that living things arise only from other living things. ## Footnote Supported by Pasteur’s experiments, this theory rejected spontaneous generation and established reproduction as the source of life.
42
What did researchers consider as a **key condition** of the **primitive Earth** for the synthesis of organic molecules?
heat ## Footnote Early Earth’s volcanic activity and high temperatures provided energy needed to form organic molecules from simple inorganic compounds.
43
What did **Charles Darwin** suggest as the 'original spark of life'?
Generated in a pond of hot water which contained a variety of chemical compounds, electricity, light, and other conditions that produced the first proteins capable of organizing themselves and producing life.
44
What came first: **DNA** or **RNA**?
RNA ## Footnote The “RNA World Hypothesis” proposes RNA was the first genetic material because it can both store information and catalyze reactions, making it essential in early life before DNA and proteins evolved.
45
Why is RNA important in the **emergence of life on Earth**?
* RNA strands can be spontaneously synthesized from monomers under abiotic conditions. * RNA can store genetic information in their own sequence. * RNA is capable of catalyzing different types of RNA and is crucial for the formation of proteins. * Artificially synthesized RNA chains can be transformed into different molecules with metabolic functions. ## Footnote RNA plays a crucial role in the formation of proteins.
46
What are the characteristics of the **Last Universal Common Ancestor**? | (LUCA)
* 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.
47
What is the **Theory of Spontaneous Generation**?
The belief that **living things arise from nonliving matter**. ## Footnote Once widely accepted, it claimed organisms like flies or microbes could appear from decaying matter, but was disproven by Pasteur’s experiments.
48
What is the **Panspermia Hypothesis**?
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. ## Footnote It suggests life arrived via comets, asteroids, or cosmic dust, seeding Earth with the building blocks of biology.
49
What is **abiogenesis**?
The theory that life **originated from nonliving chemical compounds**. ## Footnote It proposes that simple molecules on early Earth gradually formed complex organic molecules, eventually giving rise to the first living cells. Also known as **biopoesis**.
50
According to the **endosymbiotic theory**, what were mitochondria and chloroplasts before they became part of eukaryotic cells?
Free-living prokaryotic cells. ## Footnote Mitochondria evolved from aerobic bacteria and chloroplasts from photosynthetic bacteria that were engulfed by ancestral eukaryotic cells, forming a mutualistic relationship.
51
What were the byproducts from **early volcanic eruptions** that dominated Earth's atmosphere over time?
* Carbon dioxide * Sulfur dioxide * Carbon monoxide * Methane * Ammonia * Water * Chlorine gas * Nitrogen gas
52
Why was it easier for life to evolve in an **oxygen-poor** environment?
Oxygen molecules themselves are pretty damaging.
53
What happened to many of Earth's early organisms as atmospheric oxygen began to collect?
Many were unable to adapt and died out.
54
How old is Earth?
About **4.6 billion** years old. ## Footnote Radiometric dating of rocks and meteorites supports this age estimate.
55
What type of autotrophs contributed to **oxygen accumulation** in the atmosphere?
Cyanobacteria ## Footnote Through photosynthesis, cyanobacteria released oxygen, leading to the Great Oxidation Event about 2.4 billion years ago.
56
What is **extinction**?
The death of all members of a species of plants, animals or other organisms on Earth.
57
What is **mass extinction**?
A rapid and widespread **loss of many species** in a short geological period. ## Footnote The extinction rate greatly exceeds speciation, reshaping ecosystems worldwide. Some well known mass extinction events include: * Permian extinction * Ordovician-Silurian extinction * Cretaceous-Tertiary (K-T) extinction * End-Triassic extinction * Devonian extinctions
58
What is the **moment of extinction**?
The point at which the **last individual of a species dies**. ## Footnote Once the last individual of a species dies, the species is considered extinct.
59
What are some **catastrophic events** that can cause extinction?
* Massive glaciation * Meteors * Various natural disasters * Tectonic Plate Movement * Volcanism
60
How did the **Dodo bird** become extinct?
* Over-harvesting by humans. * Introduction of invasive predator species. * Habitat loss.
61
What is predicted to happen to extinction and biodiversity in the **next 100 years**?
Global biodiversity is expected to **decline**, with estimates suggesting that up to **54% of species** may face extinction risks if current trends continue.
62
What is a major consequence of **rapid climate change** on species?
It forces species to **adapt** quickly to **new climate patterns**. ## Footnote Some organisms successfully adapted while others did not. Examples: * Flourishing of tree pests. * Death of some coral species.
63
What was a major factor contributing to the **extinction** of the **Carolina parakeet**?
**Overexploitation** by hunting and fishing by humans.
64
What are the **main causes** of extinction?
* Catastrophic events * Diseases * Predators * Overexploitation * Climate change * Lack of genetic diversity
65
What are some major **human causes** of extinction?
* Overharvesting * Pollution * Habitat destruction * Introduction of invasive species * Overhunting
66
What is **interspecific competition** in ecology?
The battle between **two species for the same resources** in an ecosystem. ## Footnote Examples: * Woodpeckers and squirrels competing for nesting sights in trees. * African savanna lions and cheetahs struggling for the same food.
67
Define **competitive exclusion**.
Two species cannot persist in the same ecological habitat for an extended period without being **pushed out due to competition for limited resources**.
68
What are the **three basic types** of competition?
* Interference competition * Exploitation competition * Apparent competition
69
What is **exploitation competition?**
An indirect interaction between species over a limited resource where **one organism's use of resources depletes the total amount available to another organism**.
70
What is **interference competition?**
Direct interaction between species over a limited resource, involving **aggressive seeking to exclude** one individual from certain habitats.
71
What is **niche differentiation**?
The process by which competing species exploit their environment differently in order to coexist.
72
What is the **difference** between fundamental niche and realized niche.
* **Fundamental niche** reflects all ideal environments where a species may survive. * **Realized niche** is where the species actually live.
73
What are **ecomorphs**?
Populations of distantly related animals that have recently acquired morphological differences to adapt to certain environments.
74
What is the **Competitive Lotka-Volterra Model**?
A mathematical model formalizing the impacts of interspecific competition between populations. ## Footnote It predicts outcomes like coexistence, exclusion, or extinction.
75
What is the outcome of **interspecific competition**?
It frequently results in **extinction** for the **less well-adapted species**. ## Footnote Competitive exclusion explains why two species with identical niches cannot coexist long-term.
76
Define **fundamental niche**.
A theoretical niche that reflects all ideal environments with no limiting factors or competition in which a species may survive.
77
Define **realized niche**.
Where the species actually live, reflecting the environments they inhabit.
78
What do **fossils** provide evidence for?
**Biological diversity** and **mass extinction** of species. ## Footnote Fossils are considered historical records that help us understand changes in populations over time.
79
What role do **Earth's strata** play in understanding evolutionary events?
They **create a timeline** of evolutionary events by being laid down in order. ## Footnote The oldest strata are found at the bottom, while the youngest are at the top.
80
What significant evolutionary **evidence** have fossils provided regarding whales and dolphins?
They evolved from **four-legged** land animals. ## Footnote Fossils show ancestors of these animals had leg bones, indicating their evolutionary transition.
81
What is **biodiversity**?
The **variety of life** at the genetic, species, and ecosystem levels. ## Footnote Biodiversity supports ecosystem stability, resilience, and the availability of resources for life.
82
What is **speciation**?
The evolutionary process by which **new species arise**. ## Footnote Speciation occurs when populations of the same species become reproductively isolated, often through geographic separation or genetic divergence, leading to distinct species over time.
83
How many **mass extinctions** have occurred in Earth's history?
Five ## Footnote These include major events such as the Permian-Triassic and Cretaceous-Paleogene extinctions, each wiping out a large percentage of Earth’s species in a short geological timeframe.
84
What **opportunities** do mass extinctions provide for surviving species?
The opportunity to **spread to new environments** and habitats. ## Footnote This leads to rapid migrations and new adaptations within populations.
85
What does the **fossil record** help us understand?
How species evolve and diversify over time. ## Footnote The fossil record documents the appearance and sequence of fossils within rock layers.
ILTS Science: Biology
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