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Bio > UNIT 7 ck12’s 5.1-5.5 > Flashcards

UNIT 7 ck12’s 5.1-5.5 Flashcards

1
Q

What analogy is used to understand Earth’s history?

A

Earth’s history is compared to a 24-hour day.

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2
Q

When did humans appear in relation to the 24-hour day analogy of Earth’s history?

A

Humans appeared only during the last minute of that day.

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3
Q

What is the fossil record?

A

The record of life that unfolded over four billion years and is pieced together through the analysis of fossils.

The fossil record provides insights into the history of life on Earth.

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4
Q

What are fossils?

A

Preserved remains or traces of organisms that lived in the past.

Fossils can include hard parts like bones, teeth, or shells.

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5
Q

Why do soft parts of organisms rarely fossilize?

A

They almost always decompose quickly after death.

This decomposition process limits the chances of fossilization.

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6
Q

What parts of organisms are most likely to form fossils?

A

Hard parts, mainly bones, teeth, or shells.

These parts can mineralize and become fossils.

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7
Q

How does knowledge of modern organisms contribute to our understanding of evolution?

A

It helps us understand how life evolved.

Studying living organisms provides insights into the characteristics and adaptations of ancient life forms.

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8
Q

What must happen for remains to be preserved as fossils?

A

Remains must be covered quickly by sediments or preserved in some other way

Examples include being frozen in glaciers or trapped in tree resin.

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9
Q

What is the purpose of dating fossils?

A

To reconstruct how life changed over time.

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10
Q

What are the two methods of dating fossils?

A

Relative dating and absolute dating.

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11
Q

What does relative dating determine?

A

Which of two fossils is older or younger than the other.

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12
Q

How does relative dating work?

A

It is based on the positions of fossils in rock layers.

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13
Q

In relative dating, which layers are assumed to contain older fossils?

A

Lower layers.

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14
Q

What does absolute dating determine?

A

About how long ago a fossil organism lived.

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15
Q

What type of age does absolute dating provide?

A

An approximate age in years.

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16
Q

What is absolute dating often based on?

A

The amount of carbon-14 or other radioactive element that remains in a fossil.

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17
Q

What is a molecular clock?

A

A molecular clock uses DNA sequences (or the proteins they encode) to estimate relatedness among species

Molecular clocks help in understanding evolutionary timelines.

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18
Q

What does a molecular clock estimate?

A

The time in geologic history when related species diverged from a common ancestor

This estimation is crucial for reconstructing evolutionary history.

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19
Q

On what assumption is the molecular clock based?

A

Mutations accumulate through time at a steady average rate for a given region of DNA

This assumption allows for the calculation of divergence times.

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20
Q

What is assumed about species with greater differences in their DNA sequences?

A

They have diverged from their common ancestor in the more distant past

This principle aids in estimating evolutionary timelines.

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21
Q

Which organism shares the highest similarity with human DNA?

A

Chimpanzee

The chimpanzee shares 98% similarity with human DNA.

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22
Q

What percentage of DNA similarity does the mouse share with humans?

A

85%

The mouse has a significant similarity of 85% with human DNA.

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23
Q

What is the DNA similarity percentage between humans and chickens?

A

60%

Chickens share 60% similarity with human DNA.

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24
Q

What is the geologic time scale?

A

A tool for understanding the history of Earth and its life.

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25
What does the geologic time scale divide Earth's history into?
Divisions such as eons, eras, and periods.
26
What are the divisions of the geologic time scale based on?
Major changes in geology, climate, and the evolution of life.
27
What does the geologic time scale organize?
Earth's history and the evolution of life.
28
What began the formation of the solar system?
A rotating cloud of stardust ## Footnote This cloud contained the elements necessary for forming all matter on Earth.
29
What event occurred 14 billion years ago that contributed to the formation of matter?
The Big Bang ## Footnote It resulted in the creation of quarks and electrons.
30
What are the first atoms primarily made of?
Hydrogen and helium ## Footnote These atoms were formed from protons and neutrons.
31
What elements do stars fuse to create?
Elements from carbon to calcium ## Footnote Carbon is the foundation of life, while calcium is found in bones and teeth.
32
What process formed heavier elements like iron?
Supernova explosions ## Footnote These explosions ejected heavier elements into space.
33
How did the solar system form from the stardust cloud?
A nearby star exploded, increasing the dust cloud's rate of spin ## Footnote This led to the concentration of mass forming the sun and planets.
34
What was Earth's initial state after its formation?
Molten and lacking an atmosphere and oceans ## Footnote Earth gradually cooled to form a solid crust.
35
What gases were present in Earth's early atmosphere?
Ammonia, methane, water vapor, and carbon dioxide ## Footnote There was only a trace of oxygen in the early atmosphere.
36
What led to the formation of clouds and rain on Earth?
The cooling of the planet and a denser atmosphere ## Footnote Rain, along with water from comets and asteroids, contributed to ocean formation.
37
What element is central to all organic molecules?
Carbon
38
Who conducted an experiment to test the hypothesis of organic molecule formation?
Stanley Miller and Harold Urey
39
What did Miller and Urey use to simulate Earth's early atmosphere?
A mixture of gases
40
What was the outcome of Miller and Urey's experiment?
Several simple organic molecules had formed
41
What do living things need organic molecules for?
To store genetic information and to carry out the chemical work of cells.
42
Which organic molecules do modern organisms use to store genetic information and catalyze chemical reactions?
DNA and proteins.
43
What is the dilemma regarding the evolution of DNA and proteins?
Each type of organic molecule needs the other for its own existence.
44
What is the RNA World Hypothesis?
The speculation that RNA may have been the first organic molecule to evolve, with early life based solely on RNA.
45
Why do some scientists believe RNA was the first organic molecule?
RNA can encode genetic instructions and some RNAs can carry out chemical reactions.
46
What was needed for the first cell?
Some sort of membrane surrounding organic molecules
47
How did organic molecules such as RNA likely develop into cells?
Lipid membranes grew around the organic molecules
48
What role did membranes play in the formation of the first cells?
Prevented organic molecules from reacting with other molecules
49
Fill in the blank: The membranes surrounding organic molecules prevented them from forming _______.
new compounds
50
What does LUCA stand for?
Last Universal Common Ancestor
51
What type of cell was LUCA?
Prokaryotic cell
52
What cellular structures did LUCA lack?
Nucleus and other membrane-bound organelles
53
What type of organisms were the earliest cells likely to be?
Heterotrophs ## Footnote Heterotrophs obtain energy from other organic molecules.
54
What process evolved about 3 billion years ago to help organisms obtain energy?
Photosynthesis ## Footnote Photosynthesis allows organisms to use sunlight to make food from carbon dioxide and water.
55
What type of organisms emerged as a result of photosynthesis?
Autotrophs ## Footnote Autotrophs can produce their own food.
56
What significant change occurred in the atmosphere after the evolution of photosynthesis?
Oxygen accumulation ## Footnote The increase in oxygen levels in the atmosphere is known as the 'oxygen catastrophe.'
57
What major innovation allowed cells to utilize oxygen for energy?
Cellular respiration ## Footnote Cellular respiration enables cells to extract more energy from organic molecules using oxygen.
58
What protects DNA in eukaryotic cells?
Nuclear membrane ## Footnote The nuclear membrane surrounds the chromosomes, providing protection to the DNA.
59
What organelle is responsible for ATP production in eukaryotic cells?
Mitochondria ## Footnote Mitochondria are known as the powerhouse of the cell, generating ATP through cellular respiration.
60
How do sperm cells move?
With flagella ## Footnote Flagella are long, whip-like structures that enable motility in certain cells, such as sperm.
61
What do eukaryotic cells feed on?
Cells that make our food ## Footnote Eukaryotic cells, including those in multicellular organisms, derive nutrients from other cells, particularly photosynthetic ones.
62
What is the key difference between eukaryotic and prokaryotic cells?
Eukaryotic cells have a nucleus and membrane-bound organelles ## Footnote Prokaryotic cells, such as bacteria, lack these complexities and are generally smaller.
63
What theory explains the evolution of eukaryotic cells?
Endosymbiotic theory ## Footnote This theory suggests that eukaryotic cells arose from a symbiotic relationship between large and small cells.
64
What happens during endosymbiosis?
Large cells engulf small cells that then evolve into organelles ## Footnote This process indicates a cooperative relationship rather than a predatory one.
65
What provides evidence for the evolutionary pathway of mitochondria and chloroplasts?
Biochemistry and electron microscopy
66
What type of DNA do mitochondria and chloroplasts have?
Short and circular
67
What type of reproduction do mitochondria and chloroplasts undergo?
Binary fission
68
How many membranes surround mitochondria and chloroplasts?
Two or more membranes
69
What major group do eukaryotes likely descend from?
Archaea ## Footnote The host cell membrane and biochemistry of eukaryotes are more similar to those of Archaea.
70
When is the oldest fossil related to modern eukaryotes dated back to?
1.2 billion years ago ## Footnote This fossil is a red alga.
71
What is the estimated appearance time of eukaryotic cells?
About 2 billion years ## Footnote This timing is debated among scientists.
72
During which Eon did all three major groups of life become well established?
Proterozoic Eon ## Footnote The three major groups are Bacteria, Archaea, and Eukaryotes.
73
What key groups of organisms are mentioned as part of the diversity resulting from eukaryotic evolution?
* Animals * Plants * Fungi ## Footnote These groups populate our world today.
74
What aspect of life is highlighted as often unsung in early evolution?
Bacteria ## Footnote They represent a vast variety of single cells.
75
What do mitochondria, human cells, and resident bacteria share?
Common ancestry ## Footnote They represent a continuous history of life.
76
Fill in the blank: The evolution of eukaryotic cells led to the spectacular diversity of _______.
animals, plants, and fungi
77
True or False: Eukaryotic cells are less efficient than prokaryotic cells.
False ## Footnote Eukaryotic cells are described as powerful and efficient.

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