Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Organic Evolution > Mod 5/6 History of Life > Flashcards

Mod 5/6 History of Life Flashcards

1
Q

How old is earth?

A

4.6 Billion y.o.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Before he was a renowned evolutionary biologist, Charles Darwin accomplished in another field. What was it?

A

Geology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What was the estimate of the age of the earth?

A

70,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What area in england did Darwin study?

A

The Weald

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Who worked on heat and used heat modeling to estimate Earth at <20 myo? And what did he believe?

A

William Kelvin
Measured changes in temperature of rock and modeled using rocks in minesDid not know that the Earth was not a constant (heat flows up and down)Mine rocks were warmer than they should be due to heat flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Did darwin agree with kelvin?

A

No.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What didn’t Kelvin know when forming his hypothesis about the cooling Earth?

A

Molten rock in the mantle and core rise and fall as their temperature changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Atoms are

A

either stable or unstable•Instability was at different levels, depending on atom•Due to variation in number of neutrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Most common isotope

A

Carbon 12 (6 p + 6 n)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Most rare isotope?

A

Carbon 14 (6 P + 8 N)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is Half-Life equation?

A 
𝑁=𝑁0𝑒−λ 𝑡 
𝑁= number of unstable atoms
N0= remaining number of unstable atoms
λ= probability of decay
𝑡= time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What defines an element?

A

Number of protons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Radioisotopes

A

Some can be formed by cosmic rays •Sometimes convert nitrogen into carbon-14•Other examples•Most have been around since Earth formed•Isotopes in rocks have half-lives > 80 million years•By examining how much is left, we get an age

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

So earth is

A

4.568 billion years (4,568,000,000 years)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Radiometric dating

A

If you know the half-life (decay rate)
And you know how much of a radioisotope still remains
Compared to how much is stable
You can determine how much time has passed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Rubidium-87

A

37 protons and 50 neutrons•Half-life of 48.8 billion years
Decays into strontium-87 (Sr-87, stable)
When rocks are formed,
Contain various minerals
Each mineral contains different amounts of Rb and Sr

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What do all rocks have upon formation?

A

All rocks have same ratio of Sr-87 to Sr-86•Regardless of ratio of Rb-87 to Sr-86

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What decays to what overtime?

A

As Rb-87 decays to Sr-87•And as Sr-86 stays the same (it is stable)
The ratio Rb-87/Sr-86 decreases (in all rocks)
If this is plotted (as an isochron)
For all rock types
Slope of line is 𝑒𝑒λ𝑡𝑡−1
Used to determine time since formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Rubidium -87 decays by

A

a neutron degrading to a proton and electron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What can this dating be used on?

A

Meteorites. Overall helped solve the age of the Earth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why did darwin think fossills were difficult to make?

A 
Are eaten
Smaller organisms consume them at microscopic level
Weather erodes them
Some do fossilize though
Must have the right conditions
Still water where silt can be deposited
Mudslide that is anoxic
Volcanic ash, etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Mineralization of organic matter can happen by?

A

Minerals from water fill spaces and settle

Original organic material dissolves away

Original spaces filled with other minerals

23
Q

Why are fossils never safe?

A

Can later be exposed

Degraded by weather erosion

People come along and pick them up!

24
Q

Previous organic fossils

A

Do not tend to have rubidium and strontium

Radiometric dating not possible

Can use nearby rock for dating

25
If you were to find mineralized fossils from previously organic matter, what technique could you use to date their age?
Radioisotopic dating of nearby rock strata
26
What can fossils tell us?
Morphology Evolutionary relationships Behavioral ecology Mating, Reproduction, Feeding
27
What can fossils tell us?
Morphology Evolutionary relationships Behavioral ecology: Mating, Reproduction, Feeding Developmental Biology
28
What PHYSICAL techniques can we use to see fossil cellular structure?
SEM Scanning electron microscopes and Energy-dispersive X-ray spectroscopy of Borealopeltia Showed: More melanin on dorsal surfaces Indicated countershading Seems it was preyed on by other dinosaurs Computed tomography –allows mapping of three-dimensional characteristics of living (and fossil) organisms
29
What two pieces of evidence indicated that hadrosaurs used their head crests for communication?
Connected to nasal openings Area of brain for olfaction is small Morphology – ear bones indicated they picked up frequencies produced by resonating crests
30
Lagerstätten
•Deposit of well-preserved fossils Usually due to an anoxic environment Example: the Burgess shale (65k fossils, >93 species)•~505 to 510 mya
31
Biomarkers
Molecules in the fossil record that indicate the presence of life Some larger molecules can only form through organic pathways Some are unique to certain groups of organisms Okenane– only made by purple sulfur bacteria
32
Okenane example
Found in 1.64 billion year old rocks in Australia -indicates biological life •Also anoxic, sulfidic ocean •Waters would have been toxic to many organisms
33
Are different isotopes found in fresh and sea waters?
Yes.
34
Where do plants get carbon from?
Atmosphere, take up C12 better than C13
35
Because plants get carbon from atmospheric CO....
We Can test rock to determine if plant material is present
36
C3 vs C4 plants
C4 photosynthesizing plants have higher ratios of 13C/12C Can help to determine diet in animals Shift in human diets
37
What was the shift in human diets?
More C4 plants more recently | Or feeding on animals that ate C4 plants
38
Which of the following statements about "molecular paleontology" is true?
More recent humans appear to have shifted their diets from C3 to C4 plants (or to animals that consume C4 plants)
39
How long has life been on Earth?
It started as molten rock Many pieces came together •Formed a crust by cooling over millions of years •Denser crust rock sank •Lighter crust rock formed the continents •Rocks released gases, including water vapor •Oceans began to form
40
Eras
1. Hadean 2. Archaean 3. Proterozoic 4. Paleozoic 5. Mesozoic 6. Cenozoic
41
How old is life?
Potential evidence of carbon-12 enriched inclusions in a 4.1 billion year old zircon Not conclusive * At Darwin’s time, oldest known fossils were from Cambrian, 541 mya * Since then, fossils have been found possibly up to 3.5 bya
42
What original rock can persist?
Original rock destroyed by impacts, plate tectonics •Zircons can persist •Sometimes have isotopes that give age •Some show the composition from ancient Earth
43
Stromatolites
sedimentary rock form by layers of cyanobacteria
44
How does stromatolites form?
Combine with sand and other small rocks •Build up by layers over a long time •Rare now (because they are consumed) •Common in Precambrian times
45
First single-celled life?
Stromatolites •3.5 billion years ago •Only life for 1.5 billion years
46
At Darwin’s time, oldest known fossils were from
Cambrian, 541 mya
47
Photosynthesis revolution?
~2.7 billion years ago | •Increase O2 in the atmosphere
48
Movement of Earth’s crust alter and influences what?
Climate and influences species survival
49
Plate movement has Changes in?
``` Climate •Atmosphere •Land size •Flooding •Glaciation •Volcanic activity •Meteor impact ```
50
First eukaryotes
Had membrane-bound organelles •Endosymbiotic theory •~1.8 billion years ago
51
Multicellular eukaryotes
~2.1 to 1.2 billion years ago •Evolved from either: Aggregation Sticky offspring Probably colonial at first
52
When did animals come?
635 to 585 my •Ediacaran fauna Precambrian ~570 mya
53
Many organisms common now are “new”
``` Dinosaurs – 240 to 66 mya(except birds) •Mammals – 160 mya •Flowering plants – 136 mya •Grasses – 100 mya. •Early human ancestors – 7 mya• Homo sapiens – 300 kya ```

Organic Evolution (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions