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CH 10 > Fossil records > Flashcards

Fossil records Flashcards

1
Q

What r fossil records

A

The fossil record provides information about the history of life on Earth.
Difficult to preserve due to certain conditions which need to be ideal.

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2
Q

what are fossils

A

Fossils are the preserved remains of organisms or anything that shows (directly or indirectly)

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3
Q

Fossils may appear as

A

Moulds
Cast
Mineralised
Trace fossils

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4
Q

What does the fossil record provide information about?

A

The history of life on Earth.

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5
Q

Why is it difficult to preserve fossils?

A

Fossils are difficult to preserve because certain conditions need to be ideal for preservation.

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6
Q

What are fossils?

A

fossils are the perserved body remains, impressions or traces of a dead organism.

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7
Q

What is a mould fossil?

A

A mould fossil is an impression left in sediment or rock that shows the shape or surface of an organism.

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8
Q

What is a cast fossil?

A

A cast fossil forms when a mould is filled with sediment or minerals, creating a replica of the organism’s shape.

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9
Q

What is a mineralised fossil?

A

Mineralised fossils occur when the organic materials of an organism are replaced with minerals, preserving its structure.

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10
Q

How are fossils formed?

A

1.Remnants of an organism is rapidly covered by sediment – limiting exposure to oxygen, microorganisms (bacteria) and scavengers

2.Over time the sedimentary layers build, increasing the pressure to form sedimentary rock. soft tissues decay

3.Mineralisation occurs-minerals form to keep the structues intact by forming a layer around the structures,Within the rock, the fossilised remains form.

  1. because of the earths movement the fossils may move up to the earths surface and the sedimentary rock covering the fossil erodes leading to the exposure of the fossils
    (this sometimes leads to the dsicvoery of fossils0?
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11
Q

How are dinosaur fossilsformed

A
  1. dinosaur dies in river
  2. the body is covered with sediment. The soft tissues decompose and the hard body structures become fossilised by premineralisation.

3.The sedimentary layers acculmate and the resultnat pressure forms sedimentary rock

4.The earths movement raise the layers of the rock to the surface

5.the rock erodes, exposing the fossilied body structures

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12
Q

what is required/conditions for fossilisation

A

Rapid sediment cover

Pressure from sediment forms sedimentary rock

Removal of oxygen and bacteria for slow decay

Cool temperatures, low light availability

Undisturbed for many years from scavengers and decomposers

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12
Q

What is fossil dating

A

Fossil dating is the process of determining the age of fossils, which are the preserved remains or traces of ancient organisms.

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13
Q

Types of fossil dating

A

Relative Dating-places fossils in order by comparing their positions in rock layers.

Absolute Dating-uses radioactive decay to estimate the exact age.

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14
Q

What is the law of fossil succession?

A

fossils of the same age will be found in the same layer of sedimentary rock, and the fossils found in lower sedimentayr rock are older and fossils found in higher seidmentyar rock are younger

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15
Q

geological timescales

A

Scientists can use the stratum (layers) to determine a particular period of time

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16
Q

What are index fossils?

A

Fossils of organisms that lived during a short period but were widespread, used to identify the relative age of rock layers.

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17
Q

What are transitional fossils?

A

: Fossils that show intermediate traits between ancestral and descendant species, helping to trace evolutionary changes.

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18
Q

: What is relative dating?

A

A dating technique used to determine the relative age of a fossil by comparing its position to other fossils or rock in surrounding rock layers (strata). These

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19
Q

What is radiocarbon dating?

A

radiocarbon daitng is a form of radioactive dating that estimates the absolute age of a fossil using the decay of carbon 14 radioistope to nitrogen 14.

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20
Q

What term describes the rock layers used in relative dating? A

A

Strata.

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21
Q

How does relative dating estimate the age of a fossil?

A

By comparing its position in surrounding rock layers to other fossils or rocks.

22
Q

Does relative dating provide an exact age for fossils?

A

No, the exact age is not provided.

23
Q

When is relative dating used in terms of radioisotopes?

A

It is used if radioisotopes are reduced or not available.

24
Q

What does the law of fossil succession state about sedimentary rock layers?

A

The layer on the bottom will be older than those positioned above.

25
Q

How is sedimentary rock formed?

A

By the accumulation of sedimentary layers on top of each other.

26
Q

How do scientists determine a particular period of time?

A

Scientists can use the stratum (layers) to determine a particular period of time, this is known as a geological scale.

27
Q

How can scientists use stratum (layers) in geology?

A

Scientists can use the stratum to determine a particular period of time.

28
Q

What does the geological timescale help determine?

A

The geological timescale helps determine the relative timing of events in Earth’s history based on rock layers.

29
Q

What are index fossils and how can they be used

A

Index fossils are a group of widespread fossils which existed for a short period and have a known age

Index fossils are a group of widespread fossils which existed for a short period and have a known age

30
Q

Characteristics of index fossils

A

Abundant

Existed in many geographical areas

Lived within a known short period of time

Easy to distinguish (physically distinctive)

31
Q

Transitional fossils

A

fossils that shows traits that are common to both its ancestral group and its descendant group.

They demonstrate evolutionary pathway

32
Q

Reptilian features and Avian features

A

Reptilian Features:
Scaly skin
Cold-blooded (ectothermic)
Clawed limbs
Teeth

Avian Features:
Feathers
Warm-blooded (endothermic)
Beaks
Wings

33
Q

Absolute dating/ radiometric dating

A

Examines the amount of radioactive material left in a fossil by reheating the rock and measuring the amount of escaping gas

Used to determine the age (in years) of the fossil or rock

34
Q

Radioactive Isotope Breakdown

A

Radioactive isotopes decay into more stable products over time.

35
Q

The older the rock

A

less radioactive material left

35
Q

Half life

A

The half-life is the amount of time the mass of the radioisotope is broken down into a stable form (half remains).

Example: The half-life of Carbon-14 is 5730 years. After 5730 years, the amount of C-14 left in a fossil is half of the original amount.

36
Q

Rate of Breakdown

A

determined by calculation the half life of an isotope

37
Q

history of life-key events

A

prokaryotes(unicelluar) to eukaryotes(mutlicellular)

water to the land

simple to complex beings

38
Q

How did bacteria(prokaryote) evolve to form eyes.

A

Prokaytoces orngaism we first had on earth were living on water, overtime the bacteria evolved and devleodpea sensisitied features causingthem to become seneisitv eto light as some bacteria exposed to high uv light died, there mutation inside of bacteria which allowed bacteria is disitnguihs between night or day so during the day thyed go to the bottom ontthe water to avoid light and come to the suffice during the night, overitmethis causes htem to dvelop eyes so the snesitiviity of light resulted in the devleopmetn of eyes

39
Q

ribosomes and mitochondria are similar due to

A

ribosomes and mitochodnria both have thier own genetic material,Fossil records are incomplete because

40
Q

Fossil records are incomplete because

A

Fossil records are incomplete because conditions are not always ideal for fossilization(double check)

41
Q

fossil record

A

any information we obtain from fossils that we arrange in a chronological order and it allows us to gain an understanding of how organisms have evolved overtime and how organisms have changed.

42
Q

fossilation

A

pprocess of an organism transofrming into a fossil

43
Q

palaeontology

A

study of ancient life that is reperestned by the fossils

44
Q

How do accidental discoveries of fossils form

A

foundations, building roads, etc.).
Mining: Digging into the earth can reveal fossil-rich layers.
Natural erosion: Wind, rain, or water flow gradually expose fossils by wearing away rock and soil.
Agricultural activity: Fossils may be found when fields are plowed or the land is worked.
Hiking or exploration: Fossils are sometimes discovered by individuals exploring areas with exposed rock formations or riverbeds.its

45
Q

Carbon 14 (unstable)turns/decays into nitrogen 14 because nitrogen 14 because
Nitrogen 12 is more stable. Carbon 12 is also stable but carbon 12 cannot break down/decay because its stable.

A
46
Q

Memorise;
1. relative dating
2. absolute dating
3. radioactive isotopes
4. dating period
5 carbon dating
6. half life

A

For less than 50,000 years- its carbon-14-nitrogen 14

for move than 100 000+ then its potassium 40-argon 40

remmeber that the half life of carbon 14-ntrogen 14is 5730 years and the half life of potassium 40-argon 40 is 1.3 billion years

47
Q

how does genetic divergence occur

A
  1. geograpcial barriers
  2. selection presseures diffenre tin the same neviornment cauisng populatiosn adpat diffenrtl
  3. reproductive isolation
  4. founder effect n bottle neck effect
48
Q

Analogous structures

A

is an example of convergent evolution and is Structures that serve similar biological functions but are not derived from a common ancestor.

49
Q

Carbon 14 turns/decays into nitrogen 14 because nitrogen 14 because
Nitrogen 12 is more stable. Carbon 12 is also stable but carbon 12 cannot break down/decay because its stable.

A
50
Q

Carbon Isotopes: Carbon exists in the atmosphere as two stable isotopes, Carbon-12 (12C) and Carbon-14 (14C). Carbon-14 is a radioactive isotope that decays over time into Nitrogen-14 (14N).

Constant Proportion in Living Organisms: While an organism is alive, it continually exchanges carbon with its environment. Therefore, the ratio of 14C to 12C in its tissues is approximately equal to that in the atmosphere.

Post-Mortem Changes: Once the organism dies, it stops exchanging carbon with its environment. The 14C in its remains begins to decay into 14N at a known rate (its half-life). However, the amount of 12C remains constant because it is not radioactive and does not decay.

Determining Age: By measuring the remaining amount of 14C relative to the stable 12C in a sample, scientists can calculate how long it has been since the organism died. This is because the rate of decay of 14C is known and its initial ratio (when the organism was alive) can be assumed to match the atmospheric levels.

A
51
Q

convergent evolution

A

distantly related species evolve due to similar selection pressures).

Species do not share a recent common ancestor

Evolution due to similar selection pressures

CH 10 (3 decks)

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