11. Changes In Biodiversity Over Time

Question 1

Define evolution

Answer 1

The gradual adaptive change over geological time, in the composition of populations from ancestral species to new species

Question 2

Micro evolution

Answer 2

Small scale changes within a gene pool of a population of a species over time

Question 3

Macro evolution

Answer 3

Large scale changes involving species and a genera over time. New species evolve whilst others become extinct

Question 4

How old is the earth

Answer 4

4500 million years old

Question 5

Define stratigraphy

Answer 5

Technique used, where the relative age of a fossil can be determined by the position of that stratum

Question 6

What is stratification

Answer 6

Process of formation of layers in sedimentation rock

Question 7

What does the principle of superposition state?

Answer 7

older layers of rock are at the bottom of a sequence of strata and are overlain by progressively younger layers

Question 8

How does stratigraphy give a relative age?

Answer 8

this method of dating rocks gives the relative are of a rock layer (stratum) compared to other layers. For rock layers or strata, the oldest stratum is found at the bottom and the youngest at the top

Question 9

What are index fossils

Answer 9

Fossils of species that existed during limited periods of geologic time, and are only found in restricted depth of sedimentary rock strata and thus are used as guides to the age of the rocks in which they are preserved..
-Presence of index fossils in rock strata from different parts of the world will be deemed to have the same age

Question 10

What are the best index fossils

Answer 10

• Abundant
• Distinct from other flora or fauna
• Geographically widespread
• Found in many kinds of rocks
• Narrow in stratigraphic range

Question 11

Radiometric dating

Answer 11

Technique in which the actual age of the fossils and rocks is expressed in years

Question 12

How does radiometric dating work

Answer 12

Elements, known as parents contain radioactive isotopes that spontaneously decay (breakdown) to form stable daughter products
-The time of decay for each isotope is specific and the half life is the time taken for half the original radioactive isotope to decay

Question 13

Carbon 14

Answer 13

Nitrogen 14

Question 14

Uranium 235

Answer 14

Lead 207

Question 15

Potassium 40

Answer 15

Argon 40 used to date rocks 3 million years old

Question 16

Rubidium 87

Answer 16

Strontium 87

Question 17

Half life carbon 14

Answer 17

5,730 years. Time taken for half the amount to decay to nitrogen 14

Question 18

How can carbon dating be used

Answer 18

• Living things contain some carbon 14 in their organic material
• The ratio of carbon 1 4 12 is constant in an organism during life but after death c14 decomposed due to radioactive decay but c12 remains constant
• The longer dead the lower amount of c14 to c12, lower ration of c14 to c12

Question 19

Difference between mineralised fossil and impression fossil

Answer 19

Mineralised fossil is where the organic matter of the structures is replaced by minerals
Impression fossil is where the organic matter has disappeared and the organism exists as an impression

Question 20

Trace fossils

Answer 20

Preserved evidence of the activities of organisms such as footprints, tooth marks, track, burrows and fossilised dung

Question 21

Biosignatures

Answer 21

A biosignature is a physical or chemical sign preserved in minerals, rocks or sediments that can be inferred to be cellular or have resulted from the metabolic activities or an organism

Question 22

Best environments for fossil formation

Answer 22

Marine freshwater then terrestrial

Question 23

Steps in fossil formation

Answer 23

• THe organism dies and is buried rapidly (ash, sediments, mud) protecting it from SCAVENGERS and DECAY
• Rate of decay slowed in REDUCED OXYGEN, LIGHT and TEMPERATURE
• Layers of material build up EXERTING PRESSURE on the remains
• The weight of which COMPRESSES original sediment layer so it becomes rock.

Question 24

How does a mould form?

Answer 24

Organism decomposes slowly and leaves a cavity called a mould. Mould is filled wiht minerals and hardens to form a cast
3D model of original organism and original tissue replaced by carbon or minerals
The fossil is buried by more layers to form rock in right temp and pressure. More strata

Question 25

How do imprints form?

Answer 25

Imprints of the organisms can also fossilise. Where the imprint is preserved due to sediments filling and overing the imprint with later pressure resulting i rock formation. Later erosion of upper layers may expose a lower harder layer with imprint

Question 26

Where are most fossils found?

Answer 26

Most fossils are found in sedimentary rock, limestone sandstone, mudstone. but fossilisation can occur in ice due to action of volcanic ash.

Question 27

Why is the fossil record not complete?

Answer 27

1. Not all organisms die n areas that favour fossilisation ( oxygen and temperature too high, organisms decomposes)
2. Scavengers and decomposers consume or destroy the organism, fossilisation will not occur.
3. Soft bodied organisms are usually not preserved, bc not easily mineralised and do not fossilise due to decay. Decompose rapidly.
4. Earth movements and lava destroy fossils or make them inaccessible

Question 28

What can be concluded from the fossil record?

Answer 28

• Structure and arrangement of skeleton or bones suggest shape, size, mode of locomotion and nature of organisms habitat
• Structure and arrangement of teeth suggests diet and type of organism by comparing it to modern resembling organism
• Evolution of species occurs from simple to more complex forms

Question 29

What is a transitional fossil?

Answer 29

If a new species evolved from ancestral species some intermediate fossil evidence must exist that has features of both ancestral and present forms of the species.

Question 30

Archaeopteryx

Answer 30

• Earliest known bird fossil found.
• Had feathers, furcula (wishbone), which is also found in modern birds but also it had teeth in its beaks, claws on its wings and a long jointed bony tail, features that belong to modern reptiles

Question 31

Homology structures

Answer 31

Structures that are similar in structure but can sometimes serve a different function

Question 32

How can structural homology be seen in vertebrates?

Answer 32

• All vertebrates evolved from a common ancestor
• Pentadactyl limb found on most vertebrates has the same general structure
• Evolution occurs by modification of preexisting structures, not by production of totally new ones

Question 33

Vestigial organs

Answer 33

If organisms are related by evolutionary descent it is expected that some organisms will show the presence of functionless organs that were present and functional in ancestors.

Question 34

Common features in vertebrate embryo

Answer 34

• Pharyngeal arches present in all vertebrate embryos but develop into different structures in adults, in fish to gills, reptiles into lower jar and in mammals lower something and ear
• Tails

Question 35

Basic principle of biogeography

Answer 35

Entails that each plant and animal species originated only once. The place where this occurred in the central origin

Question 36

What can be predicted via biogeographic distribution

Answer 36

1. Native species in different isolated regions will be distinctive bc each group evolved from a different ancestral species.
2. Modern species native to a given region will be more similar to species that lived in that region in the geological past that to modern species living in a distant region with similar environmental conditions
3. Same ecological niche in different isolated regions will be occupied by different species that are descended from different ancestral species that once lived in that region

Question 37

Divergent evolution

Answer 37

Occurs when closely related species become more dissimilar over times usually in response to different environmental conditions and selection pressures.

Question 38

Adaptive radiation

Answer 38

Special case of divergent evolution in which a large number of species, each occupying a different niche, evolved over geological time from a single ancestral species

Question 39

Convergent evolution

Answer 39

Over geological time, natural selection may act on distantly related species to produce superficial similarities that are not due to a shared ancestry but reflect the fact that the species are adapted to a similar way of life, are exposed to similar selection pressures and occupy the same niche in their ecological communities

Question 40

Analogous structures

Answer 40

Features that are similar in structure and function but have arisen independently (not from a common ancestor) are analogous

Question 41

Extinction

Answer 41

End of a species. Moment of extinction is the death of the last individual of that species (although capacity to breed and recover may have been lost before that point)

Question 42

Mass extinction

Answer 42

Period in the geological history of Earth when abnormally high number of species die out over a relatively short time frame

Question 43

How do mass extinctions create great evolutionary opportunity for surviving species

Answer 43

They are able to diversify and undergo adaptive radiation in which the survivors expand into ecological niches that were left free with the loss of other species

Question 44

Extinction occurs when…

Answer 44

Suitable adaptations are not present in a species when the environment changes.

• The species can no longer compete with another species for resources
• It either evolves into a new species or it and its lineage become extinct