Biology - Review 10

Question 1

How is the geological time scale is constructed ?

Answer 1

The geological time scale is constructed using the relative order of rocks in a sedimentary rock sequence, the fossilised remains of ancient animals and plants within the rock strata, and direct dating of rocks using radiometric techniques.

Question 2

What are the geological time scale divisons?

4 divisions

Answer 2

The largest geological subdivision of the geological time scale is an eon.

Eons are subdivided into eras,

which are further subdivided into periods,

and into still smaller subdivisions called epochs.

Question 3

What happened in the In the Archaean eon?

Answer 3

Lite first appeared on Earth. Earth’s initial life forms were prokaryotes (bacteria). Stromatolites and other early prokaryotes were Earth’s sole inhabitants for more than 1.5 billion years.

Question 4

What happened in the In the Proterozoic eon?

Answer 4

• Single-celled and multicellular eukaryotes such as algae (red algae and green algae) appeared.
• The Ediacaran period includes the earliest evidence of multicellular animals called the Ediacaran fauna. These animals were small
• Soft- bodied sea creatures that resemble modern sea jellies and segmented worms.

Question 5

What were the periods of the Palaeozoic era?

6 periods

Answer 5

• Cambrian period
• Ordovician period
• Silurian period
• Devonian period
• Carboniferous period
• Permian period

Question 6

What were the periods of the Mesozoic era?

3 periods

Answer 6

• Triassic period
• Jurassic period
• Cretaceous period

Question 7

What were the periods of the Cenozoic era?

3 periods

Answer 7

• Palaeogene period
• Neogene period
• Quarternary period

Question 8

Describe

Cambrian period

Answer 8

Cambrian period—a dramatic increase in the number and complexity of marine life forms, including animals with exoskeletons.

Question 9

Describe

Ordovician period

Answer 9

Ordovician period—the emergence of the first vertebrates, the jawless armoured fishes (ostracoderms).

Question 10

Describe

Silurian period

Answer 10

Silurian period—the first known air-breathing animals were arthropods: millipedes and centipedes. The earliest arachnids also appeared. Small vascular plants colonised swampy land.

Question 11

Describe

Devonian period

Answer 11

Devonian period—jawed marine fishes evolved, along with armoured placoderms. ray-finned and lobe-finned fishes and early sharks. One group of finned fishes developed sturdy fins that they were able to support their weight at the edge of the water and led to the evolution of tetrapods.

Question 12

Describe

Carboniferous period

Answer 12

Carboniferous period—evolution of reptiles from amphibian-like ancestors. Formation of forests dominated by tree forms of spore-bearing vascular plants including lycophytes and sphenophytes.

Question 13

Describe

Permian period

Answer 13

Permian period—one massive continent called Pangaea formed, reptiles diversified, and a mass extinction event occurred in which up to 90% of species became extinct

Question 14

Describe

Triassic period

Answer 14

Triassic period—reptiles were the dominant vertebrates. The archosaur reptiles, had diversified into pterosaurs, crocodiles and the earliest dinosaurs. Evidence of the earliest mammals also emerged. Plants included cycads. ferns and Gmgko-like trees.

Question 15

Describe

Jurassic period

Answer 15

Jurassic period—dinosaurs thrived on a warm, forested Earth giving rise to the first gigantic sauropod and theropod dinosaurs. Mammals had begun to diversify. The oldest bird fossils are from the Jurassic.

Question 16

Describe

Cretaceous period

Answer 16

Cretaceous period—dinosaur diversity had reached its peak, small primitive marsupials, and insectivores were abundant and widespread. Angiosperms (flowering plants) evolved.

Question 17

Describe

Palaeogene period

Answer 17

Palaeogene period—mammals evolved into many new species, giving rise to new placental and marsupial species. Birds became abundant and primates evolved.

Question 18

Describe

Neogene period

Answer 18

Neogene period—the first of the Homo species, Homo hdbilis. evolved.

Question 19

Describe

Quaternary period

Answer 19

Quaternary period—includes the Pleistocene and Holocene epochs. Climates and sea-levels fluctuated from cold, dry glacial periods and low sea-levels to warm, wetter interglacial periods and higher sea-levels. Some animal species evolved to become giants—the megafauna, which later became extinct.

Question 20

What is the process of forming impression fossils?

Answer 20

1. Death of the organism
2. Burial of the organism by sediments
3. The weight of many layers of sediments squeezing out water between the particles of sand, silt or mud
4. Soft sediments become solid rock—sandstone, siltstone. mudstone or shale (a mixture of clay and silt) as the deposit deepens, and pressure and temperature increase.

Question 21

How can fossils be dated?

3 methods

Answer 21

Relative dating

Using index Fossils

Absolute dating

Question 22

How can fossils be dated by Relative dating?

Answer 22

Relative dating is based on stratigraphy, which places the age ot a fossil according to. or relative to, the known age of layers or strata of rock above and below the layer of rock in which the fossil is found

Question 23

How can fossils be dated by Using index Fossils?

Answer 23

Sometimes the only way to age a fossil bed is by using index fossils together with stratigraphy.

Index fossils are commonly found fossils from similar sites for which an absolute age has been determined

Question 24

How can fossils be dated by Absolute dating?

Answer 24

Absolute dating can be by using radiometric methods to measure the proportions of particular naturally occurring radioactive isotopes (e.g. the ratio of carbon-14 to carbon-12).

Two other methods are:

• thermoluminescence
• electron spin resonance

Question 25

What information can be gained from fossils?

Answer 25

Besides giving information on the appearance and structure of an organism, other information such as behaviour of the organism can be gained or inferred from examining fossils.

Question 26

What are Transitional Fossils?

Answer 26

Transitional fossils are any fossilised organisms that show intermediate traits and evidence of major change, such as animals moving from aquatic to terrestrial habitats.

Question 27

Why is the fossil record not complete?

Answer 27

The fossil record is not a complete record of all past life because the chance of a fossil forming is small. Often only hard parts of organisms are preserved and only under certain environmental conditions. The fossil record is biased in favour of organisms that lived in shallow-water sediments.

Question 28

What is Biogeography?

Answer 28

Biogeography is the study of the distribution of organisms.

Question 29

How does biogeography divide the world?

Answer 29

The world is divided into a number of continental biogeographic regions and marine zones, each with a unique set of animals and plants.

Question 30

How does continental drift explain biogeography?

Answer 30

Some patterns of distribution are best explained by continental drift—the theory that continents ride on crustal plates that gradually move.

The geographic distributions and evolutionary age of organisms can be correlated with the time of separation of land masses.

Question 31

What is Structural morphology?

Answer 31

Structural morphology (also known as comparative morphology or comparative anatomy) is the study of the form and structure of organisms.

Question 32

What are Homologous features?

Answer 32

Homologous features are those that have a fundamental similarity based on common ancestry. Often these evolve different functions. Homologous features between different organisms are evidence of evolutionary descent from a common ancestor (divergent evolution).

Question 33

What are Analogous features?

Answer 33

Analogous features are those shared by different species that have the same function but have evolved separately due to similar selective pressures. Comparative anatomy can reveal that analogous features are structurally different.

Question 34

What is a vestigial structure?

Answer 34

A vestigial structure is a reduced structure with no apparent function but is evidence of evolutionary relationship.

Question 35

What is developmental biology?

Answer 35

Developmental biology is the field of biology that studies the process of growth and development of a zygote to an adult organism.

Question 36

What are embryonic comparisons?

Answer 36

Embryonic comparisons show that general features of groups of organisms appear early in development. More specialised features, which distinguish the members of a group, appear later in development.

Question 37

What is the fossil record?

Answer 37

The fossil record is the record of the occurrence and evolution of living organisms through geological time as inferred from fossils.

Question 38

What is Palaeontology?

Answer 38

Palaeontology is the study of ancient life preserved in rocks and ancient sediments. These preserved remains include evidence of the structure of living organisms and how, where and when they lived.

Question 39

What are fossils?

Answer 39

Fossils are the preserved remains, impressions or traces of organisms found in rocks, amtier (fossilised tree sap), coal deposits, ice or soil.

Question 40

What are the 4 types of fossils?

Answer 40

• Impression fossils
• Mineralised fossils
• Trace fossils (ichnofossils)
• Mummified organisms

Question 41

What are Impression fossils?

Answer 41

Impression fossils are left when the entire organism decays but the shape or impression of the external or internal surface remains.

Question 42

What are Mineralised fossils?

Answer 42

Mineralised fossils occur when minerals replace the spaces in structures of organisms such as bones, and minerals may eventually replace the entire organism leaving a replica of the original fossil.

Question 43

What are ichnofossils?

Answer 43

Trace fossils (ichnofossils) are preserved evidence of an animal’s activity or behaviour, without containing parts of the organism (e.g. footprints).

Question 44

What are Mummified organisms?

Answer 44

Mummified organisms are those that have been trapped in a substance and changed little.

Question 45

What is natural selection?

Answer 45

Natural selection is the process in which individuals that have certain inherited traits survive and reproduce at higher rates than other individuals because of those traits, and so pass on those traits.

Question 46

What is genetic drift?

Answer 46

Genetic drift occurs when a change in the genetic make-up of a population (usually small) is caused by chance rather than natural selection.

Question 47

What is allopatric speciation?

Answer 47

Allopatric speciation occurs when populations are geographically separated, leading to divergent evolution of the isolated populations and eventually new species.

Question 48

What is divergent evolution?

Answer 48

Divergent evolution is the splitting of an ancestral species (or population) into two different species (populations). The homologous features shared by the species (populations) become different over time (diverge), taking on different functions.

Question 49

What is adaptive radiation?

Answer 49

Adaptive radiation is a form of divergent evolution in which a common ancestor gives rise to a number of new species rapidly, particularly when a change in the environment opens new environmental niches.

Question 50

What is coevolution?

Answer 50

Coevolution occurs when two interacting species evolve together in a reciprocal response to selection pressures.

Question 51

What is convergent evolution?

Answer 51

Convergent evolution is the independent development of analogous features in unrelated species (or populations). The species (or populations) become alike over time (converge).

Question 52

What is background extinction?

Answer 52

Species do not last forever but become extinct over time. Background extinction is the average rate of natural loss of species. Extinction can occur as a result of changes in the physical environment or of changes in the interaction between species, such as the arrival of a new predator or competitor.

Question 53

What are mass extinctions?

Answer 53

Mass extinctions are large-scale extinctions following disruptive changes to global climates and land masses.

Question 54

How many mass extintions have been identified?

Answer 54

Five mass extinctions are evident from the fossil record, and in each more than 50% of hard-bodied marine species became extinct.

Question 55

What is the impact of a mass extinction?

Answer 55

When a mass extinction occurs, remaining species may be able to take advantage of the changed environment and available resources. Over the course of many generations, natural selection will result in populations adapting to the various new environments, and new species evolve.