Tracing evolutionary history (1)

Question 1

First life may have evolved through four stages, What are they?

Answer 1

1. The abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nitrogenous bases.
2. The joining of these small molecules into polymers, such as proteins and nucleic acids
3. The packaging of these molecules into “protocells”.
4. The origin of self-replicating molecules that eventually made inheritance possible.

Question 2

Polymers always need enzymes to polymerize. True or false?

Answer 2

False.

While polymers typically need enzymes to polymerize, some monomers can spontaneously form when monomers on concentrated together (especially in the presence of heat

Question 3

What are protocells and how do they grow and divide?

Answer 3

Protocells were a vital step towards life, in which organic polymers started being collected within a lipid membrane-enclosed compartment (vesicles)

These protocells can grow larger and divide, and can do so at a much higher rate in the presence of clay

Question 4

How did protocells divide in the presence of clay in early Earth?

Answer 4

On early Earth, the vesicles may have absorbed clay particles to which RNA and other molecules were attached

Question 5

How did protocells develop self-replicating RNA?

Answer 5

1. RNA monomers stick to clay particles and become concentrated and some spontaneously join, forming the first small “genes”
2. An RNA chain complementary to one of these genes assembles, serving as a template for another round of RNA
3. Natural selection could have acted on protocells that contained self-replicating molecules.

Question 6

What are ribozymes?

Answer 6

Ribozymes: RNA with catalyzing properties may have existed in early Earth!

Question 7

What is macroevolution and what does it encompass?

Answer 7

Macroevolution is evolutionary change above the species level and encompasses:

-the origin of a new group of organisms through a series of speciation events

-the impact of mass extinctions on the diversity of life and its subsequent recovery.

Question 8

Explain the organisms in the Archaean eon.

Answer 8

Prokaryotes were able to photosynthesize, which saturated the oceans with oxygen and increased atmospheric O2 rapidly.

Prokaryotes who couldn’t live in aerobic environments became extinct, with only a few remaining in anaerobic habitats

Question 9

Explain the organisms in the Proterozoic eon.

Answer 9

The first unicellular eukaryotes were prokaryotes capable of using O2 to harvest energy (cellular respiration) that took up life inside larger cells (that’s why prokaryotes have no nucleus!)

As diversification continues, multicellular eukaryotes emerged

Question 10

Explain life in the Phanerozoic eon.

Answer 10

Larger and more diverse multicellular organisms didn’t emerge in the fossil record until ~600 million years ago

Cambrian explosion: a great increase in animal forms 535-525 million years ago

Question 11

What were the larger forms of life that colonized land?

Answer 11

Started with plants and fungi.

Plants today still associate with fungi which help them absorb water and minerals, providing fungi with nutrients in return

Question 12

What are the most widespread and diverse land animals?

Answer 12

The most widespread and diverse land animals are arthropods (particularly insects and spiders), and tetrapods (vertebrates with four appendages.

Question 13

What were the events in the Hadean eon?

Answer 13

1. Origin of Earth.
2. Oldest known rocks on the surface of the earth.

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Question 14

What are the important events of the Archaean eon?

Answer 14

1. Oldest fossils of prokaryotes appear
2. Concentration of atmospheric oxygen appears to increase

Question 15

What was the first important event in the Proterozoic eon?

Answer 15

The oldest fossils of eukaryotes appear.

Question 16

What were the first two important events in the Paleozoic era?

Answer 16

1. Cambrian explosion: sudden increase of animal phyla.
2. Colonization of land by fungi, plants and animals.

Question 17

What were the last 3 important events in the Paleozoic era and the Proterozoic eon?

Answer 17

1. Diversification of bony fish, first tetrapods and insects appear.
2. Extensive forests form, first seed plants, and amphibians become dominant species.
3. Origin of present-day insects.

Question 18

What were the two important events in the Mesozoic era?

Answer 18

1. Dinosaurs evolve, Origin of mammals
2. Flowering plants appear

Question 19

What were the important events in the Cenozoic era?

Answer 19

1. Earlist direct human ancestors.
2. Origins of bipedal human ancestors
3. Ice age, origin of Genus Homo

Question 20

The history of life on Earth has been shaped by __________

Answer 20

Tectonic plates

Question 21

What is the name of the supercontinent ?

Answer 21

Pangea.

Question 22

What can the movement of tectonic plates cause?

Answer 22

1. Continents to collide, pile up, and build mountain ranges
2. Produce volcanoes and earthquakes that often occur at the boundaries of Earth’s plates.

Question 23

There are 5 mass extinctions have altered the course of evolution, name 2?

Answer 23

Cretaceous and Permian extinction.

Question 24

Explain the events of the Permian extinction.

Answer 24

The Permian extinction is linked to the effects of extreme volcanic activity.

1. The eruptions raised global temperatures by 6°C, which slowed ocean water mixing and therefore caused a drop in oxygen concentration in water
2. O2 deficit led to the death of many marine organisms and promoted the growth of anaerobic bacteria
3. Gases produced by these bacteria would spill onto land, killing land plants and animals as well

Question 25

Explain the events of the Cretaceous extinction.

Answer 25

The Cretaceous extinction, which included most dinosaurs, may have been caused by the impact of an asteroid.

-Birds were the only remaining descendants of dinosaurs that remained

-An asteroid fell near the Yucatán peninsula, with the impact causing a large cloud that blocked light and severely disturbed global climate for months

Question 26

How do new forms evolve?

Answer 26

-Changes in rate and timing
-Spatial pattern
-New genes or changes in genes
-Changes in gene regulation

CeCeis SiNgle) Acronym

Question 27

What is Paedomorphosis?

Answer 27

Many evolutionary transformations can come as a result of a change in the rate or timing of developmental events.

Paedomorphosis: retention in the adult body of structures that were juvenile features in an ancestral species

Question 28

How does spatial pattern result in the evolution of new forms?

Answer 28

Homeotic genes (master control genes) determine basic features, such as where pairs of wings or legs develop on a fruit fly.

Profound impact on body form can result from changes in homeotic genes or how or where homeotic genes are expressed.

Question 29

How do new genes result in new body forms?

Answer 29

New genes or changes in genes

New developmental genes that arose as a result of gene duplications may have facilitated the origin of new body forms

Question 30

How can changes in gene regulation cause new forms?

Answer 30

Changes in gene regulation

Mutations that affect the regulation of developmental genes can lead to significant changes in form, such as the lack of forelimbs in snakes.

Question 31

What are exaptations?

Answer 31

Exaptations are structures that evolve in one context but become co-opted for another function.

(ex: dinosaurs had feathers , not to fly but for insulation)

Question 32

Species are named with the first part being the genus they belong to, followed by the species name.

Each level is called a ________

Answer 32

Taxon

Question 33

What is a clade?

Answer 33

A clade consists of an ancestral species and all its evolutionary descendants (can be on any taxonomic level

Question 34

Differentiate between a shared ancestral trait and a shared dervied trait.

Answer 34

A shared ancestral character is common to members of a particular clade but originated in an ancestor that is not a member of the clade.

A shared derived character is common to members of a particular clade and is not found in its ancestors. (these distinguish clades)

Question 35

What is parismony?

Answer 35

Parsimony is the adoption of the simplest explanation for observed phenomena

Question 36

What is molecular systematics?

Answer 36

Molecular systematics uses molecular comparisons to build phylogenetic trees

Question 37

What is a molecular clock?

Answer 37

Molecular clock, a method that estimates the time required for a given amount of evolutionary change.

Question 38

What is the sequence of eons and eras?

Answer 38

1. Hadean
2. Archaean
3. Proterozoic (Palezoic era)
4. Phanerozoic ( Mesozoic and cenozoic)