Biology 2 Chapter 25

Front 1

What are the four main stages that led to the formation of living cells?

Back 1

1. The abiotic synthesis of small organic molecules, such as amino acids and nucleotides.
2. The joining of these small molecules into macromolecules, including proteins and nucleic acids.
3. The packaging of these molecules into "probionts" droplets with membranes that maintained an internal chemistry different from that of their surroundings.
4. Origin of self-replicating molecules that eventually made inheritance possible.

Front 2

Hypothesized that Earth's early atmosphere was a reducing (electron adding) environment, which which organic compounds could have formed from simple molecules

Back 2

Chemist--Oparin and sciencist Haldane, 1920

Front 3

Confirmed Oparin-Haldane hypothesis through experimentation

Back 3

Miller and Urey (1953).

Front 4

Earth was truly reducing, T or F?

Back 4

False. New studies show that there were likely pockets around submerged volcanoes and deep-sea vents. There was probably not enough methane and ammonia to be reduced in rest of areas.

Front 5

Two key properties of life

Back 5

1. Accurate replication
2. Metabolism

* Neither can exist without the other.

Front 6

Example of protobiont

Back 6

Liposomes, lipids or other organic molecules added to water.

Front 7

First genetic material was likely RNA, T or F?

Back 7

True

Front 8

Original RNA catalysts

Back 8

Ribosomes- Can make complementary copies of short pieces of RNA.

Front 9

Half-life

Back 9

The time it takes for 50% of the parent isotope to decay.

Front 10

How far back does radiometric dating work for carbon based organisms?

Back 10

75,000 years

Front 11

What are the three eons of Earth's history and their corresponding years, along with unique features?

Back 11

1. Archaean 4.6 billion to 2.5 billion. prokaryotes, oxygen increases in 2,700 billion
2. Proterozoic- 2.5 to around 550 million, eukaryotic cells appear, diverse algae and invertebrae are formed.

(Archaean and proterozoic represent first 4 billion years).

3. Phanerozoic- 550 million to present. Formation of plants, reptiles, mammals, birds, humans, primate groups

Front 12

What are the three eras of the Phanerozoic eons and characteristics of each era?

Back 12

1. Paleozoic- Vascular plants appear, marine algea, repitile, bony fishes
2. Mesozoic- Age of reptiles, dinosaures, flowering plants, cone bearing plants, gymnospears
3. Cenozoic- mammals, birds, pollinating insects, angiosperm, primates, humans, ice ages

Front 13

When and what was the first sign of life?

Back 13

3.5 billion years ago- Stromatolites- layered rocks that form when certain prokaryotes bind thin films of sediment together. Early prokaryotes lasted from 3.5 billion to 2.1 billion.

Front 14

Most atmospheric oxygen is biological in origin, T or F?

Back 14

T. First oxygen would have precipitated to iron oxide.

Front 15

What brought about rise of O2 levels around 2.7 billion years ago?

Back 15

Ancient cyanobacteria.

Front 16

What is endosymbiosis?

Back 16

Hypothesis that mitochondria and plastids (chlroplasts and related organels) were formerly small prokaryotes that began living within larger cells.

Front 17

Serial endosymbiosis

Back 17

Mitochondria evolved before plastids (All Eu. cells have mitochondria but not all plastics.

Front 18

What is the evidence for endosymbiosis?

Back 18

1. homologous membranes to plasma membranes
2. Replicate similar to that of some prokaryotes.
3. Single, circular DNA like chromosomes of bacteria.
4. Size, nucleotide sequence, and sensitivity to certain antibiotics, more like prokaryotic ribosomes.

Front 19

Oldest known fossils of multicellular eukaryotes is?

Back 19

Small algae that lived about 1.2 billion years ago. Larger ones did not appear until around 565 million years ago.

Front 20

What caused growth of multicellular eukaryotes?

Back 20

Thawing from ice-age.

Front 21

What was the Cambrian explosion?

Back 21

Many phyla of living animals appear suddenly in fossibls formed early in the Cambrian period (535-525).

Front 22

What three living animal phyla appeared?

Back 22

1. Cnidaria (sea anenomes)
2. Porifera (sponge)
3. Mollusca (molluscs)

Prior to this all large animals were soft-bodied.

Front 23

Many animal phyla originated before Cambrian explosion, T or F?

Back 23

T, DNA suggests this hypothesis.

Front 24

When did colonization of land occur by larger forms of life (fungi, plants, animals)

Back 24

500 million years ago. Before this photosynthetic prokaryotes coated damp terrestrial surfaces over 1 billion years ago.

Front 25

Human lineage diverged when and our species originated when?

Back 25

6-7 million years ago. Species arose 195,000 years ago.

Front 26

Evolution is not goal oriented, T or F?

Back 26

T. Example of eyes. Complex eyes have evolved independently from suc basic structures many times.

Front 27

How did the evolution of the complex eye take place?

Back 27

Through a series of incremental modifications that benefited the eyes' owners at every stage.

Front 28

Exaptations-Structures that evolve in one context become co-opted for another function.

Back 28

Exaptations.

Front 29

Species selection

Back 29

Steven Stanley suggests that just as individual organisms undergo natural selection, species undergo species selection.