BIOL351 | BIOL351MODULE 1| EXAM
QUESTIONS AND ANSWERS | VERIFIED |
LATEST UPDATE 2026
When did the Earth form?
~4.6 billion years ago
When did life arise?
~3.6 billion years ago
Hadean Eon (4.6-3.8 bya)
Formation of Earth
Formation of the crust and oceans
Origins of cellular life
Archaean Eon (3.8-2.5 bya)
Divergence of Bacteria and Archaea
Origins of anoxygenic photosynthesis
Origins of cyanobacteria and oxygenic photosynthesis
Proterozoic Eon (2.5 BYA- 542 MYA)
Start of the Great Oxidation Event
Ozone Shield forming
Evidence for multicellular eukaryotes
Start of Cambrian explosion
Phanerozoic Eon
,Origins of first animals
Extinction of dinosaurs
What kind of metabolism used by some archaea may be remnant of early form of
chemiosmosis?
FeS-based
Fossil evidence places evolution of cyanobacteria and oxygenic photosynthesis
to how long ago?
~3 billion years ago
Fossilized remains are found in
stromatolites and sedimentary rocks
What are stromatolites?
layered rocks formed by incorporation of mineral sediments into microbial mat
What is a likely site for the origin of life on Earth?
Deep-sea hydrothermal vents
RNA can perform diverse functions including
backbone of essential molecules (e.g. ATP, NADH, coenzyme A)
bind small molecules (e.g. nucleotides, amino acids)
catalyze some biochemical reactions
template for own synthesis
catalyze protein synthesis
Events Hypothesized to Precede the Origin of Cellular Life
A Possible Energy-Conserving Scheme for Primitive Cells
LUCA
,last universal common ancestor
What is the difference between a prokaryotic and eukaryotic cell?
Prokaryotic cells lack a true membrane-delimited nucleus.
Eukaryotic cells have a membrane-enclosed nucleus, are more complex
morphologically and are usually larger than prokaryotic cells.
Describe the following shapes:
Spirillum
Spirochete
Anabaena (a cyanobacterium)
large Bacillus
Escherichia coli
Staphylococcus
Rickettsia
Prokaryotes
Bacteria and Archaea
no organelles (membrane-enclosed structures), no nucleus
Eukaryotes
plants, animals, algae, protozoa, fungi
contain organelles
DNA enclosed in a membrane-bound nucleus
mitochondria and chloroplasts
The simplest and smallest "organisms" are the
, mycoplasmas
Mycoplasma gentialium
a Gram-positive bacterium with a 580 kbp genome with 470 defined coding regions
Some microbes are not unicellular. Provide a few examples.
Nostoc: a photosynthetic bacterium that forms filaments
Neurospora crassa: a filamentous fungus that forms hyphae
Not all microbes are small. Provide a few examples.
armillaria ostoyae
bridgeoporus nobilissimus
Natural classification
Arranges organisms into groups whose members share many characteristics
- based on anatomical characteristics
What does the natural classification fail to provide?
information of evolutionary relatedness
Taxonomy
Identify and name different organisms
Define groups based on relatedness among the different organisms (morphological and
molecular relatedness)
binomial system of nomenclature
two names:
genus name: italicized and capitalized (e.g. Escherichia)
species epithet: italicized but not capitalized (e.g. coli)
QUESTIONS AND ANSWERS | VERIFIED |
LATEST UPDATE 2026
When did the Earth form?
~4.6 billion years ago
When did life arise?
~3.6 billion years ago
Hadean Eon (4.6-3.8 bya)
Formation of Earth
Formation of the crust and oceans
Origins of cellular life
Archaean Eon (3.8-2.5 bya)
Divergence of Bacteria and Archaea
Origins of anoxygenic photosynthesis
Origins of cyanobacteria and oxygenic photosynthesis
Proterozoic Eon (2.5 BYA- 542 MYA)
Start of the Great Oxidation Event
Ozone Shield forming
Evidence for multicellular eukaryotes
Start of Cambrian explosion
Phanerozoic Eon
,Origins of first animals
Extinction of dinosaurs
What kind of metabolism used by some archaea may be remnant of early form of
chemiosmosis?
FeS-based
Fossil evidence places evolution of cyanobacteria and oxygenic photosynthesis
to how long ago?
~3 billion years ago
Fossilized remains are found in
stromatolites and sedimentary rocks
What are stromatolites?
layered rocks formed by incorporation of mineral sediments into microbial mat
What is a likely site for the origin of life on Earth?
Deep-sea hydrothermal vents
RNA can perform diverse functions including
backbone of essential molecules (e.g. ATP, NADH, coenzyme A)
bind small molecules (e.g. nucleotides, amino acids)
catalyze some biochemical reactions
template for own synthesis
catalyze protein synthesis
Events Hypothesized to Precede the Origin of Cellular Life
A Possible Energy-Conserving Scheme for Primitive Cells
LUCA
,last universal common ancestor
What is the difference between a prokaryotic and eukaryotic cell?
Prokaryotic cells lack a true membrane-delimited nucleus.
Eukaryotic cells have a membrane-enclosed nucleus, are more complex
morphologically and are usually larger than prokaryotic cells.
Describe the following shapes:
Spirillum
Spirochete
Anabaena (a cyanobacterium)
large Bacillus
Escherichia coli
Staphylococcus
Rickettsia
Prokaryotes
Bacteria and Archaea
no organelles (membrane-enclosed structures), no nucleus
Eukaryotes
plants, animals, algae, protozoa, fungi
contain organelles
DNA enclosed in a membrane-bound nucleus
mitochondria and chloroplasts
The simplest and smallest "organisms" are the
, mycoplasmas
Mycoplasma gentialium
a Gram-positive bacterium with a 580 kbp genome with 470 defined coding regions
Some microbes are not unicellular. Provide a few examples.
Nostoc: a photosynthetic bacterium that forms filaments
Neurospora crassa: a filamentous fungus that forms hyphae
Not all microbes are small. Provide a few examples.
armillaria ostoyae
bridgeoporus nobilissimus
Natural classification
Arranges organisms into groups whose members share many characteristics
- based on anatomical characteristics
What does the natural classification fail to provide?
information of evolutionary relatedness
Taxonomy
Identify and name different organisms
Define groups based on relatedness among the different organisms (morphological and
molecular relatedness)
binomial system of nomenclature
two names:
genus name: italicized and capitalized (e.g. Escherichia)
species epithet: italicized but not capitalized (e.g. coli)
