BIOS 1108 Final Exam
1. 1.01 Identify and use the most recent common ancestor
(MRCA) to evaluate the relatedness of taxa: Long answer: The
MRCA is the most recent individual from which two or more taxa
have descended. Taxa with a more recent MRCA (closer to the tips
of a phylogenetic tree) are more closely related than those whose
MRCA is deeper in the tree.
In short: In order to find relatedness, you need to see which MRCA
has lived closer to present - The more recently 2 lineages diverged
from common ancestor, the more closely related they are
2. 1.01 How do you identify the MRCA on a phylogenetic
f this node
tree?: Locate the node where the branches of the taxa in heir degree of
question meet. The position o
shows how recently they shared a common ancestor and
indicates t relatedness.
3. 1.02 What are the four eons of geologic time in
chronological order?: - H.A.P.Phan
- Hadean, Archean, Proterozoic, & Phanerozoic
4. 1.02 What major biological events define each geologic
eon?: - Hadean
(4.6-4.0 billion years ago): Earth forms; no life yet
,No fossils due to extreme conditions
Violent environment: volcanic activity, meteor impacts, and intense
storms
Formation of Earth's crust begins
- Archean (4.0-2.5 billion years ago):
Earth's crust stabilizes; oceans begin to form
Atmosphere mostly carbon dioxide with little to no oxygen
First life appears: unicellular prokaryotes, including cyanobacteria
Evolution of oxygenic photosynthesis in cyanobacteria, releasing
oxygen into oceans
- Proterozoic (2.5 billion-541 million years ago):
Oxygen levels rise significantly (Great Oxygenation Event)
Early life flourishes: appearance of unicellular eukaryotes and
simple multicellular organisms
Photosynthetic bacteria continue altering the atmosphere
First known multicellular algae and animals (e.g., soft-bodied
organisms like sponges)
- Phanerozoic (541 million years ago-present):
Explosion of visible life (fossil record expands dramatically) Major
diversification of animals and plants
Life colonizes land; appearance of insects, vertebrates, flowering
plants, and mam- mals
,Includes all major extinction and radiation events (e.g., Cambrian
Explosion, age of dinosaurs, rise of humans)
5. 1.02 Why are prokaryotes (Bacteria and Archaea) important
for human health and the environment?: - Human Health:
Support digestion and nutrient absorption (gut microbiome).
Synthesize essential vitamins (e.g., B12, K).
Compete with and suppress harmful pathogens.
Used in medicine and biotechnology: antibiotics, vaccines,
CRISPR gene editing. Some are pathogens causing diseases
(e.g., tuberculosis, strep throat).
- Environmental Roles:
Nutrient cycling: Fix nitrogen (e.g., Rhizobium), decompose
organic material, and recycle carbon, sulfur, and phosphorus.
Oxygenation: Cyanobacteria evolved oxygenic photosynthesis,
leading to the Great
Oxygenation Event.
Bioremediation: Break down pollutants like oil and heavy metals.
Extremophiles (mostly Archaea) survive in extreme environments,
expanding our understanding of life.
Capable of multiple metabolic pathways: photoautotrophs,
chemoautotrophs, het- erotrophs, etc.
6. 1.03 Explain the endosymbiotic theory for the origin of
eukaryotes: Eukary- otes arose during Proterozoic eon as a
, result of the fusion of Archean cells with bacteria; ancient archean
engulfed ancient aerobic bacteria forming mutualistic relationship
where engulfed bacterium allowed host archaean cell to use O2
to release stored energy as host cell protected bacterial cell from
predators
- Infoldings in plasma membrane of ancestral prokaryote gave rise
to nucleus + ER
- Loss of cell wall
- In a first endosymbiotic event, the ancestral eukaryote consumed
aerobic bacteria that evolved into mitochondria
- In a second endosymbiotic event, early eukaryote consumed
photosynthetic bac- teria (cyanobacteria) that evolves into
chloroplasts
7. 1.03 What evidence supports the origin of eukaryotes
through the endosym- biotic theory?: - Evidence for
endosymbiotic theory
- Size: mitochondria and chloroplasts are approx same size as
prokaryotic cells
- Genome: mitochondria and chloroplasts have own DNA
organized in circular chromosome (genetic sequences similar to
specific bacteria)
- Reproduction: mitochondria and chloroplasts reproduce by
binary fission - Cell membrane: mitochondrial membrane contains
1. 1.01 Identify and use the most recent common ancestor
(MRCA) to evaluate the relatedness of taxa: Long answer: The
MRCA is the most recent individual from which two or more taxa
have descended. Taxa with a more recent MRCA (closer to the tips
of a phylogenetic tree) are more closely related than those whose
MRCA is deeper in the tree.
In short: In order to find relatedness, you need to see which MRCA
has lived closer to present - The more recently 2 lineages diverged
from common ancestor, the more closely related they are
2. 1.01 How do you identify the MRCA on a phylogenetic
f this node
tree?: Locate the node where the branches of the taxa in heir degree of
question meet. The position o
shows how recently they shared a common ancestor and
indicates t relatedness.
3. 1.02 What are the four eons of geologic time in
chronological order?: - H.A.P.Phan
- Hadean, Archean, Proterozoic, & Phanerozoic
4. 1.02 What major biological events define each geologic
eon?: - Hadean
(4.6-4.0 billion years ago): Earth forms; no life yet
,No fossils due to extreme conditions
Violent environment: volcanic activity, meteor impacts, and intense
storms
Formation of Earth's crust begins
- Archean (4.0-2.5 billion years ago):
Earth's crust stabilizes; oceans begin to form
Atmosphere mostly carbon dioxide with little to no oxygen
First life appears: unicellular prokaryotes, including cyanobacteria
Evolution of oxygenic photosynthesis in cyanobacteria, releasing
oxygen into oceans
- Proterozoic (2.5 billion-541 million years ago):
Oxygen levels rise significantly (Great Oxygenation Event)
Early life flourishes: appearance of unicellular eukaryotes and
simple multicellular organisms
Photosynthetic bacteria continue altering the atmosphere
First known multicellular algae and animals (e.g., soft-bodied
organisms like sponges)
- Phanerozoic (541 million years ago-present):
Explosion of visible life (fossil record expands dramatically) Major
diversification of animals and plants
Life colonizes land; appearance of insects, vertebrates, flowering
plants, and mam- mals
,Includes all major extinction and radiation events (e.g., Cambrian
Explosion, age of dinosaurs, rise of humans)
5. 1.02 Why are prokaryotes (Bacteria and Archaea) important
for human health and the environment?: - Human Health:
Support digestion and nutrient absorption (gut microbiome).
Synthesize essential vitamins (e.g., B12, K).
Compete with and suppress harmful pathogens.
Used in medicine and biotechnology: antibiotics, vaccines,
CRISPR gene editing. Some are pathogens causing diseases
(e.g., tuberculosis, strep throat).
- Environmental Roles:
Nutrient cycling: Fix nitrogen (e.g., Rhizobium), decompose
organic material, and recycle carbon, sulfur, and phosphorus.
Oxygenation: Cyanobacteria evolved oxygenic photosynthesis,
leading to the Great
Oxygenation Event.
Bioremediation: Break down pollutants like oil and heavy metals.
Extremophiles (mostly Archaea) survive in extreme environments,
expanding our understanding of life.
Capable of multiple metabolic pathways: photoautotrophs,
chemoautotrophs, het- erotrophs, etc.
6. 1.03 Explain the endosymbiotic theory for the origin of
eukaryotes: Eukary- otes arose during Proterozoic eon as a
, result of the fusion of Archean cells with bacteria; ancient archean
engulfed ancient aerobic bacteria forming mutualistic relationship
where engulfed bacterium allowed host archaean cell to use O2
to release stored energy as host cell protected bacterial cell from
predators
- Infoldings in plasma membrane of ancestral prokaryote gave rise
to nucleus + ER
- Loss of cell wall
- In a first endosymbiotic event, the ancestral eukaryote consumed
aerobic bacteria that evolved into mitochondria
- In a second endosymbiotic event, early eukaryote consumed
photosynthetic bac- teria (cyanobacteria) that evolves into
chloroplasts
7. 1.03 What evidence supports the origin of eukaryotes
through the endosym- biotic theory?: - Evidence for
endosymbiotic theory
- Size: mitochondria and chloroplasts are approx same size as
prokaryotic cells
- Genome: mitochondria and chloroplasts have own DNA
organized in circular chromosome (genetic sequences similar to
specific bacteria)
- Reproduction: mitochondria and chloroplasts reproduce by
binary fission - Cell membrane: mitochondrial membrane contains
