Page | 1
PSYC 388 Midterm Questions with
Detailed Verified Answers
Question:Proximate causality
Ans: - the 'how' questions
- biological mechanism
Ex: how do biological clocks work at the biological level
* most of the course
Question: Ultimate causailty
Ans: the 'why' question
Ex: why do we have clocks, what 'caused' them to evolve and why have they
been conserved across phylogeny
- questions of function (what is the function or purpose of the circadian clock?)
* lecture 2 topic
Question: Natural selection
Ans: differential reproductive fitness that results from differential adaptation
to features of the environment
Question: Local features
, Page | 2
Ans: more or less unique to that place
- temperature
- precipitation
- topography
drive speciation by favoring animals that have adaptations to these specific
features
Question: Global features
Ans: shared with other places; they are
- enduring
- stable
- nontrivial
- obvious: features associated with daily cycles of light (solar day)
Question: When did circadian clocks evolve?
Ans: approximately 3.5 billion years ago
Question: Multicellular organisms that exhibit circadian rhythms
Ans: - fungi: Neurospora
- plants: Arabidopsis
- animals: nematodes, fruit flies, zebrafish, reptiles, birds, mice, humans
Question: Unicellular eukaryotic oranisms (protisa) that exhibit circadian
rhythms
, Page | 3
Ans: - green algae (chlamydomonas, acetabularia)
- gonyaulax, paramecium, euglena
- have true (bona fide) circadian rhythms
Question: Prokaryotic organisms: How old are they and what are some
characteristics about them?
Ans: - about 3.5 billion years old
- no cell nuclei
- no membrane-bound organelles
Question: What prokaryotic organisms have circadian rhythms? (3)
Ans: - cyanobacteria (blue-green algae)
- human gut bacteria
- some extremophile archaea (grow in high salinity or temp)
Question: Prokaryotic organisms = the most ancient life forms on earth
(evolved ~3.5 billion years ago) and have biorhythms = what can we conclude
about circadian rhythms based on this? (4)
Ans: - they are ancient and widely conserved
- they likely appeared early in evolution
- likely evolved several times (bacteria, plants, and animals don't have the
same clock genes, which is expected if they evolved from the same organism)
- must continue to make important contributions towards survival and
reproductive fitness
Question: What is hypothesis 1A: escape from light?
, Page | 4
Ans: - ionizing radiation (high energy ultraviolet light can damage molecules
and disrupt biochemical processes such as DNA repication and gene
transcription
- earliest self-replicating organisms did not have barriers to block UV light
Question: What was the solution to not having protection against UV light?
(2)
Ans: - restrict replication/transcription to the night
- mobilize light-avoidance behaviour in *anticipation* of sunrise
Question: What is the evidence for "escape from light"?
Ans: - many genes exhibit a circadian rhythm of transcription
- most clock-controlled genes are transcribed only at night (Ex: drosophila)
- cells are more easily damaged by UV light in the early night, when cell
division and gene transcription occur (Ex: in chlamydamonas)
Question: External coordination
Ans: - 1 biological challenge faced by early life that led to evolution of
circadian clocks
- challenge of coordinating biochemistry with daily cycles of solar radiation
and temperature (external)
Question: Internal coordination
Ans: - 1 biological challenge faced by early life that led to evolution of
circadian clocks
- challenge of coordinating biochemical processes with each other so that they
occur in the the correct sequence and so that incompatible processes would
occur at different times of day
Question: Hypothesis 1b: escape from oxygen (radicals) (5)
PSYC 388 Midterm Questions with
Detailed Verified Answers
Question:Proximate causality
Ans: - the 'how' questions
- biological mechanism
Ex: how do biological clocks work at the biological level
* most of the course
Question: Ultimate causailty
Ans: the 'why' question
Ex: why do we have clocks, what 'caused' them to evolve and why have they
been conserved across phylogeny
- questions of function (what is the function or purpose of the circadian clock?)
* lecture 2 topic
Question: Natural selection
Ans: differential reproductive fitness that results from differential adaptation
to features of the environment
Question: Local features
, Page | 2
Ans: more or less unique to that place
- temperature
- precipitation
- topography
drive speciation by favoring animals that have adaptations to these specific
features
Question: Global features
Ans: shared with other places; they are
- enduring
- stable
- nontrivial
- obvious: features associated with daily cycles of light (solar day)
Question: When did circadian clocks evolve?
Ans: approximately 3.5 billion years ago
Question: Multicellular organisms that exhibit circadian rhythms
Ans: - fungi: Neurospora
- plants: Arabidopsis
- animals: nematodes, fruit flies, zebrafish, reptiles, birds, mice, humans
Question: Unicellular eukaryotic oranisms (protisa) that exhibit circadian
rhythms
, Page | 3
Ans: - green algae (chlamydomonas, acetabularia)
- gonyaulax, paramecium, euglena
- have true (bona fide) circadian rhythms
Question: Prokaryotic organisms: How old are they and what are some
characteristics about them?
Ans: - about 3.5 billion years old
- no cell nuclei
- no membrane-bound organelles
Question: What prokaryotic organisms have circadian rhythms? (3)
Ans: - cyanobacteria (blue-green algae)
- human gut bacteria
- some extremophile archaea (grow in high salinity or temp)
Question: Prokaryotic organisms = the most ancient life forms on earth
(evolved ~3.5 billion years ago) and have biorhythms = what can we conclude
about circadian rhythms based on this? (4)
Ans: - they are ancient and widely conserved
- they likely appeared early in evolution
- likely evolved several times (bacteria, plants, and animals don't have the
same clock genes, which is expected if they evolved from the same organism)
- must continue to make important contributions towards survival and
reproductive fitness
Question: What is hypothesis 1A: escape from light?
, Page | 4
Ans: - ionizing radiation (high energy ultraviolet light can damage molecules
and disrupt biochemical processes such as DNA repication and gene
transcription
- earliest self-replicating organisms did not have barriers to block UV light
Question: What was the solution to not having protection against UV light?
(2)
Ans: - restrict replication/transcription to the night
- mobilize light-avoidance behaviour in *anticipation* of sunrise
Question: What is the evidence for "escape from light"?
Ans: - many genes exhibit a circadian rhythm of transcription
- most clock-controlled genes are transcribed only at night (Ex: drosophila)
- cells are more easily damaged by UV light in the early night, when cell
division and gene transcription occur (Ex: in chlamydamonas)
Question: External coordination
Ans: - 1 biological challenge faced by early life that led to evolution of
circadian clocks
- challenge of coordinating biochemistry with daily cycles of solar radiation
and temperature (external)
Question: Internal coordination
Ans: - 1 biological challenge faced by early life that led to evolution of
circadian clocks
- challenge of coordinating biochemical processes with each other so that they
occur in the the correct sequence and so that incompatible processes would
occur at different times of day
Question: Hypothesis 1b: escape from oxygen (radicals) (5)
