4/9/25, 7:38 PSYC 388 Midterm |
AM
PSYC 388 MIDTERM EXAM QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS VERIFIED
Terms in this set (202)
- the 'how' questions
- biological mechanism
Proximate causality
Ex: how do biological clocks work at the biological level
* most of the course
the 'why' question
Ex: why do we have clocks, what 'caused' them to evolve and why
Ultimate causailty have they been conserved across phylogeny
- questions of function (what is the function or purpose of the circadian clock?)
* lecture 2 topic
differential reproductive fitness that results from differential adaptation
Natural selection
to features of the environment
more or less unique to that place
- temperature
- precipitation
Local features
- topography
drive speciation by favoring animals that have adaptations to these
specific features
shared with other places; they are
- enduring
Global features - stable
- nontrivial
- obvious: features associated with daily cycles of light (solar day)
When did circadian clocks evolve? approximately 3.5 billion years ago
- fungi: Neurospora
Multicellular organisms that exhibit
- plants: Arabidopsis
circadian rhythms
- animals: nematodes, fruit flies, zebrafish, reptiles, birds, mice, humans
- green algae (chlamydomonas, acetabularia)
Unicellular eukaryotic oranisms
- gonyaulax, paramecium, euglena
(protisa) that exhibit circadian
- have true (bona fide) circadian rhythms
rhythms
1/12
, 4/9/25, 7:38 PSYC 388 Midterm |
AM
Prokaryotic organisms: How old - about 3.5 billion years old
are they and what are some - no cell nuclei
characteristics about them? - no membrane-bound organelles
- cyanobacteria (blue-green algae)
What prokaryotic organisms have
- human gut bacteria
circadian rhythms? (3)
- some extremophile archaea (grow in high salinity or temp)
- they are ancient and widely conserved
Prokaryotic organisms = the most
- they likely appeared early in evolution
ancient life forms on earth (evolved
- likely evolved several times (bacteria, plants, and animals don't have
~3.5 billion years ago) and have
the same clock genes, which is expected if they evolved from the
biorhythms = what can we conclude
same organism)
about circadian rhythms based on
- must continue to make important contributions towards
this? (4)
survival and reproductive fitness
- ionizing radiation (high energy ultraviolet light can damage
What is hypothesis 1A: escape from molecules and disrupt biochemical processes such as DNA
light? repication and gene transcription
- earliest self-replicating organisms did not have barriers to block UV light
What was the solution to not having - restrict replication/transcription to the night
protection against UV light? (2) - mobilize light-avoidance behaviour in anticipation of sunrise
- many genes exhibit a circadian rhythm of transcription
What is the evidence for "escape - most clock-controlled genes are transcribed only at night (Ex: drosophila)
from light"? - cells are more easily damaged by UV light in the early night, when
cell division and gene transcription occur (Ex: in chlamydamonas)
- 1 biological challenge faced by early life that led to evolution of circadian clocks
External coordination - challenge of coordinating biochemistry with daily cycles of solar
radiation and temperature (external)
- 1 biological challenge faced by early life that led to evolution of circadian clocks
- challenge of coordinating biochemical processes with each other
Internal coordination
so that they occur in the the correct sequence and so that
incompatible processes would occur at different times of day
- earliest circadian clocks appear back when atmospheric oxygen
increased rapidly, killing of other anaerobic forms
- bacteria would synthesize antioxidants prior to sunrise to
remove toxic metabolites (reactive O2 mlcs, H2O2 and free
Hypothesis 1b: escape from oxygen radicals) that are created as byproducts of daytime
(radicals) (5) photosynthesis and damage cells
- these metabolites must be removed for effective aerobic metabolism
- photosynthesis is dependent on light and restricted to the day, so
clocks may have been used to control production of antioxidants so
organisms could use O2 processes
- may have been designed to 'escape from oxygen' (radicals)
- separation of incompatible processes
- Ex: nitrogen fixation: inhibited by O2 and incompatible with
photosynthesis (produces O2)
- separated spatially (different cell compartments) or temporally
Examples of hypothesis 2: Internal
(different times of day)
coordination of biochemical
processes
- Ex: enzymes for storing and releasing glucose in the liver
(glycogen synthase and glycogen phosphorylase) must be produced
at opposite times of day so as not to conflict
- a core function of circadian clocks in all 'circadian' species
is to enable anticipation of predictable daily changes in the
Why are circadian clocks still present
environment
in virtually all life forms? (3)
- Core principle: preparing in advance of daily environmental changes
is superior to reacting in response to daily changes
- environmental changes include geophysical and biological stimuli
2/12
AM
PSYC 388 MIDTERM EXAM QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS VERIFIED
Terms in this set (202)
- the 'how' questions
- biological mechanism
Proximate causality
Ex: how do biological clocks work at the biological level
* most of the course
the 'why' question
Ex: why do we have clocks, what 'caused' them to evolve and why
Ultimate causailty have they been conserved across phylogeny
- questions of function (what is the function or purpose of the circadian clock?)
* lecture 2 topic
differential reproductive fitness that results from differential adaptation
Natural selection
to features of the environment
more or less unique to that place
- temperature
- precipitation
Local features
- topography
drive speciation by favoring animals that have adaptations to these
specific features
shared with other places; they are
- enduring
Global features - stable
- nontrivial
- obvious: features associated with daily cycles of light (solar day)
When did circadian clocks evolve? approximately 3.5 billion years ago
- fungi: Neurospora
Multicellular organisms that exhibit
- plants: Arabidopsis
circadian rhythms
- animals: nematodes, fruit flies, zebrafish, reptiles, birds, mice, humans
- green algae (chlamydomonas, acetabularia)
Unicellular eukaryotic oranisms
- gonyaulax, paramecium, euglena
(protisa) that exhibit circadian
- have true (bona fide) circadian rhythms
rhythms
1/12
, 4/9/25, 7:38 PSYC 388 Midterm |
AM
Prokaryotic organisms: How old - about 3.5 billion years old
are they and what are some - no cell nuclei
characteristics about them? - no membrane-bound organelles
- cyanobacteria (blue-green algae)
What prokaryotic organisms have
- human gut bacteria
circadian rhythms? (3)
- some extremophile archaea (grow in high salinity or temp)
- they are ancient and widely conserved
Prokaryotic organisms = the most
- they likely appeared early in evolution
ancient life forms on earth (evolved
- likely evolved several times (bacteria, plants, and animals don't have
~3.5 billion years ago) and have
the same clock genes, which is expected if they evolved from the
biorhythms = what can we conclude
same organism)
about circadian rhythms based on
- must continue to make important contributions towards
this? (4)
survival and reproductive fitness
- ionizing radiation (high energy ultraviolet light can damage
What is hypothesis 1A: escape from molecules and disrupt biochemical processes such as DNA
light? repication and gene transcription
- earliest self-replicating organisms did not have barriers to block UV light
What was the solution to not having - restrict replication/transcription to the night
protection against UV light? (2) - mobilize light-avoidance behaviour in anticipation of sunrise
- many genes exhibit a circadian rhythm of transcription
What is the evidence for "escape - most clock-controlled genes are transcribed only at night (Ex: drosophila)
from light"? - cells are more easily damaged by UV light in the early night, when
cell division and gene transcription occur (Ex: in chlamydamonas)
- 1 biological challenge faced by early life that led to evolution of circadian clocks
External coordination - challenge of coordinating biochemistry with daily cycles of solar
radiation and temperature (external)
- 1 biological challenge faced by early life that led to evolution of circadian clocks
- challenge of coordinating biochemical processes with each other
Internal coordination
so that they occur in the the correct sequence and so that
incompatible processes would occur at different times of day
- earliest circadian clocks appear back when atmospheric oxygen
increased rapidly, killing of other anaerobic forms
- bacteria would synthesize antioxidants prior to sunrise to
remove toxic metabolites (reactive O2 mlcs, H2O2 and free
Hypothesis 1b: escape from oxygen radicals) that are created as byproducts of daytime
(radicals) (5) photosynthesis and damage cells
- these metabolites must be removed for effective aerobic metabolism
- photosynthesis is dependent on light and restricted to the day, so
clocks may have been used to control production of antioxidants so
organisms could use O2 processes
- may have been designed to 'escape from oxygen' (radicals)
- separation of incompatible processes
- Ex: nitrogen fixation: inhibited by O2 and incompatible with
photosynthesis (produces O2)
- separated spatially (different cell compartments) or temporally
Examples of hypothesis 2: Internal
(different times of day)
coordination of biochemical
processes
- Ex: enzymes for storing and releasing glucose in the liver
(glycogen synthase and glycogen phosphorylase) must be produced
at opposite times of day so as not to conflict
- a core function of circadian clocks in all 'circadian' species
is to enable anticipation of predictable daily changes in the
Why are circadian clocks still present
environment
in virtually all life forms? (3)
- Core principle: preparing in advance of daily environmental changes
is superior to reacting in response to daily changes
- environmental changes include geophysical and biological stimuli
2/12
