Week 9 exam notes
Thermoregulation in the arctic fox involves: thermoreceptors sending information to the
hypothalamus if body temperature is above or below the set point.
Plant leaves move in a rhythmic pattern on a 24 hour or circadian rhythm even when
placed in darkness.
In humans, hormones such as cortisol and melatonin fluctuate over a 24 hour period.
Circadian rhythms (circa = "around"; diem = "day") oscillate with a period of
approximately 24 hours.
Acclimitization or adaptation?
Abalone (Haliotis kamtschatkana) tolerate water
temperatures of 4 - 10 C in the winter months, but 8- 1. acclimitization
14 C in the summer. The enzyme, lactate
__1__ dehydrogenase is expressed in different forms 2. adaptation
(isoforms) in the summer relative to the winter.
Isoform switching helps to maintain enzyme function
regardless of body termperature.
Killer whale (Orcinus orca) herds form with a distinct
__2__ age and sex structure. They primarily prey upon
endotherms (eg. seals, porpoises, sea lions).
In late March, the brown coat of ermine (Mustela
erminea) first appears as a mid-dorsal stripe which
__1__ gradually spreads to all parts of the body. In late
October, the process is reversed and the white winter
coat appears after the moult.
The wolf (Canis lupus) has a similar appearance to a
large German shepherd dog, but it is thinner and has
__2__ longer legs and larger paws. The skull is relatively
heavy and the teeth are large. They have diverse prey,
but tend to kill 1 - 1.5 large animals each month.
Collared lemming (Dicrostonyx torquatus) remodel
their claws seasonally. In winter the pads of the third
and fourth digit bulge and the claws above the pads,
__1__ lengthen. These special claws are used to dig burrows
through snowbanks. In the spring, claw growth slows
and the pads return to a smaller size When salmon undergo acclimitization to different seasonal mean temperatures, the lethal
temperature shifts, as shown below in the table.