Temperature Flashcards

1
Q

What are the effects of temperature on biological processes?

A

Temperature affects metabolic activity, behavior, and geographical distribution of animals.

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2
Q

What range of temperatures do most vital activities in animals occur?

A

Vital activities occur between -2 and +50 °C, with most animals living in a narrower range.

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3
Q

How does temperature affect molecular and organism levels in animals?

A

At the molecular level, temperature affects the structure and function of biological membranes and the speed of enzymatic processes. At the organism level, it influences body temperature regulation and metabolic heat production.

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4
Q

What is the relationship between protein activity and temperature?

A

Temperature affects the three-dimensional structure of proteins, modifying their functional properties. Protein activity increases with temperature to a point, after which proteins denature and activity decreases.

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5
Q

How do animals adapt their enzymatic activity to different temperatures?

A

Animals adapt by modifying gene expression, expressing alternative isoforms, and adjusting enzyme activity to maintain catalytic efficiency at different temperatures.

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6
Q

How do short-term temperature changes affect enzymatic activity in animals?

A

Short-term changes can modify gene expression, enzyme activity, substrate concentration, and energy intake through the intervention of hormones or neurotransmitters.

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7
Q

What are medium-term responses to temperature changes in animals?

A

Medium-term changes involve modifying gene expression and expressing alternative isoforms to adapt enzymatic activity over days or weeks.

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8
Q

What are long-term adaptations to temperature changes in animals?

A

Long-term adaptations occur during molecular evolution, selecting enzymes suitable for particular thermal environments, focusing on enzyme flexibility and gene expression regulation.

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9
Q

How do enzymes in poikilotherm animals differ in various temperatures?

A

Enzymes in poikilotherm animals differ in structural and functional characteristics, making them more suitable for their usual body temperatures.

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10
Q

What is the relationship between specific activity and enzyme-substrate affinity?

A

The specific activity of enzymes is often related to the enzyme-substrate affinity, which is optimal at a temperature-dependent value.

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11
Q

How does global warming affect poikilotherm species?

A

Global warming may cause poikilotherms to function with non-optimized molecular systems, as natural selection might not keep up with rapid temperature changes.

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12
Q

Give an example of a fish adapted to cold temperatures.

A

The Antarctic fish Pagothenia borchgrevinki has extremely temperature-sensitive acetylcholinesterase activity, while the mullet Mugil cephalus maintains enzyme activity over a wide temperature range

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13
Q

What role do chaperonins or heat shock proteins (HSPs) play in thermal adaptation?

A

HSPs assist in the correct folding of proteins and increase significantly in response to environmental stresses such as thermal shock, preventing protein aggregation and assisting in refolding.

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14
Q

How do HSPs vary among species exposed to different environmental temperatures?

A

Species like Antarctic fish produce only basal levels of HSPs, while species in environments with large temperature variations, such as intertidal molluscs, produce higher levels of HSPs.

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15
Q

What are the primary modes of heat exchange in animals?

A

The primary modes of heat exchange are conduction, convection, evaporation, and irradiation.

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16
Q

How does body size affect thermal inertia in animals?

A

Larger body size increases thermal inertia, making it an advantage in environments with rapid temperature fluctuations.

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17
Q

What is the role of thermoreceptors in animals?

A

Thermoreceptors perceive and respond to changes in environmental temperature, activating homeostatic adjustments.

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18
Q

Where are thermoreceptors located in mammals?

A

Thermoreceptors are located in the skin (peripheral) and within the nervous system (central, in the hypothalamus).

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19
Q

What types of TRP channels are involved in thermosensation?

A

TRPV1 and TRPV2 for intense heat, TRPV3 and TRPV4 for moderate heat, TRPM8 for cold, and TRPA1 for intense cold.

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20
Q

What is the main difference between ectothermy in aquatic and terrestrial environments?

A

Aquatic ectotherms tend to have body temperatures equal to the environmental temperature due to water’s high heat capacity, while terrestrial ectotherms can have body temperatures different from the air temperature due to radiation and evaporation.

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21
Q

How do animals react to rapid changes in environmental temperature?

A

Animals react with acute responses (acclimatization and acclimation) and more complex responses like chronic responses or evolutionary adaptations over time.

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22
Q

What is the Q10 temperature coefficient?

A

Q10 is the multiplicative factor by which the metabolic rate increases for each 10 °C temperature increase, generally between 2 and 3 in ectotherms.

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23
Q

How do ectotherms react to a rapid change in environmental temperature?

A

Ectotherms react with acute responses (acclimatization and acclimation), chronic responses at the organism level, and evolutionary responses involving entire populations and gene frequency variations.

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24
Q

How do global temperature changes since 1980 affect ectotherms in different regions?

A

Temperature changes rose fastest in the Arctic and north temperate zones, more slowly in the tropics, and remained unchanged in the south temperate zone, impacting ectotherms’ basal metabolic rates accordingly.

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25
Q

What is the relationship between metabolic rate and temperature in ectotherms?

A

The relationship is exponential, defined by the temperature coefficient (Q10), indicating how metabolic rate increases with temperature.

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26
Q

What happens to fish on the Great Barrier Reef as water temperatures rise?

A

Fish like the cardinalfish lose much of their aerobic capability, limiting their ability to increase O2 consumption and engage in aerobic exercise.

  • decrease in aerobic scope
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27
Q

What is the effect of chronic temperature changes on ectotherms?

A

Chronic changes lead to compensatory adjustments in the metabolism-temperature relationship, reducing the effects of temperature variations.

28
Q

How do mussels from different latitudes respond to temperature changes?

A

Mussels from colder and warmer waters show similar pumping rates due to acclimatization, with cold-adapted mussels increasing their pumping speed more at the same temperature.

29
Q

How do poikilotherms achieve metabolic acclimation to temperature changes?

A

They change their biochemistry over time, modifying gene expression, enzyme amounts, and mitochondrial activity.

30
Q

How do ectotherms regulate their body temperature behaviorally?

A

Ectotherms select suitable microhabitats, use burrows, rocks, or shelters, and change their posture to regulate body temperature.

31
Q

What behavioral strategies do chitons use to regulate body temperature?

A

Chitons migrate below rocks during sunny daytime to maintain body temperature below 30 °C.

32
Q

How do large animals like the leatherback turtle regulate body temperature?

A

A: They rely on high thermal inertia, reducing dependence on environmental temperature and favoring partial endothermy.

33
Q

What physiological control mechanisms assist behavioral thermoregulation in the Galápagos marine iguana?

A

The iguana basks in the sun to raise body temperature, increases blood flow to the skin, and adjusts heart rate to balance heat absorption and loss.

34
Q

What are the two strategies poikilotherms use to survive at temperatures below freezing?

A

They either tolerate freezing or avoid ice crystal formation in their body fluids.

35
Q

How do tardigrades tolerate freezing?

A

Tardigrades overexpress TDP (tardigrade-specific intrinsically disordered proteins), which prevent cellular structure damage by forming “glassy” solids.

36
Q

How do marine invertebrates avoid freezing in cold water?

A

Marine invertebrates have isotonic body fluids that freeze only when the surrounding water freezes, lowering the freezing point colligatively.

37
Q

What role do anti-freeze proteins (AFPs) play in fish?

A
  • AFPs lower the freezing point of body fluids by binding to ice crystals, preventing their growth and formation
  • Producing AFPs on a basal level means that Antarctic fish continuously produce a low, constant amount of AFPs regardless of environmental conditions.
  • Basal production ensures that there is always a sufficient amount of AFPs to inhibit ice crystal growth and prevent freezing without the need for additional regulatory mechanisms.

How do they work?
- lower the freezing point of the fish’s internal fluids (not the surrounding water)
- interacting directly with the surface of ice crystals that may form within the fish’s body fluids.
- This interaction inhibits the growth of the ice crystals, preventing them from expanding and causing damage to the fish’s cells and tissues
- AFPs do not affect the freezing point of the water outside the fish, only the internal fluids where they are present.

38
Q

What are the advantages of endothermy?

A

Disadvantages include high dietary requirements, dependence on adequate environmental resources, and lower fecundity and growth rates compared to ectotherms.

39
Q

What is the thermoneutral zone (TNZ)?

A

TNZ is the range of ambient temperatures where the metabolic rate is

  • minimal
  • independent of temperature
  • corresponding to the basal metabolic rate (BMR) in resting, fasting animals
40
Q

How is body temperature homeostatically regulated in endothermic homeotherms?

A

The hypothalamus coordinates heat production, conservation, and dissipation mechanisms, initiating corrective responses based on changes in skin temperature.

41
Q

What are the primary thermoregulatory responses in mammals?

A

Responses include shivering thermogenesis, behavioral adjustments, panting, and non-shivering thermogenesis involving brown adipose tissue.

42
Q

What factors modify the thermal conductance of an animal’s body surface?

A

Factors include surface/volume ratio, presence of thermally insulating structures (e.g., subcutaneous fat, fur), and vascular circulation regulation.

43
Q

How do arteriolar-venular anastomoses regulate heat exchange?

A

They control blood flow between deep and superficial vessels, adjusting thermal conductance based on environmental temperature.

44
Q

What is the role of countercurrent vascular exchangers in thermoregulation?

A

These systems allow arterial blood to transfer heat to venous blood, reducing heat loss and maintaining temperature gradients along appendages.

45
Q

How do mammals disperse excess heat through evaporation?

A

Mechanisms include sweating (mediated by sympathetic system) and panting (increasing ventilatory rate to remove heat and water).

46
Q

How do birds and mammals achieve seasonal acclimatization?

A

Birds and small mammals primarily adjust metabolism (e.g., develop brown adipose tissue), while larger animals increase fur or feather thickness for insulation.

47
Q

What are some characteristics of marine endotherms adapted to cold environments?

A

They have mechanisms for reducing thermal conductance, behavioral adaptations, and physical features like blubber for insulation.

48
Q

What is blubber and its functions in marine endotherms?

A

Blubber is a multifunctional subcutaneous tissue important for buoyancy, energy storage, hydrodynamic shape, and thermoregulation.

49
Q

How do marine endotherms use their appendages for thermoregulation?

A

Appendages without blubber act as thermal windows to release excess heat produced by physical activity.

50
Q

How do polar bears thermoregulate in extreme cold conditions?

A

Polar bears use

  • blubber
  • thick fur
  • piloerection
  • shivering thermogenesis
  • non-shivering thermogenesis
  • vasoconstriction in appendages to retain heat
51
Q

What is the role of the periarterial venous network in polar bears?

A

It transfers heat from arterial blood to venous blood through countercurrent exchange, limiting heat loss.

52
Q

How do whales manage heat loss in their mouths?

A

Whales have a vessel structure similar to the periarterial venous network, which limits heat loss during feeding.

53
Q

How do polar birds use countercurrent heat exchange for thermoregulation?

A

Birds have countercurrent heat exchangers in their legs and wings to minimize heat loss.

54
Q

What adaptation do seabirds have to prevent cold water from contacting their skin?

A

Seabirds have waterproof feathers covered with a waxy substance from the uropygial gland.

55
Q

How do penguin feathers help in thermal insulation?

A

Penguin feathers have barbules that create a three-dimensional structure trapping air and providing insulation.

56
Q

What is controlled hypothermia, and which animals use it?

A

Controlled hypothermia is a drop in body temperature to save energy. Many bird species and marine endotherms like the king penguin use this during dives.

57
Q

What is social thermoregulation, and how do emperor penguins use it?

A

Social thermoregulation is huddling to share body heat. Emperor penguins huddle to survive the Antarctic winter.

58
Q

How do aquatic mammals regulate body temperature in warm environments?

A

They use countercurrent heat exchangers in appendages and mechanisms to maintain the temperature of genitals and fetuses.

59
Q

What are the two categories of heterotherms?

A

Regional heterotherms and temporal heterotherms.

60
Q

What is regional heterothermy?

A

Regional heterothermy is when certain body parts are warmer than the environment, often seen in large, active swimming fish and some reptiles.

61
Q

What is temporal heterothermy?

A

Temporal heterothermy is when body temperature varies with time, such as during hibernation, estivation, or daily torpor.

62
Q

How do heterothermal fish manage to keep some body regions warm?

A

They use muscle activity, countercurrent heat exchangers, and morphological adaptations like large superficial vessels.

63
Q

What is an example of cranial heterothermy in fish?

A

Many species of tuna and lamnid sharks maintain higher temperatures in their eyes and brains to protect against dysfunctions and maintain efficient vision.

64
Q

How do billfish like swordfish maintain cranial heterothermy?

A

They use a specialized thermogenic tissue, the superior rectus muscle, which generates heat through a futile cycle of Ca2+.

65
Q

How do some fish maintain visceral heterothermy?

A
  • Fish like tunas have specialized blood vessels to raise the temperature of their viscera, enhancing digestion and absorption efficiency.
  • They transfer heat from their muscles to the internal organs.
  • Maintaining a high metabolic and digestive rate is important for active predators that require rapid digestion and energy conversion
66
Q

What is the unique thermal adaptation of the opah (Lampris guttatus)?

A

The opah maintains its entire body at a temperature 5 °C higher than the environment using heat production in pectoral fin muscles and countercurrent heat exchangers in the gills.

67
Q

How does the leatherback turtle achieve partial endothermy?

A

The leatherback turtle uses large body size, thermal insulation, and increased metabolic activity to maintain a body temperature higher than the environment.