Endothermy

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Questions and Answers

Which of the following is a characteristic of non-shivering thermogenesis?

It is specialized for brown fat

It is the production of excess heat by futile cycles (correct)

It is the production of heat by sweating, licking, or panting

It is mediated by uncoupling proteins

What is the purpose of the H+ leak across the inner mitochondrial membrane mediated by uncoupling proteins?

To break down substrate

To pump out H+

To produce excess heat (correct)

To synthesize ATP

What is the function of brown fat?

To break down substrate

To synthesize ATP

To produce excess heat (correct)

To pump out H+

What happens at and above the UCT (upper critical temperature)?

Heat storage by increasing Tb or heat loss by evaporation Signup and view all the answers

What is the purpose of regional endothermy in fish?

To allow long migration through water of different temperatures Signup and view all the answers

What is the purpose of a rete mirabile?

To retain heat in a small region Signup and view all the answers

Which of the following is a characteristic of regional endothermy in tuna?

Elevated muscle temperature above water temperature Signup and view all the answers

Why did regional endothermy evolve in bony fishes?

To improve power output of muscles or vision Signup and view all the answers

Which of the following is a characteristic of endothermic homeotherms?

They maintain a high and stable body temperature (Tb) using internal heat. Signup and view all the answers

What is the equation for power required to maintain a heated object at a set point temperature of 37 °C?

P = C(Tset - Ta) Signup and view all the answers

What effect does insulation have on the power required to maintain the set point temperature?

Insulation reduces conductance and reduces power. Signup and view all the answers

What is the equation for power in the physical model when air temperature is 37 °C?

Power (W) C = |slope| Air Temperature (°C) 37 Signup and view all the answers

What is the equation for power in the physical model when air temperature is not 37 °C?

Power (W) C = |slope| Air Temperature (°C) 0 Signup and view all the answers

What is the equation for power in the physical model for endothermic homeotherms?

Power (W) C = |slope| Air Temperature (°C) Tb Signup and view all the answers

What is the cause of shivering in endothermic homeotherms?

Non-synchronous muscle contractions to generate heat. Signup and view all the answers

Which of the following is true about the thylakoid reactions in photosynthesis?

They use water and produce oxygen Signup and view all the answers

What is the energy source for the thylakoid reactions in photosynthesis?

Photons Signup and view all the answers

What can be used to measure the rate of photosynthesis?

O2 production Signup and view all the answers

What is the function of pigments in photosynthesis?

To absorb photons Signup and view all the answers

What does the absorption spectrum of a leaf represent?

The relative rate of photosynthesis Signup and view all the answers

What is the purpose of the light harvesting complex in photosynthesis?

To transfer energy from photons to the reaction center Signup and view all the answers

What is the role of the photosynthetic electron-transport chain?

To transfer electrons from water to oxidized P680* Signup and view all the answers

Which part of the chloroplast is responsible for the light-dependent reactions of photosynthesis?

Grana lamellae Signup and view all the answers

What is the role of plastocyanin in photosynthesis?

Transfers electrons to PSI Signup and view all the answers

What is the primary enzyme involved in the carbon fixation reactions of photosynthesis?

Rubisco Signup and view all the answers

What molecule is produced during the carboxylation step of the Calvin-Benson cycle?

3-phosphoglycerate (GP) Signup and view all the answers

What happens if the capacities of the electron transport chain and the Calvin-Benson cycle are mismatched?

The Calvin-Benson cycle slows down more than the photosynthetic ETC Signup and view all the answers

Which process is largely temperature-independent in photosynthesis?

Fast, physical processes Signup and view all the answers

Which of the following is a characteristic of the Rubisco enzyme?

The most abundant protein on earth Signup and view all the answers

What is the primary function of the xanthophyll cycle in photosynthesis?

Repair and regulation Signup and view all the answers

Study Notes

Endothermy and Thermoregulation in Organisms

Endothermic homeotherms maintain a high and stable body temperature using internal heat and have a high basal metabolic rate.
Ectotherms, on the other hand, rely on external sources of heat to regulate their body temperature.
A physical model shows that insulation reduces the power required to maintain a set point temperature.
Endothermic homeotherms deviate from the physical model and have a minimum energy expenditure.
The Scholander Curve describes the relationship between metabolic rate and body temperature in endotherms.
Conductance in endotherms can be changed through vasomotor responses, pilomotor responses, postural changes, and regional heterothermy.
Cold adapted animals have lower thermal conductance than tropical animals.
Seasonal acclimatization to cold tolerance can be achieved through metabolic adjustment or changes in pelage (insulation).
Excess heat production in endotherms can occur through shivering or non-shivering thermogenesis.
Brown fat is specialized for non-shivering thermogenesis.
Heat loads in endotherms can be stored or lost through increasing body temperature or evaporation.
Regional endothermy has evolved in bony fishes on at least three separate occasions, allowing them to migrate through water of different temperatures and improve their performance as predators.

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Description

Test your knowledge of endothermy and its importance in organismal physiology with this quiz. Learn about the high basal metabolic rate, heat retention mechanisms, and the differences between ectotherms and endotherms. Get ready to explore the fascinating world of maintaining a stable body temperature.