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Diekoloreoluwa Oyegunle

Faythe Miller

Christian chukwufumnanya Eluemelem

Q10 (temperature coefficient)

The Q₁₀ temperature coefficient is a measure of temperature sensitivity based on biological or chemical reactions. It is usually defined as the rate ratio of a given process taking place at temperatures differing by 10 units (℃ or K). Q10 can be used to measure temperature sensitivity in animals or plants. However, conclusions drawn by different researchers from the use of this coefficient are not universal and are not always consistent with each other. The Q₁₀ coefficient is described by exponential laws instead of power laws, which leads to deviations from linearity in the Arrhenius plots . The arrhenius plot is derived from the arrhenius equation further explained in this literature. A temperature increase by 10 units does not entail the doubling or tripling of the

A plot illustrating the dependence on temperature of the rates of chemical reactions and various biological processes, for several different Q₁₀ temperature coefficients. The rate ratio at a temperature increase of 10 degrees (marked by points) is equal to the Q₁₀ coefficient.

rate of a given process, as is usually assumed in the relevant literature

The Q₁₀ is calculated as:

$Q_{10}=\left({\frac {R_{2}}{R_{1}}}\right)^{10\,^{\circ }\mathrm {C} /(T_{2}-T_{1})}$

where;

R is the rate

T is the temperature in Celsius degrees or kelvin.

R2 has to be Where T2 is greater than T1, (T2 > T1)

R1 is the rate of the reaction at the lower temperature, T1

R2 is the rate of the reaction or biological process at the higher temperature, T2

It is also important to note that the rates, R1 and R2 must be measured using the same unit, i.e., if R1 is measured in m/s, then measured also in m/s and not m/min.

Rewriting this equation, the assumption behind Q₁₀ is that the reaction rate R depends exponentially on temperature:

$R_{2}=R_{1}~Q_{10}^{(T_{2}-T_{1})/10\,^{\circ }\mathrm {C} }$

Q₁₀ is a unitless quantity, as it is the factor by which a rate changes, and is a useful way to express the temperature dependence of a process.

For most biological systems, the Q₁₀ value is ~ 2 to 3.

Q₁₀ Temperature Coefficient in Plants

The Q₁₀ temperature coefficient does not only exist in animals but exists in plants as well. Q10 in soils, roots and stems defines the temperature sensitivity of the plant in question . Generally, researchers use Q10 when they are trying to measure temperature sensitivity of heterotrophic soil respiration. When measuring Q10 in plants it is important to note that it cannot be measured everywhere. Moreover, there is special knowledge about spatial patterns and regulating factors that are required . Spatial patterns and regulating factors include the difference in geographical location, soil organic carbon and soil moisture levels.

Q₁₀ Temperature Coefficient in Animals

In some animals, Q10 can be measured using the muscles. The temperature of a muscle in ectothermic and endothermic animals have a significant effect on the velocity and power of the muscle contraction. Performance generally declines with decreasing temperatures and increases with rising temperatures. To predict these changes, researchers use the Q10 temperature coefficient to

The effects of temperature on enzyme activity. Top - increasing temperature increases the rate of reaction (Q₁₀ coefficient). Middle - the fraction of folded and functional enzyme decreases above its denaturation temperature. Bottom - consequently, an enzyme's optimal rate of reaction is at an intermediate temperature.

measure resting metabolic rate of the muscle. The Q₁₀ coefficient represents the degree of temperature dependence a muscle exhibits as measured by contraction rates . A Q₁₀ of 1.0 indicates thermal independence of a muscle whereas an increasing Q₁₀ value indicates increasing thermal dependence. Values less than 1.0 indicate a negative or inverse thermal dependence, i.e., a decrease in muscle performance as temperature increases.

Q₁₀ values for biological processes vary with temperature. Decreasing muscle temperature results in a substantial decline of muscle performance such that a 10 degree Celsius temperature decrease results in at least a 50% decline in muscle performance . Persons who have fallen into icy water may gradually lose the ability to swim or grasp safety lines due to this effect, although other effects such as atrial fibrillation are a more immediate cause of drowning deaths. At some minimum temperature biological systems do not function at all, but performance increases with rising temperature (Q₁₀ of 2-4) to a maximum performance level and thermal independence (Q₁₀ of 1.0-1.5). With continued increase in temperature, performance decreases rapidly (Q₁₀ of 0.2-0.8) up to a maximum temperature at which all biological function again ceases .

Within vertebrates, different skeletal muscle activity has correspondingly different thermal dependencies. The rate of muscle twitch contractions and relaxations are thermally dependent (Q₁₀ of 2.0-2.5), whereas maximum contraction, e.g., tetanic contraction, is thermally independent .

See also[edit]

• Arrhenius equation
• Arrhenius plot
• Isotonic (exercise physiology)
• Isometric exercise
• Skeletal striated muscle
• Tetanic contraction
• Arrhenius plots
• soil respiration
• soil organic carbon
• resting metabolic rate