Question

Energetics and Metabolism Activity

Humans are described in a couple of different ways in relation to maintaining body temperature: homeotherm and endotherm are two common phrases. “Homeotherm” translates to “same temperature,” meaning humans maintain a stable body temperature regardless of the external environment. Related is the term “endotherm,” meaning “internal body temperature.” Humans, being warm-blooded, are dependent and capable of internally generating heat when needed. Regardless of the phrase used, the ability to maintain a stable body temperature is a critical part of our homeostasis. Therefore, we expend a lot of energy to maintain a near-constant internal environment of 37°C, which is largely accomplished by our metabolism.

Other organisms are poikilotherms or ectotherms; they cannot internally regulate their body temperature, and their body temperature can change depending on the external environment. Most fish, sharks, reptiles and amphibians fall into this category. While ectothermy is a significant energy-saving adaptation, it also means an organism’s metabolic rate is dependent upon the external environment. Higher temperatures increase metabolic rate, colder temperatures slow it down.  

In this activity, you will be examining the effects increased temperature has on the metabolic rates of three species of fish.

Go to the following website, and perform the experiment:

http://www.glencoe.com/sites/common_assets/science/virtual_labs/CT08/CT08.html

Fill in the table below with your results:

	Goldfish	Sun fish	Cat fish
Control (5°C)
10°C
15°C
20°C
25°C
30°C

1. Interpret your results from the experiment; what do these data tell you about fish metabolic rate in response to temperature?

2. How might ectotherms have to compensate for their variability in metabolic rate in terms of how much they eat?

3. Compare and contrast the basal metabolic rate of a fish and a human. How are each maintained? How might the BMR of each change in a warm environment? A cold environment?

Answer 1

1). Chemical reactions, like the ones in the process of metabolism, will speed up with warming temperatures, meaning a fish's metabolic rate increases as the surrounding water temperature increases....  The fish metabolism was highest at 30c. The more oxygen the fish consumes, the more energy it uses, causing the metabolism to be high... The drop in temperature clearly caused the drop in respiration rate. The cold temperature caused the water molecules to come closer together and trap dissolved oxygen and forced the metabolic rate of the fish to drop, thus lowering the respiration rate.....

2).Ectotherms typically have lower metabolic rates than endotherms at a given body mass. ..In cool weather the foraging activity of such species is therefore restricted to the day time in most vertebrate ectotherms, and in cold climates most cannot survive at all. In lizards, for instance, most nocturnal species are geckos specialising in "sit and wait" foraging strategies. Such strategies do not require as much energy as active foraging and do not require hunting activity of the same intensity. From another point of view, sit-and-wait predation may require very long periods of unproductive waiting. Endotherms cannot, in general, afford such long periods without food, but suitably adapted ectotherms can wait without expending much energy.....

3).

The "baseline" metabolic rate of an ish measured as the basal metabolic rate (BMR) for an endotherm or as the standard metabolic rate (SMR) for an ectotherm. Both the BMR and SMR are measures of metabolic rate in animals that are at rest, calm/unstressed, and not actively digesting food (fasting).

• For an endotherm, the BMR is also measured when the humanl is in a thermoneutral environment, that is, one where the organism does not expend extra energy (above baseline) to maintain temperature.

• For an ectotherm, SMR will vary with temperature, so any SMR measurement is specific to the temperature at which it's taken.

Endotherms tend to have basal high metabolic rates and high energy needs, thanks to their maintenance of a constant body temperature. Ectotherms of similar size tend to have much lower standard metabolic rates and energy requirements, sometimes 10percent or less of those of comparable endotherms.

Human adult males typically have a BMR of 1600to 1800 kcal/day...

For fisg i have already mentioned in 1st question...

Fish are unable to regulate their body temperature, so they are influenced by the temperature around them. If the water is warm, fish metabolism accelerates, feeding and respiration increases, and there is a general increase in movement. If the water is cooler, fish become lethargic and tend to be inactive....

As temperatures become cooler, ectotherms move around less to conserve energy. ...

The higher an organism's metabolic rate—the amount of chemical fuel it burns in a given period of time—the more heat it will produce. So, as a human is exposed to colder external temperatures, it will increase its metabolic rate, burn more fuel, and produce extra heat to keep its body temperature constant.