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Biology- Maintaining a Balance Summary

1. Most organisms are active in a limited temperature range

1. identify the role of enzymes in metabolism, describe their chemical composition and use a simple model to describe their specificity on substrates

Enzymes are proteins which act as catalysts in living things (they lower the amount of energy needed for a reaction, therefore increasing rate of reaction). Enzymes speed up reactions but are not used up by them. Enzymes catalyze only one specific reaction. For a biochemical pathway requiring multiple steps many different enzymes are required.

Model- The Lock and Key Model
At a molecular level, the shape of an enzyme permits it to bind at a particular site (active site) to the substrate molecules, causing a reaction to occur. This can be thought of as a key (the substrates) fitting a lock (the enzyme). Unless a key is right for a particular lock it doesn’t work. Enzymes are specific because they will only fit particular substrates.

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2. identify the pH as a way of describing the acidity of a substance

pH measures acidity on a scale where 7 is neutral, numbers less than 7 are acidic and numbers greater than 7 are basic or alkaline.

3. explain why the maintenance of a constant internal environment is important for optimal metabolic efficiency

Most metabolism (chemical reactions in a living thing) is controlled by enzymes. Therefore, for an organism to function efficiently, so must its metabolism. Thus, optimal conditions for enzyme activity need to be maintained for optimal metabolic efficiency. These conditions are temperature, pH level, substrate concentration and enzyme concentration.

4. describe homeostasis as the process by which organisms maintain a relatively stable internal environment

Homeostasis is the maintenance of a steady state/constant environment by means of physiological or behavioral feedback responses. It is important because it maintains the optimal metabolic conditions for organisms.

Examples of things that need to be controlled: balance, light, temperature, glucose level, water, CO2 , salt, etc.

5. explain that homeostasis consists of two stages:
– detecting changes from the stable state
– counteracting changes from the stable state

Homeostasis consists of two stages, detection of the change from a steady state, and response to counteract this change.

6. outline the role of the nervous system in detecting and responding to environmental changes

The coordination of the detection and response in homeostasis usually involves the nervous system (receptors, spinal chord, brain hypothalamus, etc.) The nervous system provides rapid coordination of internal organ systems and detects and responds to environmental changes.

7. identify the broad range of temperatures over which life is found compared with the narrow limits for individual species

Organisms live in environments with ambient temperatures (external environment temp) ranging from less than zero degrees Celsius (bacteria in snow) to 100 degrees Celsius (bacteria in boiling springs, volcanoes etc). However individual organisms cannot survive in this whole range of temperatures, and can only survive in narrow limits.

8. compare responses of named Australian ectothermic and endothermic organisms to changes in the ambient temperature and explain how these responses assist temperature regulation

Ectotherm- have a body temp that is more or less determined by the temp of the surrounding environment.

Endotherm- relatively constant body temp, usually higher than the surrounding environment.

Bearded Dragon- Ectotherm
When the bearded dragon detects low light levels a message is sent from the eye to the pituitary gland which secretes the melanocyte hormone which darkens the skin pigments so the animal can absorb more heat. Thermoreceptors in the skin can detect too much heat and cause the pigments to retract so the skin is...
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