High School Biology : Understanding Biological Equilibrium
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Example Questions
Example Question #1 : Understanding Biological Equilibrium
Which of the following is true when the body is under homeostasis?
The body is able to self-sustain without anything from the environment
The body is under dynamic equilibrium
The body cannot generate its own heat in very cold conditions
The body is at an appropriate core temperature and no longer needs to regulate body temperature
The body stops digesting foods
The body is under dynamic equilibrium
Homeostasis means "staying still" in Greek, and is a property of the human body that describes when functions and processes allow the conditions of the body to remain stable. This does not mean that the body ceases any function. It simply means that the current functions of the body are able to keep the body at a stable condition.
For example, blood glucose in the body is under homeostatic regulation by the hormones insulin and glucagon. Both hormones are always in circulation, meaning that glucose is both being released into the blood and begin taken from the blood for storage. The result is a stable amount of glucose because both processes occur together. When a meal causes blood glucose to rise, insulin levels increase and glucagon levels decrease to accommodate the change, but both hormones are still present. This creates a dynamic equilibrium in which glucose is both retained and released, allowing a stable amount to be in circulation.
Example Question #1 : Understanding Biological Equilibrium
Which of following correctly describes how a catalyst affects a chemical reaction?
Speeds up a chemical reaction by lowering the activation energy
Slows down a chemical reaction by lowering the activation energy
Speeds up a chemical reaction by increasing the activation energy
Slows down a chemical reaction by increasing the activation energy
Has no effect on the speed of the chemical reaction, but increases the amount of product produced
Speeds up a chemical reaction by lowering the activation energy
A catalyst is a substance that increases the rate of a reaction by lowering the activation energy needed for the given chemical reaction to occur. Activation energy is the input of energy required for a reaction to occur. This energy is used to break the bonds of the reactant, allowing the reaction to proceed. If a catalyst lowers the amount of energy needed for a reaction to occur, the reaction can occur at a faster rate because it reaches that lower energy level more quickly than it would have the original higher energy level.
Example Question #2 : Understanding Biological Equilibrium
Which is not an example of homeostasis?
Mitochondria create ATP through proton pumps in order to power the cellular processes
Insulin is released by the pancreas to encourage cells to retain their glucose instead of releasing it into the blood stream
Warm blooded (endothermic) animals sweat to release heat, or shiver to increase metabolic activity and increase body temperature
The kidneys work to remove excess salt, urea, and water from the bloodstream
Oxygen content in the bloodstream is low, so the heart pumps faster and speed/depth of breathing increases
Mitochondria create ATP through proton pumps in order to power the cellular processes
The situation describing ATP production is the only one in which there is no problem in need of correction. Homeostasis requires maintenance of a balance. While ATP production is an essential process, the simple function of the ATP synthase proton pump is not directly related to biological stability in homeostasis.
All other answers describe situations in which the body corrects a problem or situation and restores balance to internal mechanisms. This is the nature of homeostasis—there is a disruption to the balance, and the body adjusts in order to keep the processes running smoothly.
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