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scientists classify organisms into groups based on internal and external features.
The external structures of animals protect the animal from harm to internal organs. An example of an external structure is the skin and fur on a bear. The skin protects the internal organs, and the fur protects the skin.
Why study rat's internal and external structures? "For the pure sake of learning new things", could be one answer. We need to study external and internal structures of a rat in order to acquire correct knowledge about rats. Now for a selfish answer. Since human beings are so much like rats, when we know something more about rats, we nearly always have learned something about ourselves. More so in the past, but still today, we have less moral dilemna in doing testing on rats than on our fellow human beings. In other words, we are willing to cage them, perform experiments that cause irritation, great discomfort or death to a rat that we feel compelled not to when testing ideas with humans. We generally feel that it is immoral to give a human a condition and then to experiment with it. However, we generally don't feel that it is so immoral to give a rat a condition and then to subsequently try to experiment with it. The rat in this last context is a model of a human. what surprises most people is how good a model a rat has been to us. In other words, we are a lot like a rat.
Internal and external? 4real
Mostly water animals do external fertilization
The cartiliginous structure that gives a nose its shape. Hamsters have a blunter nose than, for example, a rat.
External structure is a term used to describe a certain type of asset. An external structure is a relationship that you must rely on that is outside of your own organization.
what are the example of —externalwhat are the example of —external
A structure outside. A skeleton of an object.
one example is to solve for the forces in each part of a system/structure if it has an external force acting on it.
skin
It has a hole in it is a rounded shape.