Answer:
External means on the outside, so it can be something like their fur color. Some other features can be number of legs, if they have wings or not, etc.
Answer;
-Electron microscopes can not view live cells because the method of preparation is lethal.
Explanation;
-The electron microscope is a type of microscope that uses a beam of electrons to create an image of the specimen. It is capable of much higher magnifications and has a greater resolving power than a light microscope, allowing it to see much smaller objects in finer detail.
-There are many different disadvantages to using a electron microscope for example they are extremely expensive which limits the availability to use them. Furthermore researchers are unable to observe the image in color, as electrons do not possess color, which may not allow the image to be understood easily.
-Additionally the use of the electron microscopes require a large space for example a whole room which may not be feasible.
Increase surface area for the purpose of absorption
Answer:
Homeostasis.
Explanation:
The insulin and glucagon hormone are important for the maintenance of the blood sugar level in the body. The glucagon increase the blood sugar level whereas insulin decreases the blood sugar level.
The homeostasis may be defined as the process of the maintenance of the normal physiological conditions of the body irrespective of the change in the external and internal environment. The change in the blood sugar level can be maintained by the insulin and glucagon hormone and is important for the homeostasis maintenance.
Thus, the answer is homeostasis.