They are ineffective against viral infections because viruses can not be treated with antibiotics.
first, third, fourth, second
Answer:
Actin filaments return to their original positions (does not occur in muscle contraction, according to the sliding filament model).
Explanation:
There are four main types of tissue: muscle, epithelial, connective and nervous. Each is made of specialized cells that are grouped together according to structure and function. Muscle is found throughout the body and even includes organs such as the heart. Our outer layer of skin is epithelial tissue.
Organisms can be made up of many<em> </em><u>cells</u>, which could be arranged into <u>tissues</u> which can make up<u> organs</u>, organs can be part of a(n)<u> system</u>. These are........i don't really know after this since you didn't give a lot to work with and i'm not even sure if this is right or not lol.
