Answer:
Viruses are considered to be non-living because they arent
Answer: With the development of powerful microscopes, scientists discovered many single-celled organisms that didn't fit into any of Linnaeus' kingdoms. As a result, a new taxon, called the domain, was added to the classification system.
Explanation:
<span>Certainly. Every organism has a variety of different characteristics. One person writing a key might choose to use different characteristics than another person would use.
For example: Here's a key for separating fish, snake, frog and mouse
1.
A. Has scales on its skin ... 2
B. Has no scales on its skin ... 3
2.
A. Breathes with gills - fish
B. Breathes with lungs - snake
3.
A. Has hair or fur - mouse
B. Has no hair or fur - frog
Here's a different key for the same four animals:
1.
A. Has four legs ... 2
B. Does not have 4 legs ... 3
2.
A. is warm-blooded - mouse
B. is cold-blooded - frog
3.
A. has fins - fish
B. has no fins - snake</span>
A protein is a polymer of amino acids.
When amino acids are joined by dehydration synthesis (a process that removes
water to form a chemical bond), they form peptide bonds. <span>There are three main components of an
amino acid, the amino group, the side chain, and the carboxylic acid group. </span>
prevents backflow into the left atrium
