<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>
Answer:
There are histones in the nucleus that DNA coils around. The part of the DNA that is coiled around the histones is not accessible, and cannot be expressed in that cell. DNA that is not wrapped around a histone can be transcribed.
Explanation:
<span>"they form a cyst: a hard covering is formed around the protozoan and metabolic rate is slowed"</span>
Organisms that are well adapted to live together to in the same area over time.
Nitrogen and Oxygen make up the greatest percentage of the atmosphere.
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