Crayfish are invertebrates which means they don't have a backbone. They are also arthropods, which means that they have a protective exoskeleton on the outside of their body. Other arthropods include insects, spiders, and centipedes. Crayfish continually shed their exoskeleton and regrow a new one. During this transition is when they are most vulnerable to predators because they aren't protected by their outer shell.
Crayfish are found all over the world in many different freshwater environments, such as rivers, creeks, springs, and swamps. But this doesn't necessarily mean that you will be able to find them. They are somewhat cryptic because they dig out homes for themselves under rocks and blend in well with their environment. Crayfish will ardently defend this dwelling against intruders using their strong front claws
Natural Selection.
It favors the better adapted organisms.
A,C,D Is the answer to the question
The degree to which chromatin is compacted greatly affects its accessibility for transcription, and thus, gene expression.
<h3>What is Transcription?</h3>
This is the process which involves copying a segment of DNA into RNA in organisms.
When chromatin is condensed, DNA becomes less accessible for transcription factors and vice versa which was why it was chosen as the most appropriate choice.
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