water molecule is one of few molecule that lack carbon atom
h2o
<u>Answer:</u>
Recent evidence suggest that feathers evolved from scales and suggest that 'feathers and pycnofibers' could be homologous.
<u>Explanation:</u>
- One of the major difficult issue related to bird evolution is the evolution of feathers.
- Feathers are considered as the most 'complex integumentary structures' which are found in vertebrates.
- Evolutionary developmental biology suggests that the 'planar scale structure' is been modified for developing into feathers by 'splitting' to form web like structures.
- Scales and Feathers consist of 'two distinct form of keratin' so it was thought that 'each type was exclusive skin structure' but recent study suggests that they are developmental expressions of same skin structures.
The nucleus contains the <u>DNA</u> (Deoxyribosenucleic Acid). It codes for all the hereditary characteristics an organism has and it is packaged into chromosomes within the nucleus.
<span>B. The algae and the spider crabs have a mutualistic relationship
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<span>E. The spider crabs are parasites of the algae.
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