<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.
Answer: "Articulating" means that the bones are moving relative to each other at a joint.
Answer:
Respiration links up the simple sugar, <u><em>glucose</em></u><em>,</em> with the gas <u><em>oxygen .</em></u>
Explanation:
In the process of respiration, oxygen is used to breakdown glucose. Water and carbon dioxide are produced due as a result of this reaction. A huge amount of energy, in the form of ATP is also released during this process. ATP is used by almost every cell of the body to carry out normal cellular functions. Energy is mainly stored in the linkage between the second and third phosphate of an ATP molecule.
Glucose, sucrose or lactose.
