<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:
X and why realationship is the Distance between two given points
Explanation:
The correct answer is nephron.
<span>
The nephron consists of Bowman’s capsule ( where blood is initially filtered ) and glomerulus which is a tuft of capillaries. Bowman’s capsule and a glomerulus together form the renal corpuscle. The renal tubule extends from the capsule and it consists of proximal convoluted tubule (selective reabsorption), a loop of Henle (establishes a salt gradient) and distal convoluted tubule (selective reabsorption). </span>
