<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.
Both auxin and cytokinin are used to increase size of stem and fruits
Cellular respiration and photosynthesis are essential to the carbon cycle because cellular respiration involves the intake of oxygen o2 and the exhale of carbon-dioxide co2 into the atmosphere. Where photosynthesis uses the carbon dioxide and water to create oxygen and sugars through energy to repeat the cycle. Respiration in general is a process where carbohydrates are turned into dihydrogen monoxide or water and co2(carbon dioxide). Living organisms together throughout the biosphere and atmosphere work together to continue this because carbon itself is an organic substance.
Answer: alpha
Explanation: Alpha particles are fast moving streams of positively charged particles that are shown to be Helium nuclei. They have a mass
number of 4 and an atomic number of 2 and a charge of +2. Alpha particles are represented as 4He2. When 238U92 becomes 234Th90, it emitted a helium nucleus 4He2. The equation for the decay is 238U92 ---> 234Th90 + 4He2.
The answer would be "the boiling and freezing points of water."
