Answer:
As they produce food by the process of photosynthesis which cannot be done by anyone else. Plants use chlorophyll, CO2 and H2O in photosynthesis( which is a biochemical process). Plants became a cause of life on earth. Hence plants are the ultimate source of food on earth.
The answer is mechanical weathering
Summer's considered the best out of the 4 seasons because most people are on summer vacation and they are able to spend quality time with their family without all the snow or cold weather.
The answer is long
The bone indicated by the arrow is femur bone. It should be classified as the long bone. Other example for long bones would be tibia and fibula. Short bone would be carpal or tarsal bones. Flat bone could be found in skull. Irregular bone would be the vertebrae or pelvic.
Cells within the body are properly arranged and their production uses up resources of the body. For example, red blood cells use iron while being produced. The body must dispose of cell properly to maintain the orderly arrangement of cells; for example, if dead skin cells were not removed, we would lose feeling in our skin due to the layer of dead cells. Moreover, the body must work to minimize wastage. This is why some of the iron from red blood cells is removed and reused.