Robert decides to go for a run when he gets home from school. As he begins running, his breathing rate starts to increase. What are the mechanisms that cause his breathing rate to increase? A.
When carbon dioxide levels in the blood decrease, the respiratory center sends signals to the alveoli to increase the volume that they expand.
B.
When oxygen levels in the blood decrease, the respiratory center sends signals to the diaphragm to increase the rate at which it contracts and relaxes.
C.
The respiratory control center senses the need for more oxygen, which causes the trachea to push and pull air more forcefully.
D.
The diaphragm senses the need for more oxygen, which causes it to expand and contract more quickly in order to inflate and deflate the lungs.

the elements of art are the visual tools that the artist uses to create a composition. these are line, shape, color, value, form, texture, and space.

the principles of art and design are balance, contrast, emphasis, movement, pattern, rhythm, and unity/variety.

the two answers are a, the population of birds with large beaks will increase on the island, and c, the trait for large beaks will be passed on to future generations through natural selection. the reason for that is because if the birds that have beaks developed for eating small seeds lose all of their food, they will go hungry and eventually starve because they physically cannot eat the large seeds, therefore making the population of large beaked birds higher. also, if the trait of large beaks are dominant on the island over small beaks, then over time the large beaked birds will reproduce more and more, while the smaller beaked birds will reproduce less and less because they can't survive with the food provided. that leads to the trait of small beaks disappearing and the trait of large beaks taking over the island.

the answer is c.

by: nicholas dooley