The restriction point is defined best as the point in the cell cycle a. where cells stop progressing through the cell cycle regardless of the stress they experience b. at which g1 ends and s-phase begins c. after which withdrawal of mitogens will not prevent cell cycle progression d. before which mitogens can not influence cell cycle progression e. after which mitogens can promote cell cycle progression

The correct answer is option c.

Explanation:

The G1 phase of the cell cycle refers to the initial phase of the cell cycle or the first phase of the cell division that needs some additional growth element called mitogen in order to carry on the process. However, these mitogens are needed until the cell attains a particular state in the G1 phase.  

If the mitogens are withdrawn prior to that state, the cell cycle will get an arrest. Once the cell has reached and passed that state it becomes completely independent of mitogen and does not care for the presence of mitogen. This state is called restriction point, which usually takes place in late G1 phase.  

After passing the restriction point, the cell is destined to go through the process of mitosis regardless of the absence of existence of mitogen. Thus, the correct answer is option c.  

thinking it would be d not too sure but i think it's right

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.