8. when testing the benefits of a new fertilizer on the
growth of tomato plants, the control group should include
which of the following? *
o
a) tomato plants grown in soil with no fertilizer
o
b) tomato plants grown in soil with the original type of fertilizer
o
c) tomato plants grown in a different type of soil with the new fertilizer
o
d) tomato plants of different varieties grown in soil with new fertilizer

A) Tomato plants grown in soil with no fertilizer

Explanation:

The control group is the group that you do not change anything. This is used as a basis or a baseline to determine whether changes you make in the experimental groups actually made a difference. An experiment is incomplete when you do not have this because it does not show any evidence that the change you made is what ellicits an effect.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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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.