To test how fertilizer affects tomato plants, a farmer divided a field of young tomato plants into 10 plots of equal size. the farmer then put fertilizer on half of the plots and no fertilizer on the other half of the pots. the experimental group in this experiment was:
a. the tomato plants in all the unfertilized plots.
b. all the tomatoes planted in the field
c. all the plots in the field
d. the tomato plants in all the fertilized plots

D. The tomato plants in all the fertilized plots

Explanation:

The independent variable in this case is the fertilizer, because it is the one that is changed in this experiment. This is your clue on how to determine the experimental group.

The experimental group is the group the independent variable is applied on. The group that is not subjected to the independent variable is called the control group.

This is done to ensure that the changes in the experimental group was indeed brought about by the independent variable by comparing the difference between the two groups.

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.