If you are standing in the northern hemisphere during the winter
A you are experiencing longer days than nights.
B you are experiencing equal hours of day and night.
С
you are experiencing longer nights than days.
D
...you are not experiencing night at all.

"a.) well–developed vascular system."

measuring light intensity

light meters can be used to measure light intensity. the meter is held at the soil surface and pointed in the direction of the maximum light intensity, and then the meter is read.

errors can be made when measuring light intensity by accidentally shading the light meter. the reliability of the results can be checked by taking many samples.

photosynthesis makes the glucose that is used in cellular respiration to make atp. the glucose is then turned back into carbon dioxide, which is used in photosynthesis. while water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.