A food web does not represent all the links in an actual ecosystem.
Explanation:
A food web is also called food cycle. It is understood by the natural interconnection of chain and their graphical representation. The concept is given by Charles Elton. He mentioned about the concept of food cycles in Animal Ecology but later this food cycle is replaced by food web.
Food web are limited representation of eco system. Ecologists can keep together all life forms broadly into one of the two categories which is called tropic levels. These two categories are autotrophs and heterotrophs
The correct codes are 63267 and 69990.
The codes are given based on the lesion if it is intradural or extradural. In our case here it is extradural cystic structure so that is why it ranges between 63265 to 63268.
We also divide the section of spine depending on where the lesion is being located. Code 63267 describes laminectomy which has evacuation of intraspinal lesion which is found in the lumbar spine.
69990 code documents the use of microscope.
Remember that a controlled variable is a variable that stays the same thoughout the experiment.
it wouldn't be a. because two different wires were used
the final length of the wax would be your dependent variable, so it wouldn't be c.
the thermal conductivity is the independent variable so it isn't d.
the original length of the wax was the same for both.
So B is your answer.