Explanation:
Classification systems function in order to organize a group of organisms into smaller groups according to some kind of logic. For example, the most used classifications system in biology is the phyllogenetic, which classifies living beings according to their evolutive affinity.
In the other hand, a dichotomous key is a "guide" used by biologists when they need to indentify an individual. It is organized in several steps regarding some key characteristics in order to guide you to which species/genus/family your individual belongs to. A dichotomous key never provides any kind of trustworthy phyllogenetic information, and should be understood only as a tool.
Answer:
B
Explanation:
It's the same thing that Pavlov did with the dogs, but instead of a can opener, he used a bell. The dogs drooled at the sound of the bell because they knew that the food was coming.
The answer would be deep roots to absorb ground water.
Cacti are found in deserts, which do not receive much rain. Cacti, like all plants, need water to live so deep roots would help the cactus obtain water.
Hope this helps!
Pulmonary ventilation provides air to the alveoli for the gas exchange process.