These are short answer questions! !

1. look at figure 18-1. why are such different animals as fish, amphibians, reptiles, birds, and mammals grouped into a single phylum?

2. how does blood cycle from the heart to the lungs, back to the heart and out the body? use the terms heart, lungs, arteries, veins, capillaries, cells, oxygen, and carbon dioxide. be clear and specific! start with the heart at the start of your description!

3. what was charles darwin’s contributions to science, and how did he develop them? describe his contributions.

4. explain how feedback inhibition you maintain body temperature. a good analogy of this subject is how your thermostat and heater or air conditioner work in your house.

5. celiac disease is a disease that affects the digestive system. when people with the disease eat foods containing gluten, a material found in wheat products, their immune system damages or destroys their villi. what are villi and why are they important? how might the lack of villi affect a person’s digestive system?

1. These animals are grouped in phylum vertebrata or “animals with backbone”. All of these animals possess a vertebral column as a form of internal support (in contrast to invertebrates wherein they rely to exoskeleton, rigid body parts, or have no form of support at all). These different animals are grouped separately by class. 

2. The right side of the heart will receive carbon dioxide rich blood from the body through the superior and inferior vena cava (systemic veins) then it will be pumped through the pulmonary artery to the lungs where blood will be oxygenated and converted to oxygen rich blood. The left side of the heart will receive the oxygen rich blood and will be pumped to the body through the aorta (systemic artery). From the body, the blood will go to the right side of the heart again hence repeating the cycle. 

3. Charles Darwin’s most popular contribution to science is that proposed and defended the theory of evolution. He did this by studying animal lineages and publishing his work “On the Origin of Species by Means of Natural Selection” on 1859

4. Feedback inhibition helps maintain the body temperature by having our sense organs (i.e. skin) detect heat or cold. If it detects heat, then the response of the body is to sweat and once its cool enough again, the body stops sweating (negative feedback). Same goes if the body is cold, the response is shivering and once the body is out of the cold, the body stops shivering. 

5. Villi are gross finger-like projections in the intestinal lumen and it functions to increase the absorptive surface area of the intestines hence efficiently absorbing nutrients. Lack of villi will decrease nutrient absorption and may lead to malnutrition.