<span>1.keeps tooth alive
</span><span>pulp
2.surface of teeth
enamel
3.tube carrying food to stomach
esophagus
4.last major organ in digestive system
large intestine
5.digestive organ located above waist, close to ribs
stomach
6.first stage of digestion takes place here
mouth
7.regular squeezing movements
peristatiss
8.blood vessel leading from heart
artery
9. windpipe
trachea</span>
Plants and animals could not live without nitrogen<span>. It is an </span>important<span> part of many cells and processes such as amino acids, proteins, and even our DNA. It is also needed to make chlorophyll in plants, which plants use in photosynthesis to make their food and energy. hope this helps!</span>
The answer is letter A. In most organisms cellular respiration usually involves oxygen to produce the most energy. Except in the process of fermentation, where the cells are deprived with oxygen causing it to form bacteria and other forms of organisms within the fermented sample.
Radioactivity due to heavy elements
Friction caused by earths fast rotation