Height can be affected by many factors, such as age, lifestyle, medical, etc. so two tall parents can have a short child
By starch, I'm assuming you mean glycogen, or animal starch.
Similarities:
Both are polysaccharide molecules made from glucose molecules linked together in a long chain.
Both are storehouses of energy.
Differences:
Glycogen is made in animal cells and is the only form of starch animals can digest (unless they have certain microbes in their intestinal tracts to break down cellulose, which all herbivores need).
Cellulose is made in plant cells.
The bonds are a bit different; the molecules are isomers. Glycogen bonds with what is called an alpha 1,4 bond, meaning that the first carbon of one glucose molecule is bonded to the 4th carbon of the next glucose molecule, but in a way that puts the bonds in a shape that falls below the plane of the molecule, and allows branching.
Cellulose bonds with beta 1,4 bonds. The first and fourth carbons of adjoining glucose molecules are still connected, but the shape of the bond falls above the plane of the molecule and does not branch.
Since enzymes are specific to their substrates, the enzymes shaped to fit glycogen bonds do not fit on cellulose bonds, which is why animals cannot digest cellulose on their own. In herbivores, there are microbes in their digestive tracts which can produce enzymes to break these bonds so the glucose can be used. In carnivores and omnivores like humans, there is no enzyme to break down cellulose so it becomes 'roughage' in our diets. It passes through the digestive tract without being broken down.
The Precambrian era envelopes the major bulk of the history of the Earth, beginning from the creation of the planet approx 4.5 billion years ago and terminating with the origination of composite, multicelled forms of life approximately 4 billion years after.
The Precambrian refers to the earliest of the geologic ages that are signified by the distinct layers of sedimentary rock. The Earth was about more than six hundred million years old when life started. The planet had cooled down from its native molten state, creating a solid crust and oceans formed by water vapor in the atmosphere.
At about three billion years ago, the atmosphere of the Earth was virtually devoid of oxygen. At approximately 2.4 billion years ago, oxygen was discharged from the seas as a waste product of photosynthesis by cyanobacteria. The levels of the gas slowly raised, attaining about 1 percent around two billion years ago.
Approximately 800 million years ago, the levels of oxygen attained about 21 percent and started to breathe life into more composite species. The oxygen-rich ozone layer was also created, protecting the surface of the Earth from the harmful solar radiation.
