There blocks or subunits in living organisms: carbohydrates,

There
are four types of macromolecules “large molecules” made up from a smaller building
blocks or subunits in living organisms: carbohydrates, lipids, proteins and
nucleic acids. Within the lab, observations was made and recorded. The food
samples that were tested for starch with the use of iodine solution, boiled
rice had the highest concentration of starch whilst onion and garlic had the
lowest concentration of starch found within them when tested with eight to ten
drops iodine and viewed under the microscope.

When
stained with the iodine solution and it appears black or blue, it indicates
that starch is present but it does not mean starch is the only the component present
in the food group. The food samples can be made up of other components such as
fiber, magnesium, iron, vitamins, protein and much more which can be present within
the food group (Claussen, 1999).

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Several
food samples was tested for starch using iodine solution when a few turned out
to be that no starch was present. This was so for example the onion; the bulb
of it was formed from specialized leaves. Chloroplast which is formed after
photosynthesis had occurred within the leaves, the few glucose formed within
that process automatically converts to starch within the onion bulb. Though the
food sample may not appear blue or black to indicate starch is present it does
not mean it has no starch. It may have little traces of them.   

Polysaccharides
are basically sugars used to store energy in some cases. It can be found within
both plants and animals. Glucose molecules is a chain of starch that has a
liner form within amylose and glycogen which are starches common storage used as
fuel in plants and animals. They are broken down into smaller molecules in the
production of energy. Iodine solution is used for testing for starch, hence
when combined/reacted with polysaccharides it stains it to a dark blueish-
blackish colour indicating that starch is present.

For
all the solutions that was tested for starch various colours appeared whereby
some hadn’t changed at all, they remained unchanged with their initial
appearance before starch was added. This may be because of starch being absent
within the solution(s).