Video Transcript
Which waste product of a plant
could be reused to synthesize its proteins? (A) Carbon dioxide, (B) oxygen, (C)
water vapor, (D) nitrogenous waste.
To answer this question, let’s
review what is needed for basic protein synthesis. Proteins are polymers of amino
acids that have been linked together. You might recall that the basic
structure of amino acid has a central carbon atom, the 𝛼 carbon, that can form four
bonds: one with an amino group, NH2, one with a carboxyl group, COOH, one with a
hydrogen, and one with a side chain that is variable depending on the amino
acid.
Every single amino acid has an
amino group, and nitrogen is a major part of the amino group. Just like animals, plants generate
nitrogenous waste products, such as urea, as a result of protein metabolism, during
which the proteins are broken down into amino acids and short chains of amino acids
called peptides.
Nitrogenous waste products can be
excreted or reused for protein synthesis if they are transformed into nitrates or
ammonium. Plants can therefore convert some
of their nitrogenous waste into reusable forms to synthesize the proteins they need
for further growth and development.
So the waste product of a plant
that could be reused to synthesize proteins, and the correct answer to this
question, is (D), nitrogenous waste.
