Question

biochemistry online practice
complete this assessment to review what you’ve learned. it will not count toward your grade.

by performing photosynthesis, plants create everything they need to build all biomolecules. is this true? why or why not? (1 point)

○ this is not true because plants need to sequester nitrogen from the soil to build amino acids.
○ this is not true because plants need to perform cellular respiration to break down the glucose into carbon, hydrogen, and oxygen.
○ this is true because photosynthesis produces glucose, and plants only need sugars, not amino acids or fatty acids.
○ this is true because photosynthesis produces glucose, which has carbon, hydrogen and oxygen—the building blocks for all biomolecules.

Explanation:

To determine the correct answer, we analyze each option:

• Option 1: Amino acids (needed for proteins) require nitrogen. Photosynthesis produces glucose (C, H, O), but plants get nitrogen from soil to make amino acids, so they can't build all biomolecules (like proteins) just from photosynthesis output. This makes sense.
• Option 2: Cellular respiration breaks glucose for energy, not to get C, H, O for biomolecules (photosynthesis already provides glucose with those elements). So this is incorrect.
• Option 3: Plants need amino acids (for proteins) and fatty acids (for lipids), not just sugars. So this is wrong.
• Option 4: Biomolecules like proteins need nitrogen (not just C, H, O from glucose), so photosynthesis alone doesn't provide all building blocks. Thus, this is incorrect.

Answer:

A. This is not true because plants need to sequester nitrogen from the soil to build amino acids.