Photosynthesis and cellular respiration are super important processes that show us how matter changes form but isn’t created or destroyed.
Photosynthesis is how plants (and some algae and bacteria) use sunlight to turn carbon dioxide (CO₂) and water (H₂O) into glucose (C₆H₁₂O₆) and oxygen (O₂). The simple equation for photosynthesis looks like this:
\[ 6CO_2 + 6H_2O + \text{light energy} \rightarrow C_6H_{12}O_6 + 6O_2 \]
In this process, plants take carbon from CO₂ and turn it into glucose, while releasing oxygen as a byproduct. The key idea is that matter (like carbon, hydrogen, and oxygen) is rearranged but not lost—it’s transformed into different molecules.
On the other hand, cellular respiration is how living things, including plants, take the chemical energy from glucose and turn it into ATP (which is like the energy currency for cells) to keep things running. The overall equation for cellular respiration can be summarized like this:
\[ C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy (ATP)} \]
During this process, glucose and oxygen are changed back into carbon dioxide and water, while releasing energy. Again, the matter is conserved. The atoms from glucose and oxygen are rearranged, forming water and carbon dioxide.
Oxygen Production: Plants make oxygen during photosynthesis, but this varies throughout the day. During the day, with plenty of sunlight, photosynthesis happens a lot, creating a lot of oxygen. But at night, without sunlight, photosynthesis stops, and while plants still do cellular respiration (which uses oxygen and produces carbon dioxide), they don’t produce any oxygen, so overall oxygen levels drop.
What Happens in the Dark: If you put a plant in complete darkness, it can’t do photosynthesis because it needs light. Without making glucose and oxygen, the plant runs out of its main energy source.
This impacts the plant’s ability to produce the four main types of biomolecules:
- Carbohydrates: Glucose is a key carbohydrate, and without it, the plant loses its energy source.
- Proteins: Plants need amino acids to make proteins, and many of those come from glucose. Without glucose, making proteins becomes harder.
- Lipids: Fats and oils are made from carbohydrates, so if the plant can’t make carbs, it can’t produce lipids either.
- Nucleic Acids: While DNA and RNA can be made from other things, without energy and building blocks from carbohydrates, making nucleic acids is tough, which can mess with the plant’s growth and reproduction.
So in conclusion, without light, a plant would eventually run out of its energy stores and wouldn’t be able to make important biomolecules. This shows how the conservation of matter is really important for understanding how energy flows and life works in plants!