Photosynthesis

Photosynthesis was the process whereby plants used chlorophyll to convert light into sustenance for themselves.

Krynoids required animal proteins while young, but could survive on normal photosynthesis later in life. (TV: The Seeds of Doom)

According to Nyssa, bright light was required for photosynthesis. The light on the plants converted carbon dioxide into carbohydrates, giving of oxygen. (TV: Four to Doomsday)

The Sixth Doctor and Mel used vionesium to speed up the rate of photosynthesis among the Vervoids so that they aged to death. (TV: Terror of the Vervoids)

The light from Jora's sun made photosynthesis extremely productive on the planet. (PROSE: Syntax)

Alternate timelines
Due to a changing climate, the fruit on fruit trees (such as oranges) in an alternate Earth glowed due to the breakdown of the photosynthesis exchange with the impurities collecting in the tree's fruit and from excess unutilised phosphor in the plant. (PROSE: Blood Heat)