This question is true, they are the only ones.
They are alike because they are the simplest form of life and the carry genetic information.
Strawberries and oranges are high in Vitamin C (in fact, a cup of strawberries has more Vitamin C than a medium-sized orange) as well as potassium. We can thus infer that Layla is probably deficient in these nutrients. To supplement Layla's intake of Vitamin C, Ruby can serve red and green peppers and kiwi, which (like strawberries) have more Vitamin C than an orange. To supplement Layla's potassium intake, Ruby can serve spinach, broccoli, and cantaloupe.
Https://www3.epa.gov/climatechange/kids/impacts/effects/ecosystems.html
this link might help you