Vaishnavi says plants don't need to respire the way animals do — they only take in carbon dioxide…

Why

Vaishnavi is describing photosynthesis correctly: in sunlight, leaves take in carbon dioxide, make food and release oxygen. Where she goes wrong is in thinking that is the whole story. Every living cell — in a root, a stem, a leaf or a seed — needs energy, and it gets that energy by respiration: breaking down food using oxygen and giving out carbon dioxide, exactly as animals do. Respiration never stops, day or night. On a sunny day photosynthesis runs so much faster that the plant gives out more oxygen than it uses, which hides its respiration. At night there is no photosynthesis, so the plant only respires. Test: sprouting seeds kept in a closed jar use up its oxygen and fill it with carbon dioxide — they have no green leaves making oxygen, yet they are clearly alive and using energy. Rudra is right: plants respire all the time, using oxygen and giving out carbon dioxide, alongside photosynthesis in the daytime.