What does a seed need before it starts growing?

Water uptake can swell a seed and support metabolic processes, while respiration supplies usable energy from reserves. A root commonly emerges before the shoot becomes established. Temperature ranges, dormancy and light responses differ among species. This model compares permissive conditions qualitatively; the progress slider represents a sequence, not a measured number of days or a guaranteed germination percentage. In the model, watch the first root emerge before the shoot and leaves. The progress control represents development stages, not a count of real days.