Based on the student's investigation, it appears that the root space has a significant effect on plant growth. In the data provided, the plants in Group A, which had less root space (3 cm deep), generally grew shorter than the plants in Group B, which had more root space (10 cm deep). For example, by Week 6, Group A plants reached an average height of 10 cm, while Group B plants grew to an average height of 18 cm. This shows that the plants with more space for their roots were able to grow taller and likely healthier.
To determine whether this effect was due to environmental factors (like water, sunlight, or soil, which were the same for both groups) or genetic factors (differences between the plants), we can look at how the plants were grown. Since both groups were the same variety of plants and were cared for under identical conditions, we can conclude that the difference in growth is likely due to the amount of root space available to them. This suggests that having more root space allows plants to absorb more nutrients and water, leading to better growth.
In summary, the data indicates that more root space helps plants grow taller, and since the experiment controlled other factors, we can say that this effect is likely due to the root space, not genetics or other environmental conditions.