Question

1. an investigation was carried out into competition between two species of grass, bromus madritensis and b. rigidus. equal numbers of seeds of b. madritensis were sown in a number of different pots. in each pot, an equal number of seeds of b. rigidus was then sown a different number of days after b. madritensis. the results are shown in the graph below. given that the total dry mass of plant material was the same in each pot, summarize the main conclusions that can be drawn from this investigation. suggest an explanation for the results when the delay before sowing b. rigidus was 30 days. percentage contribution of b. madritensis to total dry mass after 45 days. delay before planting b. rigidus/days

Explanation:

As the delay in sowing B. rigidus increases, the percentage contribution of B. madritensis to the total dry - mass increases. When the delay is 30 days, B. madritensis has a high percentage contribution (close to 100%). This could be because B. madritensis has a head - start in growth, allowing it to establish a larger root system and better access to resources like nutrients, water, and light. This gives it a competitive advantage over B. rigidus, reducing the growth and dry - mass contribution of B. rigidus.

Answer:

Main conclusion: The later B. rigidus is sown relative to B. madritensis, the greater the percentage contribution of B. madritensis to the total dry mass. Explanation for 30 - day delay: B. madritensis has established well due to the head - start, out - competing B. rigidus for resources.