Question

1. pour mixed gelatin into each of the four cups.
2. mix in the appropriate pineapple chunks.
3. record the state of the gelatin over time (solid or liquid).

analysis

1. why did cup #1 contain only j - o and no pineapple?

Explanation:

In scientific experiments, a control group is used to compare with experimental groups. Cup #1 with only Jell - o (no pineapple) serves as a control. It allows researchers to observe the natural state of the gelatin (without the influence of pineapple enzymes). This helps in determining if any changes in the other cups (with different types of pineapple) are due to the pineapple (e.g., presence of bromelain enzyme in fresh pineapple which can break down gelatin proteins) or just normal gelatin behavior.

Answer:

Cup #1 is a control. It helps in comparing the effect of different types of pineapple (boiled, canned, fresh) on the gelatin. By having a cup with just gelatin (no pineapple), researchers can see what the gelatin would be like without any pineapple - related influence (such as enzyme action from fresh pineapple). So, it is used for comparison in the experiment.