Question

1. an apple is cut into slices. half of the slices are sprayed with lemon juice. all slices are stored in a sealed plastic bag. after 4 days, they are observed to see how brown they turned.

1. the respiration rate of a goldfish is measured. the goldfish is then placed in cold water and the respiration rate is measured again.

Explanation:

Identify variables for Question 10

Using the Independent Variable, Dependent Variable, and Controlled Variables knowledge points:

• Independent Variable (IV): The factor intentionally changed by the experimenter. Here, it is whether or not the apple slices are sprayed with lemon juice (presence of lemon juice).
• Dependent Variable (DV): The factor being measured or observed. Here, it is how brown the apple slices turned (degree of browning).
• Controlled Variables (CV): Factors kept constant to ensure a fair test. These include the type of apple, the storage container (sealed plastic bag), and the duration of storage (4 days).

Identify variables for Question 11

Using the Independent Variable, Dependent Variable, and Controlled Variables knowledge points:

• Independent Variable (IV): The factor intentionally changed. Here, it is the temperature of the water (normal/initial temperature vs. cold water).
• Dependent Variable (DV): The factor being measured. Here, it is the respiration rate of the goldfish.
• Controlled Variables (CV): Factors kept constant. These include using the same individual goldfish, the same water chemistry/source, and the same measurement duration.

Answer:

Question 10

• Independent Variable: Presence of lemon juice (sprayed vs. not sprayed)
• Dependent Variable: How brown the apple slices turned (degree of browning)
• Controlled Variables: Type of apple, storage in a sealed plastic bag, and duration of storage (4 days)

Question 11

• Independent Variable: Water temperature (normal vs. cold)
• Dependent Variable: Respiration rate of the goldfish
• Controlled Variables: The same goldfish, water volume/source, and measurement method