A student investigated the effect of aged-grass compost (fertilizer made from decaying plant material) on the growth of bean plants. She thought that the compost would provide extra nutrients and make plants grow faster. Thirty bean seeds were divided into three groups and planted in different flats (boxes). All seeds germinated after 12 days and were allowed to grow for five days. The flats were each given the same amount of water and the same amount of light. Flat A was then fertilized with 3-month old compost; Flat B was given 6-month old compost; and Flat C was given no compost. At the end of 14 days the height of each plant was measured in centimeters. Choose all below that are constants in this experiment.

Question

A student investigated the effect of aged-grass compost (fertilizer made from decaying plant material) on the growth of bean plants. She thought that the compost would provide extra nutrients and make plants grow faster. Thirty bean seeds were divided into three groups and planted in different flats (boxes). All seeds germinated after 12 days and were allowed to grow for five days. The flats were each given the same amount of water and the same amount of light. Flat A was then fertilized with 3-month old compost; Flat B was given 6-month old compost; and Flat C was given no compost. At the end of 14 days the height of each plant was measured in centimeters. Choose all below that are constants in this experiment.

Amount of water

Amount of light

Type of flat

Height of the plants

Type of seed

Type of aged-grass compost

Answer 1

Amount of water

Amount of light
Type of flat
Type of seed

Answer 2

The constants in this experiment are:

- Amount of water
- Amount of light
- Type of flat
- Type of seed

Answer 3

The constants in this experiment are:

1. Amount of water: It is stated that all flats were given the same amount of water, meaning this variable was kept constant.

2. Amount of light: It is also mentioned that all flats received the same amount of light. Therefore, the amount of light was a constant in the experiment.

3. Type of flat: The experiment specified that the bean seeds were divided into three groups and planted in different flats. This means that the type of flat was kept constant within each group.

4. Type of seed: The type of seed used in the experiment was not mentioned to vary. Therefore, it can be assumed that the type of seed was constant.

The variables that were not constant in the experiment are:

1. Height of the plants: This is the dependent variable that was measured at the end of the experiment. The height of the plants varied between the different flats treated with different types of aged-grass compost or no compost.

2. Type of aged-grass compost: This is the independent variable. Different flats were treated with different types of aged-grass compost, specifically 3-month old compost for Flat A, 6-month old compost for Flat B, and no compost for Flat C.