Bio Lab Essay

Submitted By kellyp6
Words: 784
Pages: 4

Effect of Salt or Acid on Seed Germination Kelly Perioris SB13U Mr. Rennie Friday April 5, 2013

If acid is introduced to the seeds during germination, then the roots will not grow as long as there is no water given.

Why is it important to understand the effects of acid and salt on seed germination? What applications are there for this information? MATERIALS
• Petri dishes
• Paper towel
• Tap water
• pH2
• pH4
• pH6

• 100% sea water

Fold a piece of paper towel and place it in a petri dish. Place 10 seeds in the paper towel. Pour the appropriate solution on the paper towel, as indicated in the table below. Secure the lid with tape and label the petri dish.


1. Identify the independent variable(s) in this lab:
2. Identify the controlled variable(s) in this lab

Yellow Bacteria

Hexant 1 2 3 4 5 6
Household chemical N/A Mouthwash Hand sanitizer Alcohol Bleach Mr. Clean
Smallest Diameter (mm) 0 10 0 0 0 9
Largest Diameter (mm) 0 13 4 4 3 11
Mean Diameter (mm) 0 11.5 2 2 1.5 10

White Bacteria

Hexant 1 2 3 4 5 6
Household chemical Water Mouthwash Hand sanitizer Alcohol Bleach Mr. Clean
Smallest Diameter (mm) 0 14 0 10 9 0
Largest Diameter (mm) 0 27 0 10 20 0
Mean Diameter (mm) 0 20.5 0 10 10.5 0

Replicate 2 0 18.5 0 0 22 0
Replicate 3 0 7.5 7.5 0 30 0
Replicate 4 0 8 0 10.5 14 10
Replicate 5 0 8 0.5 6 16 15
Mean Diameter (mm) of 5 replicates 0 10.5 2 4.125 20.5 6.25

1. On the basis of the experimental evidence the bleach was the most effective at inhabiting the growth of bacteria because the mean diameter of all the replicates indicates that it surpasses any other chemical by nearly half making it appear to be the most effective.
2. The purpose of dipping one paper disc in water was to test the effects of water on bacteria and see how the bacteria would react. It was used a control to compare with the chemicals.
3. The purpose of calculating the mean diameter of inhabited growth from 5 different groups was to make sure the results were accurate and that any variables didn’t affect the final results. It gave a more precise final observation. Also the bacteria types from all groups were different so it showed the effects of the chemicals on a wide range of bacterium.
4. Household chemicals such as cleaners containing bleach work on inhabiting growth by the reaction it has with the bacterial cells. It reacts with the molecules and changes them and breaks down the cell wall making the bacteria fall apart. Many household chemicals such as detergents, soaps, hand lotions, disinfectants, window cleaners, surface sprays also carry an ingredient called triclosan that help to inhibit bacteria. This mechanism immobilizes the cell membrane preventing oxygen, nutrients and waste from leaving the cell therefore