# Students armed with Excel spreadsheets calculate the biotic potential of a tomato plant “taking over the world”

Subject:

Science

6, 7, 8, 9

Title – Tomatoes Take Over The Earth!
By – Erik Hanchett
Primary Subject – Science

Objective:

Determining the biotic potential of a tomato using an excel spreadsheet

Standards:

Technology: TSS6C2PO3
Science: MSS4C3PO3, 4, 5

Description:

Students will determine the biotic potential of a tomato plant by counting the seeds of one tomato and then calculate the number of plants after three generations using an Excel spreadsheet.

Activity Steps:

Procedure:

1. Write in your journal the following investigation question: How many descendants can one tomato plant leave behind in just three generations if every seed were to germinate, grow and produce fruit to its capacity?
2. Record in your journal your guess (prediction) of the number of descendants that one tomato plant can leave behind in just three generations.
3. Now graph out your prediction on the journal insert sheet (below).
4. Now calculate using the journal insert sheet, the number of tomato plants that one tomato can produce in just three generations.
• Assume that tomato plants can self-pollinate and that each plant makes 100 fruits each season and then dies.
5. Make a line graph of the population growth of your tomato over three generations on the journal insert sheet.
6. What kind of growth pattern does the graph show?
7. What will happen in just a few more generations?
8. Why doesn’t this happen in real life?
9. Use the terms exponential growth, limiting factors, and carrying capacity in a short paragraph to describe the results that you have graphed out:

Note:

An Excel sheet can be programmed so that students only have to enter the amount of seeds and Excel will automatically graph the result.

Journal Insert Sheet

Generation Stage

#### Calculation

Result
P (parent generation) Tomatoes None a.
Seeds Count seeds b.
F1 (first generation) Plants 1 plant per seed c.
Tomatoes 100 tomatoes per plant d.
Seeds d. x b. e.
F2 (second generation) Plants 1 plant per seed f.
Tomatoes 100 tomatoes per plant g.
Seeds g. x b. h.
F3 (third generation) Plants 1 plant per seed i.

Assessment: