Your first experiment!

Your first experiment!

TASIS Biological Investigators, Inc.Contract Biological Research at

competitive prices!

Your client

The Ministry for Agriculture and Land reclamation for the

Egyptian Government

Your brief…

Farmers in the Fertile Crescent have become increasingly concerned about the build-up of salt in the soil and water. The farmers know that small amounts of salt in the soil and water will not adversely affect the germination and growth of their crops. But as the salt concentration increases, negative impacts occur. Eventually, salt concentration may become so high that seeds will no longer germinate.

Some background information…

What sort of ‘salt’ are we talking about?

How do these ‘salts’ kill germinating seedlings?

• NaCl, CaCl, KCl, MgCl, HCO3, CO3, MgCO3, NO3,- NH4

+, K+

• Osmotic damage – plasmolysis, exosmosis

Your Research Project

• You have two weeks to conduct a research study and present a report, including data and graphs, on how salt concentration affects the germination of seed crops

• The Government wants to understand how much salt mung beans tolerate before they fail to germinate

You have been divided into 3 teams to tender for this project:

• Team 1:• Team 2:• Team 3:The team who develops the best experimental

design for the research project will gain a ‘homework Pass’

Experimental Design

• Working Observation: High salt concentration can adversely affect the germination of seeds

• Null hypothesis: If…………..then……….

Experimental Design

• Working Observation: Salt concentration can adversely affect the germination of seeds

• Null hypothesis: If the salt concentration of the water supply changes, then the percentage of germinating seeds does not change

• Alternative hypothesis: If the salt concentration increases, then the percentage of germinating seeds is adversely affected

Experimental Design

A few starting questions:

1. How do we define ‘germination’?2. Can we use plain old tap water? – does it

already contain salt?3. Can you think of other factors that may affect

seed germination? 4. How are the experimental conditions

affected if water evaporates from the petri dishes?

…and a few questions about study design…

1. Which concentrations of salt solution should we use?

2. Do you want this to be a controlled experiment? What will be our control groups?

3. How many test groups should we have?4. How many times will you repeat each test?5. How will we prepare our stock salt solutions?

Dependent Variable

Independent Variable

Controlled variables

Uncontrolled variables

Seeds and Salt experiment

Dependent Variable Percentage of germinated seeds

Independent Variable Sodium chloride concentration

Controlled variables

Uncontrolled variables Ambient temperatureHumidityEvaporation

Seeds and Salt experiment

Data Collection

HOW AND WHEN?• How? – any special equipment?• How? – will you record your data? – make a

table!• How often?• Do you need any equipment?

Data Collection

Predictions/ Conclusions

• Make a prediction about your conclusion. • Do you expect to find support for your

hypothesis? • Why or Why not?