Download Seed Germination Lab

Seed Germination Lab Instructions #5
Name ________________________
Use this outline to help you practice the steps of the scientific method. You will refer back to this lab
as a template for other labs.
In this lab we are studying the effect of temperature on seed germination.
Title: the title should be simple and include your independent and dependent variables. In this lab we
are studying the effect of temperature on seed germination. Your title could be “Seed Germination and
Temperature” or “The Effect of Temperature on Seed Germination.”
Statement of the Problem: The statement of the problem (you may have called it “the Big
Question” in 6th grade) expresses what you are investigating. It is usually in the format:
How does (independent variable) affect (dependent variable)?
Background Information: The background information (text and diagrams/pictures) gives you
information about the topic you’ll be investigating. This information will help you create a strong
hypothesis. Read the background info and highligh the parts in italics.
Many different types of living things live on Earth. All of these organisms share certain
characteristics. One of these characteristics is that all living things are made of cells. Another
characteristic is that all living things reproduce organisms of the same species. Living things have
evolved various methods to reproduce.
One group of organisms, seed plants, produces seeds to reproduce. Various factors that may
affect whether a seed will become a mature plant include water, water quality, temperature, gravity,
crowding, seed age, seed coat condition, amount of oxygen, and light intensity. In this experiment you
will investigate how temperature affects seed germination. Germinate means to sprout so it refers to
the early growth of the new plant from the seed. Often, germination takes place when the seed is
underground.
Seeds are really quite amazing. There are
many types of seed plants producing many types
of seeds, but all seeds have 3 main parts.
* The embryo is the immature plant that
has immature roots, stems, and leaves.
* The seed coat protects the seed from
drying out.
* Packed with the embryo within the seed
coat is the temporary food supply (called the
endosperm) to provide energy for the embryo to
germinate and to support the seedling until it is
able to perform photosynthesis and make its own
energy.
The embryo stays dormant inside the seed coat until it is triggered to germinate. The timing of
germination, also known as the breaking of dormancy, is important for the seedling’s success. In New
England, many plants produce seeds in late summer. These seeds are carried on the wind and fall to
the ground in all sorts of environments. If they were to germinate right away, the young plants would
die as soon as the weather got colder. These seeds usually are programmed to germinate only after
they have experienced a long period of low temperatures (our winter). In the spring, when the soil
temperature is warm enough and the soil is moist, the seeds will germinate and a new generation of
plants will grow.
A seed can stay dormant for a long time as long as the seed coat is intact. Water is essential for
the germination because it softens the seed coat and starts the chemical reaction within the embryo
that allow it to start growing. When conditions are perfect, the embryo will start growing and use the
stored food (endosperm) as a source of energy. This growth of the embryo is called germination. The
embryo will use up the stored food (endosperm) and the roots will grow downward and the leaves and
stems will grow upward. Once the new leaves are exposed to the environment, photosynthesis will
begin, and the plant will be able to make its own food. The plant now enters the growth phase of its
development. This investigation will only study the effects of temperature on seed germination, not
plant growth.
Variables:
Independent: The independent variable (IV) is the factor that you change on purpose in your
experiment. It has an effect on the dependent variable (DV). For example, if you were investigating
how the amount of Gatorade affects how fast a person runs, the Gatorade is the IV and how fast the
person runs is the DV.
When you do an experiment you usually have 3-5 levels of the IV so you can determine which
one affects the DV the most. For example, you could use no Gatorade, 1 cup Gatorade, and 2 cups
Gatorade as the levels of your IV. You want to have a good range of IV levels into order to get valid
data.
In this experiment, what temperatures would be good to test as our IV? Why? (Hint- go back to
your background information to see what is there about temerature.)
Dependent: The dependent variable (DV) is what you measure. This lab is about seed germination,
not plant growth, so we won’t be measuring the height of the plant. How can we indicate if a seed has
germinated? What signs would you look for? (Hint: use your background information.)
Constant: Constant variable are factors that you need to keep constant in your experiment so that
your results are only caused by the different levels of your independent variable. For example, in the
Gatorade experiment, here are some constant variables: the same runner should be used, the same
amount of food for the runner, same sneakers and clothing, same wind conditions, the same rest level,
the same measuring cup for the Gatorade, etc.
Lab Design: This includes your materials and step by step procedure. For this lab, the material list
and procedure will be given to you. It often includes a diagram that clearly illustrates the different
levels of your IV, and how you measure your DV.
Hypothesis: A hypothesis is a prediction about how your IV will affect your DV. It is not a blind
guess; it should be based on your background information and general knowledge. It must include 2
parts: a) your specific prediction and b) the reason for your prediction.
Examples: (Are these good or bad? Why?)
1. I think that Gatorade will affect the runner.
2. I think that Gatorade will affect how fast the runner goes.
3. I think that 2 cups of Gatorade will make the runner go the fastest.
4. I think that 2 cups of Gatorade will make the runner go the fastest because in my background
information I read that runners need to have proper hydration and enough electrolytes for peak
performance. 2 cups of Gatorade is the most that I am testing.
Data:
There are 2 types of data: qualitative and quantitative.
Qualitative: descriptive. In this lab, that includes color of seeds, color and texture of seed coat, smell,
etc. It is not numerical.
Quantitative: (think quantity = number) Data that are measured and assigned a numerical value. In this
lab, that includes the number of seeds germinated each day. Since this doesn’t measure a time or a
height that are easily quantified, it is important that we all have the same understanding of what a
germinated seed will look like versus one that hasn’t germinated. In this lab, if the radicle has emerged
from the seed, it has germinated.
We need to have a data table to record both qualitative and quantitative data. Because we will be
combining data from different groups, we also need sections for indivual data and class data.
Graphing:
Line Graphs- represent a change over time
Bar Graphs- represent a cause and effect relationship
You will attach your graph to your final report.
Conclusion: The conclusion section is where you determine whether your hypothesis was supported
by your data, not supported by your data, or partially supported by your data. You have to analyze your
data and look for patterns or trends. It is also the place to identify sources of error and suggest future
correction to the procedure to reduce the errors. For this lab, you will answer some guiding questions
to help you write your conclusion.