UNIT
9: LESSON 2
KERNEL SURGERY
SUBJECT: Science
OBJECTIVE: Students will learn the four major parts of a corn
kernel and the functions of each. They will also be introduced to the
awesome potential of those little capsules-their role as a seed for
new life, and their potential as a renewable source of energy for the
world.
MEASUREMENT: Students are aware of the four major parts of a
corn kernel, and can identify some of the ways the kernel is used.
BACKGROUND FOR TEACHERS:
The kernel is the most important part of a corn plant!
It is the SEED! It contains everything necessary for a new corn plant
to germinate and begin its life. This small capsule contains all the
food needed to provide energy for the germinating plant until it can
feed itself. It also contains all the genetic material (See Unit
4, Lesson 2 that will determine the traits of that plant.
It is the PRODUCT! Kernels are full of the nutrients and energy that
people (and animals) need from their food. There are over 3000 human
food uses for the kernels and their contents. See Unit
9, Lesson 1). Ground corn kernels are the major part of the diet
for most of the animals raised for meat production (See Unit
6). The starch and other components of kernels can also be used
for industrial purposes (See Unit 7
for descriptions of the ethanol fuel, plastics, and more that can be
manufactured from corn.)
There are four major types of corn (and all of them have kernels with
the same four parts):
- sweet corn that is eaten as a vegetable
-
field corn that is refined for industrial uses in addition to food
products and animal feed
-
pop corn that is eaten as a snack
-
seed corn that farmers plant in the field for crop production
A typical ear of field corn contains 600-800 kernels (See Unit
1, Lesson 2). There are over 70,000 kernels in a bushel of corn.
A bushel of corn typically sells for $ 2 to $ 3. From that bushel of
corn, from those 70,000 kernels it is possible to produce 2.5 gallons
of ethanol fuel, or 31 pounds of cornstarch, or 33 pounds of corn sweetener,
PLUS 11 pounds of animal feed, over 2.5 pounds of gluten meal, and 1.6
pounds of corn oil. (See Unit 9, Lesson 3 for
more details.)
Kernels are the seeds of new life. And they are the storehouses of
renewable energy. They are truly a-maizing!
STUDENT ACTIVITIES:
1. Ask students to read the story David Makes
Cupcakes, paying close attention to the last several paragraphs
which describe many of the food products made from corn ("There is cornSTARCH
in the sprinkles, corn SYRUP in the writing gel. The frosting is sweetened
with corn SUGAR. There is corn OIL in the cake.")
2. Hand out ears or kernels of corn to the students for them to see
and touch. They will also dissect them if it's appropriate. (Example
1)
(Note: Field corn will be difficult for young children to dissect,
but it is the best for observing the four major parts of a kernel. Mature
sweet corn will be soft, so a serrated knife is recommended. Seed corn
will be treated with fungicides to prevent seedling disease in the field,
so is NOT recommended. Frozen corn from the grocery store will at least
allow students to visualize and appreciate the kernel.)
3. This drawing (Example 1) could be used as a handout or as an overhead
transparency. Use it to teach the different components of a kernel.
-
The pericarp is the outer skin-like covering of the kernel. It
is a layer of fiber. It protects the endosperm and germ from being
physically injured, and also from some insects and diseases.
-
The tip cap is the point where the kernel was attached to the corncob.
When it was attached, it served as the major pathway for food and
water to the kernel.
-
The germ is the only living part of a kernel. It contains all the
information the kernel needs in order to grow into a corn plant,
plus vitamins and minerals the small plant will need.
-
The germ also contains corn oil; 25 percent of the germ is oil.
- The endosperm makes up over 80 percent of the kernel. It is the
source of energy and protein for the new corn plant.
There are two types of starch in the endosperm, soft and hard. The
soft is the white, almost powdery portion. The hard endosperm has starch
packed tightly together. When the kernel dries, the soft endosperm collapses
and forms a dent in the top of the kernel.
The gluten is the protein layer found on both sides of the germ.
4. Younger students can complete the dot to dot diagram of a corn kernel
and fill in the name of the parts. Older students can complete the more
detailed drawing. (Worksheet 1)
5. The students can work in teams for the dissection. Ask them to carefully
remove several kernels from the cob (if you have a cob!). The point
of attachment is the tip cap. Then ask them to carefully make a longitudinal
cut through the center of the kernel. They should now have two equal
halves they can examine with a hand lens or microscope. Ask them to
locate the pericarp, the germ, and the starch in the endosperm. (Example
1)
6. Ask students to draw a diagram of what they saw.
7. Ask students to discuss the importance of these little kernels.
Specifically discuss the importance of them as the SEEDS for new corn
plants. Then ask them to discuss the different PRODUCTS that they imagine
can be made from the kernels. Units
6, 7, 8,
and 9 all deal with these products in greater
detail!
