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SEEDS AND FRUIT
Objectives for Exam #1:
1. Describe basic seed anatomy, including the critical structures of economically important
seeds.
2. Discuss the various ways seeds and fruits can be dispersed away from their parent plant,
and provide specific examples of each form of dispersal.
3. Classify fruits based on their basic structural characteristics, and provide specific examples
of different fruit types.
Objective for Portfolio #1:
Review laboratory information by writing practice exam questions about seeds and fruit.
Safety:
The seeds and fruits in this lab are not to be consumed due to their repeated handling and
exposure to laboratory materials.
Part I: Seed and Fruit Video
Take notes on the information about plants from the video. This is an opportunity to practice notetaking (transferring audio and visual information to written form). You can also compare notes with
other students at your table (sharing lecture notes is recommended in this course).
Part II: Seed and Fruit Structure and Function
For this part of the activity, you will be rotating through four different stations to learn about basic
seed and fruit characteristics.
Station A: Seed Anatomy and Germination
A seed develops and grows after fertilization of an egg (found in a plant ovule) by a sperm (found
in the pollen grain).
1. Examine dry and water-soaked bean seeds. Seeds are basically dormant, embryonic plants.
Each seed typically consists of a protective seed coat, some form of stored food, and the plant
embryo. Why is the seed coat an important structure?
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2. Remove the seed coat of a soaked bean seed with your fingernail. Much of the seed is made
up of two large kidney-shaped, fleshy cotyledons (or seed leaves), which serve as food storage
structures. Between the two cotyledons, is the small body of the embryo. Separate the cotyledons
to expose this body. Look for the embryonic root and the embryonic miniature leaves. Sketch the
internal structure of a seed and use the handout to label the: seed coat, cotyledon, embryonic
leaves (plumule), embryonic roots (radicle).
3. An iodine solution is used to test for the presence of starch. Iodine reacts with starch and turns
it purple. Examine the handout images of bean seeds stained with iodine. Which part of the bean
seed is stained by the iodine? _________________________ Starch is a chain of smaller
molecules. From your own knowledge of nutrition, what are these smaller molecules that make up
starch (fats, proteins, or sugars)? _________________________
4. Germination is the process of a seed breaking dormancy, the embryo becoming a seedling,
and eventually a developed plant. Why is it important (from the embryo and seedling perspective)
that the cotyledons contain large quantities of starch?
5. Observe the germinating bean seeds and describe the changes occurring at each interval.
Days germinating
(derive from date)
Characteristics of germinating bean seed/seedling
.
6. Many environmental factors can initiate germination. What is the environmental factor typically
associated with initiating germination? ________________________
7. Some seeds need a specific period of cold temperatures (sometimes a certain number of
months) before germination will occur. Why may it be important for seeds to germinate during a
specific time of year (for instance spring instead of fall)?
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Station B: Economically Important Seeds
Grains, seeds from grass plants, are the primary source of energy in the human diet. Other seeds
such as beans and soybeans are an important source of protein in many diets.
1. Often people discuss eating “wheat germ” or “oat bran.” Germ refers to the embryo of a seed,
bran refers to the seed coat. Fiber is an important part of the human diet because as it passes
undigested through the human digestive tract it stimulates muscle contractions (peristalsis). Which
part of the seed, the germ or the bran, would you expect to have more fiber? _________________
2. Whole wheat flour is made from the entire hard wheat seed (also called kernel). White flour
is made by removing the _____________________ (the bran) and the ______________________
(the germ), leaving behind only the _______________________. Three B-vitamins and iron are
lost when making white flour; so many white flours are enriched by the re-addition of these
elements. White flour also has less _______________________ than whole wheat flour.
3. Pasta is often made from semolina flour. Semolina flour is made from a different type of wheat
kernel than white flour, but is similar in that both the bran and germ have been removed. With this
in mind, which of the three flours (whole wheat, white, or semolina) is most nutritious?
______________________
4. There are many types of corn. Field corn is primarily raised to feed livestock. The majority of
corn raised in the United States feeds cattle and other animals. Popcorn has small hard kernels
that trap steam and explode when heated. Sweet corn is the corn humans typically eat canned,
frozen, or on-the-cob. When the kernels are developing in these corns, sugar changes to starch,
which makes the kernels appear full and bulky. In sweet corn, the sugar does not change as
quickly to starch, so the kernels appear shriveled when dried. Which of the three types of corn on
display has the highest starch content? ________________________________
5. Brown rice is the intact rice seed, but the oils, vitamins, and proteins in its exterior layers make
it difficult to store. When part of the seed coat is removed, white rice is produced. Similar to white
flour, white rice lacks most of the B-vitamins, and also some protein, unless enriched. Instant rice
is generally white rice that has been milled, cooked, and dried. Which of these three types of rice
is the most nutritious? __________________________ Which takes the longest to cook?
_________________________
6. Soybean seed protein and fat are important components of the human diet. Examining the
soybean plants (handouts), is the soybean a grain? __________________
7. Soybeans also can increase nitrogen availability in the soil, due to a symbiotic relationship with
________________________.
8. Cotton, the world’s most economically important vegetable fiber, is produced from the hairs on
the cotton seeds. Examining the cotton seeds, what is the probable role of these hairs?
9. Two types of sunflowers are grown as crops. Oilseed sunflowers provide edible
polyunsaturated oil. What do unsaturated oils reduce in the blood (in contrast to saturated oils)?
_______________________ Non-oilseed sunflowers are often dehulled and roasted for human
consumption, and during winter months in the U.S., often used as food for ___________________.
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10. Barley is one of the most cold-hardy grains and is primarily used for animal feed and beer
production. Sorghum survives dry conditions and is primarily used as animal feed. From the
handout, which state produces the most barley? ________________________ Which state
produces the most sorghum? ______________________
11. Oats are often used in cereals. Oat bran is a significant source of _________________ in
many people’s breakfasts.
12. Millet is a grain many people have not heard of, even though it is a major food (a staple) for
about a third of the world’s population. Examining the seed, how does millet need to be processed
to become edible? ______________________________________________________________
Station C: Fruit and Seed Dispersal
1. Use the words "seed" and "fruit," to complete the next sentence. When you eat the mature,
ripened ovary of a plant, you are eating a ________________. When you eat a ______________
you are eating an embryo and storage products surrounded by a protective covering.
2. In flowering plants, seeds can be dispersed within a fruit (coconut), or on their own (black
cottonwood). What may be an advantage of dispersing seeds away from the parent plant's
location?
3. There are many different means of fruit and seed dispersal, including: wind, water, animal,
propulsion (ballistics and twisting) and gravity. From the textbook (p. 11-17), provide an
example of each of the following dispersal mechanisms.
Type of Dispersal
Plant Example
Wind
Animal (“burs and stickseeds”)
Animal (“fleshy fruits”)
Animal (“stored nuts”)
Propulsion (“ballistics”)
Propulsion (“twisting”)
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4. Examine the fruits and seeds exhibited at your table. Determine the dispersal mechanism of
each and fill in the table with this information.
Plant Name
Dispersal
Mechanism
Rationale
5. Following the eruption of Mount St. Helens in 1980, plants quickly re-colonized the areas
covered by pumice and lava.
A. From the handout provided, how were the seeds of many of the re-colonizing species (such
as fireweed) originally dispersed to the new ground? _____________________________
B. Lupines also began to recolonize the disturbed areas. Lupines have a mutually beneficial
relationship with root bacteria that increase nitrogen in the soil. Lupine also produces
enormous amounts of seed. Examining the lupine at your table, how are the seeds
dispersed? _______________________________
6. An additional method of dispersal is by water. From the handout provided, what is an example
of a fruit (and seeds) dispersed by water?
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Station D: Fruit Classification
1. A fruit is a ripened (mature) ovary that protects and may disperse seeds. When the fruit
ripens, it can be fleshy (moist) or dry. Using the following fruit key of some of the major fruit types,
classify the fruits at your table.
General Category
Fleshy Multiple
Fruits
Fleshy Aggregate
Fruits
Fruit Type
Multiple
Aggregate
Drupe
Fleshy Simple
Fruits
(one flower, one
ovary)
Pome
Berry
Hesperidium
Pepo
Capsule
Dry Simple Fruits
that rupture open
to Release Seeds
Legume
Silique
Achene
Dry Simple Fruits
that do not rupture
Samara
Caryopsis
Nut
Fruit (at table)
Description
Fruit is produced from many flowers, with
one ovary each.
Fruit is from one flower with many ovaries.
Thin outer skin, center of fruit has a single
large stone or pit.
Thin outer skin, center of fruit has a papery
barrier that surrounds several seeds.
Thin outer skin, center of fruit lacks a
papery barrier and is soft.
Firm or leathery outer skin, inside of fruit is
divided into segments.
Firm or leathery outer skin, inside of fruit is
not divided into segments.
Multiple seed compartments within fruit.
Single seed compartment that splits open
along two seams (lines).
Like legumes, but with a two-segmented
pod.
Thin fruit wall with a single seed that
attaches to the ovary wall at a single point.
An achene with a wing-like appendage.
Thin fruit wall with a single seed that
attaches completely to the ovary wall.
Hard husk surrounds a single seed.
Fruit Type (include rationale)
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Examples
Pineapple, Fig
Blackberry,
Raspberry
Cherry,
Mango
Apple
Grape,
Pepper
Lime,
Grapefruit
Watermelon,
Zucchini
Okra, Horse
Chestnut
Soybean, Pea
Cabbage,
Radish
Dandelion,
Buckwheat
Ash, Elm
Corn, Rice,
Wheat
Hazelnut,
Chestnut
2. The basic characteristics used to classify fruits also provide information on plant “strategies” for
protecting and dispersing seeds. For each of the following characteristics, consider the possible
advantage to the fruit.
Characteristic
Advantage to the fruit?
Sweetness
Bright Color
High Water Content
Low Water Content
Segments (Like an orange)
Thick exterior
Many Seeds
3. From the handout provided at your table, what nutrients do animals get from eating apples?
4. Some stores and companies in the U.S. are beginning to adopt the Overall Nutritional Quality
Index (ONQI) scores for foods and beverages. These scores rank foods from poorest nutritional
quality (1) to highest nutritional quality (100), and may be a quick and less confusing way for
consumers to select nutrient-rich foods. Factors included in determining the score include: fiber;
folate; vitamins A, C, D, E, B12, B6; potassium; calcium; zinc; omega 3 fatty acids; bioflavanoids;
carotenoids; magnesium; iron; saturated fat; trans fat; sodium; sugar; cholesterol; fat quality;
protein quality; energy density and glycemic load found in that food, beverage or recipe. Only a
small set of foods have currently been scored. Looking at the list, which fruits are ranked with a
score of 90 or higher (high nutritional quality, using the above criteria)?
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Part III: Seeds and Fruit Practice Exam Questions (for Portfolio #1)
Skill: Review laboratory information by writing practice exam questions about seeds and fruit.
Assignment: Write eight different multiple-choice questions, two questions representing each of
the four stations in Part II of this activity (Seed Anatomy and Germination, Economically Important
Seeds, Fruit and Seed Dispersal, Fruit Classification). Each question should have one correct
answer and four incorrect answers, and be written at a level of difficulty appropriate for the material
covered. Indicate which answer is correct (circle the correct answer or include an answer key
following the questions). Avoid using true/false, all of the above, or none of the above answer
choices. You can refer to last year’s exams in Appendix D at the back of this manual for examples
of multiple choice questions.
Assessment: This assignment is worth 4.0 points. Each question (and five accompanying answer
choices) is worth 0.5 point (0.2 point for the question, 0.25 point for one correct answer and four
incorrect answers, 0.05 point for indicating the correct answer).
Portfolio assignments represent your individual skills. Do not submit an assignment that is a
duplication of any other individual’s assignment.
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