SEEDS AND FRUIT

Part I: Seed and Fruit Video

Take notes on the information about plants from the video. This is an opportunity to practice note-taking (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?

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)?

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 ______.

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”)

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?

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 / Fruit Type / Description / Examples
Fleshy Multiple Fruits / Multiple / Fruit is produced from many flowers, with one ovary each. / Pineapple, Fig
Fleshy Aggregate Fruits / Aggregate / Fruit is from one flower with many ovaries. / Blackberry, Raspberry
Fleshy Simple Fruits
(one flower, one ovary) / Drupe / Thin outer skin, center of fruit has a single large stone or pit. / Cherry, Mango
Pome / Thin outer skin, center of fruit has a papery barrier that surrounds several seeds. / Apple
Berry / Thin outer skin, center of fruit lacks a papery barrier and is soft. / Grape, Pepper
Hesperidium / Firm or leathery outer skin, inside of fruit is divided into segments. / Lime, Grapefruit
Pepo / Firm or leathery outer skin, inside of fruit is not divided into segments. / Watermelon, Zucchini
Dry Simple Fruits that rupture open to Release Seeds / Capsule / Multiple seed compartments within fruit. / Okra, Horse Chestnut
Legume / Single seed compartment that splits open along two seams (lines). / Soybean, Pea
Silique / Like legumes, but with a two-segmented pod. / Cabbage, Radish
Dry Simple Fruits that do not rupture / Achene / Thin fruit wall with a single seed that attaches to the ovary wall at a single point. / Dandelion, Buckwheat
Samara / An achene with a wing-like appendage. / Ash, Elm
Caryopsis / Thin fruit wall with a single seed that attaches completely to the ovary wall. / Corn, Rice, Wheat
Nut / Hard husk surrounds a single seed. / Hazelnut, Chestnut
Fruit (at table) / Fruit Type (include rationale)

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)?

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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