Bizarre Facts in Biology



Bizarre Facts in Biology When Is a Moss Not Really a Moss?

The common names of some organisms may imply they're something entirely different from what they really are. Two such examples are reindeer moss and Spanish moss. Based on the common names, one might conclude the organisms in question are in the plant group of bryophytes and are therefore nonvascular plants with dominant gametophytes. Lace lichen (), which is sometimes mistakenly called Spanish moss, only adds to the confusion.

Reindeer moss () is like lace lichen because it is actually a lichen. It is also formed by the symbiotic relationship between a fungus and an alga. The range of this lichen is quite extensive, but it is an especially important component of the tundra biome.

Spanish moss () is actually an angiosperm. It produces tiny flowers and after fertilization a seed-containing pod forms. The seeds have a winglike structure which allows them to be caught by the wind and blown to another tree branch. Spanish moss is an epiphyte, meaning it grows on the surface of other plants. If you're still wondering how an angiosperm came to be called a moss, it's because the French and their rival Spanish explorers taunted each other with names based on the Native American name for the plant that eventually were shorted to "graybeard" and "Spanish moss."

1. What kind of organism is a lace lichen?

 

Answer: Lace lichen is a symbiotic relationship between a fungus and an alga.

Hint: Refer to the information in the "lace lichen" link. What did you learn about lichens in your text's chapter (20) about fungi?

2. For what animals is reindeer moss an important source of food? How are these animals able to digest the reindeer moss?

 

Answer: Reindeer moss makes up 60-70% of the winter diets of reindeer and caribou. These animals have microorganisms in their digestive systems (much like those of cows) capable of digesting the lichen.

Hint: Refer to the information in the "reindeer moss" link. It's not called reindeer moss because it looks like reindeer! For the answer to the second question, consider what you learned about some of the symbiotic relationships in which microorganisms are involved. Do you already know something about how cows digest all the grass they eat?

3. How is a plant that is an epiphyte different from a plant that is a parasite?

 

Answer: An epiphyte grows on the surface of other plants without doing harm to the other plants. Epiphytes don't get nutrients from the plants on which they live. Parasitic plants draw nutrients from and may harm the plants on which they live.

Hint: Refer to the information in the "Spanish moss" link. Think about what the "epi" part of the word tells you; it's like your epidermis. What did you learn about parasites in your text's chapters about microbes (19) and fungi (20)?

Web Investigations Web Investigations: Queen of the Parasites

Estimated time: 10 minutes

The queen of the parasites, Rafflesia, discussed in the chapter case study is only one of several plants that produce very stinky flowers (). Many may wonder "why stinky, putrid-smelling flowers"? Flower characteristics tend to correspond with pollinator characteristics so that a specific pollinator visits one kind of flower, which increases the accuracy of pollen transport. Rafflesia's stinky flowers may help it overcome some of the huge problems the plant has ensuring successful pollination (). If pollination of a female Rafflesia flower occurs, a small round fruit containing thousands of seeds develops. The fruit ensures the seeds are dispersed (), thereby increasing the distribution of Rafflesia plants.

A parasitic lifestyle is not unique to Rafflesia. Dodder (), a pest plant, is non-photosynthetic like Rafflesia. Mistletoe () which most people think of only at Christmas, is considered a semi-parasitic plant because it retains the ability to do photosynthesis.

1. What is another kind of plant that makes putrid-smelling flowers? Geographically, what does this plant have in common with Rafflesia?

 

Answer: Another kind of plant that makes stinky flowers is the Titum arum. It too is found on the Indonesian island of Sumatra.

Hint: Refer to the information in the "very stinky flowers" link and follow the FAQs link to find the geography answer. For the geography answer, think about what kangaroos and koalas have in common.

2. What Rafflesia flower characteristics hinder the plant's ability to ensure successful pollination?

 

Answer: Rafflesia produces unisex flowers, so a male flower must be in proximity to a female flower if pollination is to occur. High flower bud mortality minimizes the chances of male and female flowers blooming near one another. Flower blossoms last only 5-7 days. Habitat destruction means the plants are increasingly separated from each other, making it unlikely that a male and female flower will bloom near one another.

Hint: Refer to the information in the "pollination" link. Remember pollination is the transfer of pollen from flower anthers to the flower stigma. What could interfere with or prevent the transfer process? How would human activities impact Rafflesia in general and in turn impact the pollination process?

3. How are Rafflesia seeds dispersed?

 

Answer: Squirrels and tree shrews eat the fruits and then disperse the seeds in their stools.

Hint: Refer to the information in the "dispersed" link. Remember, Rafflesia is an angiosperm, so it should produce flowers and seed containers, aka _____.

4. What does mistletoe obtain from its host plant?

 

Answer: Mistletoe does its own photosynthesis but gets water and mineral nutrients from its host plant.

Hint: Refer to the information in the "mistletoe" link. Mistletoe grows on another plant, so its roots are not anchored in the ground. What do roots typically obtain from the soil for a plant?

Issues in Biology Where Have All the Food Plants Gone?

You are probably aware that the loss of biodiversity is a major environmental problem today, due primarily to habitat degradation and deforestation (see Issues in Biology for Chapters 22 and 41), but did you know that we face an equally serious loss of biodiversity in our food supply? Today, 97% of food plants that were available in 1900 are extinct, leaving the world to rely on 150 food plants, of which 20 make up 90% of our food supply. Agriculture really has two options: either cultivate crops that are adapted to local conditions, or change the conditions to suit the plants. The modernization of agriculture that began in the 1950s and '60s has taken us down the second path. Today hybrid varieties of plants are produced for high yield, uniform harvesting time, and durability for shipping across the country; and they are supported by the agrichemical industry in the form of herbicides, pesticides, and fertilizers. The result is that our food supply now depends upon a few hybrid varieties: six varieties constitute about 90% of our corn crop, four varieties about 60% of our wheat crop, and two varieties about 80% of our potato crop. The situation is similar among livestock, where, for example, Holsteins constitute about 80% of our dairy cattle and our beef cattle are mostly Angus and Hereford.

This monoculture approach to agriculture is not without problems. When a disease or pest is successful with a particular variety, the result can be disastrous. The classic example occurred when Ireland planted a single variety of potato that was susceptible to a virus. The result was the great potato famine of 1846 that drove waves of immigrants to this country. More recently, and closer to home, a fungus blighted our corn crop in 1970. Beginning in Florida, and spreading through the corn belt, it destroyed 20% of our yield that year, up to 50% in some states.

So, how did we get into this situation? Prior to the Industrial Revolution, about 150 years ago, the majority of Americans lived and worked on small farms. Industrialization, however, has had such an impact on agriculture that now only about 3% of the American workforce produces enough food for our nation and for trade on the world market. In order for an increasingly smaller labor force to sustain the agricultural needs of a growing nation, changes had to be made, and technology stepped in. Now, American agriculture is largely controlled by large corporations, with the result that a few high-yield varieties of hybrid and engineered seeds, which are dependent upon the use of agrichemicals, are the standard. Hybrid seed offers a great advantage for the seller, as hybrid plants are usually either sterile or will not breed true and cannot be saved for the next planting, so the seed must be purchased again each year. Moreover, hybrid varieties can be patented so commercial developers have proprietary control over their use. This practice has led to revolt in India, where farmers are exercising methods of protest dating back to the Indian independence movement, spearheaded by Gandhi, in order to defend their rights to grow, breed, and exchange crops without control by transnational corporations.

One solution to the problem of diminishing diversity in our food supply is the preservation of heirloom varieties of plants (), local varieties of plants that have been grown in family gardens for generations. Probably no one in this country has done more to preserve heirloom varieties than Kent Whealy (). Kent and his wife, Diane, had been given seeds from a couple of garden varieties of plants by her grandfather. These seeds had been brought over from Bavaria by his father. When the grandfather passed away that year, the Whealys decided that if these heirloom varieties were to survive, they would have to cultivate them. One of the plants was a large pink German tomato that they have grown to up to nine inches across (compare that with what you find in stores these days). In 1975 Kent began to locate others who had heirloom varieties, and since then this effort has grown into a network, known as the Seed Savers Exchange (), of some 8,000 people who are working to collect, maintain, and distribute heirloom varieties. To date, they have cataloged 17,000 varieties, including more than 4,000 of tomatoes, 700 of peas, 700 of lettuce, 600 of potatoes, and 120 of watermelons. Other seed saver organizations have also emerged, as people are beginning to appreciate native plants as part of their cultural heritage ().

The preservation of heirloom varieties offers many benefits for our agricultural system. First, these varieties are often adapted to local growing conditions, so that some varieties may be particularly useful in certain areas. Secondly, these varieties represent genetic diversity, a genetic library from which we can borrow information. For example, a gene resistant to the fungus that spread throughout our 1970 corn crop was found in an heirloom variety that had been kept in a farm museum. And finally, the heirloom varieties just taste better and continue to grow to be harvested over a longer season. So while most people are looking to the technologies of the future to sustain our agricultural productivity, some people are also looking to the past.

1. Why do some people feel that our current food supply is vulnerable to disaster?

 

Answer: Our food supply is dependent about a limited number of strains/breeds of plants and animals. That means the genetic variability in those populations is fairly limited.

Hint: Review the material in the first couple paragraphs of the issue's text. Remember what you learned about the endangered animal species like the cheetah population in chapter 15 of your textbook.

2. In what ways has modern agriculture improved our ability to feed growing populations, and what problems have we inherited with these technological advancements?

 

Answer: Today's crops are high yield and can be harvested in a minimal amount of time. The harvested materials can be shipped over long distances without being adversely affected. The problem associated with limited variation is the increased risk that an entire crop might be wiped out if the plants are or become susceptible to disease or pests. The Irish potato famine is a great example of the problem associated with depending upon one variety of plant as a primary food source.

Hint: Read the first couple paragraphs of the issue's text.  Consider what you learned about how a population is affected by a limited gene pool (review from chapter 15 of your textbook).

3. What are heirloom varieties of plants, and how might they be important to the future of our agricultural system?

 

Answer: Heirloom plants are varieties of plants that have been grown locally in family gardens for years. The importance of heirloom plants is that they're adapted to the local climate and its growing conditions. There is also a great deal of genetic diversity found in heirloom plants that may ensure a specie’s survival. Heirloom plants tend to produce better tasting fruits and vegetables and can be harvested for a longer period of time.

Hint: Read the latter portion of the issue's text.  If you've visited a zoo that participates in species survival plans you should be able to deduce a benefit of preserving heirloom plants.  You might review the mechanics of evolution covered in chapter 15 of your textbook.

Thinking Through the Concepts

1. What is meant by “alternation of generations”? What two generations are involved? How does each reproduce?

2. Explain the evolutionary changes in plant reproduction that adapted plants to increasingly dry environments.

3. Describe evolutionary trends in the life cycles of plants. Emphasize the relative sizes of the gametophyte and sporophyte.

4. From which algal group did green plants probably arise? Explain the evidence that supports this hypothesis.

5. List the structural adaptations necessary for the invasion of dry land by plants. Which of these adaptations are possessed by bryophytes? By ferns? By gymnosperms and angiosperms?

6. The number of species of flowering plants is greater than the number of species in the rest of the plant kingdom. What feature(s) are responsible for the enormous success of angiosperms? Explain why.

7. List the adaptations of gymnosperms that have helped them become the dominant trees in dry, cold climates.

8. What is a pollen grain? What role has it played in helping plants colonize dry land?

9. The majority of all plants are seed plants. What is the advantage of a seed? How do plants that lack seeds meet the needs served by seeds?

Applying the Concepts

1. You are a geneticist working for a firm that specializes in plant biotechnology. Explain what specific parts (fruit, seeds, stems, roots, etc.) of the following plants you would try to alter by genetic engineering, what changes you would try to make, and why: (a) corn, (b) tomatoes, (c) wheat, and (d) avocados.

2. Prior to the development of synthetic drugs, more than 80% of all medicines were of plant origin. Even today, indigenous tribes in remote Amazonian rain forests can provide a plant product to treat virtually any ailment. Herbal medicine is also widely and successfully practiced in China. Most of these drugs are unknown to the Western world. But the forests from which much of this plant material is obtained are being converted to agriculture. We are in danger of losing many of these potential drugs before they can be discovered. What steps can you suggest to preserve these natural resources while also allowing nations to direct their own economic development?

3. Only a few hundred of the hundreds of thousands of species in the plant kingdom have been domesticated for human use. One example is the almond. The domestic almond is nutritious and harmless, but its wild precursor can cause cyanide poisoning. The oak makes potentially nutritious seeds (acorns) that contain very bitter-tasting tannins. If we could breed the tannin out of acorns, they might become a delicacy. Why do you suppose we have failed to domesticate oaks?

Essay Challenge

1. Give a few reasons why green algae and ancestral plants are so similar.

2. Meiosis produces haploid cells. In animals (life cycles we tend to be most familiar with, since we are animals), meiosis occurs to produce the gametes used to perform sexual reproduction. Why are plants' gametes produced via mitosis?

3. What are some of the adaptations that plants had to accumulate to survive on land?

4. Why are mosses often referred to as the amphibians of the plant kingdom?

5. What is the most important feature of ferns, one that makes them so successful?

6. How have land plants adapted to reproduction outside of water?

7. What structural feature(s) would you expect to see on a pollen grain that is dependent upon the wind for dispersal? Why do plants that produce windblown pollen make TONS of it?

8. Identify three major adaptations that led to the proliferation of angiosperms (flowering plants).

9. Why do most angiosperm plants drop their leaves when the weather turns cold?

Figure Caption Questions and Answers

Figure 21-3 Bryophytes

Question: Why are all bryophytes short?

Figure 21-5 Some seedless vascular plants

Question: In each of these photos, is the pictured structure a sporophyte or a gametophyte?

Figure 21-7 Seeds

Question: Can you think of some adaptations that help protect seeds from destruction by animal consumption?

Figure 21-10 Angiosperms

Question: List the advantages and disadvantages of wind pollination. Do the same for pollination by animals. Why do both types of pollination persist among the angiosperms?

|type of pollination |advantages |disadvantages |

|wind | | |

|animal | | |

Both types of pollination persist in angiosperms BECAUSE ---- ?

1. Which of the following is true concerning the life cycle of a moss?

a. Gametophytes are nutritionally dependent upon sporophytes.

b. Protonema arise from germinated spores.

c. The zygote is protected within specialized tissues of the sporophyte.

2. Which of the following plant groups has swimming sperm and a dominant sporophyte generation?

a. bryophytes b. pterophytes c. conifers d. angiosperms

3. Which of the following statements about the life cycle of the pine is false?

a. Pollen grains contain the male gamete.

b. Pollen grains have wings so they can easily be carried by the wind.

c. Female gametophyte tissue becomes the food source (nutritive tissue) for the embryo.

d. Approximately one year after pollination, fertilization occurs, forming the zygote.

4. In which of the following plant groups is the sporophyte dependent on the gametophyte?

a. angiosperms b. bryophytes c. pterophytes d. conifers

5. Which of the following is a characteristic of the ferns?

a. The gametophyte is the dominant generation.

b. They are vascular plants, containing xylem and phloem.

c. They produce seeds on frond leaflets.

d. They produce nonmotile (nonswimming) sperm.

1. The ovule is found in the ________ and __________.

a. Pterophyta; angiosperms or flowering plants b. Bryophyta; Coniferophyta

c. Coniferophyta; Pterophyta d. Coniferophyta; angiosperms or flowering plants

2. Ferns have the ________ generation as the dominant generation. The sporophyte generation has specialized ________ tissue for transport within the plant.

a. gametophyte; cambial b. gametophyte; vascular c. sporophyte; cambial

d. sporophyte; vascular

3. The archegonium produces:

a. an egg cell. b. a seed. c. sperm cells. d. a spore cell.

4. The anther in a complete flower has the same reproductive function as the _______ in the Bryophyta.

a. archegonium b. sporangium c. indusium d. antheridium

5. The sporangium is part of the ________ generation, it produces __________.

a. gametophyte; spores b. sporophyte; spores c. gametophyte; pollen grains

d. sporophyte; seeds

6. The seed is the ______ which contains the ______ generation.

a. ovule; gametophyte b. ovule; sporophyte c. archegonium; gametophyte

d. archegonium; sporophyte

7. In the flowering plants the gametophyte:

a. develops in the flower. b. lives independently of the sporophyte.

c. is the dominant generation. d. develops into the plant's fruit.

8. One of the reasons the mosses remain small is that they lack _________ tissue.

a. reproductive b. photosynthetic c. vascular d. sporophyte

9. Pollen grains are:

a. sporophytes. b. male gametophytes. c. female gametes.

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