Chapter 31: Plants and the Conquest of Land (Part 1, Week 6)

Question 1

[Start 31.1 Ancestry and Diversity of Modern Plants]

What is referred to informally as the plants or land plants and consists of several hundred thousand modern species?

Answer 1

the kingdom Plantae

Question 2

What are multicellular eukaryotic organism that is usually photosynthetic (having plastids), primarily lives on land, and has cells with a cell wall containing cellulose?

Answer 2

Plants! :)

Question 3

How are maximal evolutionary divergence times indicated? A question asked while looking at a diagram (a cladogram) exhibiting evolutionary relationships among green algae and modern plant phyla.

Answer 3

Indicated by molecular clock and some fossil evidence which suggests when clades may first have risen.

A clade is a branch that includes a single common ancestor and all of its descendants.

Question 4

Since land plants evolved from green algae, what did they gradually acquire over time allowing them to better survive in terrestrial habitats?

Answer 4

Diverse structural, biochemical, and reproductive adapatations.

Question 5

Molecular and other evidence indicates that the plant kingdom evolved from green algal ancestors whose modern representatives primarily occupy what?

Answer 5

Freshwater habitats

Question 6

What are land plants (embryophytes) and their close relatives among the green algae?

Answer 6

Modern plants and their closest green algal relatives are together known as Streptophytes.

Question 7

Molecular, biochemical, and structural data indicate that the kingdom Plantae originated from a photosynthetic protist ancestor that, if present today, would be classified among the what?

Answer 7

Streptophyte algae

The green algae that are closely related to land plants (embryophytes).

Question 8

Streptophyte algae are related to other green algae, but have morefeatures in common with land plants. The more complex, later-diverging stretophyte algae displays several what?

Answer 8

Critical innovations. Derived features shared with land plants that fostered plant success on land.

Examples of these shared features are a distinctive type of cytokinesis, intercellular connections known as plasmodesmata, and sexual reproduction.

For this reason, complex streptophyte algae are good sources of information about the ancestors of land plants.

Question 9

What are a couple adaptations that land plants have gained that distinguish them from their close algae relatives?

Answer 9

• Bodies of all land plants are primarily composed of three-dimensional tissues, defined as close associations of cells of the same type.
• Tissues provide land plants with an increased ability to avoid water loss at their surfaces.

Question 10

How is water loss in land plants much lower than closest algae ancestors?

Answer 10

Water loss is decreased in land plants because bodies composed of tissues have lower surface area/volume ratios than do branched filaments or simpler algal bodies.

Question 11

What is the significance of land plant tissues arising from one or more actively dividing cells that occur at growing tips?

These localized regions of cell division at the growing tip are known as apical meristems.

Answer 11

The tissue-producing apical meristems of land plants produce relatively thick, robust bodies able to withstand drought and mechanical stressand produce tissues and organs with specialized functions.

Question 12

What are the distinctive reproductive features of land plants? (3 compared differents of land plant and streptophyte life cycles)

Answer 12

1. Involves a life cycle involving alternation of generations (two types of multicellular bodies alternate in time).

The diploid sporophyte generation produces spores by meiosis, and the haploid gametophyte generation produces gametes by mitosis.

By contrast, streptophyte algae feature a haploid-dominant life cycle.

2. During land plant sexual reproduction, a diploid zygote divides by mitosis to form a multicellular sporophyte embryo. A key feature is that the sporophyte embryo is nourished by maternal tissues.

Although maternal cells of streptophyte algae may nourish zygotes, the algal zygotes do not develop into multicellular embryos.

3. A mature land plant sporophyte undergoes meiosis to produce tough-walled non-flagellate reproductive cells known as spores that survive dispersal through dry air.

Streptophyte algae differ in that spores produced by meiosis are adapted for dispersal in water; they possess flagella and lack protective walls.

Question 13

What are the nine phyla of living plants that are described in class? GOOD LUCK BUD!

Answer 13

1. liverworts; formally known as Hepatophyta
2. mosses; Bryophyta
3. hornworts; Anthocerophyta
4. lycophytes; Lycopodiophyta
5. pteridophytes; Pteridophyta
6. cycads; Cycadophyta
7. ginkgos; Ginkgophyta
8. conifers; Coniferophyta
9. flowering plants, AKA angiosperms; Anthophyta

Question 14

Even though it is not clear, early fossil and molecular evidence indicates that early land plants diverged from what that arose before the first vascular plants?

It would be wise to understand which plants fall under bryophytes.

Answer 14

Small and simple bryophytes– represented by modern mosses, hornworts, and liverworts.

Question 15

What is a broad category of plants distinguished by internal water and nutrient-conducting (vascular) tissues that also provide structural support?

Answer 15

Vascular plants

This allowed these plants to become larger and more complex than bryophytes.

Question 16

Among the vascular plants, what two phylum diverged the earliest?

Answer 16

Lycophytes diverged earliest, pteridophytes arose next.

Molecular data indicate that the lycophytes are the oldest phylum of living vascular plants and that pteridophytes are the next oldest.

Question 17

Earth’s simplest land plants and each group is monophyletic? (3)

Answer 17

Liverworts, mosses, and hornworts

Collectively, liverworts, mosses, and hornworts are known informally as the
bryophytes (from the Greek bryon, meaning moss, and phyton, meaning plant).

Bryophytes display reproductive features that evolved early in the history of land plants, including a life cycle involving alternation of generations, multicellular embryos, and tough-walled spores.

Question 18

Why might it be advantageous for a mosss porangium to release spores gradually?

Answer 18

Wind speed varies, so if the sporangium released all the spores at the same time and there were little or no wind, the spores would not travel very far and the resulting offspring might have to compete with the parent plant for scarce resources.

Releasing spores gradually means that some spores may encounter strong gusts of wind that will carry them long distances, reducing competition with the parent.

Question 19

Bonus! What phylum do ferns belong to? Washington has many of them.

Answer 19

Pteridophyta

Question 20

What is typically referred to as club mosses or spike mosses because their sporangia generally occur in club-shaped clusters?

They are not true mosses.

Answer 20

Lycophytes

Question 21

Because the lycophytes and pteridophytes diverged prior to the origin of ___, they are informally known as _______ _______ plants.

Answer 21

seeds; seedless vascular

Question 22

What are tracheophytes?

Answer 22

A term used to describe ALL vascular plants.

The latter term takes its name from
tracheids, a type of specialized cell that conducts water and minerals and provides structural support.

Tracheids and other cells involved in the conduction of materials within plants form vascular tissues.

Question 23

Where do vascular tissues occur which are the organs of the vascular plant body?

Answer 23

The stems, roots, and leaves!

Question 24

What is a plant organ that contains vascular tissue and produces buds, leaves, branches, and reproductive structures to include sporangia?

Answer 24

Stems

Stems contain the specialized conducting tissues known as phloem and xylem, the latter of which contains tracheids.

Question 25

What do phloem and xylem enable vascular plants to do?

Answer 25

To move organic compounds, water, and minerals throughout the plant body.

Question 26

What does the structural support function of xylem, allowing vascular plants grow taller than nonvascular plants, rely on the presence of?

Answer 26

The compression and decay resistant waterproof material known as lignin, which occurs in the cell walls of tracheids and some other types of plant cells.

Question 27

What organ provides anchorage in the soil and also fosters efficient uptake of water and minerals?

Answer 27

Roots

Question 28

What are flattened plant organs that emerge from stems and typically function in photosynthesis?

Answer 28

Leaves

Question 29

How do lycophyte roots and leaves differ from those of pteridophytes and seed plants?

Answer 29

Lycophyte roots fork at the tips and their leaves are relatively small with one unbranched vein.

The others have roots that branch from the inside, and their leaves are much bigger and have branched veins.

Question 30

What adaptations of the stems, roots, and leaves allow lycophytes, pteridophytes, and other vascular plants to maintain stable internal water content known as moisture homeostasis? (2)

In relatively dry habitats, lycophytes, pteridophytes, and other vascular plants are able to grow to larger sizes and remain metabolically active for longer periods than bryophytes.

Answer 30

1. A protective waxy cuticle is present on most surfaces of vascular plant sporophytes. The plant cuticle contains a polyester polymer known as CUTIN, which helps to prevent attack by pathogens, as well as wax, which helps to prevent desiccation (drying out).
2. The surface tissue of vascular plant stems and leaves contains many
   stomata (singular, stoma or stomate)—specialized surface cells associated with pores that are able to open and close.

Question 31

Bonus Information about Stomatas!

Stomata first arose in bryophytes, whose mature sporophytes must dry in order to discharge spores; stomatal pores may aid this drying process.

By contrast, stomata occurring on the leaf and stem surfaces of vascular plants take in the carbon dioxide needed for photosynthesis and release oxygen to the air, while conserving plant water content.

When the environment is moist, the pores open, allowing gas exchange to occur. When the environment is very dry, the pores close, thereby reducing water loss.

Answer 31

N/A

Question 32

What are all of the living and extinct phyla of seed-producing plants?

Answer 32

Spermatophytes (the prefix sperm-, from the Greek, means seed)

Question 33

What modern seed plant phyla commonly known as what are collectively referred to as gymnosperms?

And what exactly is a gymnosperm?

Answer 33

Cycads, ginkgos, conifers, and gnetophytes.

A plant that produces seeds that are exposed rather than seeds enclosed in fruits.

Question 34

What uses spores and seeds to reproduce?

Answer 34

Gymnosperms, as do the flowering plants, the angiosperms.

Question 35

What is the informal name for gymnosperms and angiosperms?

Answer 35

Seed plants!

Question 36

What is a reproductive structure having specialized tissues that enclose a plant embryo; produced by gymnosperms and flowering plants, usually as the result of sexual reproduction?

Answer 36

A seed.

Encloses an embryo and contain stores of carbohydrate, lipid, and protein.

Embryos use such food stores to grow and develop into seedlings. The ability to produce seeds helps to free plants from reproductive limitations experienced by the seedless plants, explaining why seed plants are dominant today.

Question 37

T/F Gymnosperms produce and disperse seeds from cones, but do not produce
flowers or fruits.

Answer 37

True

Question 38

What is a distinguishing feature of angiosperms?

Answer 38

Flowers!

Flowers often develop into seed-containing fruits, another unique feature of angiosperm plants.

Question 39

What does the term gymnosperm come from in Greek?

Answer 39

Meaning naked seeds, reflecting the observation that gymnosperm seeds are not enclosed within fruits.

Despite their lack of flowers, fruits, and seed endosperm, the modern gymnosperms are diverse and abundant in many places

Question 40

What are the three things that distinguish an angiosperm?

Answer 40

The angiosperms are seed plants distinguished by the presence of flowers, fruits, and a specialized seed tissue known as endosperm.

Question 41

What is a reproductive shoot; a short stem branch bearing reproductive organs instead of leaves?

Answer 41

A flower. They are specialized in ways that enhance seed production.

Question 42

What is a structure that develops from flower parts, encloses seeds, and fosters seed dispersal in the environment?

Answer 42

Fruit

The term angiosperm comes from the Greek, meaning enclosed seeds, reflecting the observation that the flowering plants produce seeds within fruits.

Question 43

What is a nutritive tissue that increases the efficiency with which food is stored and used in the seeds of flowering plants?

Answer 43

Endosperm

Question 44

Bonus Info!

The majority of gene families that are involved in flowering plant development were also observed in the lycophyte Selaginella and the bryophyte Physcomitrella, a moss.

A comparison of the genomes of Selaginella and Physcomitrella
indicated that more than 500 genes were gained and nearly 90 genes were lost during the transition from nonvascular plants (bryophytes) to vascular plants (lycophytes).

By contrast, 1,350 more genes were gained in the evolution of traits specific to angiosperms. These data indicate that the transition from bryophyte to lycophyte was less genetically complex than was the transition from lycophyte to angiosperm.

FLIP FOR MORE BONUS INFO FUN!

Answer 44

Another interesting finding involves terpenes, which are secondary metabolites that plants produce as chemical defenses against pathogens and herbivores.

Both seedless and seed plants carry genes encoding proteins that are required to synthesize terpenes.

However, genomic analysis revealed that seedless plants rely on genes also present in microbes, but seed plants use different terpene-synthesis genes.

The diversification of new types of terpene-synthesis genes is an example of an increase in genetic complexity that accompanied the rise of seed plants.