L15 Plants pt 2

Question 1

What are the two ways we can classify land plants regarding their diversity?

Answer 1

nonvascular and vascular plants

Question 2

non-vascular plants (aka _________) are represented by 3 groups:

Answer 2

• byrophytes
• mosses, liverworts, and hornworts

Question 3

describe nonvascular plants

Answer 3

• small, simple, tough, and the 1st plant lineage to diverge after plants moved onto land
• lack vascular tissue, can dehydrate faster

Question 4

why are nonvascular plants small

Answer 4

constraints on fertilization

• sperm from male gametophyte requires water to move to female gametophyte
• sperm can only travel short distances

Question 5

describe the structure of a nonvascular plant

Answer 5

simple w/ flattened photoosynthetic structures (thallus)

• only a few cells thick
• lack internal air spaces
• no water conducting system

Question 6

what type of -phyte dominates the life cycle of nonvascular plants, and why

Answer 6

haploid gametophyte

• larger than sporophyte
• independent and supports nonphotosynthetic sporophyte

Question 7

describe the ecological importance of nonvascular plants

Answer 7

• small part of plant community
• peat bogs are useful
• makes acidic and wet conditions, producing phenols and slowing decomposition
• can store large amounts of organic carbon
• vulnerable to climate change

Question 8

what -phyte dominates in vascular plant life cycle and why

Answer 8

diploid sporophyte

• larger and independent
• evolved vascular tissue
• less dependent on water for production

Question 9

what can we divide vascular plants into

Answer 9

seedless and seed plants

Question 10

what groups can we represent seedless plants with

Answer 10

lycophytes and ferns/horsetails (pterophytes)

Question 11

pterophytes are a ______-phyletic group

Answer 11

monophyletic

Question 12

describe the structure of a seedless (fern/horsetail) plant - consider leaves, stem, and growth size

Answer 12

• fronds are distinctive b/c they are divided into pinnae
• stems grow underground (invasive)
• vascular tissue allows plants to grow larger (b/c size is limited by lack of secondary vascular tissue)

Question 13

Explain seedless plant history

Answer 13

grew to considerable size during wet period (~400mya)

• disappeared when climate changed and swamps dried up
• decomposed slowly (buried making coal deposits)

Question 14

what is the importance of seed plants

Answer 14

• dominant producers on land
• don’t require external water source for fertilization
• seeds have embryo and nutrients (endosperm) with protective coat
• pollen: use wind or animals for dispersal of male gametes

Question 15

what 2 phyla are represented by seed plants

Answer 15

gymnosperms and angiosperms

Question 16

describe gymnosperms

Answer 16

• have “naked” seeds unenclosed by ovaries
• divided into 4 distinct groups
• better adapted to drier conditions
• conifers dominate in northern latitudes

Question 17

describe cycads

Answer 17

• large cones and palm-like leaves
• able to live in nutrient-poor conditions
• most are tropical, but relatively few species exist today b/c on endangered species lists
• have insect pollination/animal dispersal

Question 18

describe ginkgos

Answer 18

• popular ornamental tree with health benefits
• high tolerance to air pollution (therefore used in cities)
• only ginkgo biloba are alive

Question 19

describe conifers

Answer 19

• most are evergreens (carry out photosynthesis all year)
• tolerate cold, dry conditions therefore outcompete angiosperms

Question 20

key features of gymnosperm life cycle

Answer 20

• dominance of sporophyte generation
• seed development from fertilized ovules
• transfer of sperm to ovules by pollen (wind transport)

Question 21

describe gnetophytes

Answer 21

• made of 3 genera
• some are tropical, some are desert
• have multicellular xylem vessels and double fertilization (same as angiosperms)

Question 22

describe angiosperms

Answer 22

• flowering
• have protected seeds enclosed by ovaries and consist of 6 groups
• better suited to life on land
• diversity is still a mystery but it’s likely because of slower rates of species loss

Question 23

what is the most widespread, diverse group of plants

Answer 23

angiosperms

Question 24

how did earliest angiosperms evolve

Answer 24

• dominating gymnosperm forests
• insect pollinators

Question 25

what are the rarer groups evolved of angiosperms

Answer 25

amborella, water lilies, star anise and relatives

Question 26

describe magniliids

Answer 26

type of angiosperm - include magnolia, laurels, black pepper, avocados - common in early angiosperm evolution in tropical areas

Question 27

describe monocots

Answer 27

~25% of angiosperms - grass and grass-like flowering plants - numerous food crops (rice, wheat, corn, sugar cane, bananas, ginger pineapple) and other economically important plants (bamboo, orchids, lilies, daffodils, tulips)

Question 28

describe eudicots

Answer 28

includes ~75% of angiosperms - 2 seed leaves upon germination - numerous economically important plants (food, forests, gardening, health resources) and other plants (carnivorous, parasitic, epiphytes)

Question 29

what are the differences between monocots and eudicots

Answer 29

- cotyledons (1 vs 2) - vein pattern (parallel vs. netlike) - vasc. tissue arrangement (scattered vs ring) - root system (fibrous vs one main taproot) - pollen grain openings (1 vs 3) - floral organ multiples (3 vs. 5)

Question 30

what does the evolution of plants show

Answer 30

adaptations that are more suitable to life on land

Question 31

what are the phylogenetic relationships that account for plant diversity

Answer 31

- vascular vs. non vascular - seed vs seedless - naked vs protected seeds