PLANTS! And first 2 major transitions of plants

Question 1

Description of Plants

Answer 1

multicellular eukaryotes, evolved from protists(green algae), Primarily terrestrial habitats and some aquatic species; Characteristic cell wall with cellulose and polysaccharides; SIGNIFICATN METABOLIC DIVERSITY(photoautrophs, chemoorganoheterotrophs, and mixotrophs); Plant Complex Life Cycle Alternation of Generations

Question 2

Plant Photoautotrophs

Answer 2

uses photosynthesis; use chloroplasts leaded with chlorophyll (pigment used in process)

Question 3

Plant Chemoorganoheterotrophs

Answer 3

primarily parasitic; no photosynthesis or chlorophyll; (Examples: beechdrops, squawroot, Indian pipe)

Question 4

Plant Mixotrophs

Answer 4

use autotrophy and heterotrophy; Examples are Venus fly traps, pitcher plants; Pitcher plants use lots of photosynthesis and colors(red and green) show this, but flies also option

Question 5

Plant Complex Life Cycle: Alternation of Generations

Answer 5

Have independent haploid(1n) and diploid(2n) life stages; Haploid Life Stages in Plants are Gametophyte (n chromosomes); Diploid Life Stage in Plants are Sporophyte (2n chromosomes)

Mitosis occurs during haploid gametophyte stage, Fertilization is beginning of diploid sporophyte stage, and Meiosis is the end of diploid sporophyte stage/transitions to beginning of haploid gametophyte stage

Question 6

Plant Evolutionary transitions

Answer 6

Water to Land-> Vascularization, Plumbing-> Seeds!!-> flowers, fruit

Question 7

Ancestor to Land Plants

Answer 7

Green algae; Two types, Charophyta and Chlorphyta(phytoplankton); Fossil and DNA evidence suggests that Charophyta are ancestor to land plants

Parka decipiens(400 million yr old fossil) that resemble modern green algae

Question 8

Transition from water to land

Answer 8

many selective pressures against it, such as structural stability nutrient uptake, and reproduction

Question 9

Land vs Water: Structural Stability

Answer 9

Water :Lots of support in free-floating in water, Rigid tissues not required to main upright(structural stability)

Land: No support really(structural stability), Natural selection for rigid cell wall, Selection for structures to take up and retain water in environment(water becomes limiting)

Question 10

Land vs. Water: Nutrient Uptake

Answer 10

where do plants get carbon(C), nitrogen(N), and phosphorous(P), other nutrients?

Water clearly has no issues with this, can absorb nutrients from the water

Land: natural selection for CO2 uptake from air, and roots to extract N, P from soil; also, selection for mutualisms with bacteria and fungi(nitrogen fixers) to get N

Question 11

Land vs. Water: Reproduction

Answer 11

in water, algae rely on swimming sperm for fertilization

Water have mobile, swimming sperm which can swim to eggs and fertilize them, allows for successful sexual reproduction

Land natural selection for sperm that do not require water to fertilize eggs, and other new modes of reproduction

Question 12

First Plants on Land

Answer 12

Nonvascular plants

Question 13

Nonvascular Plants

Answer 13

Means they have no vascular tissue to move water and nutrients around within the plant (no internal plumbing so to speak, no complex plumbing in general)

This limits habitats they can be in; found only in wet, moist, humid habitats; NEED available, stable water source (streams, lakes, consistently dense fog/mist found on mountaintops, rotting logs)

This limits size of plant, Cannot grow taller because they cannot move water and nutrients to increased heights

lack true roots(have rhizoids instead), lack true leaves(have leaf-like spikes/structures instead)

Question 14

Rhizoids

Answer 14

sponge-like tissue at base of plant that anchors plant and absorbs some water

Question 15

Leaf-like spikes/structures

Answer 15

have one, long thin cell running down center of spike; draws small amount of water from rhizoids

Question 16

Alternation of Generations in Nonvascular plants

Answer 16

Nonvascular plants Gametophyte(n) is dominant life stage; it is ALWAYS PRESENT

Nonvascular sporophyte(2n) is present during spore production; die after spore production is complete

In fertilization: mobile, swimming sperm; require water to successfully fertilize egg

In meiosis: spores spread to environment by water, wind; germinate where they land

Question 17

Three modern groups of nonvascular plants

Answer 17

Bryophyta(mosses), Anthocerophyta(hornworts), Hepaticophyta(liverworts)

**Images of differentiation between groups shown on page 22 of Notes)

Question 18

Development of Vascularization

Answer 18

2nd major evolutionary transition, All plants beyond this point in evolutionary time have vascular tissues; internal plumbing for moving water/nutrients around the plant

Question 19

Earliest Evidence of Vascularization

Answer 19

Cooksponia

Sporangia: spore producing structures on sporophyte, 420 Mya, Had single tubes running up center of them, Only fossil sporophytes found

Rhynia

400 Mya, Had extensive vascularization(tubes/vessels) running up stems, Only fossil sporophytes found, Stem cross-section shows extensive vascularization, Sporangia: spore producing structures on sporophytes

Question 20

Evolution of vascular tissues

Answer 20

Shoots/stem, leaves, roots, etc, Allow movement of water, nutrients(C,N,P) sugars(“food’) dissolved minerals, and hormones; Separate into above ground (shoots, stems, leaves) and below ground(roots); Contained specialized cells known as xylem and phloem for moving substances around the plant

Question 21

How are substances moved around the plant?

Answer 21

Starting belowground, water absorbed form soil by roots, moved through aboveground tissues(by Xylem; dead cells with thick cell walls that are interconnected)

Xylem moves water/dissolved minerals upwards through all plant tissues(UNIDIRECCTIONAL FLOW); larger “tubes” by themselves

Some water lost in transpiration

Question 22

Description of Water being Lost in Transpiration

Answer 22

when H20 moves to leaf surfaces, lost to atmosphere when mouth-like opening(STOMOTA) on leaves open, releasing water vapor

Stomata in transpiration open for gas exchange(Open stoma: take Co2 in, and then O2 out, water out as water vapor/lose H20 as water vapor)

CRITICAL TO WATER MOVEMENT: as water vapor is released, water is pulled upward, allowing for continued upward water movement with xylem

All of this above necessary/ relevant for PHOTOSYNTHESIS, without transpiration photosynthesis process does not occur

Question 23

how do plants protect their water, maintaining high levels in tissue and reducing loss to environment?

Answer 23

Stomata closed when transpiration not occurring to reduce loss of water vapor

Cuticle: avoids further water loss, waxy covering, blocks water evaporation to environment

Question 24

Photosyntheis

Answer 24

Produces sugars(for growth and reproduction)

Question 25

How do sugars get to the rest of the plant?

Answer 25

Phloem: living cells; moves sugars, hormones, and nutrients around plant in all directions(to all tissues)(MULTI DIRECTIONAL FLOW); smaller, multiple grouped “tubes”

Question 26

Benefits of Vascularization

Answer 26

Plants get taller/larger: move materials around whole plant, to great heights

Plants can now live in lower moisture habitats, greatly broadening range of habitats they occupy

**EARLY VASCULAR PLANTS still needed water for reproduction since they had mobile swimming sperm

Question 27

Vascular Plants

Answer 27

Tracheophyta: group that includes all vascular plants

Major change IN ALL VASCULAR PLANTS in dominant life stage, Shift from gametophyte(n) being dominant life stage(like in nonvascular plants) to sporophyte(2n) being dominant life stage; So sporophyte ALWAYS present, and gametophyte dies after producing haploid sperm and eggs

Question 28

Four Oldest Vascular Plant Groups

Answer 28

Club Mosses(Lycophyta), Whisk Ferns(Psilophyta), Horsetails(Equisetophyta), True Ferns(Pteridophyta)

**Review images starting on page 25 of notes

Question 29

Club Mosses(Lycophyta)

Answer 29

No true mosses, Found in moist areas and forests, look like baby pine trees trying to grow in sporophyte stage but they are not obviously

Question 30

Whisk Ferns(Psilophyta)

Answer 30

NOT true ferns, Found in high mountain habitats, sporophyte stage has sight of green stems with yellow tips, while gametophyte is disgusting orange and clear picture(you know what I am talking about)

Question 31

Horsetails(Equisetophyta)

Answer 31

Not true horsetails, Found around water; sporophyte appears to be mini conifer tree/baby tree, but is not(pointy-like end with green shoots going upwards, gametophyte looks like green goop)

Question 32

True Ferns(Pteridophyta)

Answer 32

Have true leaves(enhances photosynthetic ability, transpiration) and true roots(for taking up water and nutrients, etc.); Limited to wet/humid habitats due to mobile sperm needing water to fertilize egg

ALL SPOROPHYTES

Question 33

Reproduction in True Ferns

Answer 33

fertilization happens on gametophyte(which have special egg and sperm producing structures)

Archegonium: produces eggs
Antheridia: produce sperm
Sperm swim to egg and fertilize it
Fertilized egg leads to sporophyte
Sporangia: release spores which are spread to environment by wind and water, germinate into new gametophytes(when conditions are right)

Question 34

2 shared characteristics of ancient lineages

Answer 34

Seedless; Still found in primarily wet habitats, since they still rely on mobile swimming sperm that REQUIRE water to swim to eggs to fertilize them