25.1 Early plant life

Question 1

Problems with life on land

Answer 1

• Dessiccation by air
• No structural lift without water
• Mutagenic radiation
• No gamete swimming

Question 2

Advantages with life on land

Answer 2

• CO2 and sunlight in abundance
• Protection (no predators)
• Plants colonized it before animals
• Plants began next to water and TOLERATED dessication
• Plants moved away from water such as cacti and RESISTED dessication

Question 3

4 Major adaptations

Answer 3

1) Alternation of generations
2) Sporangium
3) Gametangium
4) Apical meristem tissue in roots & shoots
–> also a waxy cuticle and a cell wall with lignin

Question 4

Alternation of generations

Answer 4

Organism that contains both haploid and diploid multicellular stages

Haplontic = dominant haploid stage
Diplontic = dominant diploid stage
Haplodiplodontic = both phases equally relevant

Gametophyte n -> gametes n -> zygote 2n -> sporophyte 2n -> spores n->

Question 5

Embryophyte

Answer 5

Female gametophyte that shelters embryo present in land plants

Question 6

Sporangia (seedless plants)

Answer 6

• Syngamy of 2 gametes = sporophyte 2n
• Sporangia organs have sporocyte cells (mother cells)
• make 2 types of spores via meiosis (sexes)

Question 7

Homospory

Answer 7

Seedless non-vascular
- dominant gametophyte
- resulting gemetophyte from germination makes both male and female gametangia on the same individual

Question 8

Heterospory

Answer 8

Seedless vascular & some seed
- 2 morphologically different spores
- microspores (male gametophyte)
- megaspores (female gametophyte)

Question 9

Spores (seedless plants)

Answer 9

• Thick cell walls with sporopollenin polymer (which reduces dehydration)
• very tough
• not originally present in land plants

Question 10

Gametangia (seedless plants)

Answer 10

• on multisellular haploid gametophytes
• antheridium makes the sperm
• archegonia holds the embryo and egg.

Question 11

Apical meristematic tissue

Answer 11

• at tips of roots and shoots
• meristematic cells are present that grow in response to light, water and minerals
• the diameter growth is known as the lateral meristem

Question 12

Additional Adaptations (not major)

Answer 12

• taller (less light competition)
• vascular tissue
• lignin walls
• waxy cuticle and stomata
• pigments to absorb UV light
• toxic compounds (deter predators)

Question 13

6 periods of Paleozoic

Answer 13

• Cambrian
• Ordovician (land plants)
• Silurian
• Devonian (vascular fossil)
• Carboniferous
• Permean

Question 14

Streptophytes

Answer 14

All land plants and green algea so the charophytes (which are the only algal group close to plants) and chlorophytes

Question 15

Embryophytes

Answer 15

Land plants

Question 16

Non-vascular plants

Answer 16

Seedless, Bryophytes
- liverworts
- hornworts
- mosses

Question 17

Vascular seedless plants

Answer 17

Lycophytes
- club mossess
- quillworts
- spikemosses

Pterophytes
- whisk ferns
- horse tails
- ferns

Question 18

Seed plants

Answer 18

Spermatophytes
- gymnosperms
- angiosperms