Chapter 29: Plant diversity (colonization)

Question 1

What is the vital adaptation for trees and how did they help?

Answer 1

The vital adaptation for trees is in the cell wall.

Question 2

Who are the closest relatives of land plants?

Answer 2

Green algae called charophytes are the closest relatives of land plants

Question 3

What are the shared characteristics between land plants and the protist clades?

Answer 3

– Multicellularity
– Similar photosynthetic pigments
– Cellulose cell wall

Question 4

What are the traits land plants share with charophytes?

Answer 4

1. Rings of cellulose-synthesizing proteins: both plants and charophytes have distinctive circular rings of proteins embedded, and non-charophyte algae have linear sets of proteins that synthesize cellulose.
2. Structure of flagellated sperm
3. Formation of a phragmoplast. The phragmoplast is a cell structure that forms late in cytokinesis only in plants and certain charophytes.

ROCKS AND PHRAG

Question 5

Comparisons of both ______and ______-genes point to charophytes as the closest living relatives of land plants

Answer 5

Comparisons of both nuclear and chloroplast genes point to charophytes as the closest living relatives of land plants

Question 6

Land plants descended from modern
charophytes and share a common ancestor with modern charophytes. true or false?

Answer 6

False. Land plants did not descend from modern charophytes– but share a common ancestor with modern charophytes

Question 7

What is sporopollenin?

Answer 7

• In charophytes a layer of a durable polymer called sporopollenin prevents exposed zygotes from drying out.

– Sporopollenin is also found in plant spore walls

Question 8

What are the benefits charophyte ancestors provided when moving to land?

Answer 8

1. The bright sunlight was unfiltered by water and plankton
2. The atmosphere offered more plentiful carbon dioxide than did water
3. The soil by the water’s edge was rich in some mineral nutrients.
4. Fewer herbivores or pathogens

Question 9

What are the challenges presented when plants moved to land?

Answer 9

• A relative scarcity of water
• A lack of structural support against gravity

Question 10

Land plants diversified as adaptations evolved that enabled them to thrive despite the challenges. Name these adaptations.

Answer 10

1. Mycorrhizae aided in nutrient absorption
2. Development of cuticle
3. Development of sporopollenin
   - Layer durable polymer that prevents exposed zygotes from drying out

Question 11

The placement of the boundary dividing land plants from algae are the subject of ongoing debate

• Until the debate is resolved,
  we define plants as __________

Answer 11

• Until the debate is resolved, we define plants as embryophytes, – plants with embryos

Question 12

What are the derived traits of plants(i.e. traits that are not present in charophytes)?

Answer 12

1. Alternation of generations
2. Multicellular, dependent embryos
3. Walled spores produced in sporangia
4. Multicellular gametangia
5. Apical meristems

MAMWA

Question 13

What is alternation of generation in plants?

Answer 13

The life cycles of all plants alternate between two generations of distinct multicellular organisms: gametophytes and sporophytes, each generation gives rise to the other, a process that is called the alternation of generations.

Question 14

What is the cuticle and what is its function?

Answer 14

The cuticle acts as waterproofing,
helping prevent excessive water loss from the above-ground plant organs, while also providing some protection from microbial attack.

Question 15

Explain the alternation of generations.

Answer 15

The gametophyte is haploid and produces haploid gametes by mitosis

• Fusion of gametes gives rise to the diploid sporophyte, which produces haploid spores by meiosis

Question 16

Explain the multicellular, dependant embryos in land plants.

Answer 16

The diploid embryo is retained within the tissue of the female gametophyte

• Nutrients are transferred from parent to embryo through placental transfer cells
• Land plants are called embryophytes because of embryo dependency on parents.

Question 17

The sporophyte produces spores in organs called __________.

Answer 17

The sporophyte produces spores in organs called sporangia

Question 18

The sporophyte produces spores in organs called ______.

Answer 18

Sporangia.

Multicellular sporangia that produce spores with sporopollenin-enriched walls are key terrestrial adaptations of plants.

Question 19

Diploid cells called ______undergo _____to
generate haploid spores

Answer 19

Diploid cells called sporocytes undergo meiosis to generate haploid spores.

Question 20

Spore walls contain ________, which makes them resistant to harsh environments

Answer 20

Spore walls contain sporopollenin, which makes them resistant to harsh environments