Plant Diversity II - The Evolution of Seed Plants

Question 1

what are the 5 big adaptations following the rise of seedless vascular plants?

Answer 1

1. reduction of gametophytes
2. seeds
3. pollen
4. heterospory
5. flowers

Question 2

why was reducing the size of gametophytes important?

Answer 2

since gametophytes are haploid, they are more susceptible to damage from UV radiation. making the land plants sporophyte dominant helps reduce this

Question 3

why are seeds important for vascular plants?

Answer 3

-seeds act as an embryo, provide protection, provide nutrition, and are easily dispersed

Question 4

why is pollen important for vascular plants?

Answer 4

-pollen contains the male gametophyte
-can be dispersed via wind -> no flagella -> not dependent on water = resistant to desiccation

Question 5

what is heterospory and why is it important?

Answer 5

-heterospory = separate gametophytes for male & females
-makes the gametophytes smaller, making them more protected from desiccation and UV

Question 6

why are flowers important for plants? what group do flowers belong to?

Answer 6

-flowers attract pollinators
-only found in angiosperms

Question 7

what is the reproductive cycle for a female gametophyte?

Answer 7

-megasporangium makes a megaspore
-megaspore makes female gametophyte
-f. gametophyte makes an egg inside an ovule

ovule = megasporangium + megaspore + integument

Question 8

what is the reproductive cycle for a male gametophyte?

Answer 8

-microsporangium makes a microspore
-microspore makes a male gametophyte
-m. gameto makes pollen, plant sperm

Question 9

what is pollination and fertilization?

Answer 9

-pollination = movement of pollen (male gameto.) to ovule (female gameto.)

fertilization = fusion of the haploid gametes to form a diploid zygote

Question 10

what are gymnosperms and what are there three phyla?

Answer 10

gymnosperms = seeds not enclosed in fruits, big trees most often

cycadophyta = cycads
ginkophyta = ginkgoes
coniferophyta = conifers

Question 11

broadly, how do gymnosperms reproduce?

Answer 11

ex. a conifer tree

-tree makes both ovulate and pollen cones
-microsporocytes produce pollen,
megasporangium produces ovule

-these two get together -> fertilize

-when fertilization occurs, a pollen tube is formed so the male sperm can make it to the female, because of no flagella

-female megaspore produces 2-3 archegonia which will form an egg

-once the eggs are mature and the sperm are through the pollen tube, they fuse and form a zygote. ovule becomes a seed

Question 12

what are the characteristics of angiosperms?

Answer 12

-a very reduced gameto. generation
-flowers = reproductive structures
-a fruit = ripened ovary, protects seeds & aids in dispersal of seeds

Question 13

broadly, how do angiosperms reproduce?

Answer 13

-microsporangium produce microspores, which develop into pollen

-megasporangium produces four megaspores, one of which forms a female gametophyte

-after pollination, two sperm cells are discharged in each ovule

-double fertilization occurs: one sperm fertilizes the egg, forming a zygote. the other sperm fertilizes a central cell forming a 3n endospore which acts as a food supply

-zygote develops into an embryo that is packaged into a seed, that is then packaged into a fruit

-when the seed germinates, the embryo develops into a mature sporophyte

Question 14

what are basal angiosperms?

Answer 14

-less derived angiosperms, belonging to the older lineages in evolutionary history [water lily, star anise]

Question 15

what are the two main groups of basal angiosperms?

Answer 15

monocots [orchid, lily]
eudicots [zucchini, california poppy]