Lecture 3: Adaptations to land and lifecycle

List the 4 challenges aquatic plants had to place in order for plants to colonize land (learning obj #1)

1. Adapt to dry, high light (“xeric”) conditions

2. Develop transport systems for water and nutrients

3. Develop structural support

4. Find new ways to disperse reproductive cells and progeny

List the 7 adaptations that allowed ancestors of plant to begin to grow on land (learning obj #2)

1. Cuticle, a waxy coating that slows water loss

2. Stomata, closable openings that regulate gas exchange (most lineages)

3. Pigments that protect against UV radiation and increase photosynthesis efficiency

4. Spores with thick walls containing sporopollenin

5. A mutually beneficial association with fungi (mycorrhizae) that promotes nutrient uptake from the soil

6. Gametangia, (singular: gametangium) are organs that enclose gametes and prevent them from drying out:

7. Embryos, young plants contained within a protective structure.

what is the function of spores with a thick sporopollenin wall?

sporopollenin wall protects spores from drying out and decaying

define Mycorrhizae

association with fungi that provide nutrients to plants

what are the subgroups of mycorrhizae?

Mycorrhizae:  Fungi associated with underground plant parts (roots). 

Ectomycorrhizal (EM) fungi wrap themselves around the plant, increasing surface area for water and mineral absorption.

Vesicular-arbuscular mycorrhizal (VA) fungi grow into root cells & exchange water & nutrients

define apical growth

found in certain streptophyte algae- ability to grow by elongation, and branch

Embryos are found in all land plants, and the land plant clade is called …..

“Embryophyta”

define Gametangia, (singular: gametangium

sex organ that produces gametes (sperm and eggs) in gametophyte stage.

define embryo

young plants contained within a protective structure.

define cuticle

a waxy coating that slows water loss

define stromata

closeable openings that regulate gas exchange

what is the function of pigments

protect against UV radiation and increase photosynthesis efficiency

draw alternation of generations

define gametophyte

the multicellular haploid phase that produces the gametes. (Contrast with sporophyte.)

what are the two types of gametangia?

1. antheridia - make sperm

2. archegonia - which make eggs

define sporophyte

the diploid phase that produces the spores. (Contrast with gametophyte.)

define sporangium (plural: sporangia)

Sex organ that produces spores in sporophyte stage

List the 6 steps in the alternation of generations

1. Spores grow to produce haploid multicellular gametophytes, that make gametes by mitosis in gametangia.

2. There are two types of gametangia, antheridia, which make sperm, and archegonia, which make eggs.

3. Eggs are fertilized by sperm to form diploid zygotes.

4. The diploid zygote develops by mitosis into a multicellular embryo, which eventually grows into a mature diploid plant.

5. This multicellular diploid plant is called the sporophyte. It forms spore-producing sporangia (singular: sporangium).

6. Cells in sporangia produce haploid spores by meiosis.