ch 28 bio III in progress

vrididiplantae

green plants (algae and land plants)

land plants were the first group that could thrive ____

completely exposed to air

ecosystem services provided by green algae and land plants

produce oxygen via oxygenic photosynthesis

What are primary producers in terrestrial environments

land plants

how do land plants produce sugars

They convert sunlight into chemical energy and use CO₂ from the atmosphere to make sugars.

how does the loss of plants contribute to climate change

Fewer plants means less CO₂ is removed from the atmosphere, contributing to rising temperatures.

plants in medicines

about 25% of prescriptions written in the US each year include at least one molecule derived from plants

morphological traits of green algae

• unicellular, colonial, or multicellular

• marine, freshwater, or moist terrestrial habitats

• mostly aquatic

Key similar traits in Green Algae and Land plants

• same chloroplast structure

• Thylakoid arrangements are similar

• cell walls, sperm, and peroxisomes are similar

• chloroplasts synthesize starch as a storage product

vascular tissue

specialized group of cells that conduct water or dissolved nutrients throughout the plant body

nonvascular plants

• lack vascular tissue

• include mosses

• use spores for reproduction and dispersal

seedless vascular plants

• well developed vascular tissue

• use sports for reproduction

• includes ferns

seeed plants

• have vascular tissue

• make seeds

• include angiosperms and gymnosperms

seeds

embryo and nutritive tissue surrounded by touch protective layer

Green Plant Phylogeny

Monophyletic group containing all green algae and land plants.

Green algae phylogeny

Paraphyletic group that excludes land plants, even though they share a common ancestor.

Zygnematophycea

Group of green algae most closely related to land plants

Land plants phylogeny

Monophyletic group that evolved from a single successful transition from freshwater to land.

Nonvascular Plants phylogeny

Earliest-branching and most ancient living groups of land plants.

Evolution of Vascular Tissue and Seeds

each only evolved once

Seed Plants phylogeny

Monophyletic group consisting of gymnosperms and angiosperms.

what traits needed to be adopted for dry condition with intense sunlight

cuticle with stomata, flavonoids, and tracheids

cuticle with stomata

allow gas exchange - prevents water loss which keeps cells from drying out and dying

flavonoids

absorb UV - providing protection from harmful UV radiation

tracheids

moving water from tissues with access to water to tissues without

small/low - growth habitat

first land plants grew keeping most of their tissues in direct contact with moist soil - competition for space and light

what did upright plants get better access to

sunlight

issue of upright plants and how was it fixed

water transport and support - vascular tissue

how many times did adaptations to dry conditions evolve

once

sporopollenin

tough protective coating on spores that prevents them from druing out

antheridium

multicellular reproductive structure that produces sperm

archegonium

multicellular reproductive structure that produces eggs

emryo retention

zygotes remain attached to the parent plant, where they are protected and nourished

zygote

fertilized egg that develops into an embryo while attached to the parent plant

spores

resist drying, tough outer coating helps them survive for long periods, can be dispersed hundreds of miles by winds

Gametangia

specialized reproductive organs that protect gametes from drying out and physical damage

charophyceae (stoneworts)

green algae that also develop gametangia, but theirs are smaller and less complex than those of lands plants

Land plant gametangia

larger and more complex reproductive structures that protext gametes

angiosperms lack _____

gametangia - structures inside their flowers perform the same functions

evolutionary importance of gametangia

helped early plants reproduce successfully on land by protecting gametes

antheridium

sperm producing gametangia

archegonium

egg producing gametangia

egg retention

land plants keep their eggs inside archegonia instead of releasing them into water or soil

zygote development

fertilized eggs begin developing on the parent plant

multicellular embryos

develop zygotes and remain attached to and nourished by the parent plant

embryophyta

formal name for land plants

embryo retention

key evolutionary adaptationw here embryos remain attached to and nourished by the parent plant

embryo retention vs. pregnancy

analogous

gametophyte

multicellular haploid phase

sporophyte

multicellular diploid phase

Sequence of alternation of generations

1. Sporophyte produces haploid spores by meiosis

2. Spores germinate and divide by mitosis and develop into

multicellular, haploid gametophytes

3. Gametophytes produce unicellular haploid gametes by

mitosis

4. Two gametes unite during fertilization to form a diploid

zygote

5. Zygote divides by mitosis and develops into a multicellular,

diploid sporophyte

zygotes develop into ______ and spores develop into ______

sporophytes; gametophytes

sporangia

structure in which spores are produced by meiosis

gametangia

structure in which gametes are produced by mitosis

vascular plants (dominance)

sporophyte dominant - large and long lived

Gymnosperm and Angiosperm Gametophyte

Microscopic in size.

Advantage of Sporophyte Dominance

Diploid cells can respond faster to changing environments than haploid cells, especially when heterozygous at many genes.