bis2c lab 4

How are eukaryotes characterized?

How are eukaryotes characterized?

by the presence of mitochondrion, a nucleus, and membrane bound organelle

Embryophytes

land plants

algae

unicellular and multicellular photosynthetic eukaryotes often referred to a algae

synapomorphies of Embryophytes

waxy cuticles, alternation of generation, multicellular embryo, ect.

List two major lineages on the phylogeny that have vascular tissue but lack seeds

Euphyllophytes, Tracheophytes

Which group has vascular tissue, seeds, and pollen but no flowers or fruit?

Gymnosperms

mitosis

no change in ploidy, so the chromosome number is always the same (resulting in two cells)

meiosis

the chromosome number is reduced by half but can never go below one copy (resulting in four cells)

Is the zygote multicellular or unicellular?

unicellular

Haplontic life cycle

• multicellular adult stage: 1n

• Spores: present

• Gametophyte: present (for plants, not for fungi)

• Gamete Production: mitosis

Diplontic life cycle

• multicellular adult stage: 2n

• Spores: absent

• Gametophyte: absent

• Gamete Production: meiosis

Alternation of Generations life cycle

• multicellular adult stage: both

• Spores: present

• Gametophyte: present

• Gamete Production:

sporophyte

the multicellular diploid stage that produces spores

gametophyte

the multicellular haploid stage that produces gametes

Life cycle of moss

alternation of generation, have archegonium and antheridium

sporopollenin

special proteins coat around spores that prevents them from drying out

Homosporous alternation of generations

only produces a single type of spore (mosses)

Why are spores, as opposed to sperm the primary means of dispersal in moss?

They are protected by sporopollenin and are thus capable of a greater range of travel than sperm which require water

Where does the shift in the relative dominance and nutritional independence of the gametophyte and sporophyte generation happen?

in the MRCA of vascular plants (tracheophytes)

Why are moss low to the ground in terms of support and growth?

They lack lignified trachieds

Why is the trend to have a larger sporophyte over time?

allows for greater spore production as well as better dispersal

Do fern gametophyte have antheridia and archegonia?

yes

What are the two main organ system in plants?

the root system and shoot system

nodes

where the stem is divided and lateral growth can occur

indeterminate growth

both root and shoot system are this, they continue to divide throughout the plant’s life

determinate growth

predetermined growth, present in leaves

What is the diagnostic feature of a stem?

they have nodes (meristematic tissue)

Where are the meristematic tissues concentrated?

the SAM and the RAM

Apical meristems

concentrations of meristematic tissue, can differentiate into different tissue systems

axillary meristem

a group of meristematic cells found in the angle between a leaf and a stem

Root cap functions

gravity sensing, protects the RAM

What two vascular tissues are in tracheophytes?

xylem and phloem

do bryophytes have xylem/ phloem?

no

What is the first type of xylem tissue to evolve

tracheids, are shared by all vascular plants

Which xylem tissue evolved multiple times?

vessel elements

What groups have vessel elements?

Angiosperms and Gnetophytes

Primary growth

vertical growth thanks to lignin

Secondary growth

wider growth, for more vascular tissue and wider stems

BVC (bifacial vascular cambium)

produces xylem cells on the inside and new phloem cells on the outside

What do algae NOT have ?

no waxy cuticle, airborne spores, vascular system

What chlorophyll do Coleochaete and Chara use?

chlorophyll a and b (as well as caritenoids)

Innovations of land plants

• waxy cuticles/ stomata

• Protected reproductive structures; sporangia (airborne spores) and gametangia (sperm and egg)

• zygote is retained in parent organism

• (grows into embryo in sporophyte generation)

What life cycle do all bryophytes have?

homosporous alternation of generation

Why do hornworts sometimes appear blue-green?

because of the presence of cyanobacteria

Lycophytes

the first group of vascular plants/ oldest lineage of vascular plants

What type of leaf is special to lycophytes?

microphylls (lycophylls)

strobili

the clusters the sporangia are organized in

What life cycle do lycophytes have?

heterosporous alternation of generation

euphyllophytes

“true leaved”, include the seed plants and monilophytes (megaphylls)

Where did DNA inversion happen?

In euphyllophytes

life cycle of a Monilophyte

homosporous alternation of generations

What two innovations freed plants from their dependence on water and diversification?

pollen and seeds

seed plant life cycle

heterosporous alternation of generation

seed plant characteristic

• reduction of gametophyte

• pollen delivers sperm directly to the egg via a pollen tube

• Seeds represent the next sporophyte generation and enclosed by the embryo which has the nutritive tissue and seed coat

What is special about the gnetophyte?

Shares angiosperm characteristics of vessel elements and double fertilization (homoplasy)

What do angiosperms possess that gymnosperms do not?

ovary (not ovules)

How did microphylls develop?

small vascular strands extended into an outgrowth in order to supply with water and move the products of photosynthesis into the lycophyte

How did megaphylls develop?

Growth branches became asymmetric (overtopping) and the branching stems on the plant flattened (plantation) and finally webbing of photosynthetic tissue developed between branches

Turgor pressure

When water moves into a cell via osmosis the cell wall will expand creating a cell wall

How is water distributed throughout non- vascular plant?

diffusion

evotransportation

in vascular plants; the evaporation of water form the leaves pulls water from the soil into the xylem where it travels from the roots up the soot and into the leaves