good luck on the test guys 😋
What does this phylogenetic tree represent ?
Green Plants
Practice Question (Plants) - According to this updated phylogeny, the sister taxon of land plants
Is [Coleochaetophyceae + Zygnematophyceae]
Chlorophytes
a species of green algae that are
diverse
unicellular , colonial , or multicellular
found in freshwater or marine
micro- or macroalgae
Evolution of Life Cycles (fill in the blank)
Life cycles began with the evolution of sexual reproduction.
Gametes (n) combine by fertilization to make the diploid stage.
Meiosis always produces the haploid stage.
Two question used to determine the type of life cycle
is the haploid stage multicellular ?
is the diploid stage multicellular ?
Ancestral (unicellular) Life Cycle
Haploid Stage Multicellular - NO
Diploid Stage Multicellular - NO
Diploid-Dominant Life Cycle
Haploid Stage Multicellular - NO
Diploid Stage Multicellular - YES
Haploid-dominant Life Cycle
Haploid stage multicellular - YES
Diploid stage multicellular - NO
Alternation of Generations
Haploid stage multicellular - YES
Diploid stage multicellular - YES
Practice Question (Plant Life Cycle) - In this life cycle
The zygote is the only diploid cell
Practice Question (Plant Life Cycle)
Gametes are released by the “gamete-plant” aka ____
Spores are released by the “spore-plant” aka ____.
gametophyte ; sporophyte
Practice Question (Plant Life Cycle) - The life cycle shown is
Alternation of generations (#3)
Practice Question (Plant Life Cycle) - The life cycle shown is
Diploid-dominant
Practice Question (Plant Life Cycle) - The life cycle show is
Ancestral (unicellular)
Practice Question (Plant Life Cycle ) - The life cycle shown is
Haploid-Dominant
Practice Question (Plant Life Cycle) - The life cycle shown is
Alternation of generations (#4)
Practice Question (Plant Life Cycle) - The life cycle shown is
Alternation of generations (#5)
Practice Question (Plant Life Cycle) - The life cycle shown is
Alternation of Generations (#6)
Practice Question (Plant Life Cycle) - The life cycle shown is
Diploid-dominant
Practice Question (Plant Life Cycle) - The life cycle shown is
Ancestral (unicellular)
Sporopollenin
a resistant spore coating
Synapomorphies of all Land Plants
• cuticle
• mycorrhizas
Derived Trait of Streptophytes
spores with tough outer wall of sporopollenin
Advantage of Alternation of Generations
allows for organisms to perform different forms of sexual reproduction depending on their surrounding environment
Multicellular 2n embryo
some advantages of it’s multicellularity include
being able to grow at faster rates
it’s different cell types allowing for more complexity
Advantage of Plant Cuticle
• controls both the absorption and evaporation or loss of water
• provides the plant with structural support
• it also protects the plant from pathogens and other pests
Advantage of Mycorrhizas
• these fungi have a symbiotic relationship with plants
• their main advantage is allowing plant roots to draw more nutrients and water from the soil
• they can do this because they are decomposers meaning they break down plant and animal debris. this then increases nutrient availability which plants can use
Advantage of Spores with sporopollenin wall
sporopollenin renders the spores resistant to many adverse conditions and allows the spores to be transported over unfavorable terrain so that the bryophyte can colonize another area far away from where the spores were released.
Evolutionary Trends (Height)
Ancestral clades such as bryophytes have a height of about 2 centimeters, while more derived clades like angiosperms evolved to grow up to a height of 100 meters
this is contributed to land plants having vascular tissue with xylem cells that give them the support to grow that high
Evolutionary Trends ( Complex Growth)
Another characteristic that evolved is the plants' complexity,
bryophytes have flat and upright growth which through the help of lateral meristem cells would evolve to secondary growth in angiosperms making them thicker.
Evolutionary Trends (Sporophyte vs. Gametophyte Importance)
In older plant clades the sporophyte was tiny and dependent on the gametophytes; eventually, the gametophyte became reduced and microscopic while the sporophyte became more dominant and independent.
This would be due to the sporophyte adapting to dry environments making it live longer and becoming dominant.
Evolutionary Trends (Dependence on water)
ancestral plants need water for both sex and growth but in more derived plants there is less dependence on water.
This is thanks to innovations such as again, sporophytes becoming more adapted to dryness , derived plants having both seeds and pollen and sex being enclosed in a cone or flower
Practice Question (Evolutionary Trends) - Which of the following is not an evolutionary trend in the more derived plants?
more dependence on water
Bryophytes
a group of non vascular plants compromised of liverworts , mosses, hornworts
Liverworts
are gametophyte dominant with a tiny dependent sporophyte
has flat prostrate growth
they have a ribbon-like gametophyte body with dichotomous branching
Mosses
upright gametophyte
the gametophyte is dominant while the sporophyte id small and dependent
photosynthesis is conducted in the differentiated sporophyte
Moss Life Cycle Explained
Alternation of Generations Explanation
Main features of Mosses
both a male and female gametophyte
leaves
rhizoids
sporophyte with a single sporangium that performs photosynthesis and disperses spores
Practice Question (Plant Homologies) - A homology of mosses and liverworts is
Sporophyte with a single sporangium
Peat Moss
has amazing properties such as
anti fungal bacteria
being used for preservation
wound dressing
Hornworts
there are 100 species in total
have a long lived sporophyte (similarly to vascular plants) which allows it to develop independently from the gametophyte.
are gametophye (haploid) dominant
Vascular Plants
sporophyte dominant and independent
have vascular tissue (made from xylem and phloem), stems
multicelled apical meristem which allows for more complex growth
Lycophytes
there are 1200 species total
have roots
microphylls (leaves that are single veined and don’t have gaps)
are sporophyte dominant and independent
vascular tissue , stems
multicelled apical meristem
Practice Question (Vascular Plants) - In lycophytes, the mature sporophyte is _____ the gametophyte, and the sporophyte’s morphology is ____ complex than that of the gametophyte.
Independent from; more
Lycophyte strobilus advantages
compared to the bryophyte sporophyte the lycophyte sporophyte has a greater number of spores
it also has a greater dispersal of spores
Advantages of roots
allowed plants to be more stable
they obtain more nutrients from soil where they are harder to reach
Resurrection Plant
are capable of recovering from extreme cellular rehydration
are thought to have evolved or retained novel genes and regulatory mechanisms not present in sensitive species
these genes can be exploited for engineering improved stress tolerance in crop plants
Monilophytes (ferns and allies)
there are 12,000 species total (most are ferns)
roots
megaphylls (leaves that have branching veins and have a gap)
Native resurrection fern
are epiphytes or a plant that grows on another plant
is homoplasious with lycophyte resurrection plant
Practice Question (Plant Phylogeny) - For vascular plants, stems are _______ and leaves are
homologous; homoplasious
Advantage of Fern Sori
sori are groups of sporangia
produces a large spore count
gives them a high dispersal advantage
Ferns
are sporophyte dominant with a small independent gametophyte
Fern sex and Life Cycle
Horsetails
branches
leaves
sporangia
spores
cones (that produce spores)
are located at the apex because the higher up you are the likelier you are to catch a breeze for dispersal
Seed-Dispersed Plants
gymnosperms
angiosperms
have secondary growth
male gametophyte and a retained embryo
seeds
megaphylls (gapped leaves with branching veins)
What is Secondary Growth ?
it is when the stems grow thicker at lateral cylindrical meristems , using vascular cambium.
Gymnosperms
there are 800 species in total (mostly conifers)
sporophyte dominant while the gametophytes are tiny and dependent
secondary growth
male gametophyte and embryo retained
megaphylls (gapped leaves with branching veins)
Advantage of Spore Growth inside sporophyte cones
offers protection for the gametophytes
Advantage of Wind-Dispersed Pollination
does not rely on the presence of insects
Advantage of reproduction inside cones
protects the seed from environmental conditions and predators
the cones aid in spreading seeds over wider areas by opening up to animals or wind , thereby increasing the seeds chance of survival and germination
allows seeds to develop and mature over time which allows conifers to consistently produce seeds ensuring the survival of the species
Practice Question (Gymnosperms) - The pine pollen grain (top) is homologous (i.e. is the corresponding stage in the life cycle) to which structure of the moss (bottom)?
The male gametophyte
Advantage of seed over spore dispersal
they are more protected
off spring have more genetic diversity due to seeds being diploid cells
stored nutrient material that gives the seed a great growing start
Practice Question (Gymnosperms) - The mother of a pine embryo is the ____, and her function in the gymnosperm seed is to ____ the embryo.
Female gametophyte ; feed
Angiosperms
less than 250,000 species
flowers w/retained gametophytes
pollen dispersers ; sex is in indoors in ovary
endosperm (a nutritive sibling to the embryo)
fruits
sporophyte dominant with tiny dependent gametophytes
Vascular Plants
includes lycophytes, monilophytes , gymnosperms and angiosperms
have stems (organ) with vascular tissue
multicelled apical meristem :
complex embryonic tissue
Advantage of Root apical meristem not being right at the root tip
it keeps it from being damaged
this is through the help of the root cap , which acts like a protective helmet
Difference between plant Growth and animal growth ?
plant growth is modular or new added to old
animals have coordinated growth
Plant Organs
flower (only present in Angiosperms)
stem
root
metapatterns : plants are holons while organs are clonons
What is a tissue ?
layer
different cell types
w/ related functions
What is an organ ?
distinct structure
different tissues (often layered)
w/ related functions
Plant Organs (The Stem)
functions :
supports plant
transports water and nutrients to the leaves
some stems do photosynthesis
supports, produces and displays the other structures
leaves, flowers, fruits
helps with growth
used for storage
Plant Organs (Roots)
functions :
anchors the plant to the soil
they absorb water and nutrients from soil
store food
holds soil together
symbioses (fungi and bacteria)
Plant Organs (Leaf)
functions :
perform photosynthesis
transpiration
transport
cooling
competition
modified for other functions
have distinct leaf arrangement
Leaf Adaptations (Canopy)
Light : high
Temperature : high
Dry or wet : dry
Leaf Adaptations (Rainforest Floor)
Light : low-light adapted
Advantage of Leaf Size : big (more light)
Leaf glossiness (wax) : shed off water in addition to sealing water
Function of holes and splits : lets water get through to roots and allows plants below to get water
What kind of environment would root vegetables favor ?
stable ones
Practice Question (Vegetables) - Which vegetable is a root?
carrots
Vegetable Classifications
A - lemongrass are leaves
B - potatoes are stems
C - carrots are roots
Hydrophytes
Water Plants (for example lily pads)
Mesophytes
middle plants that are neither adapted to wet nor to dry environments (such as lilacs)
Xerophytes
dry plants (such as cacti)
Mesophyte leaves
single layer epidermis with wax : serves as protection
palisade mesophyll : photosynthesis
spongy mesophyll : exchange of gas
stomata with guard cells : regulate opening and closing of the pores
Practice Question (Mesophytes) - The palisade mesophyll is specialized for ___ and the spongy mesophyll is specialized for ___.
Absorbing light; gas exchange
Hydrophyte Leaves
stomata on top surface : air is absorbed on top for gas exchange
big air spaces : allows it to go back up when pushed down
Xerophyte Leaves
multi-layer epidermis with wax : acts as a barrier to reduce water loss from transpiration.
recessed stomata crypts : also reduce transpiration by protecting them from hot and dry winds.
hairs : decrease transpiration by breaking up the flow of air which gives the crypt chamber a higher humidity than its surrounding atmosphere
Practice Question (Plant Adaptations ) - Here is a cross section of a leaf that grows curled up. Stomata are indicated by pink arrows.
Xerophyte
Extreme Adaptations
advantages : not a lot of competition
disadvantages : it’s hard lol
Why does the old man cactus have hair on his head ?
protects the apical meristem from the sun and protects the cactus itself from predators
Mangroves
are classified as both hydrophytes and xerophytes
Epiphytes
a plant that lives on a plant but is not parasitic
Anthurium sp.
leaf orientation : acts as a funnel for water
root orientation : roots are attached to hang onto to tree , this also puts the roots up through the compost pile so the plant can get nutrients
Carnivorous Plants
can draw animals such as flies close to its pattern
the fly slips in and is digested
Florida yellow bladderwort leaf
poor gas exchange —> more surface area
epidermis and cuticle are thin
low nutrient availability —> carnivory
Cuscuta spp.
How does mistletoe get to a new host ?
fruit is eaten by birds which then sticks to their beak
the bird tries to wipe it off leaving behind seeds on a new branch where it will start growing again
Plant Biomimicry - Eden Project Greenhouses
resemble pollen grains
strong
lightweight
energy efficient
Plant Biomimicry - Solar Panels
these panels replicate the simple plant mechanics of a leaf
Plant Transport : Vascular Tissue
xylem and phloem are tissues that make up vascular bundles found throughout the plant
Xylem
dead vascular tissue that transports water and minerals from the roots to the leaves
moves upward