Bio 2 Exam 2

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