BIS 2C: midterm 2 study guide (PLANT)

lectures 16-23 (intro to plant ~ flowering plant)

are plants monophyletic or paraphyletic?

plants are monophyletic

what are the 2 diagnostic features of plants?

1. possession of a chloroplast that arose via primary endosymbiosis of a cyanobacterium

2. chlorophyll a

what are the 5 challenges plants had to overcome to adapt to life on land?

1. desiccation

2. water transport

3. structural support

4. UV radiation

5. dispersal of gametes and progeny

what are 3 advantages of living on land?

1. increased access to sunlight

2. increased access to gasses

3. decreased competition with other plants and herbivores (initially)

4 special innovations of algal grade plants

1. storing the products of photosynthesis as starch

2. chlorophyll b

3. egg remains attached to parent plant

4. egg enclosed by parent plant tissue

what group? contains chlorophyll a and b, uses starch as storage, egg retention, egg encasement, protected embryo

land plants

what group? contains chlorophyll a and b, uses starch as storage, egg retention, egg encasement. NO protected embryo

charales

what group? contains chlorophyll a and b, uses starch as storage, egg retention. NO egg encasement nor protected embryo

choloeochates

what group? contains chlorophyll a and b, uses starch as storage. NO egg retention, egg encasement, nor protected embryo

chlorophytes

what group? contains chlorophyll a. NO chlorophyll b, starch as storage, egg retention, egg encasement, nor protected embryo

red algae

what group is sister to land plants?

charales

is multicellular homoplasy in algal grade group?

yes, multicellularity evolved independently several times

algal group: reproduction and life cycle type

algal group reproduces asexually by means of a haplontic life cycle

meiosis results in how many daughter cells?

4

mitosis results in how many daughter cells?

2

what is fertilization and what does it result in?

haploid gamete nuclei fuse to form a single diploid cell: zygote

what are the 3 main kinds of eukaryotic sexual life cycles?

diplontic (animals), haplontic (fungi, algal), sporic (land plants)

what are 3 vegetative innovations of land plants?

1. cuticle (prevent desiccaiton)

2. pigments (UV protection)

3. microrrhizae (fungal asociations)

what are 7 reproductive innovations of land plants?

1. sporic life cycle

2. sporophyte

3. sporangia

4. air-born spores

5. sporopollenin

6. gametophyte

7. protected embryo

relationship btwn sporophyte, sporangia, air-borne spores, and sporopollenin

sporophyte is a multicellular diploid plant that contains sporangia, which produces air-borne spores protected by sporopollenin

gametophyte significance

gametophyte is a multicellular haploid plant that contains 2 types of gametangia: antheridia which produces male gametes and archegonia which produces female gametes

this plant group is analogous to the amphibians of the plant world (hybrid)

bryophytes

why are bryophytes restricted to cool, damp terrestrial habitats? (4 reasons)

1. they lack a true vascular system

2. they lack true leaves, stems, and roots

3. their cuticle is poorly developed

4. water is required for sperm to reach egg

how do non-vascular plants transport water and nutrients?

water transport relies on capillary action, nutrient transport relies on diffusion

which bryophyte lineages independently evolved to have vascular tissue: liverworts, mosses, hornworts

mosses

which group: YES land-plant innovations; NO stomata and green sporophyte

liverworts

which group: YES land plant innovations and stomata. NO green sporophyte

mosses

which group: YES land plant innovations, stomata, and green sporophyte

hornworts

what groups is sister to living vascular plants?

Rhyniophytes

what are 2 major innovations of Rhyniophytes?

1. branched sporophyte with apical sporangia

2. vascular tissue (but no tracheid cells)

what are 2 diagnostic features of vascular plants?

1. sporophyte is nutritionally independent at maturity

2. tracheid cells

xylem: function + system + composition (tissue + cell wall)

Conducts water and minerals from the roots to the aerial parts of the plant by passive Transpiration-Cohesion Tension system.

Tissue is comprised of tracheid cells that are dead at functional maturity and have cell walls that are fortified with lignin

phloem: function + system + composition of tissue

Conducts phloem sap from source to sink regions via active Pressure Flow Model.

The tissue is comprised of sieve-tube elements (that are alive at maturity) and companion cells.

what are the benefits in growing taller?

compete for sunlight and allow more effective dispersal of spores

what are 3 major innovations of vascular plants that involves homoplasy?

leaves, roots, heterospory

leaves: # of times it evolved independently + types

leaves evolved independently twice in vascular plants.

1. microphylls: leaves with single vascular strand; evolved from sterile lateral sporangia in lycophytes

2. megaphylls: leaves with many branched vascular strands; evolved from modified side branches in euphyllophytes

roots: # of times it evolved independently + types

roots evolved independently twice in vascular plants

1. simple: comprised of dichotomously branching rhizome with rootlets derived from microphyllous leaves evolved in Lycophytes

2. complex: comprised of complex branching and root hairs derived from dermis evolved in Euphyllophytes

heterospory: # of times it evolved independently + types

heterospory evolved independently three times in vascular plants

once in lycophytes, again in monilophytes, and finally in the MRCA of seed plants

homosporous

refers to male and female gametangia on a single individual plant

heterosporous

refers to male or female gametangia on separate individual plants

microsporangium

contain microsporocytes (diploid cells) that divide by meiosis to produce haploid micropores that become haploid microgametophyte

megasporangium

contain megasporocytes (diploid cells) that divide by meiosis to produce haploid megaspores that become haploid megagametophyte

2 adaptive values of heterospory

1. genetic diversity (reduces the probability of self-fertilization, which mains genetic diversity)

2. door opener: facilitated the evolution of important novelties

what are 2 main groups of seedless-vascular plants?

lycophytes and monilophytes

what are 3 diagnostic features of lycophytes?

1. lateral sporangia: stroboli; increase the number of sporangia on a give sporophyte

2. microphyll leaves

3. simple roots

what are 3 diagnostic features of euphyllophytes?

1. overtopping growth: sporophyte has a dominant axis and side branches

2. megaphyll leaves

3. complex roots

what (groups) do euphyllophytes include?

monilophytes and seed plants

how does overtopping growth come to be + adaptive value of overtopping growth

overtopping growth involves the asymmetric division of the apical meristem. It allows for taller growth and elaboration of novel organs from side branches (e.g. megaphyllous leaves & complex roots)

what plant of the lycophytes demonstrate heterospory?

spike mosses

what plant of the monilophytes demonstrate heterospory?

lepto. ferns

what groups are seed plants represented by?

gymnosperms and angiosperms

trees that exhibited secondary growth (wood) but lack seeds

progymnosperms

trees that exhibited secondary growth (wood), has fern-like leaves, and bore seeds

seed ferns

4 innovations that arose in teh MRCA of all living seed plants

1. secondary growth

2. reduced and dependent megagametophyte

3. seed

4. pollen

primary growth

refers to the ability to increase the length of the plant via apical (shoot and root) meristems

secondary growth

the ability to increase the girth of the growing plant by means of vascular cambium

bifacial vascular cambium

produces secondary xylem to the inside of the plant (gives rise to wood) and secondary phloem to the outside of the plant (bark)

3 adaptive significance of secondary growth

1. allows taller growth of the sporophyte (greater photosynthesis + dispersal)

2. constant rejuvenation of the xylem and phloem

3. formation of bark prevents water loss and infection and protects against disease

secondary growth in lycophytes (quillworts): unifacial or bifacial vascular cambium?

unifacial— yes secondary xylem, no secondary phloem

sporophyte and gametophyte evolution in seed plants: seeds

In seed plants, (mega)gametophyte is greatly reduced and is nutritionally dependent on sporophyte, allowing for the evolution of seed

gymnosperm seed components (3; from innermost to outermost)

1. diploid embryo (baby sporophyte)

2. haploid nutritive tissue (from megagametophyte)

3. diploid seed coat (from integument)

3 adaptive significance of seeds

1. dispersal of next sporophyte generation

2. protection of developing sporophyte plant (embryo)

3. dormancy until conditions are favorable

seed vs pollen

seed: from reduced megagametophyte; pollen: from reduced microgametophyte

pollen components (4)

1. 4-8 cells

2. lacks a multicellular male gametangia (antheridia)

3. 2 sperm cells

4. enclosed in sporopollenin

adaptive significance of pollen (2)

1. dispersal of sperm over great distances + genetic diversity

2. delivery of sperm without water

gymnosperms vs angiosperms

gymnosperms only have a fertilized ovule (no fruit), whereas angiosperms bear fruit

cycads, ginkgo, gnetophytes, conifers: which are dioecious, which are monoecious?

cycads and ginkgo are dioecious; gnetophytes and conifers can be both

cycads and ginkgo: sperm

sperm swim within the megagametophyte to fertilize the egg after pollination

dioecious plant

an individual plant has exclusively micropsorangia OR megasporangia

this plant was believed to be the sister group of agiosperms because they have vessel elements in their xylem and exhibit a kind of double fertilization

gnetophytes

what plant of gymnosperms have non-motile sperm?

gnetophytes and conifers

angiosperms have a long phylogenetic stem. what is the significance of this? (2)

1. made it extremely difficult to locate the position of the root of flowering plants, but eventually identified it at the ANITS grade of plants

2. long stem allowed Angiosperms to accumulate many innovations

angiosperm innovations (7)

1. flower (house micro- and megasporangia)

2. carpel (enclosed megasporangia)

3. fruit (expanded ovary)

4. double fertilization (diploid zygote & triploid endosperm)

5. endosperm (triploid tissue of angiosperm seed that nourishes developing embryo)

6. embryo sac (7 cells, 8 nuclei)

7. vessel elements & fiber cells in xylem

gymnosperm vs angiosperm: pollination

gymnosperms rely on wind polliation, whereas angiosperms are pollinated by animals (more efficient)

eudicots: # of seed leaves, organization of root vasculature, leaf venation, # pollen grooves

two cotyledons, star shaped vasculature, reticulate venation, tricolpate

monocots: # of seed leaves, organization of root vasculature, leaf venation, # pollen grooves

one cotyledon, ring shaped vasculature, parallel venation, monocolpate

duplicate-gene rooting & phytochromes + discovery

flowering plants have an extra set of phytochrome genes that are not found in seed plants.

• flowering plants include dicots and monocots → not monophyletic

drupe fruit

fruit derived from a singl eflower with one ovary that contains one ovule (e.g. plums)

berry fruit

fruit that is derived form a single flower with one ovary that contains multiple ovules (e.g. tomato)

ovary vs ovule

ovary houses the ovules and mature into fruit after fertilization. ovule contains the female egg cell and develops into a seed.

aggregate fruit

fruit derived form a single flower with multiple, separate ovaries (e.g. blackberries)

multiple fruits

fruit developed from the many separate florets of an inflorescence (e.g. pineapple)

accessory fruits

fruit developed from parts of the plant other than carpels and seeds (e.g. strawberry)

legumes

fruit that develop from one carpel with many ovules where the fruit splits lengthwise and each ovule is a bean

achenes

dry fruits that contain a single seed (e.g. sunflower seeds)

samara

an achene with wings

adaptive significance of fruit (2)

1. provides additional protection for embryo

2. facilitates dispersal of the seed

vessel elements

water and mineral transport

fiber cells

structural support

perfect flower

contains both stamens and carpels (micro and megasporangia)

imperfect flower

either has stamens OR carpels

monoecious

a single plant has both imperfect staminate and imperfect carpelllate flowers

dioecious

a single plant has either imperfect staminate OR imperfect carpellate

umbel

inflorescence comprised of flowers stemming from short stalks (pedicles) that radiate from a common point (e.g. onions)

compound umbel

inflorescence comprised of a cluster of umbels stemming from stalks (rays) that radiate from a common point (e.g. carrots)

spike

inflorescence comprised of a cluster of flowers along an unbranched axis (e.g. bunny grass)

head

inflorescence comprised of an outer ring of sterile ray florets and a central cluster of disc florets (e.g. sunflowers)

composition of embryo sac of flowering plants

• 3 antipodal cells

• 2 synergid cells

• single egg cell

• single large polar cell ( with 2 haploid polar nuclei)

what does double fertilization give rise to?

a diploid zygote ad a triploid endosperm

agiosperm seed components

diploid embryo (from 1st fertilization event), triploid endosperm (from 2nd fertilization event), diploid seed coat (from diploid integument)