Biol 204 exam 2

To which major eukaryote clade (supergroup) do fungi belong?

Unikonta

Two Clades of Unikonta

Amoebozoa (true amoebas) and Opisthokonta (fungi, animals, and related protists)

What does it mean that fungi are heterotrophic eukaryotes?

Fungi are chemoheterotrophs that feed by absorptive nutrition (decomposers)

How do fungi gain nutrition?

Fungi are chemoheterotrophs that feed by absorptive nutrition (decomposers)

Feed by absorptive nutrition

Secrete digestive enzymes that break down food

Absorb digested food into cells

Mycorrhizae around plant roots provide water and nutrient absorption for plants; plants provide fungus with carbohydrates

What substance contributes to the cell walls of fungi?

chitin (polysaccharide carbohydrate)

What is a saprobe?

living off dead or decaying organic material

Mycorrhizae

Mutualistic symbionts:  around plant roots provide water and nutrient absorption for plants; plants provide fungus with carbohydrates

Endophytes

harmless symbiotic fungi inside plant parts – make toxins that deter herbivores and defend against pathogens

hyphae (filamentous structures)

Reproductive and non-reproductive structures composed of

mycelium

mass of hyphae that make the body of the fungus

Two types of hyphae – septate

divided

Two types of hyphae – coenocyte

undivided

Haustoria

appendages of parasitic fungi

Fungi can reproduce asexually

occurs without the fusion of two gametes

Fungi can reproduce sexually

occurs through the fusion of two gametes

Spore

 haploid cell that can germinate to produce a multicellular individual without fusing with another cell

Plasmogamy

fusion of cytoplasm between two mycelia  (marriage)

Heterokaryotic

 stage where a cell contains two or more haploid nuclei following plasmogamy

Karyogamy

fusion of nuclei to form diploid zygote (nucleus)

Chytridiomycota

chytrids. 

Zoospores flagellated spores.

 Mostly aquatic saprobes or parasites

Mucurocomycoa and Zoopagomycota asexual Reproductive structure

sporangia

Mucurocomycoa and Zoopagomycota sexual Reproductive structure

Zygosporangia

Zoopagomycota

 mostly in soil. Coenocytic hyphae. 

May not be monophyletic

 sporangia: asexual  

Zygosporangia: sexual

Mucurocomycota

 include fungi that form arbuscular mycorrhizae with plants.

mostly in soil. 

Coenocytic (aseptate) hyphae. 

Reproductive structures

 sporangia: asexual  

Zygosporangia: sexual

Basidiomycota

fruiting body (basidiocarp) containing many basidia (dikaryotic) that produces sexual spores (basidiospores)

Club fungi

Important decomposers

Mutualistic mycorrhizal. Relationship with plant roots

arbuscular mycorrhizae.:

fungi growing around the root of plants and penetrate the cell roots. Nutrients from the plants. Absorbing nutrients and giving pesticides

Ascomycota

 all united by having an ascus sac containing spores (ascospores) born internally in sacs called asci

marine, freshwater and terrestrial. 

Some are single celled (yeast) , some are large and elaborate. 

Ascomycota Reproductive structures asexual spores

conidia

Ascomycota Reproductive structures sexual spores

ascospores

Basidiomycota sexual Reproductive structure

basidiocarp fruiting body

Basidiomycota asexual Reproductive structure

 reproduction via fragmentation

Lichen

fungi with photosynthetic symbiotic(mutualistic symbiotic association)

Most are ascomycota some basidiomycota

Photosynthetic symbiont is usually green alga sometimes cyanobacteria

Importance of basidiomycetes

decomposers

Some are pathogens (e.g., wheat rust, corn smut)

Many form mycorrhizae

Mushrooms

Edible (e.g., Agaricus bisporus, shitake, etc.

Poisonous (e.g., Amanita spp., destroying angel)

Hallucinogenic (e.g., Psilocybe, Amanita muscaria)

Loss of flagella

resides on land

Identify the members of Archaeplastida

Includes land plants green and red algae

Two clades of green algae (paraphyletic)

Chlorophytes and Charophytes

green algae

Unicellular 

Multicellular: colonial, filamentous, thalloid

What do “green algae” and land plants share?

Chloroplasts. Cell walls contain: cellulose

What is the function of chloroplasts?

Stacks (grana) of thylakoids contain chlorophyll a and b (pigments that absorb light for photosynthesis. Store starch

plant adaptations for a terrestrial life Apical meristems

localized region growth

plant adaptations for a terrestrial life Cuticle

 a waxy covering that helps prevent desiccation/water loss

plant adaptations for a terrestrial life Thick spore walls

prevent desiccation

plant adaptations for a terrestrial life Gametangia

 cases that enclose the gametes and prevents desiccation

Eggs (n) in archegonia; sperm (n) in antheridia

plant adaptations for a terrestrial life Alternation of generations

gametophyte (n) and sporophyte (2n) stages. The gametophyte is haploid and produces haploid gametes

plant adaptations for a terrestrial life Dependent embryos

 contained within a protective structure. Multicellular. Parent protective nutrients. 

Gametophyte

is haploid and produces haploid gametes by mitosis.

Fusion of the gametes gives rise to the diploid sporophyte, which produces

haploid spores by meiosis.

Do bryophytes (liverworts, mosses, hornworts) form a monophyletic group?

No: Paraphyletic group

Gametophyte dominant

Motile sperm (needs h2o)

No vascular tissue

Ancient

What is the sister taxon to land plants? Evidence?

Hornworts

Both share stomata – function in gas exchange (CO₂ in, O₂ out) and water retention. Shared with vascular plants.

Tracheophytes

Sporophyte is dominant

Lignified vascular tissue – xylem and phloem

Organ systems present:

Shoots

Stems, Leaves, Reproductive organs

Roots

Bryophytes

Liverworts, mosses, and hornworts

Paraphyletic group

Gametophyte dominant

Motile sperm

No vascular tissue

Ancient

Hornworts, mosses, and vascular plants share stomata – function in gas exchange (CO₂ in, O₂ out)

What is the function of vascular tissue?

duct system for conducting fluids and nutrients. Vascular tissue allowed for greatly increased height, which provided an evolutionary advantage.

Xylem

 conducts most of the water and minerals; includes tube-shaped cells called tracheids.

Phloem

cells arranged into tubes that distribute sugars, amino acids, and other organic products of photosynthesis

Leaves

 organs that increase the surface area of vascular plants

Microphylls

leaves with a single vein

Megaphylls

 leaves with a highly branched vascular system

Sporophylls

 modified leaves with sporangia (contain spores)

Sori

 clusters of sporangia on undersides of sporophylls

Strobili

cone-like structures formed from groups of sporophylls

Roots

organs that anchor vascular plants to the ground. Enable vascular plants to absorb water and nutrients from soil.

What is the significance of seedless tracheophytes?

The ancestors of modern seedless tracheophytes grew to great heights during the Devonian (~420-360 million years ago) and Carboniferous Periods (~360-300 million years ago), forming the first forests

Increased growth and photosynthesis removes CO₂ from the atmosphere and may have contributed to global cooling at the end of the Carboniferous Period (collapse of rain forests; glaciation and drop of sea level)

Decaying plants eventually became coal

Identify and discuss the synapomorphies of seed plants (Spermatophyta)

Gymnosperm

Angiosperm

Seeds: Highly reduced gametophyte, Heterospory, Pollen and ovules

Gymnosperm

megasporangia have one integument

Angiosperm

megasporangia have two integuments

Integument

tough outer layer ex skin

What is a seed, and what is the adaptive significance of them?

A seed consists of an embryo and nutrients surrounded by a protective coat (embryo+food=seed)

Adaptive significance of seeds

Protects the embryo

Nutrition of embryo

Disperses embryo – wind, water, animal dispersal

Dormancy mechanism – seeds can remain dormant for many years until conditions are right for germination

Heterospory

evolution of two types of spores

microspores

Male spores

megaspores

Female spores

What is the advantage of a reduced gametophyte in seed plants?

Gametophytes of seed plants develop within the walls of spores that are retained within the tissues of the parent sporophyte.

Pollen

(sperm) derived from microspores

Ovule

consists of a megasporangium, megaspore, and one or more protective integuments

Gymnosperms

appear in the fossil record ~305 million years ago and dominated the Mesozoic terrestrial ecosystems

better suited than non-vascular plants to drier conditions

main food of herbivorous dinosaurs

pollinated by insects over 100 million years ago

Angiosperms

Flowering plants

Largest group of land plants (~300,000 species)

Late Jurassic Period, ~140 million years ago

Cycadophyta

 large cones. female>male. Pinnately compound leaves. Tropic. Dioecious (either all male or all female)

Ginkgophyta

high tolerance to air pollution and is a popular ornamental tree. Dioecious. Used as a dietary supplement for enhanced cognition

Gnetophyta

ephedra. Sudaphed

Coniferophyta

 conifers. worldwide distribution. Monoecious (plant has both male and female organs)

Identify the two major living clades of seed plants

Monocots and eudoicots

What is a flower?

specialized shoots with up to four types of modified leaves called floral organs

Sepals

enclose the flower

Petals

attract pollinators

Stamens

inside flower produce pollen (male) microsporangium on tip 

Carpels

produce ovules (female)

A stamen of a stalk called

filament with a sac called an ahter where the pollen is produced

A carpel consists of

an ovary at the base and a style leading to a stigma, where pollen is received

Describe the life cycle of angiosperms

The flower sporophyte is composed of: both male and female structures

Male gametophytes are contained within pollen grains produced by microsporangia of anthers

The female gametophyte, or embryo sac, develops within an ovule contained within an ovary

The pollen grain that has landed on a stigma germinates and the pollen tube of the male gametophyte grows down to the ovary – sperm enters through the micropyle

Double fertilization

occurs when the pollen tube discharges two sperm into the female gametophyte within an ovule. One sperm fertilizes the egg, the other combines with two nuclei in the central cell of the female gametophyte and initiates development of food storing endosperm

After double fertilization:

 each ovule develops into a seed

The ovary develops into a fruit enclosing the seed

When a seed germniated the embryo develops into a new sorophyte

The triploid (3n) endosperm

nourishes the developing embryo. nutritive tissue in seeds of angiosperms

Extra set of genes may help in:

rapid development

increase genetic variation

Within a seed the embryo consists of a root and two seed leaves called

cotlyledon

pollination

happens in angiosperms. the transfer of pollen from an anther to a stigma

how can pollination occur

wind, water, or animals

Wind-pollinated species (e.g., grasses and many trees) release large amounts of pollen

What is a fruit?

are mature ovaries (vegetables are all edible parts of plants that aren’t fruits or seeds) Fruits are classified based on their developmental origin

Simple fruit

develop from a single or several fused carpels (e.g., peas, grapes)

Aggregate fruit

result from a single flower with multiple separate carpels (e.g., strawberries, raspberries)

Multiple fruit

develop from a group of flowers (inflorescences) (e.g., figs, pineapples)

Accessory fruit

contain other floral parts in addition to ovaries (e.g., pears, apples)