biology 2 exam 3

fungi

• single celled or multicellular

• sexual or asexual

• extract and absorb nutrients from surroundings

• mitosis occurs, but focuses on the nucleus not the cell

general bio of fungi

• multicellular fungi consist of long, slender filaments called hyphae

  • some are continuous

  • others divide by septa, but doesn’t entirely close the cell

• cytoplasms flows throughout hyphae

  • allows rapid growth under good conditions

  • nuclei can pass through cytoplasm

mycelia

mass of connected hyphae

• grows through and digests its substrate

cell wall of fungi

• fungal cell wall includes chitin

genetics of fungi

• hyphae have more than one nucleus

  • monokaryotic- 1 nucleus

  • dikaryotic- 2 nuclei

• sometimes many nuclei intermingle in the common cytoplasm of the fungal mycelium

heterokaryotic

nuclei from genetically distinct individuals

homokaryotic

nuclei are genetically similar to each other

fungi mitosis

• cell is not relevant unit of reproduction

• nuclear envelope does not break down and reform

• instead, the spindle apparatus is formed within it

• all reproduction and division occurs within the nucleus, then it splits into 2 new nuclei

reproduction of fungi

• fusion of 2 haploid hyphae

  • in some fungi, fusion immediately results in a diploid (2n) cell

  • others, have a dikaryon stage (1n+1n) before parental nuclei from diploid stage

    • holds spores and waits until ready, may form mushrooms or puff balls

spores

• most common means of reproduction

• may form from sexual or asexual processes

• most are dispersed through wind

nutrition

• obtain food by secreting digestive enzymes into surroundings

• then absorb the organic molecules produced by this external digestion

  • great surface area to volume ratio

• fungi can break down cellulose and lignin (used in cell walls)

  • decomposed wood

  • some fungi are carnivores

ecology of fungi

• fungi along with bacteria are the principal decomposers in the biosphere

• make materials available to other organisms

  • break down cellulose and lignin from wood

obligate symbiosis

essential for fungus survival

facultative symbiosis

nonessential for fungus survival

interactions of fungi with other species

• pathogens harm host by causing disease

• parasites cause harm to host

• commensal relationships benefit one partner but does not harm the other

• mutualistic relationships benefit both partners

lichens

• symbiotic associations between a fungus and a photosynthetic partner

  • cyanobacteria, green algae, or sometimes both

• most are mutualistic

• ascomycetes are found in all but about 20 of the 15,000 lichen species

mycorrhizae

• mutualistic relationships between fungi and plants

• found on the roots of about 90% of all known vascular plant species

• function as extensions of root system

  • increase soil contact and absorption

arbuscular mycorrhizae

• fungal partners are glomeromycetes

• no above ground fruiting structures

• potentially capable of increasing crop yields with lower phosphate and energy inputs

  • hyphae penetrate the root cell wall but not plant membranes

ectomycorrhizae

• most hosts are forest trees (mainly pines or oaks)

• fungal partners are mostly basidiomycetes

• at least 5000 species of fungi are involved in ectomycorrhizal relationships

• hyphae surround but do not penetrate the root

animal mutual symbioses

• ruminant animals host neocallimastigamycete fungi in their gut

• leaf cutter ants have domesticated fungi which they keep in underground gardens

  • ants provide fungi with leaves

general feature of animals

• heterotrophy- obtain energy and organic molecules by ingesting other organisms

• multicellularity- many have complex bodies

• no cell walls- they lack rigid cell walls and are usually flexible

• active movement

• diversity of form

• sexual reproduction- most animals reproduce sexually, produce eggs, which are nonmobile

• embryonic development- zygote first undergoes a series of mitotic divisions that produces a ball of cells

• tissues- cells of most animals are organized into structural and functional units

evolution of animal body plan

• symmetry

• tissues

• body cavity

• patterns of development

evolution of symmetry

all animals, besides sponges which lack any definite symmetry, have a defined symmetry along an imaginary axis drawn through the animals body

radial symmetry

body parts arranged around central axis

bilateral symmetry

body has right and left halves that are mirror images

advantages of radial symmetry

• can feed in any direction

• can protect themselves in any direction

advantages of bilateral symmetry

• cephalization- evolution of a definite brain area

• directional movement- can make them faster

evolution of body cavity

• most animals have embryos that produce three germ layers, which make them triploblastic

  • ectoderm (body coverings and nervous system)

  • mesoderm (skeleton and muscles)

  • endoderm (digestive organs and intestines)

• all triploblastic animals have bilateral symmetry

• cnidarians are diploblastic

  • have an endoderm and an ectoderm

open circulatory system

• blood passes from vessels into sinuses, mixes with body fluids, and reenters the vessels

• saving energy, but not as efficient spreading oxygen

closed circulatory system

blood moves continuously through vessels that are separated from body fluids

protosomes

• develop the mouth first from or near the blastopore

• anus develops either from blastopore or another region of embryo

deuterostomes

• develop the anus first from the blastopore

• mouth develops later from another region of the embryo

developmental fate of cells

• protostomes- determinate development (early)

• deuterostomes- indeterminate development (after several divisions)

cleavage pattern of embryonic cells

• protostomes= spiral cleavage

  • new cells form to the right or left of previous cells

• deuterosomes= radial cleavage

  • new cells form on top of previous cells

kingdom animalia

• parazoa

• eumetazoa

parazoa

• animals lack tissues and a definite symmetry (sponges)

• among most abundant animals in the deep ocean

eumetazoa

• animals with a definite shape and symmetry and tissues

sponge characteristics

• most members lack symmetry

• varies growth forms

  • larval sponges free swimming

  • adults remained attached sessile

3 functional layers of body wall

1. epithelium

2. mesophyll

3. internal cavity

outer epithelium

• made up of flattened cells

• water comes in ostia, exits through osculum

mesophyll

• middle layer- gelatinous matrix

• spicules- needles of calcium carbonate or silica

• spongin- reinforcing tough protein fibers

lining of internal cavity

• choanocytes

  • flagellated- contributes to water circulation

  • face internal cavity

  • engulf and digest food from passing water

eumetazoa

• embryos have distinct layers

• inner endoderm forms the gastrodermis

• outer ectoderm forms the epidermis and nervous system

• middle mesoderm (only in bilateral animals) forms the muscles

• true body symmetry (radial and bilateral)

phylum ctenophora

• 8 rows of comb like plates of fused cilia, beat in a coordinated fashion

• many bioluminescent

• 2 tentacles covered with colloblasts

  • discharge strong adhesive used to capture prey

phylum cnidaria

• most marine, few fresh water species

• bodies have distinct tissues but no organs

  • no reproductive, circulatory, or excretory systems

• no concentrated nervous system

  • touch, gravity, light receptors

  • latticework of nerve cells

• capture prey with nematocysts

  • unique this phylum

nematocysts

• cnidarians use nematocysts to capture prey

  • secreted within nematocyte

  • mechanisms of discharge unknown

  • some carry venom

polyps

cylindrical and sessile (coral shaped)

medusa

umbrella shaped and free living

gastrovascular space also serves as hydrostatic skeleton

• provides a rigid structure against which muscles can operate

• gives the animal shape

many polyp species build an exoskeleton around themselves

some build an internal skeleton

5 cnidarian classes

1. anthozoa

2. cubozoa

3. hydrozoa

4. scyphozoa

5. staurozoa

anthozoa

• sea anemones, most corals, sea fans

• solitary and colonial polyps

• symbiosis (zooxanthellae)

cubozoa

• box jellies

• strong swimmers, voracious fish predators

• can kill you

hydrozoa

• hydroids, hydra, portuguese man of war

• both polyp and medusa stages

• most are colonial organisms

• can kill you

scyphozoa

• jellyfish

• medusa more conspicious and complex

• true jellyfish

• ring of muscle cells allow for rhythmic contractions for propulsion

staurozoa

• star jellies

• resembles a medusa in most ways but is attached to the substratum by a stalk that emerges from the side opposite the mouth

• unique

phylum rotifera

• bilaterally symmetrical, unsegmented

• corona- “wheel animals”

  • conspicuous ring of cilia at anterior end

  • used for locomotion and sweeping food into mouth

phylum platyhelminthes

• flatworms

• flatworms are ciliated, soft bodied animals

• many species are parasitic

phylum mollusca

• second in diversity only to arthropods

• includes snails, slugs, clams, octopuses, and others

mantle (mollusk)

• bounds mantle cavity

• secrete shell

foot (mollusk)

• primary means of locomotion for many

gills (mollusk)

• ctenidia/ only seen in phylum mollusca

shell (mollusk)

• protects against predators and adverse environments

• secreted by outer surface of mantle

radula (mollusk)

• characteristics of most mollusks

• rasping, tongue-like structure used in feeding

• used for many purposes

classes of mollusks

• gastropoda- limpets, snails, slugs

• bivalvia- clams- oysters, scallops

• cephalopoda- squids, octopuses, cuttlefish, and chambered nautilus

class gastropoda

• limpets, snails, slugs

• most have a single shell- some lost it

• heads typically have pairs of tentacles with eyes

• torsion

torsion

• body itself, coiling spiral winding of shell

• unique amongst animals

• mantle cavity and anus are moved from the posterior to the front

nudibranchs

• are active predators

• exposed gills

• many secret distasteful chemicals

• some extract nematocysts from cnidarian prey and transfer them to their body surface

• kleptoalidae

class bivalvia

• have 2 shells hinged together

• clams, scallops, mussels, oysters

• siphons

• no radula, no distinct head

class cephalopoda

• only mollusk with closed circulatory system

• foot has evolved into a series of arms equipped with suction cups

• beak like jaws, can have toxic saliva

cephalopoda skin

• can change color quickly and easily

• octopods can change textures as well (make their skin look rough, smooth, ect)

annelids

• segmented worms

• body built of repeated units

• allows for specialization

annelid classes

• roughly 32,000 described species of annelids occur in many habitats

• 2 classes

  • class polychaeta

  • class clitella

class polychaeta

• clamworms, scaleworms, lugworms, sea mice, tube worms

• have paired parapodia on most segments

  • used in locomotion or gas exchange

  • chaetae on parapodia

• most gonochoric (male or female)

  • external fertilization

  • trochophore larva

deep sea tube worm riftia

• found in deep water, near hydrothermal vents

• adults do not have a gut/stomach

• sulfur-oxidizing bacteria synthesize organic compounds

arthropod phylogeny

• most successful animals

• divided into four extant classes

  • chelicerata

  • crustacea

  • hexapoda

part of arthropod success explained by

1. segmentation

2. exoskeleton

3. jointed appendages

segmentation

• in some classes, specialized into tagmata

  • head, thorax, abdomen

  • head and thorax may be fused into cephalothorax or prosome

exoskeleton

• made of chitin and protein

• protects against water loss

• requires ecdysis (molting)

jointed appendages

• may be modified into antennae, mouthparts, or wings

  • most appendages can be extended/ retracted as needed

arthropod eyes

• compound eyes are found in many arthropods

  • ommatidia

• other arthropods have simple eyes, or ocelli

  • may be in addition to compound eyes

  • simple eyes distinguish light from dark (nocturnal)

subphylum chelicerata

• spiders, ticks, mites, scorpions, daddy long legs, horseshoe crabs, sea spiders

• most anterior appendages called chelicerae

  • may function as fangs or pinchers

• body divided into 2 tagmata

  • anterior prosoma bearing all appendages

class arachnida

• many spiders catch their prey using silk webs

  • silk protein forced out of spinnerets found on the posterior of the abdomen

• other spiders actively hunt their prey

subphylum crustacea

• crabs, shrimp, lobsters, barnacles, crayfish, copepods, pill bugs, sand fleas

• have 3 tagmata

  • cephalon and thorax fused to form a cephalothorax

• 2 pairs of antennae, 3 pairs of appendages for chewing, and various pairs of legs

  • most appendages are biramous

order cirripedia

• sessile as adults

• captures food with feathery legs

subphylum hexapoda

• more than half of all named animal species

• approximately one billion billions insects are alive at any one time

external features of hexapoda

3 body origins

1. head

2. thorax has 3 segments, each with a pair of legs

   1. may have one or two pairs of wings- outgrowths of body wall

3. abdomen

   1. most insects of compound eyes

phylum echinodermata

• exclusively marine

• deuterostomes with an endoskeleton

• pentaradial symmetry

water vascular system

• radially organized

• tube feet- may or may not have suckers

  • used in movement, feeding, gas exchange

class asteroidea

• sea stars and sea daises

• important predators in many marine systems

• most have 5 arms, some have multiples of 5

classes crinoidea

sea lilies and feather stars

class holothuroidea

• sea cucumbers

class echinoidea

• sea urchins and sand dollars

• lack arms

• protective moveable spines

class ophiuroidea

• brittle stars

• largest class

• arms are equal diameter their entire length

• arms are easily autotomized

phylum chordata

• chordate endoskeleton is very different than echinoderm endoskeleton

  • chordate endoskeleton is truly internal

  • echinoderm endoskeleton is functionally similar to arthropod exoskeleton

chordate features

1. nerve cord

2. notochord

   1. may be replaced by vertebral column

3. pharyngeal slits

   1. pharyngeal pouches present in all vertebrate embryos

4. postanal tail

chordate subphylum

• phylum chorodata can be divided into 3 subphyla

• nonvertebrates

1. urochordata

2. cephalochordata

3. vertebrata

subphylum urochordata

• tunicates and salps are marine animals

• larvae are tadpole like and have notochord and nerve cord

• adults typically lose the tail and notochord

  • sessile filter feeders

  • many secrete a tunic (cellulose sac) that surrounds the animal

subphylum cephalochordata

• notochord persists throughout animals life

• have no distinguishable head

• feed on plankton using cilia-generated currents

• closest relatives to vertebrates

subphylum vertebrata

• vertebrates are chordates with a spinal column

• distinguished from non vertebrates by…

  • vertebral column- encloses and protects the dorsal nerve cord

  • head