honors biology 2 exam 1

What is heterotrophy

Organisms that depend on preexisting organic molecules for carbon and energy

What are fungi

Complex eukaryotic organisms that depend on organic molecules for energy, but are unable to digest food like animals

What are hyphae

Highly branched multicellular filament that provides a large surface area in fungi for nutrient absorption

What is mycelium

A network of branching hyphae

What is turgor pressure

A fungal material transport method involving molecules being taken up by the organism, driving water into the organism via osmosis, increasing pressure which is then decreased by growth and respiration due to molecule consumption

What is chitin

A modified polysaccharide containing nitrogen that makes up the cell walls of fungi and the hard exoskeletons of arthropods

What is a septum

A wall in fungal hyphae that partially divides the cytoplasm into separate cells

What are yeasts

Single celled fungi found in moist nutrient rich environments, that can metabolize sugar via fementation

What are ectomycorrhizae

One of the two main types of mycorrhizae; which produce a thick sheath of fungal cells (hyphae) that surround a root tip, and the hyphae that grow between cells in the interior of a root

What are endomycorrhizae

A mycorrhizae which penetrate into root cells where they produce highly branched structures (arbuscules) that provide a large surface area for nutrient exchange

What are endophytes

Fungi that live within leaves and may help the host plant by producing chemicals that deter pathogens and herbivores

What are lichen

Stable associations between a fungus and a photosynthetic organism usually being a green alga or a Cyanobacteria

What are fruiting bodies

Multicellular structures in some fungi that facilitate the dispersal of sexually produced spores

What is plasmogamy

The cytoplasmic unity of two cells

What is karyogamy

The fusion of two nuclei following plasmogamy

What does heterokaryotic mean

A stage in the life cycle of some fungi, in which plasmogamy is not followed immediately by karyogamy and the cells have infused haploid nuclei from both parents

What does dikaryotic (n + n) mean

Heterokaryotic cells that have two haploid nuclei, one from each parent in each cell

What is a mating type

A genetically distinct form of individual fungi in a species, that enables fertilization only between different types, to prevent self fertilization and promote gene crossing

What does parasexual mean

Asexual species that create genetic diversity via the crossing over of DNA during mitosis

What are chytrids

Aquatic fungi that have simple, unicellular bodies that produce gametes and spores with flagella

What are zygomycetes

A group of fungi that produce hyphae undivided by septa and do not form multicellular fruiting bodies

What are glomeromycetes

A group of fungi of low diversity but tremendous ecological importance that occurs in mycorrhizae

What are dikarya

A Fungal group that includes 98% of fungal species in which dikaryotic cells are formed

What are ascomycetes

A group of dikaryotic fungi in which nuclear fusion and meiosis take place in an elongated sac called an ascus (sac fungi)

What are basidiomycetes

A group of dikaryotic fungi in which nuclear fusion and meiosis take place in a club shaped cell called a basidium

What roles do fungi play in the environment

They decompose plant and animal tissues, play a critical role in the carbon cycle, and have ecological relationships with other organisms

Why are fungi necessary for the carbon cycle

They can locate and break down complex molecules and bulky tissue in other organisms

How do fungi have important ecological relationships

Some help increase plant growth on roots, some are agricultural pests (hergotism on wheat) , and some such as yeast are used to ferment plant carbohydrates to produce alcohol

How do fungi obtain energy

They are heterotrophs, but they can’t break down food like animals, so they absorb organic molecules directly (simple molecules pass easily, but complex molecules require enzymes to be broken down)

Why are hyphae important

The numerous thin hyphae provide fungi with a large surface area for nutrient absorption, allows it to find nutrients (due to no movement), and their rapid growth allows them to find new food patches as they grow

What is an interesting trait about mycelium

It can grow to become a large branching network, the largest covering over 2000 acres, and it can also grow to form fruiting bodies

What is turgor pressure similar to

Pholem transport in plants, due to pressure differences driving transport (concentration gradients)

What do fungi’s abilities to transport materials allow them to do

The hyphae can use materials in nutrient rich areas to fuel hyphae elongation across nutrient poor locations

What do septa do

They have pores that allow water and solutes to move between cells as well as the ability to plug them in case of injury

How do yeast reproduce

Asexually, by budding off

Where do most fungi receive nutrients

Dead organic material, which broken down contributes to the carbon cycle and places nutrients into the soil

How do fungi break down cellulose

Some fungi produce an enzyme to break down lignin (a fiber found in cellulose), which allows for easier decomposition

What kinds of fungal pathogens infect plants

Rusts, smuts, and molds infect plants

How are plant infections spread above ground

, by fungal spores carried by the wind or insects

how are plant infections spread below ground

Hyphae penetrate roots of plants

What are other ways plants get infected

Fungi infect plants through wounds, stomata, or by penetrating epidermal cells directly by degrading the wall with enzymes, then pushing hyphae into interior

How do fungal pathogens deal with invertebrates

They create hyphal rings that trap small organisms like C. Elegans

How do fungal pathogens deal with vertebrates

Many ways, such as toenail fungus, which are hard to treat due to them being eukaryotic

What are mycorrhizal relationships

Relationships between fungi and plants where the fungi supply plant roots with nutrients such as phosphorus and in return receive carbohydrates

Are mycorrhizal relationships between fungi and animals possible

Rare but yes, insects can provide fungi with shelter food, and protection in exchange for a food source

How do lichen reproduce

As a single organism, despite being an association between fungi and photosynthetic microorganisms

How are lichen built

Mostly of fungal hyphae, with an algae or Cyanobacteria forming a thin layer under the surface

How do hyphae help lichen

They help anchor lichen to a rock or tree, aid in water and nutrient uptake, and produce chemicals for defense against light and herbivores

How do microorganisms benefit lichen

They provide a reduced carbon source like a carbohydrate, as well as Cyanobacteria providing a source of nitrogen

Why are both organisms in lichen nessecary

They both exchange nutrients through hyphae that encircle or penetrate the cell walls, which allows lichen to survive as one in areas where neither could survive by themselves

What are the challenges of reproduction in fungi

Maintaining genetic variation and dispersal

How do fungi disperse in their life cycles

They produce spores that are carried by animals, the wind, or water (the aquatic spores have flagella)

What are properties of spore production

There is a low probability for proper spore location, so fungi produce huge numbers, these can be viable for long periods of time. They also allow fungi to use resources patchy in time and space, with this shortage cueing further production

How are spores formed asexually

They are produced with sporangia that are produced at the ends of hyphae, releasing spores into the air. Allowing the fungi to proliferate and disperse to new environments

What is used to spread sexual spores

Fruiting bodies on the surface, that are formed from densely packed hyphae at an elevation, leading to better dispersal

How do the shape of spores help

The football shape reduces drag and allows them to move fast

How does the asexual fungal life cycle work

Spores are produced by fungi, which are then dispersed and germinated, restarting the cycle

How do fungi sexually reproduce

Their hyphal tips grow together, and release enzymes that digest cell walls, allowing the hyphal cells to merge into a single cell with two nuclei

What is the sexual reproduction life cycle in fungi

Hyphal cells merge by the plasma, becoming dikaryotic, where later, the nuclei merge to form a diploid cell, which goes through meiosis to form spores that are dispersed to form new fungi

How do fungi accomplish sex without gender

Mating types, where fertilization can only take place with individuals with different alleles at the mating type gene

How are mating types increasing diversity

Fungal species have two or more mating type alleles, allowing for an increase in individuals they are able to mate with, increasing diversity

How does a parasexual cycle work

Nuclei in a heterokaryotic cell undergo karyogamy to form a diploid nucleus, where crossing over occurs in mitosis, leading to new gene combinations

How diverse are fungi

There are 75k known species not spread evenly through phylogeny, with 98% being dikaryotic

What are traits of chytrids

They are decomposers or pathogens found in moist environments, with single cells made of chitin that form short multinucleated structures, but lack well defined hyphae and a heterokaryotic stage, but form flagellated gametes that swim through their environment

What is the disease caused by chytrids

Chytridiomycosis caused by batrachochytrium dendrobatidis, killing amphibians

What are traits of zygomycetes

A small group of fungus, with some being decomposers (leaves, feces, food) , and others living on other organisms that grow mycelium and produce Ariel spores (Rhizopus, a black bread mold that digests simple carbon compounds)

How do zygomycetes reproduce

After karyogamy and meiosis, haploid cells produce an elevated stalk that spreads spores

What are traits of glomeromycets

They are monophyletic with low diversity, found with plant roots, increasing nutrient uptake for them

How do glomerocytes reproduce

Parasexual resulting in genetic diversity

What are traits of dikarya

Every mitotic division forms a new septum, allowing them to control the number of nuclei in each cell and proliferate

Includes edible mushrooms, yeast for beer bread and cheese, wood rotting fungi, and pathogens

What are differences in dikaryotic fungi

They evolved similar traits independently, as well as ascomycetes having a brief dikaryotic state compared to basidiomycetes having a longer state

How do ascomycetes reproduce differently

They release spores from a disc like ascus

How do ascomycetes affect human health

Ergot is a common pathogen, that when consumed can be used to treat migraines, but in high doses causes delirium and hallucinations

How can fungi influence behavior of animals

Some fungi can infect ants causing them to be beneficial to the fungus

What are traits of basidiomycetes

They make up 34% of fungi, and are made up of smuts, rusts, and a group that forms fruiting bodies

What makes the basidiomycetes life cycle different

It’s club shaped fruiting body is made up of only dikaryotic hyphae, and the products of meiosis do not undergo mitosis

How do gill shaped mushrooms spread spores

They drop from each gill from the basidum and are then moved into the atmosphere

What is coenocytic organization

An organism where the nucleus divides multiple times, but the cytoplasm does not , resulting in a large cell

What is cell adhesion

Molecules that cause adjacent cells to stick together, with little communication or transfer of resources between cells and little differentiation of specialized cell types (cells must stick together)

What is cell communication

Cells being able to communicate with one another

What is genetic programs

Cells participating in a network of genetic interactions for cell division and differentiation

What is bulk flow

Molecules moving at rates beyond those possible by diffusion across a concentration gradient

What is diffusion

Random motion of molecules with net movement from areas of higher to lower concentration

What is surface area to volume ratio

A necessary trait for cells to effectively transport molecules, with a high ratio making it easier

What are choanoflagellates

Single celled eukaryotes closely related to animals due to them having cell adhesion and cell signaling (contains genes that code for Cadherin and integrin proteins)

What is a meristem

Specific regions of growth in plants, found at the tips of roots and stems (due to cell wall and growth by division, expansion, and differentiation)

What is a blastula

A hollow, fluid filled ball of cells that develops from the morula and is an early stage of embryo development in animals

What is a gastrula

A stage of early embryo development in animals when cells of the hollow blastula migrate and reorganize to form a multilayered structure in which different cell types begin to differentiate

How many groups of eukaryotes are multicellular

36 out of 119

What are the other 83 groups of eukaryotes

Single celled organisms that eat other microorganisms or small organic particles, live suspended in water columns, or are parasites living within other organisms

Where do simple multicellular organisms originate

From colonial organisms, which stuck together for reproduction and feeding

What are traits of simple multicellular organisms

They contain adhesion molecules to allow cells to stick together, despite little communication, resource transfer, or differentiation, each cell has a full range of functions, and every cell is in contact with the environment for diffusion

What is an advantage of being multicelllular

Avoiding predation as predators cannot focus on one cell

What occurs in organisms with coenocytic organization

They are one large cell with multiple nuclei ass the cytoplasm does not divide, sometimes visible to the naked eye

What are the cons of multicellularity

Higher energy costs to develop, grow, and maintain tissues

Different functions require cells to cooperate (due to specialization during development using protein gradients)

Opportunities for individual cells to use resources to grow themselves and not the rest of the organism (cancer)

What does complex multicellularity require

Cell adhesion, cell communication, and genetic programs

What is three-dimensional organization

Multicellular organisms that have some cells in direct contact with the environment, meaning they need mechanisms for transferring environmental signals received by surface cells to interior cells, where genes will be activated in response

How many times did complex multicellularity evolve

6 times, once in animals, in green algae (leading to vascular plants), red algae, brown algae, and fungi twice

What is a key challenge of complex multicellularity

Transporting food, oxygen, and molecular signals rapidly across large distances within the body and exporting waste products out of the body

How are small distance limits via diffusion overcame by animals

A sponge places active cells close to the environment by using pores and canals

Jellyfish have thin layers of tissue, but have a thick shape due to inactive molecules

Animals have a high ratio of surface area to volume ratio in some cells, and use bulk transport