Unit 2 Bio 102 Study Guide

State the general characteristics of fungi

They are eukaryotes with membrane-bound nuclei and organelles, lacking chlorophyll and chloroplasts. They contain chitin and glucans in their cell wall. They are heterotrophs that practice external digestion into their environment to break down complex organic matter before absorbing the small molecules.

Explain the body/structure of multicellular fungi

The hyphae are long tubular filaments that grow at their tips, increasing it’s surface area and are characterized into two sections. They have a mycelium that invades the food source to secrete enzymes and absorb nutrients. Their fruiting bodies are the reproductive system that’s used to produce and disperse haploid spores into the environment.

Septate hyphae vs Coencytic hyphae

Septate hyphae are divided into individual cells by internal-cross walls called septa as septa allows ribosomes, mitochondria, and nuclei to flow between compartments. Coenocytic hyphae lacks septa, forming a continuous multi-nucleated giant cytoplasmic cell.

Mycelium

A large mass of branching hyphae that forms the overall body of the fungus, called the mycelium.

Gymnosperms

Woody, seed-producing plants characterized by “naked” seeds that develop on the surface of scales, leaves, or in cones than being inside a flowering fruit.

Angiosperms

The production of flowers, fruits enclosing seeds, and specialized vascular tissue. Making up 80-90% of all known living plant species.

Four major groups of gymnosperms

Conifers, Cycads, gnetophytes, and ginkgo.

Conifers

The largest and most diverse gymnosperm category. Includes pines, firs, spruces, etc. Has needle-like leaves with thick cuticles and sunken stomata to reduce water loss. Produces unisexual male and female cones on the same plant and relies on wind for pollination.

Cycads

Has ~300-340 species. They have stout, unbranched woody trunk that’s covered by large, palm-like leaves. The plants are strictly male or female and produce massive centrally located cones. May use beetles for pollination instead of wind.

Gneptophytes

~95-100 species, with three known genera. Broad-leafed tropica vines (gnetum), desert shrubs (epherdra), or welwitschia. Has vessel elements in their xylem and they have modified reproductive structures that are similar to primitive flowers.

Ginkgo

1 speceis. A large, deciduous tree that can be identified by its fan-shaped leaves with dichotomous venation. It’s dioecious and produces pairs of exposed ovules on stalks that mature into fleshy, fruit-like seeds.

What are the major differences between angiosperms and gymnosperms?

The reproductive structures, seed development, resource use, and anatomy.

Protists

Any eukaryotic organism that isn’t a plant, animal, or fungus, but has characteristics similar to one. For example, animal-like protists like animals do by finding nutrients in the food around theme as they can’t make their food unlike plant-like protists.

What are dinoflagellates?

A group of single-celled eukaryotic organisms that are known for having two whip-like tails called flagella that allows them to spin and move.

Stramenophiles

Major eukaryotic lineage microorganisms and multicellular organisms. They have two unequal flagella during a stage in their life cycle with one long flagella on it’s behind that’s shorter than the other two.Some organisms have cell walls with silicon dioxide (diatoms) or cellulose (water molds).

Lichens

A composite organism formed from a symbiotic relationship between fungus and some photosynthetic partner; either green algae or cyanobacteria.

Fungi are important to humans and other organisms-what are mycorrhizal associations, how do they work?

Mycorrhizal association is a mutually beneficial symbiotic relationship between specialized soil fungi and plant roots.

Life cycle of seedless, non-vascular plants

During mitosis the gametophyte produces haploid gametes, gametes then fuse to form a zygote during fertilization, the zygote develops into a diploid during mitosis, the sporophyte produces haploid spores via meiosis, and finally the spores germinate and divide the former haploid gametophyte before the cycle repeats.

Endosymbiotic theory

The theory that the mitochondria and chloroplasts originated as free-living prokaryotic bacteria that were eaten by larger ancestral host cells and then established a mutually beneficial symbiotic relationship.

Primary vs Secondary endosymbiosis

Wwhen a eukaryotic cell eats a living prokaryote. Organelles formed in this way are surrounded by two membranes. While secondary endosymbiosis are free-living eukaryotic cell eats and keeps another eukaryotic cell that has already gone through primary endosymbiosis.

What can be included in stramenopiles

Diatoms, brown algae, and oomycetes

Diatoms

Unicellular and has carotenoids so they may appear yellow-ish brown. Only the male gametes have flagella and it makes carbs or oils as storage products. Deposits silicon in their cell walls that are then put together like a petri dish. Major primary producers in both the ocean and freshwater ecosystem. Does ~1/5 of all photosynthetic carbon fixation on Earth. Walls can’t decompose.

Brown Algae

Multicellular and has carotenoid fucoxanthin (makes it brown in color). Mostly marine and attaches to rocks via holdfast. The glue of the holdfast is the algnic acid.

Oommycetes

Water molds, Absorptive heterotrophs that secrete enzyme to digest large food molecules into smaller molecules that can be absorbed, their cell wall is made up of cellulose. They feed on dead organic matter.

How is brown algae used by human beings?

in ice cream or cosmetics most frequetly.

Dinoflagellates that live endosymbiotically in corals are useful to the coral because they

photosynthesize and produce carbs used as food by the coral

What are the four phases of slime mold life cycle?

Vegetative phase phase, aggregation phase, multicellular slug phase, fruiting body

Vegetative phase

Where the haploid amoebae lives independently in the soil and reproduces by preying on bacteria and dividing via binary fission every few hours as long as food is abundant.

Aggregation phase

When bacteria runs out, the amoebae stops dividing and begins the social developmental cycle. Then it forms a tight multicellular mound.

Multicellular slug phase

The mound reorganizes into a finger-like shape that falls over to create a “slug”. It behaves like a single organism and moves toward light (phototaxis) and warmth (thermotaxis) to find an optimal environment for spore release.

Fruiting body

Slug stops moving and cells differentiate into two types, stalk cells or spore cells. Disperses when moist again and the spores released germinate into new individual amoebae starting the cycle.

What is the species that’s covered by the green block?

Land plants

What is the species that’s covered by the green block?

Polysporangiophytes

What is the species that’s covered by the green block?

Vascular plants

What is the species that’s covered by the green block?

Lycophytes

Life cycles of ascomycota

There are two life cycle phases asexual and sexual reprodution. During asexual reproduction, conidiophores produce haploid asexual spores called conidia through mitosis. The conidia then blow or wash away, land on a suitable substrate, and germinate into a new genetically identical haploid. The single celled yeasts then reproduce asexually through budding.

Sexual reproduction of ascomycota

The ascogonium develops a hair like projection that then fuses with the male structure, then the cytoplams and nuclei move from the antheridium into the ascogonium. During the dikaryotic stage, the nuceli don’t fuse immediately, and pair up, then croziers help coordinate simultaneous nuclear division. Ascocarps are then formed around these dikaryotic hyphae and inside the tips of those hyphae, the two haploid nuclei fuse to form a diploid zygote. The nucleus goes through meiosis making four haploid nuclei which then go throuhg a single round of mitosis making eight haploid ascospores lined up inside the ascus. The ascus has internal pressure and ruptures or forcefully shoots ascospores into the air then germinates on a new suitable structure.

Life cycle of basidiomycota

The haploid basidiospore lands and germinates, then grows a network of filamentous cells called the primary mycelium. Then it joins another mycelia and their membranes and cytoplasm fuse together via plasmogamy. The nuceli don’t fuse but pair up (N+N) inside the cells, making dikaryotic hyphae. These hyphae produce clamp connections to ensure each new cell gets one of each compatible nucleus during cell division. The dikaryotic mycelium compacts and forms a macroscopic fruiting body (basidiocarp), but all other hyphae remain dikaryotic. Inside the mushroom gills there’s terminal cells called basidia. Inside the basidia, the two separate haploid nuclei fuse through karyogamy. The diploid nucleus imediately goes through meiosis, making 4 nuclei. Thes four nuclei migrate outward into four external appendages at the tip of the basidium, making basidiospores. The basidiospores are then discharged into the air to be carried by the wind.

Life cycle of Zoopangomycota

The body firs consists of fine, coenocytic hyphae with walls made of chitin, and haustoria are used to extract nutrients. Where reproduction takes place depends on the subphylum. Asexual spores are then detached and dispersed through the air. Sexual reproduction occurs during harsh environments and hyphae from two compatible mating types meet then fuse cytoplasms. The sepcialized hyphae (gametangia) merge to make thick walled zygosproangium that has one or more diploid of multinucleate zygospores. The zygospore acts as a resting structure that can survive extremn cold, dryness, or lack of food for long periods.

What are embryophytes, tracheophytes and monilophytes according to the phylogenetic tree of land plants?

Embryophytes are land plants, tracheophytes are vascular plants, and monilophytes are ferns (vascular plants). All are genetically similar to one another and one evolved after the first.

Based on this generalized flower structure, where can megagametophytes and microgametophytes be found?

The megagametophytes can be found in the ovule of the flower which is located in the pistil. The microgametophytes can be found in the pollen sacs of the anther, known as the pollen grain.

What is the role of megagametophytes and microgametophytes in fertilization?

Microgametophytes produce sperm cells and delivers the sperm from pollen grains, through the pollen tubes, and then it ends up at the ovule. Megagametophytes guide the pollen to the tube, allowing the sperm to then fertilize the egg, there is then central cell fertilization (double fertilization).

What is double fertilization?

A unique reporductive process in flowering plants where two sperm cells from a single pollen grain fuse with two different female gametes inside the embryo sac. One sperm cell fuses with the egg cell to form a diploid (2n) zygote which then develops into the plant embryo. The second fertilization occurs when the second sperm cell fuses with two nuclei into the center of the embryo sac to form a triploid (3n) primary endosperm nucleus. The nucleus divides to form an endosperm that feeds the growing embryo.

What is a perfect plant?

A perfect plant has both male and female reproductive organs.

Monoecious

Monoecious means that the plant has both male and female reproductive parts located in the same individual plant.

Dioecious

When a plant is strictly female(only seed-baring) or male (pollen baring).

Alternation of generation

A reproductive life cycle where an organism shifts between two distinct multicellular phases: haploid sexual phase and diploid asexual phase.

When does sexual reproduction occur for zoopagomycota?

During harsh environmental conditions or nutrient stress

How are the life cycles of basidiomycota, ascomycota, and zoopagmycota different?

Ascomycota and basidiomycota both undergo sexual reproduction in ideal conditions and stressfulones, but zoopagomycota only does so when in unideal conditions.

Genetic composition of sporophytes

Always a diploid (2n), that has two full sets of chromosomes

Genetic composition of gametophytes

Always a haploid (n), with a single set of chromosomes.

Homosporous plants and alternation of generation

Produce only one uniform type of spore through meiosis which then grows into a bisexual gametophyte that has male and female reproductive organs (antheridia and archegonia), typically present in mosses and most ferns.

Hetersporous plants and alternation of generation

The diploid sporophyte produces two types of spores via meiosis (microscpores and megaspores). Microspores germinate into male gametophytes while megaspores develop into female gametophytes. This is for all seed plants (gymnosperms and angiosperms), excluding some lycophytes and ferns.

Among land plants in which direction does the size of the sporophyte and gametophyte get larger/smaller?

In land plants, sporophytes get larger and more dominant while gametophytes get smaller and more reduced.

For which group(s) of land plants is the sporophyte dependent on the gametophyte and via versa?

Sporophytes are dependent on the gametophyte in bryophytes, gametophytes are dependent on sporophytes in gymno & angiosperms.