They are heterotrophs that absorb nutrients from dead or decaying organic matter. They have centrioles and lack cell walls with chitin. Include cellular slime mold, acellular slime molds, and water molds.
Spend most of their life as free-living, amoeba-like cells.
Hard to say if it is unicellular or multicellular because unicellular for most of their life, but when they aggregate, they act like a single multicellular organism.
1) Send out chemical signals to attract other cells of the same species
2) Over the course of a few days, thousands of cells aggregate into a large slug-like colony that begins to function as a single organism
3) Colony migrates several cm, then stops
4) Colony produces a fruiting body
5) Spores are scattered from the fruiting body
6) Each spore gives rise to a single amoeba-like cell
7) Cycle repeats itself
*In this case, two amoeba-like cells fuse to form a zygote (2N), which then releases more amoeba-like cells. Always begin life as amoeba-like cells.
** All parts of cellular slime mold reproduction and life is haploid (N), except the zygote
Start life as free-living amoeba-like cells, but aggregate to form the plasmodium (plasmodia) (2N).
The acellular slime molds within the plasmodium are surrounded by a cell membrane.
Eventually, small fruiting bodies (sporangia) will arise from this plasmodium.
2) 2 Amoeba-like cells fuse to produce an offspring (zygote) (2N)
3) Zygotes aggregate and fuse to produce structures with many nuclei (plasmodium)
4) Plasmodium gives rise to fruiting body (sporangia) (2N)
5) Sporangia (2N) gives off spores(N) (these spores are haploid (N) because the sporangia used meiosis to produce them)
6) Spores scatter to the ground where they form into flagellated or amoeba-like cells
7) The amoeba-like or flagellated* cells fuse to form diploid zygotes (2N) and start the process again
*The flagellated cells fuse in a sexual union to produce diploid zygote cells that repeat the cycle
Thrive on dead or decaying organic matter in water, and some are plant parasites on land.
Are multinucleate because the hyphae have no cell walls.
Have cell walls made of cellulose and produce motile spores (unlike fungi)
Not true fungi!
They do not have walls between their cells, which causes water molds to be multinucleate.
Takes place in specialized structures in the hyphae:
Antheridium (produces male nuclei)
Oogonium (produces female nuclei)
Fertilization, or sexual fusion, occurs within the oogonium, and the spores that develop into the new organisms
1) Portions of the hyphae develop into zoosporangia
2) Each sporangium produces flagellated spores
3) Flagellated spores swim away in search of food
4) When they find food, zoosporangia develop into hyphae
5) Hyphae grow into new organisms
They develop multicellular embryos and carry out photosynthesis using green pigments of chlorophyll a and b.
Most plants are autotrophs, but a few are parasites or saprobes that live on decaying material.
Has alternation of generations.
2) Water and Minerals- for photosynthesis, growth, and staying moist (not drying out)
3) Gas exchange- need oxygen for cellular respiration, and carbon dioxide for photosynthesis
4) Movement of water and nutrients- for distributing the products of photosynthesis away from just the leaves, and bring water and minerals collected in the roots to the rest of the plant
It had chloroplasts and carried out photosynthesis much like plants today.
sporophyte in plants= a diploid (2N) phase present in plants, that produces spore.
gametophyte in plants= a haploid (N) phase present in plants, that produces gametes.
Plant spores are haploid (N) reproductive cells formed in the sporophyte plant by meiosis that can grow into individuals.
The new individual is the gametophyte.
A gamete is a reproductive cell that is produced by mitosis and fuses during fertilization with another gamete to produce a new individual, the diploid sporophyte.
nonvascular plants- no vascular tissue to conduct water and nutrients- draw up water from the ground by osmosis, so relatively small
life cycle depends on water for reproduction- at at least one stage in their life, they produce sperm that must swim through water to reach the eggs of other individuals
Groups: Mosses, Liverworts, Horworts
Grow well in habitats with water sources. Adapted to living in wet habitats where the soil has poor nutrients
Can tolerate cold temperatures
They are not true stems or leaves, though, because they do not contain vascular tissue.
The leaves of mosses are 1 cell thick.
No true roots, so have rhizoids.
1) Moss spore lands in moist place and germinates and grows into a mass of tangled green filaments (protonema)
2) As protonema grows, it forms rhizoids that grow into the ground and shoots that grow into the air
3) The shoots grow the gametophyte part of the moss plant
4) Gemetes are formed in reproductive structures at the tip of the gametophytes
5) Sperm are produced in the antheridia and eggs are produced in the archegonia (some species produce sperm and eggs on the same plant, others have separate plants)
6) Sperm fertilizes egg and forms a zygote (beginning of the sporophyte stage)- it grows out of the body of the gametophyte and depends on it for water and nutrients
7) Inside the mature sporophyte, haploid spores are produced by meiosis
8) When capsule opens, haploid spores are carried by wind and start cycle again
Found only in soil that is damp year-round
Structure: Gametophytes form broad and thin structures that draw up moisture directly from the surface of the soil.
asexual (some liverworts): by means of gemmae/ gemma cups. When washed out of the gemma cup, the gemmae can divide by mitosis to produce a new individual.
Found only in soil that is damp year-round
Structure: Gametophytes look very much like those of liverworts.
Gametophyte is the dominant, recognizable stage of the life cycle and it is the stage that carries out most of the plant’s photosynthesis. Sporophyte is dependent on the gamete for water and nutrition.
Dependence on water
1) Sporophyte, which produce haploid spores, grow at the top of the gametophyte plant
2) When spores are ripe, they are shed from the capsule
* In some species gametes (sperm and eggs) are produced on separate male and female gametophyte plants
a transport subsystem that carries water upward from the roots to every part of the plant
allow water to move through a plant more effectively than by diffusion alone.
phloem transport solutions of nutrients and carbohydraytes produced by photosynthesis. like xylem, the main cells of phloem are long and specialized to move fluids throughout the plant body.
water conducting tissue located in the center of the root.
seedless vascular plant
seedless vascular plant
sporangia on underside of fronds, grouped into clusters called sori
production: spores germinate and develop into haploid gametophytes