Term
| two or more species living together in a prolonged and intimate relationship |
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Definition
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Term
| symbiosis in which both organisms benefit |
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Definition
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Term
| symbiosis in which one benefits, and the other suffers |
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Definition
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Term
| mutualism between fungus and roots of a plant; affects 80% of plant species |
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Definition
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Term
| found in woody trees and shrubs in temperate zone; also known as sheathing mycorrhizae; fungus wraps around root, so root is not in contact with the soil |
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Definition
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Term
| in ectomycorrhizae, thin filaments produced by fungus |
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Definition
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Term
| In ectomycorrhizae, fungal hyphae do/do not penetrate root cells. |
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Definition
| Do not. Hyphae worm their way through the cell wall and any air spaces in the root. |
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Term
| network of interconnected mycorrhizae between adjacent plants |
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Definition
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Term
| most common mycorrhizal association; internal association where fungal hyphae penetrate into the cortex of the root but not the plasma membrane of individual cells |
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Definition
| endomycorrhizae/vesicular arbuscular mycorrhizae |
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Term
| How much of a plant's sugar is absorbed by the rhizal fungi? How does the plant compensate for this loss? |
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Definition
| 15%. The plant increases photosynthesis. |
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Term
| the action or process of being turned inside out or folded back on itself to form a cavity or pouch |
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Definition
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Term
| Instead of penetrating the cell membrane, mycorrhizae cause ________ of the cell membrane, increasing its surface area. |
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Definition
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Term
| Hyphae can form ________, sites of nutrient transfer, or ________, storage sites. |
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Definition
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Term
| What does the rhizal fungus get from the mycorrhizal relationship? |
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Definition
| energy in the form of sugar, as well as amino acids |
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Term
| What does the plant get from the mycorrhizal relationship? |
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Definition
- greater surface area for absorption
- fungus secretes acids to dissolve minerals
- fungus is better at taking up certain minerals (P, Zn, Cu)
- protection from micro organisms that would be attracted by leaked sugars
- fungus is more tolerant of toxins in the soil
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Term
| For what plants is mycorrhizae especially beneficial? |
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Definition
- plants on the forest floor without access to light
- food plants
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Term
| How do plants get the majority of their nitrogen? Why is this method necessary? |
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Definition
| Most of their nitrogen comes from nitrogen fixing bacteria. They need this form because plants cannot use nitrogen gas. |
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Term
| What are two types of fixed nitrogen that plants use? |
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Definition
| ammonium (NH4+) and nitrate (NO3) |
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Term
| How is fixed nitrogen (N2) made? |
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Definition
- volcanic eruptions
- lightning
- forest fires
- decomposition of organic material
- industrial processes (chemical fertilizers)
- nitrogen-fixing bacteria
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Term
| Where does the majority of fixed nitrogen come from for plants? |
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Definition
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Term
| Most fixed nitrogen is produced by the bacterium _________. |
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Definition
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Term
| Rhizobium is a bacterium that forms a symbiotic relationship with plant roots. What type of plant is the only one that allows for this relationship to occur? |
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Definition
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Term
Establishment of Relationship between Rhizobium and Plant Roots
essentially a proccess of infection
- Plant roots release a _________ to attract the rhizobia.
- Rhizobia attach to ________ and release a growth factor.
- Root hairs curl to enclose the bacteria.
- _________ of root hair degrades so that bacteria has direct access to plasma membrane
- __________ thread is formed to make a pathway for bacteria to enter the root.
- When infection thread reaches the end of the root hair cell, it fuses with the __________, and rhizobia are released into the __________.
- Formation of new infection thread into ________ cell(s) takes place. Rhizobia penetrate to cortical cells of the root.
- Pinching off of infection thread takes place within plant plasma membrane. _________, vesicles containing rhizobia, are released.
- Presence of bacteroids causes corticle cells to divide rapidly to form a ___________.
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Definition
- chemical signal
- root hairs
- nothing
- cell wall
- infection
- cell membrane, apoplast
- adjacent cells
- Bacteroids
- nodule
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Term
| tumor-like lump of cells on the root that contain nitrogen-fixing bacteroids |
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Definition
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Term
| Rhizobium creates __________ in the nodule, which along with energy, causes the fixation of nitrogen into ammonium. |
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Definition
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Term
| Why can't rhizobium fix nitrogen without a plant? |
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Definition
- nitrogen fixation requires energy, which comes form the plant's sugars
- nitrogenase that rhizobium creates requires the anaerobic atmosphere within the root nodule
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Term
| How does a plant produce the anaerobic atmosphere within the nodule? |
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Definition
| Plants use leghemoglobin to bond oxygen and keep it away from nitrogenase. |
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Term
| symbiosis between a fungus and a photosynthetic organism, both of which are single-celled |
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Definition
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Term
| With what photosynthetic organisms can fungus bond to form a lichen? |
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Definition
| a green alga or a cyanobacterium |
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Term
| Lichens dominate _ percent of the earth's vegetation. |
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Definition
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Term
| What are the three types of lichens? |
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Definition
| crustose, foliose, and fruticose |
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Term
| form of lichen that is flat and grows on rocks |
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Definition
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Term
| form of lichen that is leafy and forms on bark and rocks |
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Definition
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Term
| branched and shrubby form of lichen |
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Definition
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Term
| What do lichens need for growth? |
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Definition
| water, minerals, and light? |
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Term
| How does a fungus benefit from being in lichen? |
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Definition
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Term
What does the photosynthetic organism get from becoming a lichen? |
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Definition
| water, minerals, protection from the harsh environment and from desiccation |
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Term
The lichen consists of
- an upper and lower _________, layers of tightly woven fungal hyphae filaments that provide protection
- a _________ layer-loosly arranged hyphae around photosynthetic cells
- a __________ - a loose layer of hyphae that serves as a place of storage
- __________- extensions of the hyphae whose functions are anchorage and absorption
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Definition
| cortex, photosynthetic, medulla, rhizines |
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Term
| What are the two forms of reproduction in lichens? |
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Definition
| fragmentation and soredia |
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Term
| Both forms of lichen reproduction are ________. |
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Definition
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Term
| form of reproduction where lichen breaks off into propagules, masses of fungal hyphae and photosynthetic cells |
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Definition
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Term
| What allows lichen to survive? |
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Definition
| their ability to take up and lose large amounts of water |
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Term
| What is implied by the term "harsh environment"? |
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Definition
| weather extremes and water scarcity |
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Term
| Name an example of mutualism |
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Definition
- bull's horn acacia and ants
- yucca flower and yucca moth
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Term
| obligate parasites; species that can only survive as parasites and have no capability for photosynthesis |
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Definition
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Term
| plant that can perform photosynthesis and can live on its own, but can and will live off the host whenever possible |
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Definition
| hemiparasites/facultative parasites |
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Term
| parasites that live on the surface of the host |
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Definition
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Term
| parasites that are mostly hidden within the body of the host |
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Definition
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Term
| modified root that is a specialized connection between the parasite and host that allows for uptake of water and nutrients |
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Definition
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Term
| Why do parasitic plants have a high density of stomata? |
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Definition
| to allow for greater transpiration and greater suction force |
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Term
| The relationship between a parasitic plant and its host is usually established when? |
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Definition
| at the time of germination |
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Term
| Name an example of a parasitic plant. |
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Definition
- mistletoe
- dodder/witch's hair
- broomrape
- epifagus
- indian pipe
- rafflesia (remember: vileplume)
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