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The soil layer surrounding plant roots, called the rhizosphere, has been shown in some cases to _____.

A) contain archaea which produce antibiotics that prevent the growth of most bacteria

B) contain fungi that produce an endotoxin which inhibits the growth rhizomes

C) produce vitamins essential for the uptake of nitrogen

D) inhibit the growth of fungal pathogens

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Tod Thiel
Tod ThielLv2
28 Sep 2019
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Related questions

. You are interested in continuing the work of Dr Mendes. What is one additional question that you might logically ask about this issue? Justify the question that you propose by logically describing why this is an important question to ask. Design and describe how to run an experiment to test the question you proposed. Be very specific. Make sure that the design is feasible (no growing plants on Jupiter). Include the following: · Independent and dependent variables · Control variables · Equipment and supplies needed · Outline the basic protocol to follow. · Describe WHY and HOW you will manipulate variables

here is the full question:

Do soil microorganisms protect against crop disease?

The rhizosphere, the soil layer surrounding plant roots, is a complex community in which archaea, bacteria, fungi, and plants interact with one another. After plants are attacked by fungal or bacterial pathogens, soil from the rhizosphere may protect plants from future attacks. Such protective soil is called disease-suppressive.

Researchers investigated whether microorganisms were responsible for the protective effects of disease-suppressive soils. Disease-suppressive soil was obtained from an agricultural field in the Netherlands in which sugar beet crops had previously been attacked by a fungal pathogen, Rhizoctonia solani. Other soil was collected from the margin of the field. The researchers predicted that soil from the margin would not offer protection against pathogens.

The researchers then planted and raised sugar beets in greenhouses, using 5 different soil treatments. Each soil treatment was applied to 4 pots, and each pot contained 8 plants. The pots were inoculated with Rhizoctonia solani and placed in greenhouses kept at 20°C with a 16-hour light: 8-hour dark cycle. After 20 days, researchers determined the percentage of infected sugar beet seedlings for each soil treatment. The results of the experiment are shown in the table.

Soil Treatment

Percentage of Seedlings

with Fungal Disease

Disease-suppressive soil

3.0

Soil from margin of field

62

Soil from margin of field

+10% disease-suppressive soil

39

Disease-suppressive soil heated

to 50∘C for 1 hour

31

Disease-suppressive soil heated

to 80∘C for 1 hour

70

(Data from R. Mendes, et al. Deciphering the rhizosphere for disease-suppressive bacteria, Science 332: 1097-1100 (2011)).


True or False????? HELP

1. In the field of epidemiology, increased prevalence of a disease in a population is the universal signal that disease control and treatment are not effective.

2. Cytoplasmic membranes of prokaryotes typically contain more proteins than cytoplasmic membranes of eukaryotes microorganisms.
3. Sanger (or dideoxy) DNA sequencing produces relatively short DNA sequence data, but is by far the least expensive DNA sequencing method currently available.
4. The (italicizes) abbreviation lac Z refers explicitly to the beta galactosidase protein/ enzyme.
5. Archaeal pathogens have been linked to some of the most virulent infectious diseases. 6. A bacterial mutant that is unable to make an amino acid required for growth (relative to its wild-type strain is termed an auxotroph.
7. When counting plaques to enumerate phage particles (as in the BIOL2026 Laboratory), the plaque represents lacK, not presence, of bacterial growth.
8. Because of competition with plant roots for nutrients, microbial numbers in the rhizosphere are typically much lower than in surrounding bulk soil.
9. Chemolithoautotrophy is the strategy that facilitates the existence of biological communities deep beneath the earth’s surface and near hydrothermal vents.

10. In a primary treatment (1 °) system of a municipal sewage/ wastewater treatment plant, the main goal is to remove ammonium (NH4+) using specific bacterial enrichment cultures.
11. The small intestine in human is the main site of microbial breakdown of partially digested food.
12. Root nodules of legumes contain nitrogen fixing bacteria.
13. Anoxygenic photosynthesis involves using/ removing electrons from H2O.
14. Algae and Cyanobacteria utilize generally the same two-photosystem biochemical mechanisms in the light- reaction of photosynthesis.
15. In bacteria, the only known reason proton motive force is generated is to power ATP synthase in cellular respiration/ oxidative phosphorylation.
16. Anaerobic respiration is only carried out by prokaryotes, however fermentation can be carried out by both prokaryote and eukaryal microorganism.

17. The general structure and biochemical “motors” of flagella are similar between Bacteria and eukaryotic cells, but fundamentally different in the Archaea.
18. Antibiotic resistance genes appeared in microbes (for the first time ever) only after human .. producing and releasing massive amounts of antibiotics to the environment.
19. Experiment by Esther Lederberg, and then later by Luria and Delbruck (that won them a Nobel prize), illustrated that genetic mutations in bacteria arose in the absence of selective pressures, rather than in response to selection.
20. Quaternary sensing is a mechanism used by bacteria to sense other bacteria and regulate gene expression accordingly (e.g. In the case of expressing the liac operon or initiating EPS production in biofilms).

Fungi Fungi are the great decomposers of the biosphere. Most plants form mycorrhizae with fungi to increase absorptive area without having to grow more roots, in this relationship fungi recieve carbohydrates from plants. Humans consume fungi, mushrooms, may use fungi as a source of drugs for blood pressure, antibiotics and immunosuppresive drugs. Fungi are used in biotechnology to produce fermetation products, and some have been very useful models to study gentics in eukaryotic cells that are unicellular such as yeasts. About one third of fungi may cause infections, mycoses, in plants, animals and humans. Fungi tolerate concentration of salt and sugar that plasmolyze bacteria in perserved foods exposed to air which contains fungal spores may germinate and may spoil food. Fungi have two body shapes, molds and yeasts. Mold are large and made of long filamentous hyphae. Hyphae form mats called mycelium ( plural is mycelia). Mycelia may extend for miles underground, making fungi the largest organism on earth. The visible portion of subterrean fungi are the fruitng bodies such as mushrooms. Yeasts are globular and unicellular. They may bud forming up 24 daughter cells from a single cell. When budding is incomplete it may produce a psuedohypa. Fungi that may exist in both body types are dimorphic fungi. In general, the yeast form of a dimorphic fungus is a pathogen, the filamentous form is not pathogenic. Examples are Histoplasmosis capsulatum (histoplasmosis) and Coccidiodes immitis (coccidioidomycosis). Fungi are saprobes, they absorb nutrients from the remains of dead plants or they lasso nematodes. Fungi may derive nutrients from a living plant utilizing haustoria which are modified hyphae that penetrate living plant tissue. Some fungi use melanin to absorb gamma rays which they convert to chemical energy. Some herbivores have fungi in thier gut microbiome to help digest plants. Zygomycota contains 1100 species and reproduces asexually through sporangiaspores, which form in a sac called a sporangium on a stalk called a sporangiaphore. An example is Nosema which is an obligate intracellular parasite in insects and honeybees. Ascomycota havd 32,000 species form haploid ascospores in sacs called ascus (asci plura) and reproduce asexually with condiospores which develop on the tips of hyphae on stalks called conidiophores. Examples are Claviceps purpurea, ergot, which grows on grain and causes abortions in cattle and hallucinations in humans. Penicillium the source of the first antibiotic discovered by Fleming in the 1940s. Saccharomyces, a facultative anaerobe, ferments sugar to produce alcohol and carbon dioxide gas and is used in baking and brewing. Neurospora was used as a model to study molecular biology, Beadle and Tatum established one gene one enzyme using this model organism.

14. Why are there more antibacterial drugs than antifungal drugs? Basidiomycota have fruiting bodies called basidiocarps. Basidiospores are dispersed by the wind and germinate in warm moist environments. An example is the pathogen Cryptococcus neoformans the leading cause of fungal meningitis

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