1.
Which of the following is a true statement concerning nematodes?
Correct Answer
C. There are 15,000 species, most are free-living, but about 100 are plant parasites.
Explanation
The correct answer states that there are 15,000 species of nematodes, with the majority being free-living and only about 100 species being plant parasites. This means that most nematodes do not rely on plants for their survival and instead live independently.
2.
Which of the following is NOT a normal feature of soybean roots?
Correct Answer
D. Cysts
Explanation
Cysts are not a normal feature of soybean roots. Cysts are formed as a result of infection by nematodes, which are microscopic worms that can cause damage to plant roots. While root tips, root hairs, and leguminous nodules are all normal features of soybean roots, the presence of cysts indicates an unhealthy condition.
3.
Which of the following are examples of holoparasites?
Correct Answer
D. Both (a) and (c) are correct.
Explanation
Both Dodder (Cuscuta spp.) and Broomrape (Orobanche spp.) are examples of holoparasites. Holoparasites are plants that completely rely on their host plants for nutrients and water, obtaining them through specialized structures called haustoria. They lack chlorophyll and are unable to photosynthesize, making them entirely dependent on their host plants for survival. Witchweed (Striga spp.) is not a holoparasite as it is a partial or hemiparasite, capable of photosynthesis to some extent. Therefore, the correct answer is Both (a) and (c) are correct.
4.
"Watersoaking" and "wilting" of plants results from thawing after freezing temperatures because:
Correct Answer
C. Protoplasts and apoplast freeze; ice crystals form, cell membranes rupture.
Explanation
When plants are exposed to freezing temperatures, the water inside the cells freezes and forms ice crystals. This freezing causes the protoplasts (the living part of the cell) and the apoplast (the non-living part of the cell) to freeze as well. As the ice crystals form, they create pressure on the cell membranes, causing them to rupture. This leads to the water-soaking and wilting of the plants once the temperatures thaw. Cold temperatures causing irreversible denaturation of enzymes and disruptions in photosynthesis are not the direct causes of water-soaking and wilting in this scenario.
5.
Plant-microbe interactions are dynamic.
Correct Answer
A. True
Explanation
Plant-microbe interactions are dynamic because they involve a constant exchange of signals and responses between plants and microorganisms. These interactions can be beneficial, such as when microbes help plants absorb nutrients or protect them from pathogens, or detrimental, such as when pathogens cause diseases in plants. The dynamic nature of these interactions means that they can change over time and vary depending on various factors, including environmental conditions and the specific microorganisms and plants involved. Overall, the statement "Plant-microbe interactions are dynamic" is true.
6.
Which of the following are PREFORMED, MECHANICAL barriers to pathogen infection?
Correct Answer
D. All of the above
Explanation
The correct answer is "All of the above". Cuticle, trichomes on plant surfaces, and small stomates are all examples of preformed, mechanical barriers to pathogen infection. The cuticle is a waxy layer on the surface of plants that acts as a physical barrier to prevent pathogens from entering. Trichomes are small hair-like structures on plant surfaces that can physically trap and deter pathogens. Small stomates are tiny openings on the surface of leaves that can close to prevent pathogen entry. Together, these barriers provide multiple layers of defense against pathogen infection.
7.
Which of the following is an example of a flavonoid phytoalexin?
Correct Answer
B. Pisatin (produces by pea plants)
Explanation
Pisatin is an example of a flavonoid phytoalexin because it is produced by pea plants. Flavonoid phytoalexins are secondary metabolites produced by plants in response to pathogen attack or other stresses. They play a role in plant defense by inhibiting the growth of pathogens.
8.
Some plant parasitic nematodes have a muscular pumping organ associated with their esophogus. This is called a:
Correct Answer
D. metacorpus (median bulb)
Explanation
Some plant parasitic nematodes have a muscular pumping organ called a metacorpus or median bulb, which is associated with their esophagus. This organ helps them to pump food and nutrients from the host plant. The other options mentioned, such as cuticle, stylet, migratory endoparasite, and none of the above, are not correct because they are not specifically related to the muscular pumping organ of nematodes.
9.
Damage to roots by lesion nematodes can result in:
Correct Answer
C. All of the above
Explanation
Damage to roots by lesion nematodes can result in all of the above. Lesion nematodes can cause damage to roots and associated organs, which can then lead to the invasion of secondary pathogens. This can result in stunting, chlorosis, and wilt above-ground. Therefore, all of the given options are correct.
10.
Dodder (Cuscuta spp.)
(we did not talk about this in class as much this year)
Correct Answer
B. GeograpHic range = Entire U.S.
Explanation
Based on the given information, Dodder (Cuscuta spp.) has a geographic range that covers the entire United States.
11.
Dwarf mistletoe (Arceuthobium spp.)
Correct Answer
A. GeograpHic range = Western U.S., Great Lakes, Canada
Explanation
Dwarf mistletoe is found in the Western U.S., Great Lakes region, and Canada. It is not found in the entire U.S. or only in the Eastern U.S. This suggests that the plant has a specific distribution pattern and is not widespread across the entire country.
12.
Neutral pH favors uptake of __________ and _________; whereas, slightly acidic soils favor uptake of __________.
Correct Answer
B. Nitrogen, pHospHorus; iron
Explanation
Neutral pH favors the uptake of nitrogen and phosphorus because these nutrients are more available and soluble in neutral conditions. On the other hand, slightly acidic soils favor the uptake of iron because it becomes more soluble and accessible to plants in acidic conditions.
13.
Obligate saprophyte + phyllosphere =
Correct Answer
B. No disease
Explanation
An obligate saprophyte is an organism that can only obtain nutrients from dead or decaying organic matter. The phyllosphere refers to the surface of plant leaves, where many microorganisms reside. In this context, the combination of an obligate saprophyte and the phyllosphere suggests that the organism is able to thrive and obtain nutrients from the dead organic matter present on the leaves, without causing any harm or disease to the plant. Hence, the correct answer is "No disease."
14.
Mutualist + Host =
Correct Answer
B. No disease
Explanation
When a mutualist and a host interact, they form a mutually beneficial relationship where both parties benefit from each other. In this scenario, there is no mention of any negative outcome or harm caused by this interaction. Therefore, the correct answer is "No disease" as the relationship between the mutualist and the host does not result in any disease.
15.
Pathogen + Non-host =
Correct Answer
B. No disease
Explanation
When a pathogen is combined with a non-host, it means that the pathogen is introduced to a species that it does not typically infect. In this scenario, since the non-host species is not susceptible to the pathogen, it will not develop any disease. Therefore, the correct answer is "No disease."
16.
Pathogen + Susceptible Host =
Correct Answer
A. Disease
Explanation
When a pathogen comes into contact with a susceptible host, it can lead to the development of a disease. Pathogens are microorganisms such as bacteria, viruses, or fungi that can cause harm to the body. A susceptible host is an individual who is vulnerable to the pathogen's effects due to factors such as a weakened immune system or lack of immunity. The interaction between the pathogen and susceptible host can result in the manifestation of symptoms and the onset of a disease. Therefore, the correct answer is "Disease."
17.
Pathogen + Resistant Host
Correct Answer
B. No disease
Explanation
When a pathogen infects a host, it can cause a disease. However, if the host is resistant to the pathogen, it means that the host's immune system is able to effectively fight off the pathogen and prevent the development of the disease. In this scenario, since the host is resistant to the pathogen, there would be no disease present.
18.
Which of the following are PREFORMED, CHEMICAL barriers to pathogen infection?
Correct Answer
E. All of the above
Explanation
All of the substances listed (simple phenols/phenolic acids, cyanogenic glycosides, lactones, and saponins) are preformed, chemical barriers to pathogen infection. These compounds are naturally produced by plants and are part of their defense mechanisms against pathogens. They can inhibit the growth and development of pathogens, prevent their entry into plant tissues, or disrupt their cellular processes. Therefore, all of the listed substances act as chemical barriers to protect plants from pathogen infections.
19.
Successful induced plant defense can be associated with:
Correct Answer
E. Both "a" and "c" are correct
Explanation
Successful induced plant defense can be associated with the formation of a lignituber and the formation of tyloses. A lignituber is a woody swelling that forms at the base of a plant in response to injury or stress, providing structural support and preventing the spread of pathogens. Tyloses are balloon-like structures that form in xylem vessels, blocking the movement of pathogens and reducing the spread of infection. Therefore, both the formation of a lignituber and the formation of tyloses contribute to successful induced plant defense.
20.
How many larval stages occur with most plant parasitic nematodes?
Correct Answer
D. 4
Explanation
Most plant parasitic nematodes go through four larval stages during their life cycle. These stages are called J1, J2, J3, and J4. Each larval stage represents a different developmental stage of the nematode, with the J4 stage being the final larval stage before the nematode becomes an adult. These larval stages are important for the nematode's growth and development, as well as for its ability to infect and damage plants.
21.
Which description fits the lesion nematode?
Correct Answer
A. Migratory, endoparasitic
Explanation
The lesion nematode is described as migratory, endoparasitic. This means that it moves through the soil and enters the roots of its host plant to feed and reproduce. It does not stay in one place (sedentary) and it lives inside the host plant (endoparasitic).
22.
Facultative parasite =
Correct Answer
B. Organism that is normally sapropHytic but is capable of being
parasitic.
Explanation
A facultative parasite is an organism that is normally saprophytic, meaning it obtains nutrients from dead organic matter, but has the ability to become parasitic when necessary. This means that it has the capability to obtain nutrients from a living host organism, although it does not rely on this method exclusively.
23.
Obligate parasite =
Correct Answer
D. Organism that can grow only as a parasite in association with its host
plant and cannot be grown in artificial culture media.
Explanation
The correct answer is "Organism that can grow only as a parasite in association with its host plant and cannot be grown in artificial culture media." This answer describes an obligate parasite as an organism that relies entirely on a host plant for its growth and cannot survive or be cultivated in artificial culture media. This distinguishes it from other options that mention different characteristics of parasitic plants, such as the presence or absence of chlorophyll or the ability to obtain nutrients from the host plant's xylem.
24.
Hemiparasite =
Correct Answer
A. Parasitic flowering plant that contains chloropHyll when mature and obtains water and mineral nutrients by connecting to the host plant's xylem by a haustorium.
Explanation
The correct answer is a parasitic flowering plant that contains chlorophyll when mature and obtains water and mineral nutrients by connecting to the host plant's xylem by a haustorium. This explanation accurately describes a hemiparasite, which is a type of parasitic plant that is partially dependent on its host for nutrients and water, but is also capable of photosynthesis due to the presence of chlorophyll. The haustorium is a specialized organ that allows the hemiparasite to connect to the host plant's vascular system and extract resources.
25.
Holoparasite =
Correct Answer
C. Parasitic flowering plant that lacks chloropHyll and must rely totally on
the contents of the xylem and pHloem of the host plant.
Explanation
A holoparasite is a parasitic flowering plant that lacks chlorophyll, which means it cannot perform photosynthesis and produce its own food. Instead, it relies entirely on the nutrients and water obtained from the xylem and phloem of the host plant. This type of plant cannot survive independently and is completely dependent on its host for survival.
26.
Which of the following abiotic conditions results in damage to plant cell membranes?
Correct Answer
D. All of the above
Explanation
All of the above abiotic conditions can result in damage to plant cell membranes. High temperatures can cause the cell membranes to become more fluid and increase permeability, leading to leakage of cellular contents. Low temperatures can cause the cell membranes to become more rigid and decrease permeability, impairing the transport of molecules in and out of the cell. Water deficit or dessication stress can cause the cell membranes to shrink and lose their integrity, leading to cell death. Therefore, all three abiotic conditions can cause damage to plant cell membranes.
27.
Which of the following is NOT an example of disease symptoms caused by pathogen-produced growth regulators?
Correct Answer
D. Tomato wilt
Explanation
Tomato wilt is not an example of disease symptoms caused by pathogen-produced growth regulators. Pathogen-produced growth regulators typically result in symptoms such as crown gall, "green islands," giant cells, and fusiform swellings. However, tomato wilt is caused by a different pathogen and does not involve the production of growth regulators.
28.
Endoparasitic nematodes =
Correct Answer
E. Both (c) and (d) are correct
Explanation
Endoparasitic nematodes are a type of nematode that live inside the host organism. They can be found in various hosts such as animals, plants, and humans. These nematodes typically have specialized structures that allow them to penetrate and inhabit the tissues or organs of the host. "Root knot nematodes" are a specific group of endoparasitic nematodes that infect plant roots, causing the formation of characteristic knots or galls. Therefore, both options (c) and (d) are correct as endoparasitic nematodes live inside the host and include root knot nematodes.
29.
How does the soybean cyst nematode (Heterodera glycines) survive in the soil?
Correct Answer
B. Cysts (females containing numerous eggs)
Explanation
The correct answer is cysts (females containing numerous eggs). The soybean cyst nematode survives in the soil by forming cysts, which are protective structures produced by the females. These cysts contain numerous eggs, allowing the nematode to reproduce and persist in the soil. The cysts can remain in the soil for several years, waiting for favorable conditions to hatch and infect soybean plants. This survival strategy helps the nematode to persist in the soil and continue to cause damage to soybean crops.
30.
Place the following aspects of the dodder life cycle in the proper relative order (from first to last):
Correct Answer
A. 1. Twining stems that coil from germinating seeds; 2. Orange stems - soil connection withers;
3. Dense mat of dodder stems and vines; 4. Seed production.
Explanation
The correct order of the aspects of the dodder life cycle is as follows: first, twining stems that coil from germinating seeds, then orange stems - soil connection withers, followed by a dense mat of dodder stems and vines, and finally seed production.
31.
A benzoic acid =
Correct Answer
A.
Explanation
Benzoic acid is a colorless crystalline solid that is used as a food preservative and has the chemical formula C6H5COOH. It is derived from benzene and is a carboxylic acid. Benzoic acid is commonly found in fruits such as cranberries, plums, and apples. It is also used in the production of various chemicals, including dyes, perfumes, and pharmaceuticals.
32.
A cinnamic acid =
Correct Answer
B.
Explanation
Cinnamic acid is an organic compound with the chemical formula C9H8O2. It is a white crystalline solid that is slightly soluble in water. Cinnamic acid is commonly found in the bark of cinnamon trees and other plants. It is used in the production of perfumes, flavorings, and pharmaceuticals. Cinnamic acid has been studied for its potential antioxidant and anti-inflammatory properties, making it a valuable compound in the field of medicine.
33.
A cyanogenic glycoside =
Correct Answer
C.
Explanation
A cyanogenic glycoside is a type of compound that contains a sugar molecule (glycoside) attached to a cyanide group. When ingested or metabolized, these compounds can release toxic hydrogen cyanide gas, which can be harmful or even fatal to living organisms. Cyanogenic glycosides are found in various plants and serve as a defense mechanism against herbivores.
34.
An unsaturated gamma lactone =
Correct Answer
D.
Explanation
An unsaturated gamma lactone refers to a compound that contains a gamma-lactone ring with at least one double bond present in the molecule. A gamma-lactone is a cyclic ester with a carbonyl group at the gamma position. The presence of a double bond in the molecule indicates that there is a degree of unsaturation, meaning that the compound has the potential to undergo additional reactions or participate in conjugation. This unsaturation can affect the compound's reactivity and properties, making it different from a saturated gamma lactone.
35.
A saponin =
Correct Answer
E.
Explanation
A saponin is a type of chemical compound that is commonly found in plants. It is known for its ability to produce a soapy or frothy texture when mixed with water, which is why it is often used in the production of soaps and detergents. Saponins also have various other properties, such as being able to lower cholesterol levels and having anti-inflammatory effects. Additionally, they are often used in traditional medicine for their potential health benefits.
36.
Which of the following makes up the "transpiration stream" (in order from first to last):
Correct Answer
C. 1. soil water; 2. movement of soil water into root apoplasts; 3. movement of water through
xylem; 4. loss of water through plant stomata in leaves
Explanation
The correct answer is 1. soil water; 2. movement of soil water into root apoplasts; 3. movement of water through xylem; 4. loss of water through plant stomata in leaves. This sequence accurately represents the process of the transpiration stream in plants. It starts with soil water being absorbed by the roots and moving into the root apoplasts. Then, the water travels through the xylem, which is the plant's vascular tissue responsible for transporting water. Finally, water is lost through the stomata in the leaves via transpiration.
37.
What is the MOST important reason that a pathogen infects a plant?
Correct Answer
D. Acquire nutrients
Explanation
Pathogens infect plants primarily to acquire nutrients. Plants provide a rich source of nutrients that pathogens need for their growth and reproduction. By infecting plants, pathogens can access and utilize these nutrients, which are essential for their survival. This allows the pathogens to thrive and continue their life cycle, while potentially causing harm to the infected plant.
38.
Gums are composed of:
Correct Answer
E. All except "d" are correct.
Explanation
The correct answer is that all of the options except "d" (lignin and chitin) are correct. This means that gums are composed of arabinoxylans, galactans, and mannans. The presence of these substances in gums is well-documented and they play important roles in the structure and function of gums. Lignin and chitin, on the other hand, are not typically found in gums and are not considered to be components of gum composition.
39.
Gums are composed of:
Correct Answer
E. All except "d" are correct.
Explanation
The correct answer is that all options except "d" are correct. This means that gums are composed of arabinoxylans, galactans, and mannans. Lignin and chitin are not components of gums.
40.
Ectoparasitic nematodes:
Correct Answer
E. Both (b) and (d) are correct
Explanation
Ectoparasitic nematodes are parasites that live outside the host. They do not have a stylet, which is a piercing mouthpart found in some nematodes. "Dagger nematodes" are a type of ectoparasitic nematode. Therefore, both options (b) and (d) are correct.
41.
Which of the following hosts would be appropriate for rotation with soybean, in order to reduce soybean cyst nematode populations in a given field?
Correct Answer
E. A, b, and c are correct answers
Explanation
Wheat, sorghum, and corn are appropriate hosts for rotation with soybean to reduce soybean cyst nematode populations because they are non-host crops. By planting these crops in rotation with soybean, the nematodes that rely on soybean as a host will not have a suitable environment to reproduce and their populations will decline. Another legume may not be as effective in reducing nematode populations because it can still provide a suitable host for the nematodes.
42.
Dodder (Cuscuta spp.) =
Correct Answer
C. Damage: Very destructive to corn, sorghum, and soybean.
Explanation
Dodder (Cuscuta spp.) is a parasitic plant that attaches itself to host plants and derives nutrients from them. It is particularly destructive to corn, sorghum, and soybean crops, causing significant damage to their growth and yield. While it may not be severely destructive to other crop plants, it is known to cause substantial economic losses in the agricultural industry. This makes it a major concern for farmers cultivating corn, sorghum, and soybean crops.
43.
Which of the following conditions worsen salt toxicity damage?
Correct Answer
E. All of the above.
Explanation
All of the listed conditions - prolonged water deficit stress, low relative humidity, high temperatures, and high (alkaline) soil pH - can worsen salt toxicity damage. Prolonged water deficit stress can lead to an increase in salt concentration in the soil, exacerbating the toxicity. Low relative humidity and high temperatures can increase the rate of evaporation, leading to the concentration of salts in the soil. High (alkaline) soil pH can also contribute to salt toxicity as it can increase the availability of toxic ions in the soil. Therefore, all of these conditions can worsen salt toxicity damage.
44.
Non-specific toxin produced by fungal plant pathogens:
Correct Answer
A. Kill cells of any host
Explanation
The correct answer is "kill cells of any host". This is because non-specific toxins produced by fungal plant pathogens have the ability to kill cells of any host they infect. This is one of the ways these pathogens cause damage and contribute to the development of diseases in plants.
45.
Nematodes are simple animals that LACK which of the following anatomical systems:
Correct Answer
A. Circulatory/vascular system
Explanation
Nematodes are simple animals that lack a circulatory/vascular system. This means that they do not have a specialized network of blood vessels or a heart to circulate nutrients and oxygen throughout their bodies. Instead, they rely on diffusion to transport these substances to their cells. Nematodes do have a digestive system, reproductive system, nervous system, and musculature for movement.
46.
Sedentary, endoparasitic nematodes include:
Correct Answer
E. Both (a) and (d) are correct
Explanation
Sedentary, endoparasitic nematodes are nematodes that live inside their host and do not move around much. The soybean cyst nematode and root knot nematodes are examples of sedentary, endoparasitic nematodes. Therefore, both option (a) (soybean cyst nematode) and option (d) (root knot nematodes) are correct.
47.
What is a haustorium?
Correct Answer
B. Feeding structure
Explanation
A haustorium is a feeding structure found in parasitic seed plants. It allows these plants to obtain nutrients from their host plants by penetrating their tissues. The haustorium acts as a connection between the parasitic plant and the host plant, allowing the transfer of nutrients from the host to the parasite. This feeding structure is essential for the survival and growth of parasitic seed plants.
48.
Dwarf mistletoe (Arceuthobium) =
Correct Answer
A. Damage: Destructive timber disease (100,000 homes worth of timber lost/year)
Explanation
Dwarf mistletoe is a destructive timber disease that causes the loss of a significant amount of timber each year, equivalent to the value of 100,000 homes. It is not severely destructive to crop plants, but it is highly destructive to specific crops such as corn, sorghum, and soybean. Therefore, the correct answer emphasizes the significant impact of dwarf mistletoe on timber resources rather than its effects on crop plants.
49.
Place the following water potentials in correct relative order from highest to lowest:
Correct Answer
A. Ψsoil > Ψroot > Ψshoot > Ψleaves >> Ψair
Explanation
The correct order of water potentials from highest to lowest is Ψsoil > Ψroot > Ψshoot > Ψleaves >> Ψair. This means that the water potential is highest in the soil, then decreases as it moves up through the roots, shoots, and leaves, and is lowest in the air. Water potential is a measure of the potential energy of water molecules and determines the direction and rate of water movement in plants.
50.
Stomata, root tips, wounded branches, and insect feeding sites are all examples of:
Correct Answer
C. Infection courts
Explanation
Infection courts refer to the specific sites on a plant where pathogens can enter and infect the plant. Stomata, root tips, wounded branches, and insect feeding sites are all examples of infection courts because they provide entry points for pathogens to invade the plant tissues. These sites are vulnerable and can be exploited by pathogens to establish an infection. Therefore, they can be considered as infection courts.