Stimulation Of Plant Defenses: Quiz 1

The given statement suggests that the defense or resistance mechanisms of a host plant against a pathogen are ultimately determined by the genetic material (genes) of the pathogen. This means that the pathogen's genetic makeup plays a crucial role in determining how the host plant responds to the pathogen's attack. This implies that the pathogen's genes have the ability to manipulate or overcome the host plant's defense mechanisms, highlighting the importance of understanding the genetic basis of both the pathogen and the host plant in order to effectively combat plant diseases.

Both passive and active modes of defense include structural and chemical defenses. Passive defense mechanisms involve physical barriers such as thorns, shells, or tough outer coverings that protect organisms from predators. Active defense mechanisms, on the other hand, involve chemical substances produced by organisms to deter or harm potential threats. These chemical defenses can include toxins, irritants, or repellents. Therefore, it is true that both passive and active modes of defense utilize structural and chemical defenses to protect organisms.

A plant lacking secondary metabolites would likely be susceptible to infection by pathogens. Secondary metabolites in plants play a crucial role in defense mechanisms against pathogens. These compounds can act as toxins or deterrents to inhibit the growth and spread of pathogens, protecting the plant from infection. Without these secondary metabolites, the plant's ability to defend itself against pathogens would be compromised, making it more vulnerable to infections.

Fungal pathogens can enter their host through multiple means. They can use enzymes called cutinases to break down the host's protective cuticle layer. They can also exert mechanical force through specialized structures called appressoria to penetrate the host's surface. Additionally, they can exploit existing wounds or openings such as stomatal pores to gain entry. Therefore, the correct answer is that fungal pathogens can enter their host by means of enzymes, mechanical force, and wounds/stomatal pores.

Both plant and animal immune systems have the ability to develop memory of past pathogens, allowing them to mount a faster and more effective response to subsequent infections. They also establish physical barriers, such as the skin or cell walls, to prevent pathogens from entering the body. Additionally, both plant and animal immune systems release molecules, such as antibodies or antimicrobial peptides, to fend off pathogens and inhibit their growth. Therefore, all of the given statements are true.

Phytoalexins are indeed antimicrobial compounds that are synthesized from remote precursors. These compounds are produced by plants in response to microbial infection or other stresses, and they help to inhibit the growth of pathogens. This defense mechanism is an important part of a plant's immune system, allowing it to protect itself from harmful microorganisms.

As a plant pathogen, the first obstacle to invading a host plant would be the physical barriers on the exterior of the plant. These physical barriers can include the plant's outer layer of cells, such as the epidermis, which acts as a protective barrier against pathogens. Additionally, the plant may have structures like trichomes or thorns that can physically impede the pathogen's entry. Overcoming these physical barriers is crucial for the pathogen to establish an infection and access the plant's nutrients and resources.

Cutin, waxes, and suberins are not types of secondary metabolites used in chemical defenses. They are actually types of lipids that are found in the outer layers of plants and serve as protective barriers against water loss, pathogens, and other environmental stresses. While some secondary metabolites, such as alkaloids and phenolics, can be involved in chemical defenses, cutin, waxes, and suberins do not fall into this category.

A plant pathogen is called necrotrophic when it kills the cells of the host plant. This means that the pathogen obtains nutrients and energy by killing and decomposing the host cells. It relies on the death of the host cells for its own survival and reproduction. This is in contrast to biotrophic pathogens, which obtain nutrients from living host cells, and hemibiotrophic pathogens, which initially rely on living host cells but eventually switch to killing them. The term "virulent" does not specifically describe the relationship between a plant pathogen and its host cells.

An avirulent pathogen refers to any type of normally pathogenic organism or virus that utilizes host resources but does not cause extensive damage or death. This means that while the pathogen can still infect and live off the host, it does not result in severe harm or mortality.

Non-protein amino acids are not incorporated into essential proteins. Essential proteins are made up of the 20 standard amino acids that are necessary for the proper functioning of the body. Non-protein amino acids may have other functions in the body, such as serving as neurotransmitters or being involved in the synthesis of other molecules, but they are not used to build essential proteins. Therefore, the statement that non-protein amino acids are incorporated in essential proteins is false.

Chlorophyll a is a pigment found in plants that is essential for photosynthesis. It is responsible for capturing light energy and converting it into chemical energy. Terpenes, which are organic compounds, can be found in chlorophyll a. These terpenes play a role in various biological processes in plants, including defense against herbivores and attracting pollinators. Therefore, chlorophyll a is a correct answer as it is a source of terpenes.