Chapter 4 · Immunity in Plant: practice questions

Plants can be attacked by pathogens such as which of the following?

• ALight, heat, and ultraviolet rays
• BMineral salts, nitrogen, and iron
• CBacteria, fungi, and viruses
• DOxygen, water, and carbon dioxide

What does the plant's first line of defence against pathogens consist of?

• AThe corpus luteum and its hormones
• BPhysical and chemical barriers
• CAntibodies and memory B cells
• DWhite blood cells and lymph nodes

What are the antimicrobial chemical substances that a plant produces in response to infection called?

• AThe cuticle
• BInsulin
• CPhytoalexins
• DChlorophyll

The walls of some fungi are broken down by enzymes the plant secretes, such as chitinase. What does this enzyme break down?

• AChitin in the fungal wall
• BWater
• CCellulose in the plant wall
• DProtein in the plant

How does a plant recognize a pathogen so that it can begin its defence?

• AThrough receptors that recognize molecules specific to the pathogen
• BThrough the lymphatic system that carries the pathogen to the roots
• CThrough white blood cells that circulate in the plant's xylem vessels
• DThrough antibodies made by the leaf cells after they are infected

When does a plant produce pathogenesis-related proteins (PR proteins)?

• AMonths before any infection, as a store for later use
• BAs part of systemic resistance after an infection
• COnly during photosynthesis, in the leaves exposed to light
• DDuring flowering, to help attract insects for pollination

If a pathogen managed to get past the cuticle and the cell wall, what would the plant then rely on?

• AInduced responses such as the hypersensitive response and the production of antimicrobial substances
• BStopping growth completely and waiting for the pathogen to leave the plant tissues by itself
• CSurrendering to the pathogen, since a plant has no other defences once its outer barriers are breached
• DOpening all its stomata so that the pathogen is washed out with the water that evaporates from them

What is the main difference between the hypersensitive response (HR) and systemic acquired resistance (SAR)?

• AThe hypersensitive response covers the whole plant while systemic acquired resistance is local
• BBoth occur only at the site of infection
• CThe hypersensitive response is local at the site of infection, while systemic acquired resistance covers the whole plant
• DBoth mean the death of the whole plant

A mutant plant has all the defences that exist before infection, but it cannot form any defence in response to an infection. Against which attack would it still be protected as well as a normal plant?

• AA fungus that has entered the xylem vessels through a cut and is spreading upwards
• BBacteria that release a toxin after they have entered the tissues of a leaf
• CA fungus whose mycelium is spreading from one cell to the next inside a leaf
• DFungal spores landing on the undamaged waxy surface of a young green stem

What is the most appropriate explanation for a plant that, after a minor infection in one leaf, becomes stronger at resisting infections in other leaves?

• AAn increase in photosynthesis that gave the other leaves more energy to resist
• BThe opening of the stomata in the other leaves so that pathogens could not settle there
• CPure chance, with no real change in how the other leaves resist infection
• DSystemic acquired resistance that spread through the whole plant via a chemical signal