Ch 30: Plant Defense

Question 1

Biotrophic Pathogens

Answer 1

A plant pathogen that obtains resources from living cells.

Question 2

Necrotrophic Pathogens

Answer 2

A plant pathogen that kills cells before drawing resources from them.

Question 3

Host Plants

Answer 3

A plant species that can be infected by a given pathogen.

Question 4

Virulent

Answer 4

Describes pathogens that are able to overcome a host’s defenses and lead to disease.

Question 5

Avirulent

Answer 5

In plants, describes pathogens that damage only a small part of the plant because the host plant is able to contain the infection. In animals, describes nonpathogenic microorganisms.

Question 6

R Proteins

Answer 6

Any one of a group of receptors in plant cells, each expressed by a different gene, that function as part of the plant’s immune system by each binding to a specific pathogen-derived protein.

Question 7

R Genes

Answer 7

Any one of the group of genes that express the R proteins in plants.

Question 8

Hypersensitive Response

Answer 8

A type of plant defense against infection in which uninfected cells surrounding the site of infection rapidly produce large numbers of reactive oxygen species, triggering cell wall reinforcement and causing the cells to die, thus creating a barrier of dead tissue.

Question 9

Systemic Acquired Resistance

Answer 9

The ability of a plant to resist future infections, occurring in response to a wide range of pathogens.

Question 10

Small Interfering RNA (siRNA)

Answer 10

A type of small double-stranded regulatory RNA that becomes part of a complex able to cleave and destroy single-stranded RNA with a complementary sequence.

Question 11

Ti Plasmid

Answer 11

A small circular DNA molecule in virulent strains of R. radiobacter containing genes that can be integrated into the host cell’s genome, as well as the genes needed to make this transfer.

Question 12

Latex

Answer 12

A white sticky liquid produced in some plants.

Question 13

Alkaloids

Answer 13

Any one of a group of nitrogen-bearing compounds that can affect the nervous system of animals, produced by some plants as a defense against herbivores.

Question 14

Terpenes

Answer 14

Any one of a group of compounds that do not contain nitrogen and are produced by some plants as a defensive mechanism.

Question 15

Phenols

Answer 15

Any one of a class of chemical compounds, produced by some plants as a defensive mechanism.

Question 16

Tannin

Answer 16

Any one of a group of phenols found widely in plant tissues that bind with proteins and reduce their digestibility.

Question 17

Protease Inhibitors

Answer 17

Any one of a group of phenols found widely in plant tissues that bind with proteins and reduce their digestibility.

Question 18

Trade-off

Answer 18

An exchange in which something is gained at the expense of something lost.

Question 19

Plants are able to defend themselves against viruses that have invaded their cells by:

Answer 19

recognizing viral RNA and interrupting its replication.

Question 20

Some herbivores are known as _____, feeding on a wide variety of plant species.

Answer 20

generalists

Question 21

Alkaloids such as nicotine are relatively _____ for plants to produce because _____.

Answer 21

expensive; alkaloids contain high levels of nitrogen, which is often a growth limiting nutrient

Question 22

Density-dependent mortality describes a situation in which seedlings:

Answer 22

of common species are more likely to be infected by pathogens.

Question 23

In specific resistance, if a plant does not have an appropriate R protein, what will happen when it comes into contact with a pathogen?

Answer 23

The AVR protein will block the plant’s basal resistance, allowing the pathogen to infect the cell.

Question 24

The hard-mineral silica plates found in some grasses is an effective defense because silica:

Answer 24

is abrasive and wears down insect mouth parts, so insects feed less efficiently and more slowly.

Question 25

The presence of thorns is an example of _____ defenses.

Answer 25

constitutive

Question 26

Insects consume approximately _____ percent of all plant production each year.

Answer 26

20

Question 27

A tobacco farmer is walking through her fields. On a tobacco plant leaf, she notices several small brown spots surrounded by what appears to be necrotic or dying tissue. What kind of response is the plant demonstrating?

Answer 27

The plant is demonstrating a hypersensitive response.

Question 28

One of the first chemotherapy drugs, vincristine, was discovered in the Madagascar periwinkle and is a(n):

Answer 28

alkaloid

Question 29

T/F: N. attenuata produces variable levels of nicotine in response to the level of herbivory on the plant.

Answer 29

True

Question 30

A number of plants produce terpenes. Does the production of terpenes have an advantage over the production of alkaloids?

Answer 30

There is an advantage because terpenes do not require nitrogen for their production.

Question 31

Nitrogen-bearing compounds that affect animal nervous systems and are often bitter tasting belong to which class of compounds?

Answer 31

Alkaloids

Question 32

T/F: In some cases, plant investments in defense can limit growth more than pathogen or herbivore damage would.

Answer 32

True

Question 33

T/F: Plants and animals use the same 20 amino acids to construct proteins, but some plants have additional amino acids.

Answer 33

True