Chapter 14 (herbivory)

mechanical thorns, spines sticky hairs, trichomes

A plant's first line of defense is _____. - ____ and _____ deter vertebrate herbivores, though not invertebrates that are small enough to chew around the thorns. - _____ ____ or _____ on the leaves trap and kill small insects.

carbon-based, tannins nitrogen-rich

Carbon-Nitrogen Balance Hypothesis Low-Soil Nitrogen Levels - Plants tend to use nitrogen for growth and to produce more _____ defenses, mostly digestibility-reducing phenolic compounds such as _____. Low-Carbon Conditions - In shady environments where light is limited and photosynthesis is constrained, carbon is used for growth and plants are more likely to produce ______ toxins.

phenolic tannins colored aging

Chemical Defenses (Alkaloid/Phenolic/Terpenoid)?? _____ _____ are found in many plant species and act as a deterrent to animals, either because of a bitter taste or due to toxic effects. The water leaching from fallen forest leaves is rich in this chemical and makes streams coffee _____. They are also found in grape skins and play a role in the flavor of red wine. _____ breaks down tannins making wine less bitter.

contain, cyclic, ring-like bitter, unpleasant

Chemical Defenses Alkaloids are a group of structurally related molecules that ____ (contain/lack) nitrogen and usually have a ____, ___-___structure. They are ____ tasting molecules and often have an _____ odor.

alkaloid die speed up , blocked

Chemical Defenses Atropa Belladonna Plant - what kind of plant is this? ______ (Alkaloid/Phenolic/Terpenoid) Animals that eat this plant and consequently ingest atropine become very sick and may ___. In humans, atropine causes the heart to _____ to dangerous rates, because the nerve inputs that normally keep a check on the heart rate are ______ by atropine.

Alkaloids

Chemical Defenses Examples: caffeine, nicotine, atropine, morphine, ergot, and quinine Spices such as bay leaf, garlic, paprika, pepper, and tarragon.

terpenoids

Chemical Defenses Many of the spices used in cooking are rich in different types of _____ (alkaloids/terpenoids/phenolics), i.e., cinnamon, cloves, mint, and ginger.

phenolic compounds benzine ring 5000 flavonoids chocolate, vanilla

Chemical Defenses ____ ____ all contain a cyclic ring of carbon with three double bonds, known as a _____ ____, within their structure. Approximately ____ phenolic compounds are known. - _____ are produced by many plant species and create a variety of flavors and smells. - The flavors of _____ and ____ largely come from a mixture of flavonoid molecules.

phenolic compounds

Chemical Defenses Examples: flavonoids, tannins, and lignins.

Terpenoids 5-carbon isoprene methanol pollinators pharmaceutical

Chemical Defenses Over 25,000 _____ have been identified. They are synthesized from ___-carbon _____ units. They have a wide array of functions in plants, including defense. - They are volatile and are responsible for the odors emitted by many types of plants, such as _____ produced by mint. - The odors of terpenoids may attract ______ or repel animals that eat plants. - They are found in many traditional herbal remedies and are under medical investigation for potential _______ effects.

mechanical adaption behavioral adaption digestive enzymes microbial symbionts host manipulation

Herbivores can overcome plant defenses in 5 ways Example Flat, grinding teeth Feed when plant defenses are lowest Mixed function oxidases Microbes in stomachs Gall-inducing insects.

thorn, resources, herbivores decreased, increased

Mechanical defenses such as _____ are costly to produce and may divert _____ from other plant functions. Some ecologists have suggested that such defenses are only switched on in the presence of _____ In the mountains of Spain experiments showed that thorn density ______ (decreased, increased) over the course of two years when plants were protected from Ibex and domestic sheep. Fruit set also ______ (decreased, increased) where thorns were removed.

smell bad, bitter tasting, toxic array, share medicinal, $1 trillion

Most of these chemicals (3)___ ___, ___ ___, or _____ and they deter herbivores from feeding and plant pathogens from colonizing and establishing. - Plants produce an ___ of secondary metabolites and many plants _____ the same metabolites. Many of these compounds have _____ properties that are beneficial to humans. The global economic value of plant related drugs is $__ ___ annually.

quantitive, qualitative

Plant chemical defenses can be classified as _____ or _____, depending on the volume of defense present in the plant.

mechanical defense chemical defense mutualisms with defensive agents associational resistance mimic semiochemicals

Plants have strategies to avoid being eaten Examples... Thorns, sticky hairs, silica Alkaloids, phenolics, terpenoids Bull's horn acacia and ants Purple loosestrife growing next to Myrica Ecdysteroids mimic insect-molting hormone.

chemicals metabolic pathway secondary metabolites, secondary chemicals

Powerful _____ provide a second line of defense against herbivores. - Such compounds are not part of the primary _____ ____ that plants use to obtain energy. They are therefore referred to as ____ ____ or ____ ____

apparent, oak trees, quantitative unapparent, weeds, qualitative

Qualitative and quantitative defenses are correlated with plant apparency. ______ plants are long-lived, large, and always apparent to the herbivores such as (type of plant ______. They can tolerate foliage loss before _____ (qualitative/quantitative) poisons kick in. ______ plants are small, difficult to find, and unavailable to herbivores for long periods such as (type of plant) ____. They need ____ (qualitative/quantitative) poisons which work long before the plant is completely eaten.

sticky resins tough fibers silica indigestible, grind down

Some plants produce ____ ____ that gum up the mouthparts of insects. ____ ____ common in plant bark, seed coats, and the outside of nuts discourage herbivore feeding. Grasses and palms sequester ____, which make them difficult to chew - Both fibers and silica, which are ____ to animals, ___ ____ mammalian teeth and insect mandibles, reducing feeding efficiency.

semiochemicals pheromones allelochemicals disrupt

The behavior of many insect herbivores is altered by chemical messengers known as ______. - In some cases, these are _____, which act as sex attractants between males and females. - In others, they are ______ that affect behavior between different species. Plants produce analogs of these chemicals that serve to ____ herbivore behavior.

contain lack lack

Three general chemical classes of defenses can be recognized: - Alkaloids, which _____ nitrogen - Phenolics, which _____ nitrogen - Terpenoids, which ____ nitrogen

self-regulation parasites, predators spines, cuticles, chemicals

Three hypotheses have been proposed to answer the question of why more plant material is not eaten by herbivores. Herbivores may have evolved mechanisms of _______ to prevent the destruction of host plants, ensuring a future supply of food. (not likely) ______ and ______ might keep herbivore numbers low, thus sparing the plants. (likely) The plant world is not as helpless as it appears. It is armed with defensive ____, tough ____, and noxious _____. (likely)

abscise , prevent eggs, discouraged

Types of Additional Plant Defenses Plants may selectively _____ leaves heavily infested by sessile insects such as leaf miners or aphids, causing the leaves to fall to the ground. This _____ the insect from completing its life cycle. Some specialized species-specific plant defenses exist. Example: some tropical vines produce physical structures that mimic ____ of the Heliconius butterflies, whose larvae feed on them. Because females are less likely to lay eggs where other eggs are present, oviposition is _______.

carbon-nitrogen balance hypothesis secondary metabolites

____ - ____ ____ ____: An attempt to explain how the types of defenses produced are influenced by the environmental conditions. It suggests that carbon and nitrogen are allocated to production of ____ ____ only after requirements for growth are met first.

optimal defense flowers, seeds higher cyanogenic glycosides

_____ _____ hypothesis Suggests that certain plant parts, such as ____ or _____, are not so easily replaced as others, such as leaves or twigs. - Such parts contain a ____ (higher/lower) proportion of a plant's defenses. - Seeds of many edible fruits contain _____ _____ .

constitutive induced resources, diverted (redirected)

______ defenses are always present in the plant. _______ defenses are only switched on when herbivores attack. - Plants do not always have to use valuable ______ in the continued production of defenses, which allows resources to be _____ to other functions.

quantitative , prevent tannins, resins, 60% small, more

______ defenses are substances that are ingested in large amounts by the herbivore as it eats and that ____ energy gain from the digestion of food. - Examples are ____ and ____ in leaves, which may constitute ___% of the dry weight of the leaf. - These compounds are not toxic in ____ (large/small) doses but the ____ (more/less) leaf the herbivores ingests, the more difficult it is for them to digest it.

qualitative 1% cyanogenic, atropine

______ defenses are toxic substances that are effective in very small doses. These compounds are present in leaves at low concentrations, less than ___% of dry weight. - Examples include _____ compounds in leaves. ____ produced by deadly nightshade is a most potent poison.

monophagous polyphagous

_________ herbivores, which are usually insects, feed on one plant species or just a few closely related species. _______ species, which are mainly mammals, feed on many different host species, often from more than one family