Campbell 39: Plant Responses To Light

direction; intensity

plants detect the _____, ______, and wavelength of light, in addition to detecting the presence of light

blue-light photoreceptors, phytochromes

list the two major classes of light receptors

blue-light photoreceptor

type of light receptor that controls hypocotyl elongation, stomatal opening, and phototropism

red; far-red

phytochrome is made in the Pr form. When Pr absorbs _____ light, it turns into the Pfr form.
When Pfr absorbs _____ light, it reverses back into the Pr form

Pr; Pfr

overnight, phytochrome resets to the ____ form. during the day, phytochrome is mostly converted to the _____ form

shade avoidance

in the _____ _____ response, phytochrome shifts in favor or Pr, inducing vertical growth

clock

phytochrome conversion marks sunrise and sunset, providing the plant’s biological ______ with environmental cues

photoperiod

the relative lengths of night and day being the environmental stimulus that plants use most often to detect the time of year

short-day, long-day, day neutral

list the 3 types of control of flowering by photoperiod

short-day plants

a species that flower when a light period is shorter than a critical length

long-day plants

species that flower when a light period is longer than a certain number of hours

day neutral plants

species where flowering is controlled by plant maturity or age, not photoperiod

night; day

its actually the length of the ____ that controls flowering, not the length of the _____

single

some species flower after only a ____ exposure to the required photoperiod

vernalization

some species need a different environmental stimulus in addition to the required photoperiod to trigger flowering, including ________

cold

vernalization is a pretreatment with ____ to induce flowering

abiotic stress

nonliving stresses for plants that include drought, flooding, salt stress, heat stress, cold stress, nutrient deficiency/toxicity, and ozone

drought, flood, salt, heat, cold, nutrient deficiency/toxicity, ozone

list the 7 abiotic stresses on a plant

biotic stress

living stresses that include herbivores and pathogens

herbivores, pathogens

list the two biotic stresses on plants

stomata; wounds

pathogens enter through _____ or _____ in plant tissue

pathogen-associated molecular patterns (PAMPs)

the first line of immune defense depends on the plant’s ability to recognize _____ _____ ____ _______, molecular sequences which are specific to certain pathogens

antimicrobial

PAMP recognition starts a chain of signaling events leading to the production of ______ chemicals and toughening of the cell wall

hypersensitive response (HR), systematic acquired resistance (SAR)

list the two types of plant immune/defense responses

short-term; localized

the HR immune response is ______ ____ and ______

long-term; widespread

the SAR immune response is ____ ____ and ______

death; confines

the HR causes cell and tissue ____, induces production of enzymes, and stimulates change in the cell wall that _____ the pathogen

salicylic; primes

In the SAR, methylsalicylic acid is synthesized around the infection site and carried into the phloem to other remote sites where it is converted to ______ acid which ____ the defense system to respond rapidly to another infection

herbivory; fitness

_______ is when a plant tissue is eaten by an animal, lowering the plants _____

physical; chemical

plants counter herbivory with _____ and _____ defenses