Phytochrome & Photoperiodism, and Genetic Engineering

Question 1

signal transduction how plants perceive enviormental factor (process)

Answer 1

E.g. Light, gravity, temperature
___
Phytochrome
_____
Affects hormone levels
____
Get a response

Question 2

Phytochrome

Answer 2

preception of light

Question 3

Phytochrome is not a

Answer 3

plant harmone

Question 4

what color pigment that detects light quality

Answer 4

blue

Question 5

Two stable forms of phytochrome:

Answer 5

Pr
Pfr

Question 6

Pr

Answer 6

absorbs red light

Question 7

Pfr

Answer 7

absorbs far light red

Question 8

when either Pr or Pfr absorbs light it

Answer 8

it is converted to
the other form

Question 9

Far-red light is light with wavelengths

Answer 9

700-800 nm
not visible becuase any number > 760 nm is not visible

Question 10

inactive form

Answer 10

Pr

Question 11

active form

Answer 11

Pfr

Question 12

Pr are where

Answer 12

In dark grown plants In plants not under canopy
or shaded plants under In plants in Spring & Fall
canopy of leaves
*Leaves in canopy absorb red
light; far-red makes it to forest floor

Question 13

Pfr are where

Answer 13

In plants not under canopy
or shaded plants under In plants in Spring & Fal

Question 14

Pr and Far-red light: does what to plants that have them

Answer 14

1) Plants are etiolated (long and spindly)
2) Seed germination inhibited (in some species)
3) No flowering

Question 15

Pfr and Red light does what to plants that have them

Answer 15

1.) promote normal growth (de-etiolation)

2) Germination of seeds promoted

3) flowering

Question 16

Photoperiodism

Answer 16

Plant responses to day length

Question 17

Photoperiodism in flowering short day plants

spring plants

Answer 17

Flower if day is shorter than 12-14 hours

spring
violet
strawberries

Question 18

long night plants

fall plants

Answer 18

“Long night” plants need 10-12 hours of uninterrupted
darkness to flower

Aster
ragweed
mums
poinsettias

Question 19

Short day plants

Answer 19

Aster
poisettias
straberries
ragween
mums
violets

Question 20

Long day plants =

Answer 20

short night plants
Flower if days are longer than 12-14 hours
* “Short nights”: plants need <10-12 hours of darkness to
flower (or continuous light)
* E.g. spinach, potatoes, lettuce, wheat

Question 21

Day-neutral plants=

Answer 21

= unaffected by photoperiod
* Often tropical
* E.g. carnations, garden beans, tomatoes, roses, cotton,
dandelions

Question 22

Phytochrome

Answer 22

Germination and
Form of Seedlings

Question 23

why do Some plants require red light to germinate

Answer 23

Red part of the spectrum converts Pr to Pfr,
unblocking the germination mechanism

Question 24

At first emergence from soil, light changes

Answer 24

Pr to
Pfr in a seedling

– This reduces ethylene production,
straightening the seedling.
– Pfr inhibits elongation of stems
–Leads to de-etiolation.

Question 25

de-etiolation.

Answer 25

is a series of physiological and biochemical changes a plant shoot undergoes in response to sunlight.

Question 26

Transgenic plants

Answer 26

Produced by inserting
genes from virtually any organism into plants

Question 27

Study of crown galls caused by Agrobacterium
tumfaciens has opened up the field of

Answer 27

plant
genetic engineering

Question 28

Agrobacterium
tumfaciens

Answer 28

Soil dwelling bacterium

Question 29

Causes Crown Gall Tumor:

Answer 29

1) wound
2) bacteria enter wound
3) tumor forms

Question 30

Can grow crown gall cells in tissue culture after

Answer 30

removing the bacterium on a medium without auxins
and cytokinins.
-Normal cells require auxins and cytokinins for cells to
divide in tissue culture
* Crown gall tumors overproduce auxins and cytokinins

Question 31

Agrobacterium tumefaciens inserts its

Answer 31

DNA (in form of
plasmids) into plant cell DNA

Question 32

Plasmids are

Answer 32

Circles of DNA

Question 33

Ti plasmid=

Answer 33

tumor inducing plasmid causes crown
gall, has genes for auxin and cytokinin synthesis
-Ti plasmid inserts into plant cell DNA which now
contains bacterial plasmid DNA
* Genetic transformation of plant cell DNA to now
overproduce auxins and cytokinins resulting in tumor
formation

Question 34

Crown gall forms on

Answer 34

dicots not monocots

Question 35

Agrobacterium tumefaciens are used as to do what

Answer 35

Agrobacterium tumefaciens used as a vector
for introducing foreign DNA into plant cells.

Question 36

the agrobacteriums used as a vecto only works in

Answer 36

dicots not monocts

Question 37

particle guns

Answer 37

Particle guns - Shoot DNA into plant tissue
– Tungsten or gold pellets coated with cloned gene
shot into plant cells.
– Process of how this works is a mystery.

Question 38

Transgenic Plants

Answer 38

• Transgenic corn, soybean,
  cotton, and canola varieties have
  herbicide and insect resistance.
• Golden rice has genes for beta
  carotene synthesis (Vitamin A
  precursor).
• Ornamental varieties not seen in
  nature have been engineered.
• Moonshadow carnations have
  a petunia gene for blue color.

Question 39

Pros of transgenic plants

Answer 39

Farmers may use fewer and less noxious chemicals for crop
production if insect resistance genes have been inserted.