Biology Questions and Answers

Biology Questions and Answers

42. What are the plant organs
    responsible for the perception
    of light variation? What is the
    pigment responsible for this
    perception?

Leaves are mainly resperception of light inteponsiblnsity in plants.e for (^)
The pigment that performs this
perception aphotoperiodism is called pnd commandshytochrom (^) e.

43. How does the
    photoperiodism affect the
    flowering of some plants?

Flowering is a typicalobserve example of photoperiodism. and easy to (^)
Most flowering plants flowspecific periods of the year er only duringor when
placed under some conditions of daily
illumination. blossoming dThis occurs bepends on the duration ecause theirof (^)
the photoperiod that in its turn varies
with the season oalso affected by exposition to certainf the year. Flowerin g is
temperatures.

44. What is the critical
    photoperiod? How can the
    critical photoperiod relate to
    flowering be experimentally
    determined?

The criticalthe photoperiod duration photoperiod is the limit offor the
occurrence of some biological response.
This limit can be a maximum minimum, according to the or a

characteristics of the biological response

and to the studied plant.

To determine the critical photoperiod

relating to plants of the same flowering, 24 groups ofspecies can be taken (^)
and the following experiment can be
done: Each group is sudifferent photoperiod, the first group tobmitted to a (^)
1 hour of daily exposure to light, the
second to 2 hours, thand so on, until the last group ise third to 3 hours,
exposed to 24 hours. It is observed
later that beyond a specific duration oflight exposure plants present or do not (^)
present flowsubmitted to ering and the remainina shorter photoperiod g
present opposite behavior. The duration
of the light exposure these two groups is ththat separate critical es
photoperiod.

45. How do plants classify
    according to their
    photoperiodism-based
    flowering?
    Accordinflowering plants classifyg to their photoperiodism-base as long-day d
    plants, those that dphotoperiods than the criticalepend on longer
    photoperiod to flower, as short-day
    plants, those that dphotoperiods than the criticalepend on shorter
    photoperiod to flower, and as indifferent
    plants, whose depend on the photoperiod.flowering does not

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