Physiology and Biochemistry-Photoperiodism [IAS (Admin.) Mains Botany]: Questions 1 - 6 of 10

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Question 1

Appeared in Year: 2015 (IFS)

Describe in Detail Subjective▾

How do seasonal variations in day length conditions influence flowering patterns of plants? Give a comprehensive account of the structure and mode of action of the photoreceptor involved. (Paper II)

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Explanation

Seasonal Variations in Day Length and Flowering Patterns of Plants

  • Seasonal variation in day length condition influence flowering pattern of plant as it is observed that some plant need a periodic exposure to light to induce flowering.
  • Some plants require the exposure to light for a period exceeding a well-defined critical duration before flowering t…

… (543 more words, 45 figures) …

Question 2

Appeared in Year: 2017 (IFS)

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Phytoremediation is not an ultimate solution to all the maladies of air and water. Explain in detail with specific examples.

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Explanation

Phytoremediation

Plant to Sequester Phytoremediation
  • The capacity of plants to sequester heavy metal ions by binding them to phytochelatin used to detoxify soils polluted with heavy metals.
  • On such soils plants are grown, which by breeding or genetic engineering have a particularly high capacity for heavy metal uptake by the roots and of phytochelatin…

… (327 more words, 14 figures) …

Question 3

Appeared in Year: 2015

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What are the characteristics of phytochrome induced responses in flowering of higher plants? How do they control flowering?

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Explanation

Phytochrome

  • Phytochrome is a protein with a chromatophore. It occurs in two possible forms.
  • The form which absorbs red light (660nm) is called Pr and the form which absorbs far red light (730nm) is termed as Pfr.
  • The chromophoric group which gives two colors to the protein is an open chain tetrapyrrole pigment like the phycobilin allophycocyanin.
  • Two f…

… (522 more words, 43 figures) …

Question 4

Appeared in Year: 2019 (IFS)

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How do photoperiodic response and photo inductive cycles influence flowering?

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Explanation

  • Light controls all aspects of plant growth. Like plant՚s structure, form, shape, physiology, growth, reproduction, development and, any other.
  • On the basis of light factor classification of plants is done into
    • photophobic plants
    • photophilous plants

Direct Effects of Light on Plants

  • Formation of chlorophyll pigment.
  • Number and position of chloroplasts.
  • Ver…

… (308 more words, 8 figures) …

Question 5

Appeared in Year: 2019 (IFS)

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How is phytochrome associated with flowering?

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Explanation

Phytochrome

  • Phytochrome is a protein with a chromatophore. It occurs in two possible forms.
  • The form which absorbs red light (660 nm) is called Pr and the form which absorbs far red light (730 nm) is termed as Pfr.
  • The chromophoric group which gives two colours to the protein is an open chain tetra pyrrole pigment similar to the phycobilin allophycocy…

… (558 more words, 32 figures) …

Question 6

Appeared in Year: 2018

Describe in Detail Subjective▾

How do plants monitor day length? Discuss the various categories of plants based on their photoperiodic responses. What happens when the dark period is interrupted by night break and why?

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Explanation

How Plants Monitor Day Length

Plants monitor day length using a molecule called phytochrome. Phytochrome is a light-sensitive pigment that exists in two forms: Pr (red light absorbing) and Pfr (far-red light absorbing) . When Pr absorbs red light, it converts to Pfr. When Pfr absorbs far-red light, it converts back to Pr.

The ratio of Pr to Pfr in a …

… (930 more words, 11 figures) …