#light signalling MCQ

cryptochrome

In darkness, COP1/SPA1 complex mainly causes:

Degradation of HY5 (B) is correct here. This is core cryptochrome: once you know the definition or pathway step, Degradation of HY5 is the clear fit. The wrong ones are A) Activation of HY5; C) Activation of cryptochrome; D) Inhibition of ubiquitination. If the topic is about gradients or potentials, water/solutes move from higher to lower of the relevant quantity.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

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PHYTOCHROME+PYQS

A mutation in phyB generally results in plants that:

That points to B: Leaf abscission. Compared with the other options, Leaf abscission is the one that correctly describes the PHYTOCHROME concept. The wrong ones are A) Cell division; C) Photosynthesis; D) Dormancy. If you’re stuck, eliminate anything that contradicts a basic fact you already know for this topic.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

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PHYTOCHROME+PYQS

Phytochrome interacting factors (PIFs) primarily act as:

The right choice is B: Negative regulators of photomorphogenesis. In PHYTOCHROME, that matches how the process or concept actually works — the other choices mix up related ideas or use the wrong mechanism. Skip these: A) Positive regulators of photomorphogenesis; C) Photoreceptors; D) Hormones. A quick check: if an option needs energy, pumps, or the opposite direction of movement, ask whether that really applies.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

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PSS-Sec-E-Sensory biology

In absence of COP1 in nucleus, plants show:

B fits best: Photomorphogenesis. Keep the PSS-Sec-E-Sensory biology basics straight and Photomorphogenesis stands out as the precise answer. Avoid: A) Skotomorphogenesis; C) Delayed flowering; D) Dwarfism. Light and flowering items often hinge on which photoreceptor or day-length rule is in play.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

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PSS-Sec-E-Sensory biology

Cryptochrome 1 interacts with which complex to regulate HY5 stability?

Correct option is B, COP1–SPA1. In PSS-Sec-E-Sensory biology problems like this, the accurate statement is COP1–SPA1; the others are common mix-ups. Not these: A) BRI1–BAK1; C) FT–FD; D) GID1–DELLA. Tissue transport questions usually turn on xylem vs phloem, living vs dead cells, or source vs sink.

Ref: Best CSIR NET Plant Physiology books: Master Unit 6 with Taiz & Zeiger and Salisbury & Ross. Crack Part C experimental questions with top textbooks.

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