TLS Online TPP Program

#Question id: 4618


Which of the following observations helped Darwin shape his concept of descent with modification?

#Zoology
  1. Species diversity declines farther from the equator.

  2. Fewer species live on islands than on the nearest continents.

  3. Birds live on islands located farther from the mainland than the birds' maximum nonstop flight distance.

  4. South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.

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TLS Online TPP Program

#Question id: 37968

#Plant Biotechnology

Assertion (A): In cereals like rice and wheat, the choice between embryo or callus formation can be manipulated. 
Reason (R): Modifying the medium composition in these species can induce either embryos or calli.

Select the correct option from:

TLS Online TPP Program

#Question id: 37969

#Plant Biotechnology

Statement I: Cold treatment (3–6°C) helps in retarding the aging of the anther wall, thereby allowing more microspores to switch from gametophytic to sporophytic development.
Statement II: Maize responds best to standard cold treatment temperatures of 3–6°C rather than higher temperatures like 14°C

TLS Online TPP Program

#Question id: 37970

#Plant Biotechnology

Statement I: Hot treatment (e.g., 30°C for 24h) in Brassica stimulates embryogenesis by causing the dissolution of microtubules and displacement of the spindle.
Statement II: This thermal shock leads to normal division of the microspore nucleus.

TLS Online TPP Program

#Question id: 37971

#Plant Biotechnology

Statement I: Ethrel (2-chloroethylphosphonic acid) treatment increases haploid production by inducing multinucleated pollen grains.
Statement II: Pollen grains induced by Ethrel treatment are characterized by having a high density of starch grains.

TLS Online TPP Program

#Question id: 37972

#Plant Biotechnology

Statement I: Commitment to androgenesis is achieved mainly by the overexpression of pollen maturation ('late') genes.
Statement II: In wheat, the synthesis of a metallothionein-like protein during induction is regulated by Abscisic Acid (ABA).

TLS Online TPP Program

#Question id: 37973

#Plant Biotechnology

Statement I: In cereal species like rice and wheat, modifying the medium composition can determine whether the cell mass forms an embryo or a callus.
Statement II: The formation of a callus versus a globular embryo is strictly dependent on the temperature and cannot be influenced by the species type.