Optionals IAS Mains Botany: Questions 345 - 354 of 511

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Question 345

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Appeared in Year: 2017 (IFS)

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Essay▾

Molecular basis of sex determination.

Explanation

Sex Determination

  • It is a biological system that determine the development of the sexual characters of an organism.
  • Most of the mechanisms of the determination of the sex are controlled in molecular level.
  • They classified into these categories
    • Sex chromosome mechanism or Heterogamesis
    • Genic balance mechanism
    • Male haploidy or haplodiploidy mechanism
    • Single…

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Question 346

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Appeared in Year: 2017 (IFS)

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Essay▾

Chi square test.

Explanation

Chi Square Test

  • Chi- square is most popular method to determine the goodness of fit.
  • To solve any problem take four steps
    • State the hypothesis
    • Formulate the analysis plan
    • Analyze sample data
    • Result interpretation

State the Hypothesis

  • Every hypothesis test requires a Null hypothesis (H0) and the alternative hypothesis.
  • Both hypothesis state such a way that t…

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Question 347

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Appeared in Year: 2017 (IFS)

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Essay▾

With suitable example, explain the tripartite sex determination.

Explanation

Sex Determination

  • It is a biological system that determines the development of the sexual characters of an organism.
  • In some angiosperm the tripartite sex determination is seen.

Tripartite Sex Determination

Involvement of three sex chromosome to determine the development of sexual characters of an organism. For example- XXX or XXY, etc.

For Example

  • In Ac…

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Question 348

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Appeared in Year: 2017 (IFS)

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Essay▾

Evidences of organic evolution.

Explanation

Evidences of Organic Evolution

  • Organic evolution the process in which the changes occur in the population of organism in response to environmental changes.
  • There are many evidence of organic evolution

Evidence 1

Palaeontology

  • Palaeontology is scientific study of fossils.
  • Fossils provide strongest and direct evidence that support the theory of organic evo…

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Question 349

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Appeared in Year: 2017 (IFS)

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Essay▾

Describe the methods of breaking seed dormancy. Trace the physiological changes involved during seed germination.

Explanation

Methods of Breaking Seed Dormancy

What is seed dormancy?

  • Seed dormancy is an adaptation that prevents seed from germinating during unsuitable ecological condition.
  • There are many methods to break seed dormancy some of them are natural while some of them are natural.
Methods of Breaking Seed Dormancy

Natural Methods

  • Over-ripening of the fruit and seed.
  • Inh…

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Question 350

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Appeared in Year: 2017 (IFS)

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Essay▾

Enumerate the Sporophytic and gametophytic feature of psilotum. Comment on systematic position.

Explanation

Psilotum

Sporophytic and Gametophytic Feature of Psilotum

Sporophytic Feature

  • Sporophytic body composed of subterranean Rhizome and dichotomously branched aerial shoots.
  • The rhizome is cylindrical, prostrate and dichotomously branched.
  • Sometimes it is seen the branching trends to become lateral or irregular due to injury in the region of meristematic.
  • Th…

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Question 351

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Appeared in Year: 2017 (IFS)

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Essay▾

Describe with illustrations about chromosomal behaviour during meiosis with translocation, inversion and duplication.

Explanation

Meiosis

Meiosis is a process where single cell divide twice and produce cells containing half of the original genetic material.

Meiosis I

Chromosomal Behaviour During Meiosis

Meiosis II

Chromosomal Behaviour Meiosis II

Chromosomal Behaviour

  • In meiosis two rounds of chromosome segregation occur but only after single replication.
  • Pairing occur during prophas…

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Question 352

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Appeared in Year: 2017 (IFS)

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Essay▾

Role of carotenoids in plants.

Explanation

Role of Carotenoids in Plants

  • There are different pigments present in the plant like chlorophyll and carotenoid etc.
  • Carotenoids are red, yellow and orange pigments found in chromoplast in plants.
  • It is precursor of vitamin A.
  • Pigment help to accomplish the fruit ripening. Green-to-red.
  • The red colour is due to lycopene. Not in all cases the change in f…

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Question 353

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Appeared in Year: 2017 (IFS)

Write in Short

Short Answer▾

Explain the pigments observed in Rhodophyceae.

Question 354

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Appeared in Year: 2017 (IFS)

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Essay▾

Describe Algal Phylogeny.

Explanation

Algal Phylogeny

  • The term phylogeny is the evolutionary development and diversification of species or any particular feature.
  • The algae are an assemblage of morphologically diverse, photosynthetic Protists that are ubiquitous in distribution.
  • To understand algal phylogeny, it has been revolutionized with molecular evolutionary methods.
  • The molecular phy…

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