IFS (Forests Services) Botany (Mains): Questions 73 - 80 of 160

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Question number: 73

» Genetics, Molecular Biology and Evolution » Sex Chromosomes

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Appeared in Year: 2014

Essay Question▾

Describe in Detail

What is accounted for by Lyon’s hypothesis? Cite an example. (Paper 2 - Section A)

Explanation

  • The Lyon’s hypothesis was described by Mary Lyon in 1962.

  • The Lyon’s hypothesis does not related to germ cells and explains the phenomenon of heterozygous female carries of X-lined recessive disorders showing features of the condition.

  • The Lyon’s hypothesis was also explains the phenomenon of Barr bodies.

  • The Lyon hypothesis relates to

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Question number: 74

» Ecology and Plant Geography » Endemism

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Appeared in Year: 2014

Essay Question▾

Describe in Detail

Write brief notes on the following in about 150 words each: Endemism (Paper 2, Section B)

Explanation

Endemism means the situation in which a species is restricted to a particular geographic region as a result of factors such as isolation or in response to abiotic conditions.

  • Endemic species is only found in a given region or location and nowhere else in the world. If they are extinct in their endemic ecosystem, they are lost forever.

  • The

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Question number: 75

» Physiology and Biochemistry » Secondary Metabolites

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Appeared in Year: 2014

Essay Question▾

Describe in Detail

Describe various structural and chemical defence mechanisms developed by plants. (Paper 2, Section B)

Explanation

  • Plants need to protect themselves from various threats.
  • So, some plants have modified parts that are used for defence.
  • These defense mechanisms are used to protect plants from herbivorous animals and insects and also from insects laying eggs on the plant.

Structural Defense Mechanisms

Microscopy visible structural characteristics present on t

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Question number: 76

» Cell Biology » Chromosomes

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Appeared in Year: 2014

Essay Question▾

Describe in Detail

Explain the following in about 150 words each: Basic chromosome number may be different from haploid number. (Paper 2 - Section A)

Explanation

  • The number of chromosomes per cell is fixed for a given species.
  • In human beings, the number of chromosome is 46, this is called diploid number where in gametes, and the number of chromosomes is only half of the diploid number and is 23 and is called haploid number. The haploid chromosome number is produced during meiosis.
  • An organism with any

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Question number: 77

» Physiology and Biochemistry » Growth Substances

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Appeared in Year: 2014

Essay Question▾

Describe in Detail

Write brief notes on the following in about 150 words each: Allelopathy (Paper 2, Section B)

Explanation

  • Allelopathy is the suppression of growth of one plant species by another or same species due to the release of toxic substances.
  • Allelopathy is a biological phenomenon where one plant inhibits the growth of another.
  • Through the release of allelochemicals, certain plants can greatly affect the growth of other plants either in a good or bad way b

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Question number: 78

» Physiology and Biochemistry » Fruit Ripening

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Appeared in Year: 2014

Essay Question▾

Describe in Detail

Explain various physiological processes that help in fruit ripening. How can this knowledge help overcome problems likely to be faced because of climate change? (Paper 2, Section B)

Explanation

  • Ethylene is a natural plant hormone associated with the growth, development, ripening and aging of many plants.

  • This phytohormone is said to promote ripening in a variety of fruits including bananas, pineapples, tomatoes, mangoes, melons, and papayas.

  • It is produced in varying quantities depending on the type of fruit. But when the concent

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Question number: 79

» Physiology and Biochemistry » Chemiosmotic Theory

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Appeared in Year: 2014

Essay Question▾

Describe in Detail

Describe the process explained by chemiosmotic theory. (Paper 2, Section B)

Explanation

Chemiosmosis is the process by which chemical ions move from an area of high concentration to an area of low concentration across a selectively permeable membrane.

  • Chemiosmosis is the process by which ATP, or adenosine triphosphate, is synthesized.

  • The chemiosmotic hypothesis was proposed by Peter D. Mitchell in 1961. In 1978 the chemist w

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Question number: 80

» Angiosperms » Anatomy

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Appeared in Year: 2013

Short Answer Question▾

Write in Short

Draw scientifically accurate diagrams of the following and label the parts: T. S. of any stem showing interxylary and intraxylary phloem (Paper 1, Section B)