12th Class Fsc Biology Online Preparation for chapter 22 (Variation and Genetics)

Online Short Questions For Chapter 8 "12th Class Biology Chapter 22 Short Questions Preparation "

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Biology - 12th Class Biology Chapter 22 Short Questions Preparation

Question # 1

What is XO-XX mechanism of sex determination?

  • Ans 1: This pattern of Inheritance is found in grasshopper and protenor bug.Male is XO because male has one x chromosomes,the other x chromosomes is missing and female is xx,it is homogametic because it forms all gametes of same type with one X chromosome.Male is heterogametic because it forms two types sperms: half sperms have X chromosomes and other half are without X chromosomes.
    When sperm with X chromosomes is fused with an egg having X chromosomes female offspring is produced and when sperms without X chromosomes is fused with egg then male offspring will be produced.
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Prepare Complete Set Wise Questions For Chapter 8 "12th Class Biology Chapter 22 Short Questions Preparation "

12th Class Biology Chapter 22 Short Questions Preparation - Set 1

Question # 1

What is XO-XX mechanism of sex determination?

  • Ans 1: This pattern of Inheritance is found in grasshopper and protenor bug.Male is XO because male has one x chromosomes,the other x chromosomes is missing and female is xx,it is homogametic because it forms all gametes of same type with one X chromosome.Male is heterogametic because it forms two types sperms: half sperms have X chromosomes and other half are without X chromosomes.
    When sperm with X chromosomes is fused with an egg having X chromosomes female offspring is produced and when sperms without X chromosomes is fused with egg then male offspring will be produced.
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12th Class Biology Chapter 22 Short Questions Preparation - Set 2

Question # 1

What is Pleiotropy? Give one example.

  • Ans 1: When a single gene affects two or more traits the phenomenon is called pleiotropy. E.g, genes that effect growth rate in human also influence both weight and height.
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12th Class Biology Chapter 22 Short Questions Preparation - Set 3

Question # 1

What is law of segregation?

  • Ans 1: The two coexisting alleles for each trait in an individual segregate from each other at meiosis, so that each gamete has only one the two alleles.Alleles unite again random fertilization of gametes when zygote is formed.
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12th Class Biology Chapter 22 Short Questions Preparation - Set 4

Question # 1

How sex is determined in plants?

  • Ans 1: Plants show a variety of sexual situations.Some species like Ginkgo are dio-ecious having plants of separate sexes.Male plants produce flower with only stamens and female plants produce flower with only carpels.Some dioecious plants have a difference of sex chromosome between the sexes.These have an X-Y system.These plants typically exhibit an X-choromosome autosome balance system for sex determination.
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12th Class Biology Chapter 22 Short Questions Preparation - Set 5

Question # 1

What is hypophosphatemic rickets?

  • Ans 1: It is an X linked dominant trait.It is rare hereditary disease.it does not result from vitamin D deficiency but its cause is a genetic communication failure at molecular level.The genes encoding bone proteins never receive vitamin D message to function.
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12th Class Biology Chapter 22 Short Questions Preparation - Set 6

Question # 1

What are sex influenced traits?Give an example.

  • Ans 1: Sex influencing traits occurs in both males and females but more common in one sex.It is controlled by an allele that is dominant in one sex but recessive in other.The difference in expression is due hormonal difference in two sexes.E.g, patteren baldness is sex influenced trait.
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12th Class Biology Chapter 22 Short Questions

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