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The phenomenon observed in some plants w...

The phenomenon observed in some plants wherein parts of the sexual apparatus is used for forming embryos without fertilisation is called:

A

Parthenocarpy

B

Apomixis

C

Vegetative propagation

D

Sexual reproduction

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The particles of colloidal solution possess electrical charge which is responsible for the stability of these solutions. The charge on colloidal particles arises because of selective adsorption of ions which are common with their own lattice. The presence of charge on colloidal part!cles can be determined with the help of phenomenon known as electrophoresis. However, when some electrolyte is added, the charge on the particles of dispersed phase gets neutralized and precipitation takes place. This process is also called coagulation. The coagulation is given by Hardy Schulze rules. According to these rules the ions carrying the charge opposite to that of sol particles are effective and coagulating power of an electrolyte is directly proportional to the fourth power of the valency of the ion. Coagulation can also occur by mutual precipitation, by electrophoresis, by persistent dialysis or by heating or cooling. Which charge is responsible for stability of colloidal particles ?

The particles of colloidal solution possess electrical charge which is responsible for the stability of these solutions. The charge on colloidal particles arises because of selective adsorption of ions which are common with their own lattice. The presence of charge on colloidal part!cles can be determined with the help of phenomenon known as electrophoresis. However, when some electrolyte is added, the charge on the particles of dispersed phase gets neutralized and precipitation takes place. This process is also called coagulation. The coagulation is given by Hardy Schulze rules. According to these rules the ions carrying the charge opposite to that of sol particles are effective and coagulating power of an electrolyte is directly proportional to the fourth power of the valency of the ion. Coagulation can also occur by mutual precipitation, by electrophoresis, by persistent dialysis or by heating or cooling. What is electrophoresis ?

The particles of colloidal solution possess electrical charge which is responsible for the stability of these solutions. The charge on colloidal particles arises because of selective adsorption of ions which are common with their own lattice. The presence of charge on colloidal part!cles can be determined with the help of phenomenon known as electrophoresis. However, when some electrolyte is added, the charge on the particles of dispersed phase gets neutralized and precipitation takes place. This process is also called coagulation. The coagulation is given by Hardy Schulze rules. According to these rules the ions carrying the charge opposite to that of sol particles are effective and coagulating power of an electrolyte is directly proportional to the fourth power of the valency of the ion. Coagulation can also occur by mutual precipitation, by electrophoresis, by persistent dialysis or by heating or cooling. What is precipitation ?

The existence of negatively charged particle in an atom was shown by J.J. Thomson as a result of the studies of the passage of electricity through gases at extremely low pressure known as discharge tube experiments. When a high voltage of the order of 10,000 volts or more was impressed across the electrodes, some sort of invisible rays moved from the negative electrode to the positive electrode these rays are called as cathode rays. Cathode rays travel in straight path in absence of electrical and magnetic field . Cathode rays consist of material part and charged particles? Cathode rays produce X-rays and light is emitted when they strike on ZnS screen. Cathode rays penetrate through thin sheets of aluminium and other metals . They affect the photogenic plate and passes heating effect when they strike on metal foil. The raito of charge to mass i.e charge/mass is same for all the cathode rays irrespective of the gas used in the tube. The existence of positively charged particle in an atom was shown be E. Goldstein. He repeated the same discharge tube experiments by using a perforated cathode. It was observed that when a high potential difference was applied between the electrodes, not only cathode rays were produced but also a new type of rays were produced simultaneoulsy from anode moving towards cathode and passes through the holes or canal of the cathode. These termed as canal rays or anode rays. These rays travel in straight lines and consists of positively charged particles. These rays have kinetic energy and produces heating effect also. The e/m ratio of these rays is smaller than that of electrons. Unlike cathode rays, their e/m value is dependent upon the nature of the gas taken in the tube. These rays produced flashes of light on ZnS screen and can pass throughs thin metal foils. They can produce physical and chemical changes and are capable to produce ionisation in gases. For cathode rays the value of e/m:

MBD-SEXUAL REPRODUCTION IN FLOWERING PLANTS -Exercise
  1. The phenomenon observed in some plants wherein parts of the sexual app...

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  2. What is the genetic constitution of endosperm in angiosperms?

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  3. Mention the reason for difference in ploidy of zygote and primary endo...

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  4. Name the sperm lysins.Which orgenelle secrete it.What is its function?

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  5. Fertilization is not an obligatory event for fruit production in certa...

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  6. Where would you look for coleoptile and coleorhiza?

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  7. On the basis of structure of the embryo, how would you identify whethe...

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  8. In a flower, if the megaspore mother cell forms megaspores without und...

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  9. In some plants, the female gamete develops into embryo without fertili...

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  10. Define triple fusion. What is bagging technique?

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  11. Why are banana seedless?

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  12. How tapetal cell in microsporangium can become binucleate?

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  13. What is Apomixis ? What is its importance ?

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  14. Differentiate true fruit and false fruit. Give example in each case.

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  15. Give the structure of pollen grain.

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  16. Discribe the post-fertilisation changes in a flower.

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  17. Describe the stages in embryo development in a dicot plant.

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  18. Why the cleavage in mammals referred as simple holoblastic?

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  19. Draw a diagram of fertilized embryo sac showing zygote and PEN.

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  20. Why does endosperm development precede embryo development in angiosper...

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