Home
Class 12
BIOLOGY
[A] : Sensescence in the time when age ...

[A] : Sensescence in the time when age as- sociated defects are manifested.
[R]: Certain genes may be undergoing se- quential switching on & off during one s life.

A

if both are true and reason is correct explanation

B

both are true reason is not correct explanation

C

assertion is true but reason is wrong

D

and both are wrong

Text Solution

Verified by Experts

The correct Answer is:
A
Promotional Banner

Topper's Solved these Questions

  • GROWTH, REPAIR, REGENERATION AND AGEING

    DINESH PUBLICATION ENGLISH|Exercise Check your Grasp|10 Videos

  • GROWTH, REPAIR, REGENERATION AND AGEING

    DINESH PUBLICATION ENGLISH|Exercise Brain Teasers-VI[B]|6 Videos

  • GROWTH, REPAIR, REGENERATION AND AGEING

    DINESH PUBLICATION ENGLISH|Exercise Brain Teasers-VI[B]|6 Videos

  • GENETIC BASIS OF INHERITANCE

    DINESH PUBLICATION ENGLISH|Exercise Check your Grasp|30 Videos

  • HUMAN EVOLUTION

    DINESH PUBLICATION ENGLISH|Exercise Brain Teasers-VII|181 Videos

Similar Questions

Explore conceptually related problems

Assertion: Senescence is the time when age associated defects are manifested. Reason: Certain genes may be undergoing sequential switching on and off during one's life.

Assertion: Senescence is the time when age associated defects are manifested Reason: Certain genes may be undergoing sequential switching on and off during one's life

Assertion . Senescence is the time when age associated defects are manifested Reason . Certain genes may be undergoing sequential switching on and off during one's life

When an atom or an ion is missing from its normal lattice site, a lattice vacancy (Schottky defect) is created. In stoichimetric ionic crystals, a vacancy of one ion has to be accompanied by the vacancy of the oppositely charged ion in order to maintain electrical neutrality. In a Frenkel defect an ion leaves its position in the lattice and occupies an interstitial void. This is the Frenkel defect commonly found along with the Schottky defects and interstitials. In pure alkali halides, Frenkel defects are not found since the ions cannot get into the interstitial sites. Frenkel defects are found in silver halides because of the small size of the Ag^(+) ion. Unlike Schottky defects, Frenkel defects do not change the denstiy of the solids. In certain ionic solids (e.q. AgBr) both Schottky and Frenkel defects occur. The defects discussed above do not disturb the stoichiometry of the crystalline material. There is large variety of non-stoichiomertic inorganic solids which contain an excess or deficiency of one of the elements. Such solids showing deviations from the ideal stoichiometric composition from an inmportant group of solids. For example in the vanadium oxide, VO_(x) , x can be anywhere between 0.6 and 1.3. There are solids which are difficult to prepare in the stoichiometric composition. Thus, the ideal composition in compounds such as FeO is difficult to obtain (normally we get a composition of Fe_(0.95)O but it may range from Fe_(0.93)O " to " Fe_(0.96)O ). Non-stoichiometric behaviour is most commonly found for transition metal compounds though is also known for some lanthanoids and actinoids. Zinc oxide loses oxygen reversibly at high temperature and turns yellow in colour. The excess metal is accommodated interstitially, giving rise to electrons trapped in the neighbourhood. The enhanced electrical conductivity of the non-stoichiometric ZnO arises from these electrons.ltrbgt Anion vacancies in alkali halides are produced by heating the alkali halide crystals in an atmosphere of the alkali metal vapur. When the metal atoms deposit on the surface they diffuse into the crystal and after ionisation the alkali metal ion occupies cationic vacancy whereas electron occupies anionic vacancy. Electrons trapped in anion vacancies are referred to as F-centers (from Farbe the German word for colour) that given rise to interesting colour in alkali halides. Thus, the excess of potassium in KCl makes the crytal appear violet and the excess of lithium in LiCl makes it pink. When LiCl is heated into the vapour of lithium, the crystal acquires pink colour. This is due to

When an atom or an ion is missing from its normal lattice site, a lattice vacancy (Schottky defect) is created. In stoichimetric ionic crystals, a vacancy of one ion has to be accompanied by the vacancy of the oppositely charged ion in order to maintain electrical neutrality. In a Frenkel defect an ion leaves its position in the lattice and occupies an interstitial void. This is the Frenkel defect commonly found along with the Schottky defects and interstitials. In pure alkali halides, Frenkel defects are not found since the ions cannot get into the interstitial sites. Frenkel defects are found in silver halides because of the small size of the Ag^(+) ion. Unlike Schottky defects, Frenkel defects do not change the denstiy of the solids. In certain ionic solids (e.q. AgBr) both Schottky and Frenkel defects occur. The defects discussed above do not disturb the stoichiometry of the crystalline material. There is large variety of non-stoichiomertic inorganic solids which contain an excess or deficiency of one of the elements. Such solids showing deviations from the ideal stoichiometric composition from an inmportant group of solids. For example in the vanadium oxide, VO_(x) , x can be anywhere between 0.6 and 1.3. There are solids which are difficult to prepare in the stoichiometric composition. Thus, the ideal composition in compounds such as FeO is difficult to obtain (normally we get a composition of Fe_(0.95)O but it may range from Fe_(0.93)O " to " Fe_(0.96)O ). Non-stoichiometric behaviour is most commonly found for transition metal compounds though is also known for some lanthanoids and actinoids. Zinc oxide loses oxygen reversibly at high temperature and turns yellow in colour. The excess metal is accommodated interstitially, giving rise to electrons trapped in the neighbourhood. The enhanced electrical conductivity of the non-stoichiometric ZnO arises from these electrons.ltrbgt Anion vacancies in alkali halides are produced by heating the alkali halide crystals in an atmosphere of the alkali metal vapur. When the metal atoms deposit on the surface they diffuse into the crystal and after ionisation the alkali metal ion occupies cationic vacancy whereas electron occupies anionic vacancy. Electrons trapped in anion vacancies are referred to as F-centers (from Farbe the German word for colour) that given rise to interesting colour in alkali halides. Thus, the excess of potassium in KCl makes the crytal appear violet and the excess of lithium in LiCl makes it pink. Stongly heated ZnO crystal can conduct electricity. This is due to

When an atom or an ion is missing from its nomal lattice site a lattice vacanecy (Schottky defect) is created. In stoichmeteric ionic crystals, a vacancy of one ion has to be accompanied by the vacancy of the oppositely charge ion in order to maintain electrical neutrality. In a Frenkel defect an ion leaves its position in the lattice and occupies an interstitial void. This id the Frenkel defect commonly found along with the Schottky defects and interstitial. In pure alkali halides. Frenked defects are not found since the ions cannot get into the interstitial sites. Frenkel defects are found in silver halides because of the small size of the Ag^(+) ion. Unike Schottky defects, Frenkel defect do not change the density of the solids. in certain ionic solids (e.g., AgBr) both schottky and Frenkel defect occur. The Defects idiscussed above do not disturb the stoichiometery of the crystalline material. there is large variety of non-stoichiometric inorganic solids which contains an excess or deficienty of one of the elements. Such solids showing deviations from the ideal stoichiometric composition from an important group of solids. For example in the vanadium oxide, VO_(x),x can be anywehere between 0.6 and 1.3 there are solids such as difficult to prepare in the soichiometric omposition thus, the ideal composition in compounds such as FeO is difficult to obtain (normally we get a compositiion of Fe(0.95) O but it may range from Fe_(0.93) O to Fe_(0.96)O ). Non-stoichiometric behavious is most commonly found for transition metal compounds through is also known for some lathanoids and actinoids. Zinc oxide loses oxygen reversible at high temperature and turns yellow in colour. the excess metal is accomodated interstitial, giving rise to electrons trapped in the neighbourhood, the enchanced electrical conductivity of the non-stoichiometric ZnO arises from these electrons. Anion vacancies in alkali halides are produced by heating the alkali halid crystals in an atmosphere of the alkali metal vapour. when the metal atoms deposit on the surface they diffuse into the cystal and after ionisation the alkali metal ion occupies cationic vacancy whereas electron occupies anionic vacancy. Electrons trapped i anion vacancies are referred to as F-centers (From Farbe the German word for colouf) that gives rise to interesting colour in alkali halides. Thus, the excess of potassium i KCl makes the crystal appear violet and the excess of lithium in LiCl makes it pink. Which of the following is most appropritate crystal to show Fremkel defect ?

A point charges Q is moving in a circular orbit of radius R in the x-y plane with an angular velocity omega . This can be considered as equivalent to a loop carrying a steady current (Q omega)/(2 pi) . S uniform magnetic field along the positive z-axis is now switched on, which increases at a constant rate from 0 to B in one second. Assume that the radius of hte orbit remains constant. The application of hte magnetic field induces an emf in the orbit. The induced emf is defined as the work done by an induced electric field in moving a unit positive charge around a closed loop. It si known that, for an orbiting charge, the magnetic dipole moment is proportional to the angular momentum with a porportionality constant lambda . The magnitude of the induced electric field in the orbit at any instant of time during the time interval of the mangnetic field change is

A point charges Q is moving in a circular orbit of radius R in the x-y plane with an angular velocity omega . This can be considered as equivalent to a loop carrying a steady current (Q omega)/(2 pi) . S uniform magnetic field along the positive z-axis is now switched on, which increases at a constant rate from 0 to B in one second. Assume that the radius of hte orbit remains constant. The application of hte magnetic field induces an emf in the orbit. The induced emf is defined as the work done by an induced electric field in moving a unit positive charge around a closed loop. It si known that, for an orbiting charge, the magnetic dipole moment is proportional to the angular momentum with a porportionality constant lambda . The magnitude of the induced electric field in the orbit at any instant of time during the time interval of the mangnetic field change is

DINESH PUBLICATION ENGLISH-GROWTH, REPAIR, REGENERATION AND AGEING-Revision Question From Competitive Exams.
  1. Which one is not a case of epimorphosis ?

    Text Solution

    |

  2. Based on cellular mechanisms there are two major types of regeneration...

    Text Solution

    |

  3. [A] : Sensescence in the time when age as- sociated defects are manif...

    Text Solution

    |

  4. Assertion: Smaller the organism, higher is the rate of metabolism per ...

    Text Solution

    |

  5. The greatest ability of regeneration amongst the animals is found in

    Text Solution

    |

  6. Growth through increase in volume is

    Text Solution

    |

  7. Ageing is due to accumulation of harmful proteins . The theory is

    Text Solution

    |

  8. Free radicals are formed through

    Text Solution

    |

  9. Read the statement and find out true/false (a) Type of regeneration...

    Text Solution

    |

  10. Programmed cell death is scientifically termed as

    Text Solution

    |

  11. Regeneration of liver is

    Text Solution

    |

  12. Axolotl larva shows i. Neoteny and paedogenesis ii. Absence of thyroxi...

    Text Solution

    |

  13. Regeneration of Hydra would be faster if it is cut off from

    Text Solution

    |

  14. One of the major reasons for apoptosis is

    Text Solution

    |

  15. It can regenerate entire alimentary canal.

    Text Solution

    |

  16. Match the columns and choose the correct combination

    Text Solution

    |

  17. Reserve cells are

    Text Solution

    |

  18. Genes in the somatic cells of the body undergo mutation with the passa...

    Text Solution

    |

  19. Choose the correct option of alphabets for phases in accompanying grow...

    Text Solution

    |

  20. A gradual decrease in size of tail during metamorphosis of frog is due...

    Text Solution

    |