Home
Class 12
BIOLOGY
Both algae and fungi are not independent...

Both algae and fungi are not independently capable of initiating seral changes on bare rocks but lichens can do so becase they

A

Adapt suitably to xeric conditions

B

Are a combination of alge and fungi

C

Can secrete acids for weathering

D

Do not require much sunlight

Text Solution

AI Generated Solution

The correct Answer is:
**Step-by-Step Solution:** 1. **Understanding the Question**: The question asks why lichens can initiate seral changes on bare rocks, while algae and fungi cannot do so independently. 2. **Defining Seral Changes**: Seral changes refer to the ecological succession process that transforms bare or uninhabitable environments into more complex ecosystems. This process often starts with pioneer species that can survive in harsh conditions. 3. **Role of Algae and Fungi**: Algae and fungi, when present independently, do not have the capability to initiate these changes. Algae primarily require sunlight for photosynthesis, while fungi do not contribute to the weathering process on their own. 4. **Understanding Lichens**: Lichens are a symbiotic association between algae and fungi. This means that they work together, combining the strengths of both organisms. 5. **Acid Secretion**: One of the key reasons lichens can initiate seral changes is that they can secrete acids. These acids help in the weathering of rocks, breaking them down into smaller particles that can eventually form soil. 6. **Weathering Process**: Weathering is essential for soil formation, as it involves the breakdown of rocks into smaller particles. This process is crucial for creating a substrate where other plants can grow. 7. **Conclusion**: Therefore, lichens can initiate seral changes on bare rocks because they are a combination of algae and fungi that work together to secrete acids, facilitating the weathering of rocks and the formation of soil. **Final Answer**: Lichens can initiate seral changes on bare rocks because they are a symbiotic association of algae and fungi that secrete acids, which contribute to the weathering of rocks and the formation of soil. ---
Promotional Banner

Topper's Solved these Questions

  • Ecology

    TRUEMEN BIOLOGY ENGLISH|Exercise ASSERTION AND REASON|75 Videos

  • ENVIRONMENTAL ISSUES

    TRUEMEN BIOLOGY ENGLISH|Exercise CHECK YOUR CONCEPT (Environmental Issues/Pollution)|7 Videos

Similar Questions

Explore conceptually related problems

Lichens are called pioneer colonisers of bare rock. How can they help in formation of soil?

A : Lichens do not grow in polluted area having SO_(2) . R : Lichens secrete carbonic acid and oxalic acid on barren rocks. (a) If both assertion & reason are true and the reason is the correct explanation of the assertion (b) If both assertion & reason are true but the reason is not the correct explanation of the assertion (c) If assertion is true statement but reason is false (d) If both assertion and reason are false statements

Two containers A and B of equal volume V_(0)//2 each are connected by a narrow tube which can be closed by a value. The containers are fitted with pistons which can be moved to change the volumes. Initially the value is open and the containers contain an ideal gas (C_(p)//C_(v)=gamma) at atmospheric pressure P_(0) and atmospheric temperature 2T_(0) . The walls of the containers A are highly conducting and of B are non-conducting. The value is now closed and the pistons are slowly pulled out to increase the volumes of the containers to double the original value. (a) Calculate the temperature and pressure in the two containers. (b) The value is now opened for sufficient time so that the gases acquire a common temperature and pressure. Find the new values of the temperature and the pressure.

The force of interaction between the molecules of same substance is called cohesive force hile force of interaction between molecules of different substances is called adhesive force . Both the forces are attracive and have a range of about 10 A . If we consider a molecule . A well inside a liquid we find that it is equally attracted by the surrounding molecules in all the directions ( with a sphere of radius 10 Å ) and so it does not experience any resultant force . On or near the surface of a liquid , the molecules do not exist on the free side and so a molecule ( say B ) experiences a resultant force vertically downwards into the liquid . For this reason , the molecules of the surface have a tendency to go into the liquid . Thus , the surface tends to contract and gives rise to surface tension . As surface molecules like B experience a net downward force of cohension and have tendency to go down , so in increasing the area of the surface more molecules are to be shifted to the surface from inside . Thus , more mechnical work will have to be done against the net downward force of cohension . This work is stored by the molecules in the surfaces as potential energy called free surface energy . Furthermore , molcules like P , in contact with the liquid will stick to the solid surface , i.e will meet it if the force of adhesion A is greater than net force of cohension C . The liquid will not the solid surface if C gt A Also , molecules like Q at the surface in contact with the solid will experience a net force of cohension C_(R) . If adhesion A is greater then cohension C_(R) , the resultant force will be F . As the liquid can't support tangential force , F must be perpendicular to the surface of the liquid . So , the menisus will be concave and the angle of contact will be acute ( gt 90^(@)) . However , if adhesion is lesser than cohension , the resultant force F will be directed into the liquid and so the menisus ( which is perpendicular to F as liquid support tangential force ) will be convex and the angle of contact will be obtuse ( gt 90^(@)) A liquid particle B , which is present in the vicinity particle A can exert a force on A if the distance of B from A is

The force of interaction between the molecules of same substance is called cohesive force hile force of interaction between molecules of different substances is called adhesive force . Both the forces are attracive and have a range of about 10 A . If we consider a molecule . A well inside a liquid we find that it is equally attracted by the surrounding molecules in all the dirctions ( with a sphere of radius 10 Å ) and so it does not experience any resultant force . On or near the surface of a liquid , the molecules do not exist on the free side and so a molecule ( say B ) experiences a resultant force vertically downwards into the liquid . For this reason , the molecules of the surface have a tendency to go into the liquid . Thus , the surface tends to contract and gives rise to surface tension . As surface molecules like B experience a net downward force of cohension and have tendency to go down , so in increasing the area of the surface more molecules are to be shifted to the surface from inside . Thus , more mechnical work will have to be done against the net downward force of cohension . This work is stored by the molecules in the surfaces as potential energy called free surface energy . Furthermore , molcules like P , in contact with the liquid will stick to the solid surface , i.e will meet it if the force of adhesion A is greater than net force of cohension C . The liquid will not the solid surface if C gt A Also , molecules like Q at the surface in contact with the solid will experience a net force of cohension C_(R) . If adhesion A is greater then cohension C_(R) , the resultant force will be F . As the liquid can't support tangential force , F must be perpendicular to the surface of the liquid . So , the menisus will be concave and the angle of contact will be acute ( gt 90^(@)) . However , if adhesion is lesser than cohension , the resultant force F will be directed into the liquid and so the menisus ( which is perpendicular to F as liquid support tangential force ) will be convex and the angle of contact will be obtuse ( gt 90^(@)) The free suface energy , stored in the surface is because of work done

A situation is shown in which two objects A and B start their motion from same point in same direction. The graph of their velocities against time is drawn. u_A and u_B are the initial velocities of A and B respectively. T is the time at which their velocities become equal after start of motion. You cannot use the data of one question while solving another question of the same set. So all the questions are independent of each other. 7. After 10 s of the start of motion of both objects A and B, find the value of velocity of A if u_A = 6 ms^-1 , u_B = 12 ms^-1 and at T velocity of A is 8 ms^-1 and T = 4s

TRUEMEN BIOLOGY ENGLISH-ECOSYSTEM -MCQ
  1. The tendency towards increased variety and density of species at commu...

    Text Solution

    |

  2. Climax communities

    Text Solution

    |

  3. Both algae and fungi are not independently capable of initiating seral...

    Text Solution

    |

  4. Math List-I with List-II and select the correct answer using the codes...

    Text Solution

    |

  5. Agroecosystem is unstable because of

    Text Solution

    |

  6. Primary consumers in detritus food chain are

    Text Solution

    |

  7. Putrefying organisms are

    Text Solution

    |

  8. A pea-cock eats snakes which eat frogs. These eat hoppers which in tur...

    Text Solution

    |

  9. Which of the food chain directly depends on solar radiations?

    Text Solution

    |

  10. Converters or transducer organisms in the food chain are called

    Text Solution

    |

  11. In parasitic food chain, the pyramid of number is

    Text Solution

    |

  12. Ascending trophic level in grazing food chain pyramid represents

    Text Solution

    |

  13. Phytoplankton are dominant in

    Text Solution

    |

  14. Which ones are reservoirs of Phosphorus and Nitrogen cycles respective...

    Text Solution

    |

  15. An organism contains carbon molecules which have passed through three ...

    Text Solution

    |

  16. Identify the following food chain: Dead animal Blow fly maggots rarr C...

    Text Solution

    |

  17. Ecological efficiency is

    Text Solution

    |

  18. Breakdown of detritus into smaller particles by earthworm is a process...

    Text Solution

    |

  19. Decomposers like fungi and bacteria are (i) Autotrophs (ii) Heterotr...

    Text Solution

    |

  20. The process of mineralisation by micro organisms helps in the release ...

    Text Solution

    |