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Ecosystems — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYEcosystems5 Marks
Question
  1. Draw a simplified model of phosphorus cycling in a terrestrial ecosystem.
  2. Write the importance of such cycles in ecosystems.
✓

Answer

  1. Refer to Fig. 14.5 in the text.
  2. The nutrients are cycled such that they are brought back to soil from where producers can taken them.

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Transgenic animals can serve as factories that in some cases, may produce large amount of proteins more efficiently. Transgenic mice have been engineered to express human antibodies by introducing large segment of human DNA encoding human immunoglobulin genes. In transgenic large animals such as cow or sheep proteins of pharmaceutical value can be produced in large quantities in milk which is later purified. Transgenesis can be used to alter many phenotypic properties including growth rate, fat composition, milk production, hair texture, etc.

  1. The production of transgenic animals includes
  1. Identification and separation of desired gene.
  2. Combining the desired gene with appropriate vector.
  3. Introduction of vector in cells, tissues or embryos.
  4. All of these.
  1. In transgenic animals, i.e., cow and sheep proteins of pharmaceutical value are produced in large quantities in the
  1. Blood.
  2. Accumulated fat.
  3. Mammary glands.
  4. None of these.
  1. Mouse is mostly preferred animal for studies on gene transfer because.
  1.  Short oestrous cycle.
  2. Long gestation period.
  3. Short generation time.
  4. Production of one or two offspring per pregnancy.
  1. Both (A) and (C)
  2. Both (A) and (B)
  3. Only D
  4. Both (C) and (D).
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  1. Growth rate.
  2. Fat composition.
  3. Milk production.
  4. All of these.
  1. Assertion: Transgenic mice have been engineered to express human antibodies.

Reason: Large segment of human DNA encoding human immunoglobulin have been transferred to mice.

  1. Both assertion and reason are true and reason is the correct explanation of assertion.
  2. Both assertion and reason are true but reason is not the correct explanation of assertion.
  3. Assertion is true but reason is false.
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