Tag: membranous and non-membranous organells

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Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Which of these is not found in the nucleus?

  1. Nucleoplasm instead of cytoplasm

  2. Functioning ribosomes

  3. Chromatin that condenses to chromosomes

  4. Nucleolus that produces rRNA
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ribosomes are synthesized in the nucleolus but function in the cytoplasm. Therefore, functioning ribosomes are not found within the nucleus.

Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Acetabularia used in Hammerling's nucleocytoplasmic experiments is

  1. Unicellular fungus

  2. Multicellular fungus

  3. Unicellular uninucleate green alga

  4. Unicellular multinucleate green alga
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

  • Acetabularia is a genus unicellular or single-celled green algae belonging to the family Polyphysaceae which are found in subtropical waters.

  • They are gigantic in size and complex in form, therefore, used in experiments in cell biology.
  • Hammerling's nucleocytoplasmic experiments state that the cytoplasm is the centre for all the metabolic activities in the cell and the nucleus is the controlling centre. 
  • So, the correct answer is 'Unicellular uninucleate green alga'.
Multiple choice biology cell-the basic unit of life nucleus organelles in cell membranous and non-membranous organells

Hammerling's experiments on Acetobularia involved exchanging

  1. Cytoplasm

  2. Nucleus

  3. Rhizoid and stalk

  4. Gametes.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Acetabularia cell is composed of three segments: the "rhizoid" or base which contains the nucleus, the "stalk," and the "cap." 
  • In his experiments, Hammerling grafted the stalk of one species of Acetabularia onto the rhizoid of another species. In all cases, the cap that eventually developed on the grafted cell matched the species of the rhizoid rather than that of the stalk.
  • This experiment shows that the base is responsible for the type of cap that grows. The nucleus that contains genetic information is in the base, so the nucleus directs cellular development.
  • So, the correct option is 'Rhizoid and stalk'.