Question

Experiments on Acetabularia by Hammerling proved the role of
a. Cytoplasm in controlling differentiation
b. Nucleus in heredity
c. Chromosomes in heredity
d. Nucleo-cytoplasmic ratio

Answer 1

Hint: Acetabularia is a green algae, which is present in the subtropical water regions, it is a single-cell organism, which is gigantic in size and complex in the form, and this acetabularia is an excellent example or Model organism for studying cell biology.

Complete answer:
It is a unicellular organism, and it is 0.5 to 10 mm tall.
This acetabularia has 3 anatomical structures, which include, Bottom rhizoid is a set of short roots, and in the Middle a long stalk is present and at the Top Umbrella of branches. They all fuse to form a cap.
This acetabularia is not like other algae, this contains only one nucleus, which means uninucleate, and that too it is present in the Rhizoid.
The nucleus present in the acetabularia allows the regeneration if the cap is removed.

Hammerling Experiment:
- Hammerling did two types of experiments with the species of acetabularia.
- In the first one, he exchanged the caps between the two individual species, which are A. mediterranea, they contain a small disc-shaped cap, and A. Crenulata contain branched flowers like a cap.
- He exchanged both caps and observed that each cap slowly changed from it’s an original form to the typical cap for that species.
- Where it shows that the nucleus controls the shape and form of the cap.
- The second experiment, where he introduced the nucleus of the one species into another nucleus, and a hybrid one is formed as a result.
- So the nucleus of the cell which contains the genetic information generally directing the cellular development.

Hence, the correct answer is option (B).

Note: Acetabularia has a unique complex structure, because of this form and shape, it has become a model organism for studying the gene expression and for the morphogenesis, where it also transfers mRNA molecule from the nucleus to apical base.