Cell Biology

The material of the nucleus stained by the basic dyes was given the name chromatin by Flemming.

Ribosomes are the granular structures first observed under the microscope by George Palade.

Camillo Golgi first observed a densely stained reticular structure near the nucleus. It consists of many disc-shaped sacs or cisternae.

The figure shows a longitudinal section of a flower with a single ovule. The part labeled ’x’ represents the thalamus. The thalamus is the part of the flower that forms the receptacle which supports the rest of the floral organs.

The correct matches are:

• A. Genetically engineered host cell - II. A genetically modified organism (GMOs) is inserted into a host cell for manipulation.
• B. GM cotton - IV. GM cotton uses *Bacillus thuringiensis* for pest resistance.
• C. Gene therapy - I. Gene therapy is used to treat ADA deficiency (Adenosine Deaminase deficiency).
• D. ELISA (enzyme-linked immunosorbent assay) - III. ELISA is based on antigen-antibody interactions to detect specific proteins or antigens.

Therefore, the correct option is (4): A-II, B-IV, C-I, D-III.

Tight junctions: Create a seal between adjacent cells, preventing the leakage of substances across the tissue. They prevent the passage of molecules between cells.

Adhering junctions: Provide strong mechanical attachments between adjacent cells, acting like “spot welds.” They don’t facilitate communication.

Gap junctions: Form channels between adjacent cells, allowing for the passage of ions, small molecules, and signals. They facilitate communication, not create gaps.