Question 1
Paper 2Medium16 marksCellulose in plant cell walls and glycoproteins on cell surfaces are examples of biological structures associated with different functions.
In a model of cell-surface recognition, probe A binds only to the A antigen and probe B binds only to the B antigen. The probes represent recognition molecules on another cell. A “+” indicates that binding was detected.
| Red-cell sample | Probe A binding | Probe B binding |
|---|---|---|
| P | + | − |
| Q | − | + |
| R | + | + |
| S | − | − |
For this question, a red-cell sample with A antigen only is group A; with B antigen only is group B; with both antigens is group AB; and with neither antigen is group O.
Explain how the structure of cellulose makes it suitable for its role as a structural polysaccharide in plant cell walls.
Use the results in the table to determine the ABO group of each sample, P, Q, R and S.
Explain how glycoproteins contribute to cell-cell recognition. Use ABO antigens and the results in the table in your answer.