(3 marks) (3 marks)
(3 marks)
Questions
1 Suggest what would happen to the fish if they had no homeostatic mechanism.
2 The branchial MR cells are rich in mitochondria,
a Use information in Figure 1 to suggest the importance of the mitochondria.
b Suggest how the cell maintains a sufficient oxygen supply for the
mitochondria
3 Na /K-ATPase is a protein in the cell membrane. This protein is regulated by pH
changes. Use the information in the diagram to suggest a mechanism for
switching on the Naf/K-ATPase linked to cell surface membrane.
4 Use Figure 1 to predict the changes to the internal environment of the cell when
the Na'/K'-ATPase is active. Suggest a mechanism for maximum sodium uptake
from the water by the cell.
5 Suggest a function for the channel protein B.
6 Bafilomycin A1 is an antibiotic that specifically inhibits V-ATPase.
a What is meant by the term "specific" in this context?
b Predict how the water potential of the blood of the killifish might change in the
presence of this antibiotic.
(4 marks)
(5 marks)
(2 marks)
(1 mark)
(3 marks)