In nature, leeches attach themselves to the cow grazing in the field

CBSE Class 12 CBSE Class 12 Biology
1

In nature, leeches attach themselves to the cow grazing in the field (shown in figure I). In some medical treatments, doctors attach leeches onto the swollen hand of a patient to prevent accumulation of blood (shown in figure II).
(i) State the type of interaction in figure I and II.
(ii) Under what conditions the doctors advice leech therapy?
(iii) Why are leeches used for treating patients?

2

(i) The interaction in figure I is parasitism (one organism is benefitted and other is harmed) and in figure II, the interaction is mutualism (both organisms are benefitted).
in-nature-leeches-attach-themselves-to-the-cow-grazing-in-the-field-222
(ii) The doctors often use leech therapy after a microsurgery (attaching tissues and connecting thin arteries and veins). If the veins are not connected properly, excess blood can pool-blocking the entry of oxygenated blood and eventually leading to death of reattached tissue.
(iii) Leeches are used to treat such a condition due to the presence of hirudin in their saliva. Hirudin is an anticoagulant factor which prevents the blood from pooling in the reattached tissues.