Fig. 1 shows a simplified diagram of a cut that has started to clot. Platelets gather at the damaged blood vessel and a mesh forms across the opening. The c...
Question 1 Report
Fig. 1 shows a simplified diagram of a cut that has started to clot. Platelets gather at the damaged blood vessel and a mesh forms across the opening. The clot stops blood leaving the body and can reduce entry of bacteria into deeper tissues.
(a) Name the blood component that begins clotting. [1]
(b) Describe how a clot helps prevent infection. [2]
(c) Suggest why a person with a very low platelet count may lose more blood from a cut. [2]
(d) What type of white blood cell can engulf bacteria that enter a wound? [1]
Answer Details
(a) Platelets are the blood components that begin the clotting process. [1]
(b) A clot forms a barrier, often becoming a scab, over the damaged area. This blocks bacteria from entering deeper tissues or the blood. [2]
(c) With very few platelets, clots form more slowly or less effectively. The damaged blood vessel therefore remains open for longer, allowing more blood to escape. [2]
(d) A phagocyte can engulf bacteria entering a wound. [1]
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