Circulatory system - blood

Question 1

how do red blood cells carry oxygen

Answer 1

shaped as a biconcave disc - large surface area for absorbing oxygen
don’t have a nucleus - more room to carry oxygen
red pigment - haemoglobin which binds to the oxygen to become oxyhaemoglobin
this then spits back to release the oxygen

Question 2

how do white blood cells defend against infection

Answer 2

change shape and engulf unwelcome microorganisms - process called phagocytosis
others produce antibodies to fight unwelcome microorganisms antitoxins to neutralise unwanted toxins
they do have a nuleus

Question 3

how do platelets help blood clots

Answer 3

small fragments of cells
no nucleus
stop blood pouring out and microorganisms going in
lack of causes excessive bleeding and platelets

Question 4

what does plasma carry in blood

Answer 4

red and white blood cells
nutrients - glucose and amino acids
carbon dioxide
urea
hormones
proteins
antibodies and antitoxins