Blood

Question 1

main parts of blood

Answer 1

• plasma (55%)
• red blood cells (45%)
• white blood cells (<1%)
• platelets (<1%)

Question 2

blood plasma

Answer 2

liquid part of the blood

-carries the blood cells through the blood vessels
-contains many dissolved substances:
(CO2, glucose, hormones, digested food molecules)

Question 3

white blood cells

Answer 3

• larger than red blood cells
• contain a nucleus
• part of the immune system (attack pathogens in the body)

several different types:

• phagocytes
• lymphocytes

Question 4

phagocytes

Answer 4

about 70% of white blood cells

engulf and destroy unwanted microorganisms that enter the blood

Question 5

lymphocytes

Answer 5

about 25% of white blood cells

produce antibodies when a foreign body (e.g. microorganism) enters the body, which attack pathogens

Question 6

platelets

Answer 6

• fragments of larger cells produced by cells in bone marrow
• have no nucleus
• function is to cause blood to clot when a blood vessel has been damaged
• the clot blocks the wound and prevents pathogens getting into the blood

Question 7

How do platelets stop bleeding? (2)

Answer 7

• proteins on their surface enable them to stick to breaks in a blood vessel and clump together
• secrete proteins that result in a series of chemical reactions that make blood clot

Question 8

adaptations of a red blood cell

Answer 8

-contain haemoglobin which carries oxygen

• bioconcave shape means it has a large surface area
• means it is easier for oxygen to diffuse into and out of the cell
• no nucleus
• has more room for haemoglobin to carry more oxygen