Single closed circulatory systems

Question 1

In what type of organisms are single closed circulatory systems found?

Answer 1

Fish and annelid worms

Question 2

How does blood/transport medium flow in single closed circulatory systems?

Answer 2

Blood flows though heart + pumped around whole body + passes through 2 sets of capillaries before returning into heart.
Blood travels once through the heart in each complete circulation of the body.

Question 3

In single closed circulatory systems, what does blood pass through before returning to the heart?

Answer 3

2 sets of capillaries

Question 4

In single closed circulatory systems, what happens when blood passes through the first set of capillaries?

Answer 4

Exchange of CO2 and O2

Question 5

In single closed circulatory systems, what happens when blood passes through the second set of capillaries?

Answer 5

Exchange of substances between blood and cells

Question 6

In single closed circulatory systems, why does blood return to the heart slowly? What does this result in?

Answer 6

Blood passes through 2 sets of narrow capillaries before reaching heart, which slows it down
Limited efficiency of gas exchange processes, so these organisms have low activity levels

Question 7

What do fish have that makes their single circulatory system effective?

Answer 7

Fish have a countercurrent gaseous exchange system in gills - allows lots of O2 absorption from water

Question 8

What other reasons are there for why fish can be active with single closed circulatory systems?

Answer 8

Body weight is supported by water + body temperature doesn’t need to be maintained = reduced metabolic demands