section 2: transport in animals - topic 1: circulatory systems

Question 1

why do multicellular organisms need a transport system?

Answer 1

• relatively big
• low SA:V ratio
• high metabolic rate
• very active = large number of cells are respiring very quickly so they need a constant, rapid supply of glucose and oxygen
• carbon dioxide also needs to be removed from cells quickly

in sum: to make sure that every cell has a good enough supply of useful substances and has its waste products removed

Question 2

what are the 4 types of circulatory systems?

Answer 2

double
single
open
closed

Question 3

how many times does the blood pass through the heart in a single circulatory system?

Answer 3

once for each complete circuit of the body

Question 4

what animals have a single circulatory system?

Answer 4

fish

Question 5

how many times does the blood pass through the heart in a double circulatory system?

Answer 5

twice for each complete circuit of the body

Question 6

what animals have a double circulatory system?

Answer 6

mammals

Question 7

what is the process of the mammalian double circulatory system?

Answer 7

• right side of the heart pumps blood to the lungs to pick up oxygen (pulmonary system)
• from the lungs, it travels to the left side of the heart, which pumps it to the rest of the body (systemic system)

Question 8

what is an advantage of the mammalian double circulatory system?

Answer 8

the heart can give the blood an extra push between the lungs and the rest of the body
^ this makes the blood travel faster, so oxygen is delivered to the tissues quicker

Question 9

what is a closed circulatory system?

Answer 9

where the blood is enclosed inside blood vessels

Question 10

what animals have closed circulatory systems?

Answer 10

all vertebrates i.e. fish and mammals

Question 11

what is the process of a closed circulatory system?

Answer 11

• the heart pumps blood into capillaries
• these branch out into millions of capillaries
• substances like oxygen and glucose diffuse from the blood in the capillaries into the body cells, but the blood stays inside the blood vessels as it circulates
• veins take the blood back to the heart

Question 12

what is an open circulatory system?

Answer 12

where blood isn’t enclosed in blood vessels all the time - instead, it flows freely through the body cavity

Question 13

what animals have an open circulatory system?

Answer 13

some invertebrates i.e. insects

Question 14

how does the open circulatory system in insects work?

Answer 14

• an insects heart is segmented
• it contracts in a wave, starting from the back, pumping the blood into a single main artery
• that artery opens up into the body cavity
• the blood flows through the insects organs, gradually making its way back into the heart segments through a series of valves