Circulation System

Question 1

Why do large multicellular organisms need a circulation system?

Answer 1

to transport substances around their bodies

Question 2

why do small organisms not need a circulation system?

Answer 2

they can rely on diffusion because they have a large sa:v and the diffusion distance is small

Question 3

what substances are circulated round the body in animals?

Answer 3

o2 
co2 
urea 
glucose
amino acids 
salts 
hormones 

most of these are dissolved in water

Question 4

what is mass transport?

Answer 4

moving substances in large quantities over long distances in one direction.

Question 5

Mass flow -

Answer 5

Liquids can be forced around a circulatory system by a pump. The pump generates pressure and the liquid moves from areas of high pressure to lower pressure.

Question 6

single circulation system -

Answer 6

blood passes through the heart once during each cycle.

Question 7

Double circulatory system -

Answer 7

Blood passes through the heart twice in one complete circuit of the body e.g. in a human

Question 8

circuit of the double circulation system -

Answer 8

heart to lungs to heart to body to heart

Question 9

what properties make water good for transport ?

Answer 9

• liquid from 0 to 100
• good solvent
• high specific heat capacity
• ice is less dense than liquid water

Question 10

what is a dipole water molecule?

Answer 10

Water molecules have a slight negative charge at the oxygen end and a slight positive charge at the hydrogen end. Hydrogen bonds form between water molecules causing it to become a liquid.

Question 11

what is water a good solvent of?

Answer 11

ionic, charged and polar substances

Question 12

why is water a good solvent of ionic, charged and polar substances?

Answer 12

Due to attraction between particles in the chemicals and the polar water molecules.

Question 13

what substances do not dissolve in water?

Answer 13

non polar substances

Question 14

give an example of a non polar substance

Answer 14

lipids