Topic 1 - Lifestyle, health and risk

Question 1

1.1 why do many animals have a heart and circulation?

Answer 1

diffusion too slow due to large distance substances would have to travel to reach all cells

Question 2

1.1 what is mass transport system, and what is it used for?

Answer 2

in mammals: circulatory system, heart being used to pump blood around the body
used to carry raw materials from specialised exchange organs to the body cells, and to remove metabolic waste

Question 3

1.2 what is the purpose of water in living organisms?

Answer 3

as a solvent: substances dissolve in it

transportation

Question 4

1.2 describe water as a dipole molecule

Answer 4

the oxygen atom is slightly negatively charged, and the hydrogen atoms are slightly positively charged
oxygen - atom attract hydrogen + atoms, form hydrogen bonds

Question 5

1.2 define cohesion

Answer 5

the attraction between molecules of the same type (eg 2 water molecules)
water molecules are very cohesive because they are dipolar

Question 6

1.2 how does cohesion of water aid transportation?

Answer 6

cohesion helps water flow, therefore great for transporting substances

Question 7

1.2 describe how water is a good solvent

Answer 7

• many important substances in biological reactions are ionic, one positively charged atom and one negatively charged atom
• because water is dipolar, + end of water molecule will be attracted to the - ion and the - end of the water molecule will be attracted to the + ion
• ions surrounded by water molecules, dissolving

Question 8

1.3 arteries carry blood from where to where?

Answer 8

from the heart to the rest of the body

Question 9

1.3 what are 4 characteristics of arteries?

Answer 9

• thick walled
• muscular
• contain elastic tissue
• small lumen

Question 10

1.3 why are arteries muscular and elastic?

Answer 10

• helps to cope with high pressure blood flow from the heart

- elasticity allows the artery to return to its original shape after expanding with high pressure

Question 11

1.3 veins carry blood from where to where?

Answer 11

from the body back to the heart

Question 12

1.3 characteristics of veins

Answer 12

• wider lumen
• little elastic / muscle tissue
• contain valves

Question 13

1.3 what is the purpose of valves in veins?

Answer 13

only open one way, prevent back flow of blood

Question 14

1.3 why are capillaries only one cell thick?

Answer 14

speeds up diffusion of substances (eg glucose and oxygen)

Question 15

1.3 what are the networks of capillaries called, and how do they help metabolic exchange?

Answer 15

• capillary beds

- increase surface area for exchange