Transport in animals

Question 1

What are the factors that influence need for a transport system?

Answer 1

> size
SA to volume
level of metabolic activity

Question 2

Size

Answer 2

> diffusion pathway is bigger in larger organisms
diffusion rate is too slow
outer cells use up energy so inside cells dont get any

Question 3

Surface area to volume

Answer 3

> small animals have a large SA:V ratio so for each gram of tissue they have a sufficient area for exchange to occur
large animals have a smaller ratio so less surface for exchange

Question 4

Level of metabolic activity

Answer 4

> if an animal is active it needs good supply of energy for movement
also need energy to keep warm

Question 5

What are the features of a good transport system?

Answer 5

> a fluid pr medium to carry nutrients, oxygen and wastes around the blood - blood
pump to create pressure - heart
exchange surfaces that enable surfaces to enter and leave blood - capillaries
tubes and vessels to carry blood via mass flow
two circuits - to pick up and deliver oxygen

Question 6

Single circulatory system

Answer 6

> blood flows through heart once for each circuit

> heart -> gills -> body -> heart

Question 7

Double circulatory system

Answer 7

> two separate circuits
one carries blood to the lungs to pick up O
other circuit carries O and nutrients around the body
blood flows through heart twice
heart -> body -> heart -> lungs -> heart

Question 8

Disadvantages of a single circuit

Answer 8

> blood pressure drops as blood passes through capillaries
low pressure means blood wont flow quickly
rate at which substances are delivered to respiring tissues is slow

Question 9

Advantages of double circuit

Answer 9

> blood flows quicker due to higher pressure

> vessels can carry blood at higher pressures