Module 2Exchange and transport

1.2.5 Transport in animals

Learning Objectives Success Criteria

• Explain the need for transport systems in multicellular animals in terms of size, activity and surface-area-to-volume ratio.

• Explain the meaning of the terms single and double circulatory systems with reference to the circulatory systems of fish and mammals

• List the features of a good transport system(Grade E - D)

• Explain why large, active animals need a transport system(Grade C –B)

• Explain why a double circulatory system is more efficient than a single circulatory system(Grade B – A)

FISH DISSECTION?

Closed circulatory systems

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Why need a transport system?

Single-celled organisms, such as bacteria and amoeba (below), can obtain nutrients and excrete waste simply by diffusion.

nutrients waste products

Multi-cellular organisms, such as insects, fish and mammals, require a more specialized transport system. Why is this?

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Surface area to volume ratio

In larger organisms, diffusion of substances would occur far too slowly to enable them to survive:

Single-celled organisms have a very large surface area to volume ratio, because the diffusion path is so short.

Describe 3 factors that would affect the need for transport systems..

This is not just because of its size, however: more important is an organism’s surface area to volume ratio.

•List the features of a good transport system

(Grade E - D)

1 Size

1)If an animal has several layers of cells, any oxygen and nutrients will not reach the deeper cells within the body

•Explain why large, active animals need a transport system

(Grade C –B)

2 Surface Area to Volume Ratio

• Larger animals have a small surface-area-volume-ratio.

• Larger volume due to range of tissues. • Their surface area is not large enough to

supply all the oxygen and nutrients needed by internal cells.

3 Level of Activity

• If an animal is active it will require a good supply of oxygen and nutrients to supply the energy for movement.

• Mammals also require more energy to keep themselves warm.

Features of a good transport system

Division of labour

Our circulatory system has 2 loops- one sends blood to the lungs-pulmonary system and the other sends blood to the rest of the body – systemic system.

Features of a good transport system

• Medium/fluid to carry nutrients and oxygen• Pump to create pressure• Exchange surface• Vessels/tubes to contain medium• 2 circuits

– Pick up oxygen– Deliver oxygen

Closed circulatory systems

Advantages of Double over Single

• Double circulatory system – blood travels through the heart twice for each complete circuit of the body

• Efficient so deliver nutrients quickly• Can increase pressure of blood flow • Quicker supply oxygen• Can keep pressure to exchange surface low to

avoid damage

Plenary: True or False

1. Mammals are more active that fish due to need to maintain body temperature

2. Surface area to volume ratio effects need for a transport system

3. Single circulatory system means a single chambered heart

4. Systemic circulation means the route of blood through the lungs

5. Surface area to volume ratio is effected by an animals shape

Plenary: True or False1. Mammals are more active that fish due to need to

maintain body temperature2. Surface area to volume ratio effects need for a

transport system3. Single circulatory system means a single chambered

heart4. Systemic circulation means the route of blood

through the lungs5. Surface area to volume ratio is effected by an

animals’ shape• Any answers you wrote false for now please write

what the true statement would be

Plenary: Answers1. Mammals are more active that fish due to need to maintain

body temperature• True

2. Surface area to volume ratio effects need for a transport system

• True

3. Single circulatory system means a single chambered heart]• False: Single circulatory system means blood does one circuit

4. Systemic circulation means the route of blood through the lungs

• False: Systemic circulatory system means the route of blood through the body

5. Surface area to volume ratio is effected by an animals’ shape• True