Transport in animals 3.2.1

Question 1

Why do we have a circulatory system?

Answer 1

Within all living organisms, substances need to be moved from one place to another.

Question 2

What sort of substances need to be moved throughout a living organism?

Answer 2

• Nutrients (glucose)
• Oxygen
• Waste - lactic acid/carbon dioxide etc.
• Hormones

Question 3

Why do small organisms not require a bloodstream (transport system)?

Answer 3

As they can rely on simple diffusion for all of their substances - due to their large surface area to volume ratio.

Question 4

State 3 factors influencing the need for a transport system

Answer 4

• Size
• Surface area to volume ratio
• Level of metabolic activity

Question 5

How does size influence the need for a transport system?

Answer 5

• In large organisms, the diffusion pathway is increased, due to the many layers of cells within them.
• This causes the diffusion distance to be too long and less material will reach the cells deep inside the body.

Question 6

How does SA:V ratio influence the need for a transport system?

Answer 6

• Large animals have a small surface area to volume ratio as their volume is much larger than their surface area.
• Therefore, they require a system which allows them to meet their demand of substances.

Question 7

How does the level of metabolic activity influence the need for a transport system?

Answer 7

• Large organisms have high metabolic rates
• Diffusion alone would not be able to intake all the substances required for large, active warm blooded animals.

Question 8

Name 4 features of a mass flow transport system.

Answer 8

• Suitable transport medium (blood)
• A pump to create pressure (heart)
• Exchange surfaces that enable substances to enter and leave the blood (capillaries)
• Vessels/tubes to carry the blood by mass flow

Question 9

State the two types of circulatory systems

Answer 9

• Open and closed

Question 10

What type of organism has an open circulatory system?

Answer 10

Invertebrates, which have no vessels

Question 11

State the working features of an open circulatory system

Answer 11

• Have a long muscular heart that pumps haemolymph in and out of cavities at low pressure
• The heart has pores called Ostia which haemolymph enters through
• The haemolymph is pumped towards the head by peristalsis (involuntary constriction and relaxation of muscles - wave like motion)
• Less energy is required for haemolymph to be distributed

Question 12

Name 2 disadvantages of an open circulatory system

Answer 12

• Blood pressure is low and blood flow is slow
• Circulation of blood (haemolymph) may be affected by movements/lack of movements of the body

Question 13

What is the fluid known as in an open circulatory system

Answer 13

Haemolymph

Question 14

What is the large cavity known as in an open circulatory system

Answer 14

Haemocoel

Question 15

What influences the movement of haemolymph within the haemocoel

Answer 15

Due to the movement of the organism

Question 16

Name 4 features of a closed circulatory system

Answer 16

• Blood is enclosed in blood vessels
• High blood pressure
• This means that blood travels faster so it is more efficient
• Transport is independent of body movements

Question 17

What are the two subsystems of closed circulatory systems?

Answer 17

Single and double

Question 18

Do fish have an open or closed circulatory system?

Answer 18

Closed

Question 19

State the sequence of blood flow in fish

Answer 19

Heart -> gills -> body -> heart

Question 20

What takes place in the gills?

Answer 20

Gas exchange

Question 21

How many times does blood flow through a fish in a single circuit?

Answer 21

Once

Question 22

What is counter current and where does it take place?

Answer 22

Takes place in the gills
- Water carrying oxygen flows in one direction and deoxygenated blood flows in another direction

Question 23

How are counter currents beneficial to fish?

Answer 23

As they allow a steep concentration gradient to be maintained, therefore equilibrium is not reached and diffusion is constantly taking place

Question 24

Why do birds and mammals have a double circulatory system?

Answer 24

As they need far more oxygen than fish, therefore require a constant internal environment which requires a lot of energy

Question 25

How many times is blood pumped through the heart in a single circuit of a double circulatory system?

Answer 25

Twice

Question 26

State the sequence of blood flow in a double circulatory system

Answer 26

Heart -> body -> heart -> lungs -> heart

Question 27

How is a double circulatory system beneficial, relating to the return of blood from the lungs

Answer 27

As the blood returning from the lungs gets an extra boost (high pressure) which means we can have a high metabolic rate

Question 28

What occurs in the systemic circulatory system?

Answer 28

Oxygen rich blood is carried around the body from the heart to the cells
- Carries deoxygenated blood back to the heart

Question 29

What occurs in the pulmonary circulatory system?

Answer 29

Deoxygenated blood is carried to the lungs, and oxygenated blood is carried back to the heart.

Question 30

Name 4 features of an efficient transport system

Answer 30

• A circulating fluid or medium to carry materials around the body
• A muscular pump to create pressure, that will push the fluid around the body
• Vessels to convey the medium from one region to another (arteries, veins, capillaries)
• Exchange surfaces - enable useful materials to enter the blood and to leave it again when they’re needed

Question 30

State 3 advantages of double circulation

Answer 30

• Two systems means the oxygenated and deoxygenated blood will not mix
• Oxygenated blood can be delivered to the body quickly at high pressure
• The blood flowing through the lungs is at low pressure, so it does not damage the tiny vessels and allows gas exchange to occur