Transport in animals 3.2*

Question 1

what is a double circulatory system?

Answer 1

One in which the blood flows through the heart twice for each circuit of the body

Question 2

What is a single circulatory system?

Answer 2

One in which the blood flows through the heart once for each circuit of the body

Question 3

what are the three main things that influence the need for a transport system?

Answer 3

• size
• SA:V
• level of metabolic activity

Question 4

Why do very small animals not need a separate transport system?

Answer 4

Their cells are surrounded by the environment in which they live and diffusions supplies enough O2 and nutrients to keep the cell alive

Question 5

How does size influence the need for a separate transport system?

Answer 5

Large organisms have a larger diffusion pathway and the diffusion rate decreases so less will reach the cells deep inside the body

Question 6

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

Answer 6

The smaller animals have a larger SA:V so for each gram of tissue in their body they have a sufficient area of the body surface through which exchange can occur

Question 7

How does metabolic rate influence the need for an exchange system?

Answer 7

If an animal is very active the cells need good supplies of nutrients and oxygen to supplu energy for their movement

Question 8

What are the features of a good transport system?

Answer 8

• a medium to carry nutrients
• a pump to create pressure to push the fluid around the body
• exchange surfaces that allow substances to anter and leave the blood
• tubes or vessels to carry the blood by mass flow
• two circuits

Question 9

What are the advantages of a double circulatory pump system?

Answer 9

• blood pressure must not be too high in the pulmonary circulation to not damage the lungs
• heart can increase the pressure after the lungs to pump it round the body
• systemic circulation can carry blood at a higher pressure than the pulmonary circulation

Question 10

What are the disadvantages of the single circulatory system?

Answer 10

• the blood pressure drops as blood passes through the tiny capillaries
• the blood flow is slow as it moves towards the body
• the rate at which O2 and nutrients are supplied to respiring tissues and CO2 and urea are removed is limited