B2.2 The Challenges of Size - Animal Transport Systems

Question 1

What is surface area to volume ratio?

Answer 1

The surface of an area per unit volume of an object.

Question 2

In what format should surface area to volume ratio be presented?

Answer 2

• It should be calculated as a ratio
• It should be simplified so volume = 1cm³

Question 3

Why can a tapeworm rely upon diffusion alone to provide nutrients, where as multicellular organisms can not?

Answer 3

The larger the surface area to volume ratio the more easily and quickly nutrients can diffuse, as diffusion distances are small e.g the tape worm.

Increase size of organism = decrease surface area to volume ratio, therefore diffusion distance becomes to great to allow an organism to meet the cells’ demands.

Question 4

State three examples of adaptations to animal cells to improve surface area to volume ratio.

Answer 4

Villi - intestines

Microvilli - intestines

Cilliated epithelial cells - lungs

Alveoli - spherical shape

Question 5

State adaptations to plants to increase surface area to volume ratio.

Answer 5

Broad flat leaves - increase SA for capturing light & gaseous exchange via the stomata

Root hair cells

Question 6

Explain the adaptations of the lungs to maximise the rate at which oxygen enters the body.

Answer 6

• Single cell wall
• Ventilation moves air in and out of lungs to maintain concentration gradient
• Capillary network means good blood supply, which maintains concentration gradient
• Spherical shape increases surface area

Question 7

Explain the adaptations of the villi to maximise the rate of diffusion and active transport in the small intestine.

Answer 7

• Single cell wall
• Capillary network means good blood supply, which maintains concentration gradient
• Fingerlike shape increases surface area
• Microvilli increases surface area further
• Many mitochondria to provide energy for active transport

Question 8

Why are transport systems needed?

Answer 8

To transport a substance to where it is needed once it has diffused.

Question 9

Name four transport systems in humans.

Answer 9

Respiratory

Circulatory

Digestive

Endocrinology

Nervous

Urinary

Question 10

What is the circulatory system?

Answer 10

Heart and blood vessels

Question 11

How does the circulatory system of a fish compare to the human circulatory system?

Answer 11

The fish has a single circulatory system, humans have a double circulatory system.

Question 12

State the difference between oxygenated and deoxygenated blood.

Answer 12

• Oxygenated = high levels of oxygen
• Deoxygenated = low levels of oxygen

Question 13

Name the the three types of blood vessel shown below.

Answer 13

• A = vein
• B = capillary
• C = artery

Question 14

Name the adaptations of the three blood vessels below.

Answer 14

• A = vein, thin outer wall, thin layer of muscle and elestic fibres, large lumen
• B = capillary, very small lumen, single cell wall
• C = artery, thick outer wall, thick layer of muscle and elestic fibres, small lumen

Question 15

Explain why humans are said to have a double circulatory system.

Answer 15

Blood is pumped out of the heart twice, once to the lungs and once to the rest of the body

Question 16

What are the benefits of having a double circulatory system?

Answer 16

• Deoxygenated and oxygenated blood does not mix
• Blood is under higher pressure as it does not have to travel as far
• High pressure means the materials are transported around the body more quickly

Question 17

State the difference between cardiac muscle and the muscles in the rest of your body?

Answer 17

• Heart is made of cardiac muscle that contracts without recieving nerve impulses from our brain
• Muscle in the rest of your body (e.g in your arm) require a nervous signal to stimulate contraction

Question 18

Label the heart below

Answer 18

Question 19

Describe the pathway through the human circulatory system.

Answer 19

1. Deoxygenated blood enters the lungs.
2. Oxygen enters the blood. CO₂ leaves.
3. Blood enters the heart through the pulmonary vein, into the left atria.
4. Blood is pumped through the heart from the left artria to the left ventricle, via the bicuspid valve.
5. Blood is pumped out of the left ventricle through the Aorta and goes to the rest of the body.
6. Oxygen diffuses out of the blood and CO₂ diffuses in.
7. Blood enters the right atria of the heart through the vena cava.
8. Blood is pumped through the heart from the right artria to the right ventricle, via the tricuspid valve.
9. Blood is pumped out of the right ventricle, to return to the lungs via the pulmonary artery.

Question 20

Name the four key components of blood and their function.

Answer 20

1. Red blood cells - small biconcave cells that contain haemoglobin and have no nucleus to enable and maximise oxygen transport.
2. White blood cells - large cells fight disease by making antibodies, or changing their shape to engulf pathogens.
3. Platelets - tiny structures/fragments of cells that help blood to clot
4. Plasma - Made up of 90% water, straw coloured fluid in which the other components of blood float within. Acts as a transport medium for digested food, waste products, hormones and antibodies.

Question 21

State the type of blood cell which is most common in the blood.

Answer 21

Red blood cells