Exchange and transport in animals

Question 1

Why do we need to transport oxygen in and out of the body?

Answer 1

• Oxygen is required aerobic respiration, which produces carbon dioxide a waste product.

Question 2

Why do animals need specialised exchange surfaces?

Answer 2

Allow efficient transport of substances from one area to another. Usually have large surface area and small distance for substances to travel

Question 3

What is surface area : volume ratio?

Answer 3

Higher the surface area to volume ratio, the easier it is for organisms to exchange substances

Question 4

Why do multicellular organisms have transport systems?

Answer 4

• Because they are large they a low surface area to volume ratio, which means that substances can’t transport easily from outside the body through the skin.

Question 5

What do alveoli do and how are they adapted for gas exchange between the lungs and blood?

Answer 5

• The oxygen leaves the alveolus to enter the bloodstream and carbon dioxide enters the alveolus to leave the body.
• Small and in clusters –> large surface area
• Alveoli walls are thin, reduce how far the gases need to move

Question 6

What factors affect diffusion

Answer 6

• Surface area: More surface area means that there are more available molecules to move across
• Concentration gradient: substances move faster if there is a big difference in concentration gradient?
• Distance: substances diffuse quickly when they haven’t got far to move

Question 7

What is Fick’s law

Answer 7

Describes rate of diffusion and its factors
rate of diffusion ∝ (surface area * concentration difference)/ thickness of membrane

Question 8

What is blood made up of?

Answer 8

• Plasma
• Red blood cells
• White blood cells
• Platelets

Question 9

What does plasma do?

Answer 9

Liquid that carries around everything in the blood:
- RBC, WBC and platelets
- nutrients: glucose and amino acid
- carbon dioxide
- urea
- Hormones
- Proteins
- Antibodies and antitoxins

Question 10

What do platelets do?

Answer 10

• Small fragments of cells which clot at a wound, stops blood pouring out and microorganisms entering

Question 11

What do white blood cells do?

Answer 11

• Phagocytes change shape to engulf unwelcome microorganisms
• Lymphocytes produce antibodies against microorganisms so that they can be marked. Also produce antitoxins which neutralise toxins produced by microorganisms

Question 12

What do red blood cells do and how are they adapted to do so?

Answer 12

• Carry oxygen from the lungs to all the cells in the body
• Shaped in a biconcave way to have a large surface area for more room for oxygen
• No nucleus, more space for oxygen
• Has haemoglobin which binds to oxygen to form oxyhaemoglobin

Question 13

How do arteries work and how are they designed??

Answer 13

• Carry blood away from the heart
• Small lumen
• Thick walls made of elastic fibres and smooth muscle
• Muscles make them strong and elastic fibres allow them to stretch and spring back.

Question 14

How do capillaries work and how are they designed?

Answer 14

• Arteries branch into capillaries
• capillaries are narrow, can carry blood really close to every cell to exchange substances
• Permeable walls so substances can diffuse in and out
• One cell thick, increases rate of diffusion because less distance travelled

Question 15

How do veins work and how are they designed?

Answer 15

• Capillaries join together to form the veins.
• Blood pressure is low, elastic fibres and smooth muscles are thin.
• Lumen is larger to help blood flow.
• Valves to stop blood flowing in wrong direction

Question 16

What is a double circulatory system?

Answer 16

Heart pumps blood around body in 2 circuits
- First circuit, heart pumps deoxygenated blood to the lungs to take in oxygen via the pulmonary artery, oxygenated blood returns to the heart via the pulmonary vein.
- Second circuit pumps oxygenated blood to the rest of the body through the aorta. The deoxygenated blood re-enters through the vena cava.

Question 17

How does the heart work

Answer 17

• deoxygenated blood enters through the vena cava and goes through the right atrium which moves blood into the right ventricle through a valve, which pumps it through the pulmonary artery through a valve, to the lungs
• oxygenated blood returns from the lungs through the pulmonary vein to the left atrium, which moves blood to the left ventricle through a valve, which pumps blood through a valve, which then goes around the whole body via the aorta
• The left ventricle has a thicker wall. Needs more muscle to pump the blood around the whole body, while the right ventricle just needs to pump it to the heart
• Valves prevent backflow

heart left and right is opposite to the logical way

Question 18

What is cellular respiration?

Answer 18

an exothermic reaction which takes place aerobically or anaerobically. It happens continuously in cells to release energy for metabolic processes

Question 19

Difference between aerobic and anaerobic respiration?

Answer 19

• Aerobic happens when there is a lot of oxygen, anaerobic happens when there is less.
• Anaerobic respiration only needs glucose, while aerobic needs glucose and oxygen
• Formula for aerobic is glucose + oxygen –> carbon dioxide + water, anaerobic is glucose –> lactic acid
• Anaerobic yields less energy than Aerobic

Question 20

What is the cardiac output formula?

Answer 20

cardiac output = stroke volume x heart rate

Question 21

How do you investigate respiration? CP

Answer 21

• Take a test tube and put it in a water bath with a set temp, put soda lime at the bottom of it. This absorbs carbon dioxide
• Place cotton wool above it. Place small organisms like maggots on the wool. The wool prevents the maggots from coming in contact with the corrosive soda lime.
• Put a bung on the test tube and attach a capillary tube through it.
• Add coloured liquid at the end of the capillary tube. It’s distance should be marked with a scale which is attached to it.
• After 5 minutes, see how much the bubble has moved. That difference divided by time is rate of respiration.
• Moves because oxygen decreases and pulls the air bubble inwards.
  Repeat with more temperatures