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Question 1

Why is it necessary to transport waste products such as urea out of the body?

Answer 1

It can become toxic, CO2 can can also build up and dissolve in the blood, making it acidic

Question 2

What is the function of alveoli?

Answer 2

Gas exchange by diffusion between air in lungs and blood in capillaries

Question 3

What are the adaptations of alveoli?

Answer 3

1. Small and arranged in clusters
   —> creates a large surface area for faster diffusion
2. Provide a large blood supply
   —> maintains concentration gradient
3. Walls are very thin
   —> there is a short distance for diffusion, increasing the rate

Question 4

What factors affect diffusion?

Answer 4

1. Surface area
   —> as surface area increases, so does diffusion rate
   —> more space for particles to move so diffusion happens faster
2. Concentration difference
   —> larger difference in concentration, faster rate of diffusion
3. Distance
   —> more distance = slower diffusion

Question 5

How are red blood cells adapted for its function?

Answer 5

1. Biconcave disk shape
   —> increases surface area
   —> more oxygen carried
2. No nucleus
   —> so it can contain more haemoglobin

Question 6

How are white blood cells adapted to its function?

Answer 6

1. Has receptors on membrane
   —> recognises pathogens
2. Can change shape
   —> engulfs pathogens

Question 7

What does plasma do?

Answer 7

liquid that carries dissolved substances

Question 8

What is the function of platelets?

Answer 8

small fragments of cells that helps blood clot after an injury

Question 9

What is the function of arteries?

Answer 9

Carries blood AWAY FROM THE HEART

Question 10

What is the function of veins?

Answer 10

Carries blood INTO the heart

Question 11

What are the adaptations of arteries?

Answer 11

1. Thick walls
   —> withstand high pressure
2. Small lumen
   —> reduces volume

Question 12

What are the adaptations of veins?

Answer 12

1. Contain valves
   —> prevent back flow of blood
2. Large lumen
   —> maximises blood flow

Question 13

What are the adaptations of capillaries?

Answer 13

1. One cell thick
   —> short diffusion pathway
2. Permeable walls
   —> substances can move past them

Question 14

What is cellular respiration?

Answer 14

An exothermic reaction which occurs continuously in living cells to release energy for metabolic processes

Question 15

What does fick’s law state?

Answer 15

Rate of diffusion is proportional to surface area and concentration difference