SB8 - Exchange and transport in animals

Question 1

Why do organisms need to transport substances out of the body?

Answer 1

To prevent waste products from accumulating

Question 2

Where does the exchange of substances occur?

Answer 2

Across the cell membrane

Question 3

What do specialised exchange surfaces allow?

Answer 3

Efficient transport of substances from one area to another

Question 4

What are the transport processes that organisms use?

Answer 4

• Diffusion
• Osmosis
• Active transport

Question 5

Why do unicellular organisms not need to have specialist exchange surfaces or transport systems?

Answer 5

As diffusion, osmosis and active transport through the cell membrane occur at a sufficient rate to meet the needs of the organism

Question 6

Why do multicellular organisms need to have specialist exchange surfaces or transport systems?

Answer 6

As the distance between the surface of the organism to its centre is relatively long
—> As diffusion, osmosis and active transport cannot happen sufficiently to meet a larger organism’s needs otherwise

Question 7

Why do large, multicellular organisms need exchange surfaces?

Answer 7

Large, multicellular organisms already have relatively small surface areas (SA) in comparison to their volumes

Question 8

Give an example of transport systems in animals

Answer 8

Blood & circulatory system

Question 9

Give an example of transport systems in plants

Answer 9

• Xylem
• Phloem

Question 10

Give some examples of some exchange surfaces

Answer 10

• Root hair cells of plants
• Walls of nephrons in the kidneys

Question 11

What are some common characteristics of exchange surfaces?

Answer 11

• Short distance for diffusion
• Large surface area

Question 12

How does having a large surface area aid exchange surfaces?

Answer 12

Greater the surface area = the more particles can move through
—> Resulting in a faster rate of diffusion

Question 13

How does having a thin membrane aid exchange surfaces?

Answer 13

Provides a short diffusion pathway, allowing the process to occur faster

Question 14

How does having an efficient blood supply (in animals) aid exchange surfaces?

Answer 14

Creates a steep concentration gradient, so diffusion occurs faster

Question 15

Why can single celled organisms use diffusion to transport molecules into their body?

Answer 15

They have a relatively large surface area to volume ratio
—> They have low metabolic demands, diffusion across the surface of the organism meets demands

Question 16

What is the purpose of alveoli?

Answer 16

Allows gas exchange between the lungs and blood

Question 17

How is alveoli adapted to diffusion?

Answer 17

• Walls of alveoli are thin
• Capillaries provide a large blood supply
• Very small & arranged in clusters

Question 18

How does alveoli being small & arranged in clusters aid diffusion?

Answer 18

Creating a large surface area for diffusion to take place over

Question 19

How does alveoli having a large blood supply aid diffusion?

Answer 19

Maintains the concentration gradient

Question 20

How does alveoli having thin walls aid diffusion?

Answer 20

There is a short diffusion pathway

Question 21

What are the factors which affect the rate of diffusion?

Answer 21

• Temperature
• Surface area of the membrane
• Concentration gradient

Question 22

Describe the effect of concentration gradient on the rate of diffusion?

Answer 22

The greater the difference in concentration, the faster the rate of diffusion
—> Bc more particles are randomly moving down the gradient than are moving against it

Question 23

Describe the effect of temperature on the rate of diffusion?

Answer 23

The greater the temperature, the greater the movement of particles
—> More collisions therefore faster rate of diffusion

Question 24

Describe the effect of surface area of the membrane on the rate of diffusion?

Answer 24

The greater the surface area, the more space for particles to move through
—> Faster rate of diffusion

Question 25

What is the *equation* used to calculate the **rate of diffusion**?

Answer 25

Question 26

What is the **blood** made up of?

Answer 26

* Plasma * Red blood cells * White blood cells * Platelets

Question 27

What is the **purpose** of **platelets**?

Answer 27

Cell fragments that have no nuclei - important in the clotting mechanism of the blood

Question 28

What is the **purpose** of the **red blood cells**?

Answer 28

They carry oxygen molecules from the lungs to all the cells in the body

Question 29

List how **red blood cells** are adapted to its **function**?

Answer 29

* Biconcave disc shape * No nucleus * Contains haemoglobin

Question 30

How does **red blood cells** having a **biconcave disc shape** help its function?

Answer 30

Provides a large surface area

Question 31

How does **red blood cells** having **no nucleus** help its function?

Answer 31

Allows more room to carry oxygen

Question 32

Describe why *blood* can be **dark red**

Answer 32

There is **less** oxygen attached to the haemoglobin molecules

Question 33

Describe why *blood* can be **bright red**

Answer 33

There is **a lot** of oxygen attached to the haemoglobin molecules

Question 34

What is the **purpose** of the **plasma**?

Answer 34

The liquid that carries the components in the blood

Question 35

What is the **purpose** of the **white blood cells**?

Answer 35

They are a part of the immune system

Question 36

What are the *types* of **white blood cells**?

Answer 36

* Phagocytes * Lymphocytes

Question 37

What are the **types** of **blood vessels**?

Answer 37

* Arteries * Veins * Capillaries

Question 38

What is the **purpose** of **arteries**?

Answer 38

Carries blood AWAY from the heart

Question 39

Describe how the **arteries** are *adapted* to its *function*

Answer 39

* Layers of muscle in the walls make them strong * Elastic fibres allow them to stretch This helps the vessel to withstand the high pressure created by pumping of the heart

Question 40

What is the **purpose** of **veins**?

Answer 40

Carries blood TOWARDS the heart

Question 41

Describe how the **veins** are *adapted* to its *function*

Answer 41

* The lumen is wide to allow the low pressure blood to flow through * They have valves to ensure the blood flows in the right direction

Question 42

What is the **purpose** of **capillaries**?

Answer 42

Allows the transfer of substances between the blood and tissues

Question 43

Describe how the **capillaries** are *adapted* to its *function*

Answer 43

* One cell thick - short diffusion pathway * Permeable walls - substances can move across them

Question 44

What is the **circulatory system**?

Answer 44

The system that moves blood through the body and removes waste products

Question 45

Describe the **structure** of the **heart**

Answer 45

* Muscular walls * Muscular wall of the left ventricle is thicker * 4 chambers that separate the oxygenated blood from the deoxygenated blood * Valves * Coronary arteries cover the heart to provide its own oxygenated blood supply

Question 46

What is the **purpose** of **muscular walls** in the **heart**?

Answer 46

Provides a strong heartbeat

Question 47

Why is the **muscular wall** of the **left ventricle thicker** in the **heart**?

Answer 47

Blood needs to be pumped all around the body rather than just to the lung like the right ventricle

Question 48

What is the **purpose** of the **valves** in the **heart**?

Answer 48

To prevent the backflow of blood

Question 49

Which side of the *heart* is **oxygenated blood**?

Answer 49

Left

Question 50

Which side of the *heart* is **deoxygenated blood**?

Answer 50

Right

Question 51

What is the **average natural resting rate** of the **heart**?

Answer 51

70bpm

Question 52

What **system** does the **heart** use to *pump blood around the body*?

Answer 52

Double circulatory

Question 53

Describe the **pathway** of blood

Answer 53

* Blood flows into the right atrium through the vena cava, and left atrium through the pulmonary vein * Atria contracts forcing the blood into the ventricles * The ventricles contract, pushing the blood in the right ventricle into the pulmonary artery to be taken to the lungs & blood in the left ventricle to the aorta to be taken around the body

Question 54

When is an **artificial pacemaker** used?

Answer 54

When the individual has an irregular heartbeat

Question 55

What is the **equation** for **cardiac output**?

Answer 55

Question 56

What is **stroke volume**?

Answer 56

The volume of blood expelled from the heart in one contraction

Question 57

What is **heart rate**?

Answer 57

The number of beats per minute

Question 58

What is **cellular respiration**?

Answer 58

An exothermic reaction which is a series of chemical reactions that release energy from glucose

Question 59

Why is **respiration exothermic**

Answer 59

Some energy is transferred out of the cells by heating - keeps animals warm

Question 60

Compare **aerobic respiration** w/ **anaerobic respiration**?

Answer 60

Question 61

Why do **organisms** need **energy**?

Answer 61

* Chemical reactions * Muscle contraction * Keeping warm

Question 62

What is **aerobic respiration**?

Answer 62

The chemical reaction in cells that uses oxygen to break down nutrient molecules to release energy

Question 63

What is **anaerobic respiration**?

Answer 63

The chemical reaction in cells that breaks down nutrient molecules to release energy without using oxygen

Question 64

What is the **formula** for **lactic acid**?

Answer 64

Question 65

What is **oxygen debt**?

Answer 65

The amount of oxygen required to break down the lactic acid that has built up

Question 66

Why is **lactic acid** dangerous for our bodies?

Answer 66

Lactic acid builds up in muscle cells and lowers the pH of the muscle tissue (making the conditions more acidic) ---> Acidic conditions can denature the enzymes in cells

Question 67

What is **repaying the oxygen debt**?

Answer 67

The process of breaking down the lactic acid

Question 68

What other **organisms** apart from *humans* can **anaerobically respire**?

Answer 68

* Plants * Yeast

Question 69

What is **fermentation** important in?

Answer 69

* Brewing * Manufacture of bread

Question 70

# Core practical: Rate of respiration in living orgaisms Describe the method you will use to conduct this experiment

Answer 70

Pick a small organism that you would like to measure the rate of respiration of (e.g maggots, or leaves) 2. Place 5cm 3 of soda lime into a test tube 3. Place gauze on top and a small amount of the organism being tested on top of this 4. Attach a three-way tap, capillary tube and syringe to the test-tube. Plug the test-tube with a stopper 5. Insert a small amount of coloured liquid into the capillary tube 6. Turn the 3-way tap to allow air to enter the test tube for 5 minutes. After 5 minutes, close the 3-way tap. 7. Record how far the coloured liquid has moved against a scale.

Question 71

What is a **respirometer**?

Answer 71

A machine to measure the effect of temperature on the oxygen consumption of small organisms

Question 72

Describe how a **simple respirometer** should look like

Answer 72