Exchange And Transport Systems

Front 1

Smaller animals have a higher what?

Back 1

Surface area to volume ratio.

Front 2

Why do smaller animals need a higher metabolic rate?

Back 2

To generate enough heat to stay warm.

Front 3

What two major adaptations do exchange surfaces have?

Back 3

• A large surface area.

• They are thin providing a short diffusion pathway.

Front 4

How do single-celled organisms exchange gases?

Back 4

• They exchange gases across their body surface.

Front 5

Why can single-celled organisms do this?

Back 5

• They have a relatively large surface area.

• A thin surface.

• A short diffusion pathway.

Front 6

Why is there no need for a gas exchange system?

Back 6

• Oxygen can take part in biochemical reactions as soon as it diffuses into cell.

Front 7

What sort of system do fish use for gas exchange?

Back 7

Counter-current system.

Front 8

What does a counter-current system ensure?

Back 8

• Water and blood flow in opposing directions.

• There is always a higher concentration of oxygen in water than blood so as much oxygen as possible diffuses into blood.

Front 9

What does the counter-current system maintain?

Back 9

A steep concentration gradient.

Front 10

What does each gill contain and what does this provide?

Back 10

• Lots of thin plates called gill filaments.

• They provide a large surface area for gas exchange.

Front 11

What are these gill filaments covered in?

Back 11

Tiny structures called lamellae which increase the surface area even more.

Front 12

The lamellae have lots of what, and a thin surface layer of cells to what?

Back 12

Lots of blood capillaries and a thin surface layer of cells to speed up diffusion.

Front 13

What do insects use to exchange gases?

Back 13

Tracheae.

Front 14

How does air move into the tracheae?

Back 14

Through pores on the surface called spiracles.

Front 15

How does oxygen reach the respiring cells?

Back 15

Oxygen travels down a concentration gradient.

Front 16

What do the tracheae branch off into and what do these have?

Back 16

• Tracheoles

• Thin, permeable walls that go to individual cells.

Front 17

Where do plants exchange gases?

Back 17

At the surface of the mesophyll cells.

Front 18

How is the surface of mesophyll cells adapted for its function?

Back 18

It has a large surface area.

Front 19

What are the pores in the epidermis called?

Back 19

Stomata.

Front 20

What type of cells control the opening and closing of the stomata?

Back 20

Guard cells.

Front 21

If insects are losing too much water what can they do?

Back 21

Close their spiracles using abdominal muscles.

Front 22

What 2 adaptations do insects have to reduce water loss and how?

Back 22

Water proof waxy cuticle and tiny hairs; reducing water potential gradient.

Front 23

What happens to the guard cells as water enters them during the day and what happens to the stomata as a result?

Back 23

• The guard cells become turgid.

• The stomata open.

Front 24

If the plant starts to get dehydrated what happens?

Back 24

• The guard cells lose water and become flaccid.

• The stomatal pore closes.

Front 25

Give 3 examples of xerophytic adaptations?

Back 25

• Stomata are sunk in pits and there is a layer of hair on the epidermis that trap moist air.

• Curled leaves protect the stomata from the wind which could increase the rate of evaporation.

• A reduced number of stomata so there are fewer places for water to escape.

• Waxy, waterproof cuticles on leaves and stems.

Front 26

As you breathe in, air enters what part of the gas exchange system in humans?

Back 26

The trachea.

Front 27

The trachea divides into 2 what?

Back 27

Bronchi; one bronchus per lung.

Front 28

What are the air sacs called in which the bronchioles end?

Back 28

Alveoli.

Front 29

What does ventilation consist of?

Back 29

Inspiration and expiration.

Front 30

Describe what happens during inspiration?

Back 30

External intercostal and diaphragm muscles contract.

Ribcage - upwards and outwards; diaphragm flattens.

Volume of thoracic cavity increases; pressure inside lungs decreases.

Air moves down pressure gradient; high pressure in air - lower pressure in lungs.

Inspiration is an active process.

Front 31

Describe the process of expiration?

Back 31

External intercostal and diaphragm muscles relax.

Ribcage - downwards and inwards; diaphragm becomes domed shape.

Volume of thoracic cavity decreases; pressure inside lungs increases.

Air moves down pressure gradient; high pressure in lungs - lower pressure in air.

Expiration is a passive process.

Front 32

What happens during forced expiration?

Back 32

The external intercostal muscles relax and internal intercostal muscles contract.

Front 33

The movement of intercostal muscles during forced expiration is what?

Back 33

Antagonistic.

Front 34

What gases are exhanged in the alveoli?

Back 34

Oxygen and Carbon Dioxide.

Front 35

How are the alveoli adapted for gas exchange?

Back 35

• Thin exchange surface; alveolar epithelium is only one cell thick.

• Large surface area provided by the large number of alveoli.

Front 36

How is a steep concentration gradient of oxygen and carbon dioxide maintained?

Back 36

The flow of blood (internal medium) and ventilation.

Front 37

What is tidal volume?

Back 37

The volume of air in each breath.

Front 38

Define ventilation rate?

Back 38

The number of breaths per minute.

Front 39

What is forced expiratory volume?

Back 39

The maximum volume of air that can be breathed out in one second.

Front 40

What is forced vital capacity?

Back 40

The maximum volume of air forcefully breathe out after long breathe in.

Front 41

What happens during digestion?

Back 41

Food is broken down into smaller molecules; they can be absorbed from the gut into the blood.

Front 42

How are large biological molecules broken down?

Back 42

By hydrolysis reactions.

Front 43

What do hydrolysis reactions do?

Back 43

The break the bonds by adding water.

Front 44

What are carbohydrates broken down by?

Back 44

Amylase and membrane-bound disaccharidases.

Front 45

What bonds are broken when amylase hydrolyses starch into maltose?

Back 45

Glycosidic bonds.

Front 46

Where is amylase produced and where does it work?

Back 46

• Salivary glands; released into the mouth.

• Pancreas; released into small intestine.

Front 47

Where are membrane-bound disaccharidases found?

Back 47

Attached to cell membranes of epithelial cells.

Front 48

What do membrane-bound disaccharidases do?

Back 48

They break down disaccharides into monosaccharides; eg. maltose into glucose.

Front 49

What enzyme breaks down lipids?

Back 49

Lipases, with bile salts.

Front 50

What are lipids broken down into; what bonds does this involve breaking?

Back 50

Monoglycerides and fatty acids by hydrolysing ester bonds.

Front 51

Where are lipases made and where do they work?

Back 51

Pancreas; work in the small intestine.

Front 52

Where are bile salts produced and what do they do?

Back 52

Made in the liver; emulsify lipids - form small droplets.

Front 53

What do several small lipid droplets have?

Back 53

A larger surface area for the lipases to work on.

Front 54

Monoglycerides and fatty acids stick with the bile salts to form what structures?

Back 54

Micelles.

Front 55

What are proteins broken down by?

Back 55

Endopeptidases and Exopeptidases.

Front 56

What do these different proteases do?

Back 56

Catalyse the break down of protein into amino acids by hydrolysing the peptide bonds.

Front 57

Explain the differences between endopeptidases and exopeptidases?

Back 57

• Endopeptidases act to hydrolyse peptide bonds within a protein.

• Exopeptidases act to hydrolyse peptide bonds at the ends of protein molecules.

Front 58

Where are proteases synthesised and where do they work?

Back 58

Pancreas; work in small intestine.

Front 59

What are dipeptidases and how do they work?

Back 59

• Exopeptidases that work specifically on dipeptides.

• They seperate the two amino acids that make up a dipeptide by hydrolysing the peptide bond.

Front 60

Where are dipeptidases usually located?

Back 60

In the cell surface membrane of epithelial cells.

Front 61

What happens to the products of digestion?

Back 61

They are absorbed across cell membranes.

Front 62

How are monosaccharides absorbed across cell membranes?

Back 62

• Glucose and galactose - active transport; sodium ions via a co-transporter proteins.

• Fructose is absorbed via facilitated diffusion.

Front 63

How are monoglycerides and fatty acids absorbed across cell membranes?

Back 63

• Micelles help to move them towards the epithelium.

• Monoglycerides and fatty acids are lipid soluble; diffuse directly across the epithelial cell membrane.

Front 64

How are amino acids absorbed across epithelial cell membranes?

Back 64

• Sodium ions are actively transported out of the epithelial cells into ileum.

• They then diffuse back into cells through sodium-dependant transporter proteins in epithelial cell membranes, carrying amino acids with them.

Front 65

What is haemoglobin?

Back 65

A large protein with a quaternary structure - made of 4 polypeptide chains.

Front 66

What does each chain have?

Back 66

A haem group.

Front 67

Each molecule of haemoglobin can carry how many oxygen molecules?

Back 67

4.

Front 68

What does this mean?

Back 68

That haemoglobin has a high affinity for oxygen.

Front 69

Where does oxygen associate with haemoglobin and what does it form as a result?

Back 69

Oxygen joins to haemoglobin in the alveoli to form oxyhaemoglobin.

Front 70

Where does oxygen dissociate with haemoglobin?

Back 70

At respiring body cells.

Front 71

What is partial pressure of oxygen/carbon dioixide?

Back 71

The concentration of oxygen or carbon dioxide.

Front 72

When does oxygen load onto haemoglobin to form oxyhaemoglobin?

Back 72

When there is a high partial pressure of oxygen.

Front 73

When does oxyhaemoglobin unload its oxygen? to form haemoglobin?

Back 73

When there is a low partial pressure of oxygen.

Front 74

What happens as a result of cells respiring?

Back 74

Respiring cells; lower pO2 - increase pCO2; oxyhaemoglobin unloads oxygen.

Front 75

What do dissociation curves show?

Back 75

How saturated the haemoglobin is with oxygen at any given partial pressure.

Front 76

When pO2 is high haemoglobin will what, because it has a high affinity for oxygen?

Back 76

Readily associate with oxygen.

Front 77

When pO2 is low haemoglobin will what, because it has a low affinity for oxygen?

Back 77

Readily dissociate with oxygen.

Front 78

Why is the graph an 'S' shape?

Back 78

When haemoglobin binds with the first O2 molecule; shape alters - easier for other molecules to join.

Front 79

How does the haemoglobin of organisms living in environments with low concentration of oxygen compare to humans?

Back 79

Higher affinity of oxygen - the dissociation curve is to the left of ours; more readily associates

Front 80

Why do organisms that are active have a lower affinity for oxygen compared to humans?

Back 80

Respiring cells need more oxygen; the curve is to the right of ours; more readily dissociates.