Chapter 6 - Exchange

Question 1

Who has a larger surface area to volume ratio out of a mouse and an elephant?

Answer 1

Mouse

Question 2

What are the 2 possible scenarios that might be asked about in relation to surface area to volume ratio

Answer 2

• The absorption of oxygen in single celled organisms

- Heat conservation/loss between mammals

Question 3

How does extreme enter a single celled organism or a flatworm

Answer 3

Direct diffusion

Question 4

What is a single celled organisms SA:VOL like

And how does oxygen diffuse into it

Answer 4

Very high SA:VOL

O2 observed through membrane

Question 5

What does it mean if a mammal has a higher SA:VOL than another?

Answer 5

They lose more heat per gram of body weight

Question 6

What does a mammal have to do if it loses more heat per gram of body mass

Answer 6

• Requires a faster rate of respiration

- As it needs more oxygen to maintain body temperature

Question 7

How does an elephants rate of respiration differ to a mice?

Answer 7

Elephants is slower as they don’t need as much oxygen to maintain body temperature due to a smaller SA:VOL

Question 8

What does the rate of diffusion for gas exchange depend upon? (Fick’s law)

Answer 8

Surface area of membrane
Diffusion distance (thickness)
Concentration gradient

Question 9

What is fick’s law

Answer 9

Rate of diffusion is proportional to

Surface area x concentration difference/diffusion distance

Question 10

Explain how gas exchange occurs in insects

Answer 10

• Air enters through spiracles into trachea
  Trachea divide into tracheoles
• Oxygen diffuses does concentration gradient along tracheoles
• Tracheoles are closely surrounded by cells so oxygen diffuses into cells
• Ventilation occurs, where air in trachea and tracheoles is replaced to maintain concentration gradient of oxygen between air and cells

Question 11

What are examples of water loss adaptations in insects

Answer 11

• Body is covered by waxy cuticle to reduce evaporation

- Insects can close spiracles

Question 12

Why are insects not able to grow to a large size?

Answer 12

Insects rely on diffusion to exchange gases directly between the environment and its cells, therefore a short diffusion pathway is needed
This means that they can’t grow to a much larger size

Question 13

What is the way in which gas exchange in fish occurs referred to as

Answer 13

Counter current flow

Question 14

What is meant by counter current flow

Answer 14

Water and blood moving in opposite directions

Question 15

What is the purpose of counter current flow

Answer 15

• A high concentration gradient can be maintained across the entire surface, water is always next to blood with a low oxygen concentration

Question 16

What are some adaptations that increase efficiency of diffusion in fish

Answer 16

• Filaments and lamellae have a large surface area
• Thin epithelium(short diffusion distance
• Circulation of blood, means that deoxygenated blood replaces oxygenated blood to maintain concentration gradient
• Ventilation of water means that oxygen is not lost by diffusing back into water

Question 17

What are dicotyledonous plants

Answer 17

Plants with leaves

Question 18

Explain gas exchange in dicotyledonous plants

Answer 18

• Air enters through stomata

- Gas exchange of CO2 and O2 occurs in mesophyll

Question 19

What is an adaptation of mesophyll and why is this

Answer 19

They are spongy, so can increase surface area

Question 20

How are dicotyledonous plants adapted to reduce water loss and how does this happen

Answer 20

• Guard cells can open and close stomata
• If a plant has a lot of water, cells are hard
• If it has a lack of water, cells are flacid, and if guard cells are flacid they close the stomata

Question 21

What is a xerophytic plant

Answer 21

A plant in dry conditions eg cacti

Question 22

What are 5 adaptations of xerophytic plants

Answer 22

• Curled leaves (spikes)
• Stomata sunken in pits
• Hairs on epidermis of leaf (bottom)
• Thick waxy cuticle
• Few stomata

Question 23

How do curled leaves, sunken stomata and hairs on epidermis help to reduce water loss

Answer 23

• Reduces ventilation of air
• Therefore water vapour accumulates within the leaf (outside stomata)
• This decreases diffusion gradient for water vapour
• Reduces water loss

Question 24

How does a thick waxy cuticle reduce water loss in xerophytic plants

Answer 24

• Reduces evaporation of water from leaf, thus reduces water loss

Question 25

How does having fewer stomata reduced water loss for xerophytic plants

Answer 25

Fewer stomata mean there is less opportunity for water loss via stomata

Question 26

What are the adaptations for efficient gas exchange in humans? (Surface area)

Answer 26

- Alveoli at end of bronchioles - Large number of them - They have a folded membrane to increase surface area - Many small capillaries to increase surface area

Question 27

What are the adaptations for efficient gas exchange in humans? (Concentration gradient)

Answer 27

- Ventilation through breathing replaces air with high CO2 and low O2 concentration - Circulation of blood, deoxygenated blood is replaced by blood with high CO2 and low O2 concentration - Both increase concentration gradient

Question 28

What are the adaptations for efficient gas exchange in humans? (Diffusion distance)

Answer 28

- Thin epithelia In alveoli and capillaries - One cell thick - Short diffusion pathway

Question 29

What is meant by tidal volume

Answer 29

Volume of air breathed in or out per breath at rest

Question 30

What is meant by ventilation/breathing rate

Answer 30

Number of breaths per minute

Question 31

What is meant by pulmonary ventilation

Answer 31

Total volume of air breathed in per minute

Question 32

Calculation for pulmonary ventilation

Answer 32

Tidal volume x breathing rate

Question 33

What is meant by oxygen consumption

Answer 33

Volume of oxygen used per min

Question 34

What is meant by vital capacity

Answer 34

Maximum volume of air that can be exhaled after maximum volume of air inhaled

Question 35

What is meant by residual volume

Answer 35

Volume of air that can’t be breathed out after maximum inhale and exhale

Question 36

What is the effect of exercise on tidal volume

Answer 36

Increases, deeper breaths

Question 37

What is the effect of exercise on breathing rate

Answer 37

Increase, faster breaths

Question 38

What is the effect of exercise on pulmonary ventilation

Answer 38

Increase, more breaths per min

Question 39

What is the effect of exercise on oxygen consumption

Answer 39

Increases, due to more respiration

Question 40

Draw a spirometer trace and label it with vital capacity, residual volume and tidal volume

Answer 40

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Question 41

Explain the mechanics of breathing for inspiration

Answer 41

- Diaphragm contracts (flattens) - External intercostal muscles contract, rib cage moves up and out - Increasing volume of thorax (chest cavity) - Decreases air pressure in thorax, so air moves in from high to low pressure

Question 42

Explain the mechanics of breathing for expiration

Answer 42

- Diaphragm relaxes (becomes domed) - External intercostal muscles relax - Rib cage moves down and in - Decreases volume of thorax - Increases air pressure in thorax - Air moves out from high to low pressure

Question 43

Explain the mechanics of breathing for forced expiration

Answer 43

- Internal intercostal muscles contract - Pulls rib cage down more and faster - Internal and external intercostal muscles are an antagonistic pair

Question 44

What is meant by digestion

Answer 44

Large biological molecules are hydrolysed (broken down) by enzymes into smaller molecules that can be absorbed across a cell membrane

Question 45

Explain digestion of carbohydrates

Answer 45

- Amylase hydrolyses glycosidic bonds in starch (polysaccharide) - Form maltose (disaccharide) - Maltase hydrolyses glycosidic bonds in maltose - Form 2 glucose molecules

Question 46

How are carbohydrates absorbed

Answer 46

After being digested into glucose, they are absorbed by co-transport with sodium ions

Question 47

Where is amylase found and where is it made

Answer 47

Found in saliva | Made in pancreas

Question 48

Where is maltase made

Answer 48

Small intestines

Question 49

What is sucrose broken down into

Answer 49

Glucose and fructose

Question 50

What is lactose broken down into

Answer 50

Glucose and galactose

Question 51

Explain the digestion of lipids

Answer 51

- A lipid droplet (triglyceride) is emulsified by bile salts - Emulsified means make them smaller, thus increase SA:VOL - Lipase (enzyme) breaks the emulsified lipid droplets down into a monoglyceride and 2 fatty acids

Question 52

What are micelles

Answer 52

Tiny droplets of monoglycerides and fatty acids

Question 54

Where are bike salts produced

Answer 54

Liver

Question 55

What are the three ways that proteins are broken down

Answer 55

Endopeptidase Exopeptidase Membrane bound dipeptase

Question 56

What does endopeptidase do

Answer 56

Hydrolyses peptide bonds within a polypeptide

Question 57

What does exopeptidase do

Answer 57

Hydrolyses peptide bonds at the end of polypeptides

Question 58

What does membrane bound dipeptase do

Answer 58

Hydrolyse the peptide bonds between dipeptides

Question 59

Explain how amino acids are absorbed

Answer 59

- Co-transport with sodium - sodium pumped out - Low concentration of sodium - Sodium diffuses in via carrier protein - Amino acids are also absorbed via co-transport (against concentration gradient)

Question 60

How are lipids absorbed

Answer 60

- Once broken down into micelles, these release monoglycerides close to surface of the cell - These are small non-polar molecules so diffuse in to epithelium of cell