3.1.1 Exchange Surfaces COMPLETE

Question 1

DEFINITION- Diffusion

Answer 1

Net movement of particles from a higher to a lower concentration, passive process

Question 2

Factors affecting diffusion

Answer 2

• SA
• Temperature
• Conc. gradient
• Length of diffusion path
• Pressure
• Permeability

Question 3

The problems with larger organism

Answer 3

When something gets bigger its SA:V is reduced as volume increases more than SA

Question 4

Large surface area

Answer 4

A larger surface area for a substance to diffuse across means more of it can cross in a given time

Question 5

Short Diffusion Path

Answer 5

Shorter distance for a substance to diffuse across so it’ll take less time

Question 6

Diffusion gradient

Answer 6

Concentration must be higher one side than the other for diffusion down a gradient to take place

Question 7

Protection for drying out

Answer 7

Water vapour will diffuse out of the cell, too much water loss will cause the membrane to change shape or die

Question 8

Exchange In Mammalian Lungs

Answer 8

SA: Lots of alveoli
Thin: Each alveolus is one epithelial cell thick
Conc. gradient: Constant ventilation replaces the air to maintain it
Drying out: Kept moist by water diffusing out of other cells

Question 9

Exchange in Plant Leaves

Answer 9

SA: Lots of leaves, also lots of spongey mesophyll cells
Thin: Gases diffuse directly into the cells
Conc. gradient: Wind replaces the air around leaf
Drying out: Guard cells swell up and close the stomata

Question 10

How is the Alveolus Adapted

Answer 10

• Elastic fibres in the walls allow them to recoil and stretch
• One cell thick
• Thin layer of surfactant fluid keeps them moist and reduces tension
• NOT SA

Question 11

Role of the Macrophages

Answer 11

Patrol alveolar surfaces and scavenge for any harmful material. If they find any they will engulf them, some however can’t be digested

Question 12

Distribution and function of the cartilage

Answer 12

Found in the trachea and bronchi

Supports and holds them open preventing collapse

Question 13

Distribution and function of smooth muscle

Answer 13

Found in the walls of the trachea, bronchi and bronchioles

Involuntary muscle that narrows the lumen

Question 14

Distribution and function of the elastic fibres

Answer 14

Found in the walls of all the airways and alveoli

Recoil of the elastic tissue will widen the air way and force air out the alveoli

Question 15

Distribution and function of Goblet cells

Answer 15

Found throughout the ciliated epithelium

Secrete a sticky mucus that traps particles and prevent drying out

Question 16

Distribution and function of the ciliated epithelium

Answer 16

Found in the trachea, bronchi and bronchioles

Cilia move in a synchronised pattern to waft mucus up the airway to the back of the throat.

Question 17

Respiratory System

Answer 17

Organs and tissues that carry out ventilation and gas exchange

Question 18

Respiration

Answer 18

The reaction that utilises ATP to release energy from glucose, occurs in every living cell.

Question 19

Inspiration

Answer 19

Breathing in

• External intercostal muscles contract moving ribcage up and out
• Diaphragm flattens as muscle contracts
• Thoracic cavity volume increases
• Pressure lower than outside body
• Air flows down the pressure gradient

Question 20

Exhalation

Answer 20

Breathing out

• External intercostal muscles relax
• Elastin fibres between alveoli recoil
• Volume decreases, pressure increases so air moves out
• More air is forced out when internal intercostal muscles move ribcage down and in
• Abdominal muscles contract so diaphragm releases upwards

Question 21

Breathing

Answer 21

Physical changes that occur in the ribcage and diaphragm to cause ventilation
Forced breathing uses the internal intercostal muscles

Question 22

Ventilation

Answer 22

Movement of gases into and out of the lungs

Question 23

Tidal Volume

Answer 23

Volume of air moved in and out of the lungs with each breath at rest.

Question 24

Vital Capacity

Answer 24

The largest possible volume of air that can be moved into and out of the lungs in one breath.
Effected by age, size, exercise

Question 25

Inspiratory Reserve volume

Answer 25

How much more air can be breathed in over and above the tidal volume

Question 26

Expiratory Reserve Volume

Answer 26

How much more air can be breathed out over and above the tidal volume

Question 27

Residual Volume

Answer 27

Volume of air that always remains in the lungs even after the biggest possible exhalation

Question 28

Dead Space

Answer 28

Parts where no gaseous exchange takes place i.e. in the trachea.
Still vital parts as without them no ventilation could happen

Question 29

Spirometer

Answer 29

A tool used to measure breathing rate and vital capacity. Soda lime is used to absorb and CO2 released. Precautions include using a clean disposable mouth piece, a nose clip, supply of fresh air to breath in.
Lines draw up indicate the person breathing out

Question 30

Breathing Rate

Answer 30

Number of breaths per minute

Count the number of peaks within a set period of time, then work that out for one minute.

Question 31

Ventilation Rate

Answer 31

Total volume of air breathed in or out in one minute.

Breathing rate x Mean Tidal Volume

Question 32

Calculating Oxygen Consumption

Answer 32

Chamber must be filled with pure oxygen, soda lime must also be added to absorb the CO2
Tidal volume of air going back into the container will be decreasing so the pen line has a gradient.
Therefore by calculating the gradient we can work out the volume of O2 being used.

Question 33

Gas Exchange in Bony Fish

Answer 33

Often are large active organisms this means they have a low SA:V but a high metabolic rate they’re also multicellular. Water has a low O2 content so moving water in and out would waste energy.

Question 34

Adaptions of gills in bony fish

Answer 34

Large SA or diffusion
Rich blood supply to maintain gradient
Thin layers to shorten diffusion path
Tips of adjacent gills overlap increases resistance to the flow of water so more time for diffusion
Water moving over gills and blood move in opposite direction as a countercurrent

Question 35

Buccal- Opercular Pump

Answer 35

Ensures water constantly flows over gills.
The mouth opens and the floor of the buccal cavity is lowered so volume increases and pressure decreases. Water moves in then the mouth closes to increase the pressure again.
Water is pushed from the buccal cavity to the operculum outwards and the pressure there decreases helping water flow over the gills

Question 36

Tracheal system

Answer 36

A system of air filled tubes in insects

Question 37

Problems with gas exchange in insects

Answer 37

They’re very active so lots of O2 needed, high risk of desiccation, no blood carrying O2, exoskeleton makes gas exchange difficult

Question 38

Gas exchange in insects

Answer 38

Air enters through small openings in the thorax and abdomen called spiracles, water is also lost. To reduce this spiracle spinsters can open or close them.
The trachea leads away from the spiracles, these are lined with chitin. These brach to form tracheoles this is where gas is exchanged.

Question 39

Tracheal Fluid

Answer 39

Found at the end of tracheoles, limits the penetration of air as lactic acid builds up and water moves out by osmosis

Question 40

Spiracle

Answer 40

An external opening or pore that allows air in and out of the trachea

Question 41

Mechanical Ventilation in insects

Answer 41

Muscular pumping movement of the thorax and abdomen change the volume and therefore pressure forcing air in and out of the insect.

Question 42

Collapsible Air Sacs in insects

Answer 42

These act as reservoirs increasing the volume of air moving through the exchange system, they’re usually deflated and inflated by the movement of the abdomen and thorax.