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biology > Exchange > Flashcards

Exchange Flashcards

1
Q

What substances must be exchanged with the environment in an organism?

A

Heat
Respiratory gases
Excretory products
Nutrients

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2
Q

What factors affect the rate of exchange?

A 
Length of diffusion pathway
Surface area
Concentration and pressure gradient 
Carrier proteins
Temperature
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3
Q

What are the methods of exchange?

A

Active, bulk and Co transport
Osmosis
Simple facilitated diffusion

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4
Q

How do you calculate the volume and surface area of a sphere?

A

SA=4x3.124xr^2

Volume= 4/3x3.142xr^3

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5
Q

Why is sa:vol smaller in large animals?

A

As size increases volume increases faster than sa

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6
Q

Why do mammals require a specialised exchange surface and transport system?

A

Small sa:vol
Not enough can diffuse in and out to supply volume
Large diffusion gradient= can’t reach cell quick enough

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7
Q

What are the adaptions of a specialised exchange surface? Give examples

A

Layer of cells one cell thick

Movement of internal and external mediums

Large sa:vol

Selectively permeable membrane

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8
Q

What is the advantage of having a large surface area?

A

More carrier and channel proteins

More places to diffuse across

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9
Q

What is the disadvantage of having a thin surface membrane?

How is this overcome?

A

Easily damaged and dehydrated

Inside organism

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10
Q

Why do mice have a high metabolic rate?

A

Move lots more

Large sa:vol

Heat lost easily
Constantly replaced by energy released via Respiration
High rate of Respiration

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11
Q

Why do single celled organisms not need a circulatory system?

A

Short diffusion pathway meaning substance can be supplied quick enough

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12
Q

Why do single celled organisms have a high rate of exchange?

A

Large sa:vol

Short diffusion pathway

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13
Q

How are the tracheas in humans and insects similar?

A

Humans = cartilage

Insects= chitin

Rings

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14
Q

What is a spiracle and how is it adapted?

A

Pore in side of insects

Hairs and ability to close to conserve water

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15
Q

Why are insects limited to the size they can grow to?

A

Must remain small to retain short diffusion pathway

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16
Q

How are Respiratory gases moved in an insect?

A

Mass tansport: Abdominal pumping

Drawn in (lactate produced lowering wp so water drawn into muscle cells so last part= gas phase)

Diffusion down partial pressure gradient

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17
Q

Describe the structure of the gills

A

Gill arches

Gill filaments

Gill lamella

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18
Q

What is the operculum ?

A

Hard bony flap that deoxygenated water leaves out of

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19
Q

How are the gills adapted?

A

Thin surface (one cell thick)

Movement of external and external mediums

Good blood supply

Large sa

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20
Q

Why might fish die in warm water?

A

Oxygen is less soluble in warm water (already not very soluble)

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21
Q

Why do fish require specialised gas exchange surfaces?

A

Small sa:vol

Waterpriof and gas tight outer coating

Oxygen not very soluble in water

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22
Q

What best describes this mechanism: blood flows one way as water flow in the opposite direction?

A

Countercurrent exchange principle

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23
Q

Why is the countercurrent exchange principle important?

A

Prevents equilibrium being reached

Diffusion across whole length of gill

Blood always next to wtae reith higher oxygen concentration

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24
Q

What is the opposite to countercurrent flow?

A

Parallel flow

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25
Q

During the day what is the net movement of co2 and o2 in a leaf? Why?

A

Co2 in o2 out

Rate of Photosynthesis exceeds respiration

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26
Q

During the night what is the net movement of co2 and o2 in a leaf? Why

A

O2 in co2 out

Photosynthesis doesn’t occur at night

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27
Q

What occurs at dawn and dusk?

A

Compensation point as rate of Photosynthesis and Respiration are equal

No net diffusion

28
Q

How do guard cells open and close the stomata?

A

Make sugar
Lower wp
Water moves in
Makes turgid as thick inflexible inner wall creates opening

29
Q

What is different about guard cells?

A

Have thick and inflexible inner wall

Have chloroplasts to make sugar to lower wp

30
Q

What state are guard cells in when the stomata is closed?

A

Plasmolysis

31
Q

Why do plants not have ventilation or ma’s transport system?

A

Have thin diffusion pathway so can diffuse

Ventilation would cause too much water loss

32
Q

Adaptions of leaf for gas exchange

A

Flat and thin (large sa and short diffusion pathway)

Air spaces in mesophyll= large sa and diffusion in gas phase so quicker

33
Q

How do insects limit water loss?

A

Hairs around spiracles trap moist air

Waterproof cuticle over chitin exoskeleton

Spiracles can close

Small sa:vol = minimise área over which water lost

34
Q

How do plants limit water loss?

A

Close stomata

Waxy cuticle

35
Q

How do xerphytic plants reduce water loss?

A

Reduce sa = circular cross section

Curl leaves, hairs around stomata, sunken stomata= trap moist air

Thick Waxy cuticle

36
Q

Why might having needle shaped leaves be contravertial for plants?

A

Smaller sa:vol

Less gas exchange

37
Q

What is a xerphytic plant?

A

Plant adapted to live in areas of short water supply

38
Q

Give examples of xerphytic conditions

A

Salt marshes= hard to obtain water

High wind speeds= high conc gradient

Sand dunes= water drains away

Very cold= water trapped in ice

39
Q

Why are large volumes of gases exchanged in large organisms?

A

High body temp= high metabolic rate= more respirtion

Many cells to supply

40
Q

What structure does air pass to get to the lungs?

A 
Nasal cavity
Epiglottis
Larynx
Trachea
Bronchus
Bronchioles
Alveoli
41
Q

Why are the lungs inside the body?

A

The prevent dehydration and damage due to thin layer of one cell

42
Q

What are the lungs?

A

Two lobed structures

43
Q

Describe the structure or the trachea

A

C shaped ring of cartilage =prevent collapse

Thick Smooth muscle

elastic fibers

Ciliated epithelial cells=waft mucus up

Goblet cells= produce mucus

44
Q

Describe the structure of the Bronchus

A

Small sections of cartilage

Ciliated epithelial cells

Goblet cells

Smooth muscles

Glands

45
Q

Describe the changing structure of the Bronchioles as you go towards the alveoli

A

More smooth muscle less/no cartilage

Contact to regulate ventilation

Made of epithelial cells

46
Q

Describe the structure of a alveoli bundle

A

Alveoli with tissue fluid, collagen and elastic fibres between them

Network of capillaries

47
Q

Describe the structure of a alveoli and their function

A

Squamous epithelial cells= reduced diffusion pathway

Water= because cell membranes are permeable

Elastic fibres allow recoiling

48
Q

Describe how the capillaries near the alveoli are adapted for gas exchange

A

Squamous endothelial cells=short diffusion pathway

Red blood cells compressed up to walls

Blood is slowed

49
Q

Why might alveoli seem to be different sizes when looked at through a microscope?

A

Cut in different planes

50
Q

How are the lungs adapted for gas exchange?

A

Short diffusion pathway:
Squamous endo and epithelial cells
Compressed erythrocytes

Maintain conc gradient:
Elastic fibres= recoil
Flow of blood
Ventilation

Large sa:
Alveoli and pulmonary capillary walls

Flow of blood slows= more time to diffuse
Alveoli packed closely together

51
Q

Why do people with asthma struggle to breath?

A

Muscles in Bronchus and Bronchioles contract reducing diameter of lumen

Goblet cells produce excess thick mucus

Reduced air flow

52
Q

What is emphysema?

A

When the walls of alveoli break down and fuse

Large alveoli of reduced number = smaller sa:vol

Thick walls = long diffusion pathway

Elastin not replaced

53
Q

What is fibrosis and why does it cause breathing difficulties?

A

Elastic fibres in lungs become stiff

Reduce volume of lungs (can’t strech)

54
Q

What are the risk factor for lung disease?

A

Genetic makeup

Smoking

Infection

Occupation

Air pollution

55
Q

Describe inhalation

A

External intercostal muscles contract, internal relax

Diaphragm contracts and flattens from dome shape

Sternum and runs move up and out

Elastic fibres strech

Volume in lungs increases

pressure in lungs decreases below atmospheric pressure

Air moves in down pressure gradient

56
Q

When does the cartilage in the trachea provide its function?

A

During inspiration and pressure drops

57
Q

Define inhalation

A

Pressure in lungs decreases below atmospheric pressure and air moves into lungs

58
Q

Define exhalation

A

Pressure in lungs increases above atmospheric pressure air is forced out of lungs

59
Q

Describe exhalation

A

Internal intercostal muscles contract (only during exercise ) and external relax

Elastic fibres of lungs recoil

Diaphragm relaxes and returns to dome shape

Sternum and ribs move in and down

Volume of lungs decreases and pressure increases above atmospheric pressure

Air is expelled

60
Q

Is inspiration active?

A

Yes because external intercostal muscles contract

61
Q

Is expiration active?

A

No passive when at rest as elastic fibres recoil

62
Q

What is the equation for pulmonary ventilation?

A

Pulmonary ventillation=

Tidal volume X breathing rate

63
Q

Define and give units for pulmonary ventilation

A

Volume of air moved into lungs in a minute

Dm^3min^-1

64
Q

Define and give units for tidal volume

A

Maximum volume of air inspired after maximum exhalation at rest

Dm^3

65
Q

Define and give units for breathing rate

A

Breaths per min

Breathsmin^-1

66
Q

How does reducing stomata diameter help plants survive?

A

Less water lost

More water available for Photosynthesis

biology (28 decks)

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