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A Level > Module 3 biology > Flashcards

Module 3 biology Flashcards

1
Q

Factors affecting the need for an exchange/circulatory system

A
  • Size
  • SA:V ratio
  • Level of activity
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2
Q

Features of a good exchange surface

A
  • Large surface area
  • Thin so a small diffusion distance
  • Good blood supply to maintain concentration gradient
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3
Q

What do intercostal muscles do in inspiration?

A

Contract to raise the ribs

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4
Q

What are features I missed about alveoli?

A

They are permeable to O2 and CO2

Lined with moisture so have a surfactant to reduce surface tension of cohesion of H2O that can cause alveoli to collapse

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5
Q

Surfactant

A

Reduces surface tension

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6
Q

What are alveoli made of?

A

Squamous epithelial cells

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7
Q

What supports the trachea?

A

C shaped rings of cartilage, containing chondrocyte cells

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8
Q

What are airways made of?

A

Ciliated epithelial cells and goblet cells

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9
Q

How does the muscle work in the airways?

A

Smooth muscle contracts and can only be elongated again by elastic fibres

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10
Q

What does a spirometer do?

A

It measures air movement in and out of the lungs as a person breathes

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11
Q

How does a spirometer work?

A

Chamber of air and water
Lid moves down when breathing in, and up when breathing out
Soda lime absorbs the CO2

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12
Q

Precautions for using a spirometer

A

Use a healthy person
Use fresh soda lime
No air leaks
Sterilise mouth piece

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13
Q

Vital capacity

A

Maximum volume of air that can be moved by the lungs in one breath

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14
Q

What does the vital capacity depend on?

A

Age
gender
size
level of fitness

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15
Q

Residual capacity

A

Volume of air that remains in lungs even after force expiration

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16
Q

Why can oxygen intake be calculated from spirometer trace?

A

The volume of air in the spirometer chamber decreases

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17
Q

How to calculate breathing rate

A

Number of peaks on the spirometer trace

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18
Q

What is the operculum

A

Flap covering gills

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19
Q

Structure of gill

A

Bony arch
Gill filaments/primary lamellae
Secondary lamellae/gill plates on their surface
Capillaries near the surface of these

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20
Q

How do gills ensure lots of oxygen is taken up?

A

Countercurrent flow in the gills

Blood flows through gill filaments the opposite way to the flow of water

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21
Q

Buccal cavity

A

The mouth
lowers to decrease pressure inside and draw in water
Raises to increase pressure when mouth is closed and force water over gills

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22
Q

Tracheal system

A

Exchange system in insects

Direct to tissues

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23
Q

How does the tracheal system work?

A

Air enters in spiracles
Gaseous exchange between air and tracheal fluid
Travels in tracheae

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24
Q

Tracheal fluid

A

Gaseous exchange site

Can withdraw into body fluid when the organism is active to allow more SA for oxygen to be absorbed

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25
Q

How do insects regulate ventilation?

A
  • Flight muscles can expand/contract air sacs in tracheal system
  • Wing movement can increase/decrease thorax volume
  • Locusts increase abdomen volume when spiracles are open at the front of their body, and decrease when they’re open at back to cause flow of ventilation
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26
Q

Features of a good transport system

A

Fluid to carry nutrients/O2/waste
Pump
Exchange surfaces
Tubes for mass flow

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27
Q

Disadvantages of a single circulatory system

A

Blood pressure drops more

Rate of delivery of things is limited

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28
Q

Advantages of double circulatory system

A

Higher pressure
Can have different pressures between Pulmonary and systemic circulation
Heart increases pressure

29
Q

How does an open circulatory system work?

A
  • Pump is a long muscular tube
  • Blood enters the tube from the body through ostia (pores)
  • Blood is pumped towards the head by peristalsis
  • By head blood pours back into body cavity
30
Q

Disadvantages of open circulatory system

A

Blood pressure low
Slow flow
Affected by body movements

31
Q

Endothelium

A

Inner lining of blood vessels

One cell thick

32
Q

What do veins have that no other vessel has?

A

Valves to prevent back flow

33
Q

Erythrocytes

A

Red blood cells

34
Q

What is the function of tissue fluid?

A

Surrounds body cells so exchange of gasses can occur at the plasma membrane

35
Q

Where does tissue fluid go?

A

Some goes back into capillaries by oncotic pressure

Some goes into the lymphatic system

36
Q

What separates the ventricles?

A

The septum

37
Q

Structure of the heart muscle

A 
Cross bridges between fibres - cause squeezing action
Numerous mitochondria
Myofibrils
Separated by intercostal disks
Sarcomeres - contractile units
38
Q

Cardiac cycle

A

Diastole
Atrial systole
Ventricular systole

39
Q

How do valves in the heart shut?

A

Pressure inside rises
Blood pushes upwards into valve pockets
Tendinous chords prevent valves turning inside out

40
Q

Ectopic heartbeat

A

Missed heartbeat, too early or late

41
Q

What is the term for the amount of O2?

A

Oxygen tension or partial pressure of oxygen

42
Q

What is the s shaped curve called relating to oxygen?

A

Haemoglobin dissociation curve

43
Q

What is the term for the change in structure of haemoglobin when O2 binds?

A

Conformational change

44
Q

What are the ways CO2 is transported?

A

Dissolved in the blood plasma
Carbaminohaemoglobin - bound directly to Hb
Hydrogen carbonate ions (HCO3-)

45
Q

How are hydrogen carbonate ions made?

A
  • CO2 and H2O react with carbonic anhydrase enzyme to form carbonic acid (H2CO3)
  • Carbonic acid dissociates to H+ and HCO3- ions
  • HCO3- diffuse out of erythrocyte
  • Chloride shift- chloride ions enter to maintain pH
  • H+ ions combine with Hb to form HHb
46
Q

The Bohr effect

A

The effect that extra CO2 has on haemoglobin, explaining the release of more O2 where there’s lots of CO2

47
Q

Bohr shift

A

The haemoglobin dissociation curve shifts to the right and down

48
Q

What is the direction of flow in xylem?

A

One direction - up

49
Q

What is the direction of flow in phloem

A

Both directions

50
Q

Endodermis

A

Sheath around the vascular bundle in roots that is at the same point as the Casparian strip and causes water to flow through the symplast pathway

51
Q

Cambium

A

Meristematic tissues between the xylem and phloem in the stem

52
Q

What is the structure of phloem?

A

Sieve tube elements (with sieve plates at the end of the cells)
Companion cells

53
Q

What is the structure of companion cells?

A

Contains the nucleus
Contains lots of mitochondria for ATP
Contains plasmodesmata between the companion cell and the sieve tube elements

54
Q

How do companion cells work?

A

Active loading

  • H+ ions are actively transported out of the companion cells
  • A concentration gradient is set up
  • Cotransport occurs when H+ ions diffuse back into the companion cell with sucrose via facilitated diffusion
  • Sucrose diffuses through the plasmodesmata into the sieve tube
55
Q

How does translocation work?

A

Mass flow- hydrostatic pressure causes sap to move from the source to the sink

56
Q

What is a source?

A

Any part of the plant that loads sucrose into the sieve tube of phloem
eg. leaves producing sucrose from photosynthesis or roots turning starch into sucrose

57
Q

What is a sink?

A

Any part of the plant that removes sucrose from sieve tubes

58
Q

What are plasmodesmata?

A

Gaps in the cell wall containing cytoplasm connecting two cells

59
Q

What is the apoplast pathway?

A

Goes around/between cells

Mass flow

60
Q

What is the symplast pathway?

A

Water enters the cytoplasm, then passes through the plasmodesmata

61
Q

Vacuolar pathway

A

Similar to symplast pathway, but can travel through the vacuoles as well

62
Q

How does water leave the leaf?

A
  • Water enters the leaf in the xylem
  • Osmosis causes water to move into the spongy mesophyll layer
  • Water evaporates from the spongy mesophyll layer from the cell walls into the air pockets
  • Water vapour diffuses out of the open stomata down the water potential gradient
63
Q

What is the function of transpiration?

A
  • Maintains turgidity
  • Transports minerals
  • Supplies water for photosynthesis and growth
  • Keeps the plant cool
64
Q

What affects rate of transpiration?

A 
Light intensity
water availability
Humidity
Temperature
Air movement
65
Q

How do you measure the rate of transpiration?

A

With a potometer, measure the amount the meniscus has moves

66
Q

What needs to be done to the experiment (measuring the rate of transpiration) to make it work?

A

No air bubbles - set up under water
Healthy shoot
Cut stem under water at an angle
Dry leaves

67
Q

What is the Casparian strip?

A

Strip in roots that makes sure the water is in the symplast pathway going through the endodermal cells to allow the water to enter the xylem

68
Q

How is water moved through the xylem?

A

Capillary action - adhesion because the xylem is narrow
Transpiration pull - cohesion

Root pressure - active transport of minerals lowers the water potential so draws more water into the xylem at the roots

69
Q

What are hydrathodes?

A

Part of the plant that releases water (dew) which evaporates and aids transpiration

A Level (25 decks)

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