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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
How do insects regulate ventilation?
- 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
26
Features of a good transport system
Fluid to carry nutrients/O2/waste Pump Exchange surfaces Tubes for mass flow
27
Disadvantages of a single circulatory system
Blood pressure drops more | Rate of delivery of things is limited
28
Advantages of double circulatory system
Higher pressure Can have different pressures between Pulmonary and systemic circulation Heart increases pressure
29
How does an open circulatory system work?
- 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
Disadvantages of open circulatory system
Blood pressure low Slow flow Affected by body movements
31
Endothelium
Inner lining of blood vessels | One cell thick
32
What do veins have that no other vessel has?
Valves to prevent back flow
33
Erythrocytes
Red blood cells
34
What is the function of tissue fluid?
Surrounds body cells so exchange of gasses can occur at the plasma membrane
35
Where does tissue fluid go?
Some goes back into capillaries by oncotic pressure | Some goes into the lymphatic system
36
What separates the ventricles?
The septum
37
Structure of the heart muscle
``` Cross bridges between fibres - cause squeezing action Numerous mitochondria Myofibrils Separated by intercostal disks Sarcomeres - contractile units ```
38
Cardiac cycle
Diastole Atrial systole Ventricular systole
39
How do valves in the heart shut?
Pressure inside rises Blood pushes upwards into valve pockets Tendinous chords prevent valves turning inside out
40
Ectopic heartbeat
Missed heartbeat, too early or late
41
What is the term for the amount of O2?
Oxygen tension or partial pressure of oxygen
42
What is the s shaped curve called relating to oxygen?
Haemoglobin dissociation curve
43
What is the term for the change in structure of haemoglobin when O2 binds?
Conformational change
44
What are the ways CO2 is transported?
Dissolved in the blood plasma Carbaminohaemoglobin - bound directly to Hb Hydrogen carbonate ions (HCO3-)
45
How are hydrogen carbonate ions made?
- 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
The Bohr effect
The effect that extra CO2 has on haemoglobin, explaining the release of more O2 where there's lots of CO2
47
Bohr shift
The haemoglobin dissociation curve shifts to the right and down
48
What is the direction of flow in xylem?
One direction - up
49
What is the direction of flow in phloem
Both directions
50
Endodermis
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
Cambium
Meristematic tissues between the xylem and phloem in the stem
52
What is the structure of phloem?
Sieve tube elements (with sieve plates at the end of the cells) Companion cells
53
What is the structure of companion cells?
Contains the nucleus Contains lots of mitochondria for ATP Contains plasmodesmata between the companion cell and the sieve tube elements
54
How do companion cells work?
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
How does translocation work?
Mass flow- hydrostatic pressure causes sap to move from the source to the sink
56
What is a source?
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
What is a sink?
Any part of the plant that removes sucrose from sieve tubes
58
What are plasmodesmata?
Gaps in the cell wall containing cytoplasm connecting two cells
59
What is the apoplast pathway?
Goes around/between cells | Mass flow
60
What is the symplast pathway?
Water enters the cytoplasm, then passes through the plasmodesmata
61
Vacuolar pathway
Similar to symplast pathway, but can travel through the vacuoles as well
62
How does water leave the leaf?
- 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
What is the function of transpiration?
- Maintains turgidity - Transports minerals - Supplies water for photosynthesis and growth - Keeps the plant cool
64
What affects rate of transpiration?
``` Light intensity water availability Humidity Temperature Air movement ```
65
How do you measure the rate of transpiration?
With a potometer, measure the amount the meniscus has moves
66
What needs to be done to the experiment (measuring the rate of transpiration) to make it work?
No air bubbles - set up under water Healthy shoot Cut stem under water at an angle Dry leaves
67
What is the Casparian strip?
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
How is water moved through the xylem?
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
What are hydrathodes?
Part of the plant that releases water (dew) which evaporates and aids transpiration

A Level (25 decks)

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