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Biology AQA A Level > Exchange Ch.6 > Flashcards

Exchange Ch.6 Flashcards

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1
Q

Which has a bigger surface area:volume ratio, smaller organisms or bigger organisms?

A

Smaller organisms= bigger sa:volume ratio

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2
Q

How have larger organisms evolved to having a smaller sa : volume ratio

A

Have an exchange surface with large area

Have flattened shape (leaf) cells :close to exchange surface

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3
Q

How is exchange of substances with the environment change depending on sa : volume ratio?

A

With bigger sa: volume ratio there is faster exchange.

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4
Q

How is heat exchange change depending on sa : volume ratio?

A

Bigger sa: volume ratio means greater heat exchange and heat loss

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5
Q

Fick’s Law Equation

A

Rate of diffusion = (conc. gradient x sa) / thickness of surface

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6
Q

What three things give a fast rate of diffusion

A

A big surface area, steep concentration gradient and short diffusion pathway (thin walls)

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7
Q

How is gas exchange done in a unicellular organism

A

Diffusion through the skin surface

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8
Q

How is gas exchange done in insects

A

They have a tracheal system. Spiracle (on body surface) to Trachae to Tracheoles to Cells

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9
Q

How does the Tracheal System work?

A

1) Mass transport- Muscles contract squeeze the trachea and enables the mass movements of air in and air out
2) Air moves along the concentration gradient. Low oxygen and high carbon dioxide at the end of Tracheoles
3) End of Tracheoles have water where gases are dissolved. Anaerobically respiring cells produce lactic acid which makes the water potential more negative. As a result cells take in water, and water volume at the end of tracheoles volume decreases and air is pulled in.

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10
Q

Where is the site of gas exchange in fish?

A

In the gills

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11
Q

How are the gills adapted for efficient gas exchange

A

1) Gill filaments and Lamellae produce a big surface area
2) Thin Epithelium so short diffusion pathway
3) Counter current System maintains a concentration gradient.
4) Rich blood supply

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12
Q

How does the Counter Current System ensure gas exchange

A

The blood and the water flow in opposite directions. This means the water always has a greater concentration of oxygen than in the capillaries and a favourable concentration gradient is maintained. As a result oxygen diffuses into the blood throughout.

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13
Q

How are plants adapted to having an efficient Gas exchange

A

1) Stomata is close to cells so short diffusion path.
2) Air gaps in the spongy mesophyll layer allow space for air to diffuse in.
3) Lots of paliside cells/ large surface area of cells for rapid diffusion
4) Thin flat leaves provides large surface area for gas exchange.

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14
Q

How are xerophyte plants adapted to limit water loss?

A
  • Thicker waxy cuticle (waterproof)
  • Rolled leaves
  • stomata in pits
  • Spines not leaves
  • hairs around stomata
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15
Q

How are insects adapted to limit water loss?

A
  • Small sa: volume ratio
  • Spiracles close often as they can and have air sacs to store air while spiracles are closed.
  • Body surface was waterproof.
  • Spiracles have hairs around them to trap humid air. This decreases the water potential gradient.
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16
Q

What is the route for Human Gas Exchange

A

Trachea to Bronchi to Bronchioles

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17
Q

How are the Trachea, Bronchi and Bronchioles adapted?

A

Trachea and Bronchi have muscas and cillia and rings of cartilage which give structural support and prevent tube collapsing

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18
Q

How is Human Gas Exchange adapted rapid diffusion

A

1) Red blood cells slow
2) Short diffusion pathway
3) Steep conc. gradient
4) Large surface area

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19
Q

What is the cell wall of the aveoli and capillaries made of

A

Aveoli- epithelia cell

Capillaries- endothelial cells

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20
Q

How does Emphysema affect in Aveoli reduce gas exchange

A

Aveoli wall is destroyed reducing surface area and increasing diffusion path. There is also less elastic fibre which means when the aveoli stretched is can not recoil and exhale carbon dioxide out.

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21
Q

Describe the process in Inspiration

A

Diaphragm contracts + flattens. External intercostal muscles contract pulling ribcage upward and outwards. This increases volume and decreases pressure, drawing air into the lungs.

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22
Q

Describe the process of Expiration

A

Diaphgragm relaxes. Internal intercostal muscles contract pulling ribcage downwards and inwards. This decreases volume and increases pressure. Air moves from higher pressure in the lungs to lower pressure in the atmosphere.

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23
Q

Risk Factor

A

A factor that increases the likelihood of a particular negative outcome.

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24
Q

Correlation

A

When there seems to be a relationship between two variables

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25
Q

Describe how carbon dioxide in the air reaches the mesophyll cells in a leaf

A

Carbon dioxide enters via stomata opened by guard cells. Carbon dioxide diffuses through air spaces down diffusion gradient.

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26
Q

Describe how oxygen in aveloli enters the blood capillaries

A

Oxygen diffuses across aveoli epithelium lining and the capillaries endothelium lining.

27
Q

Describe and explain how the lungs are adapted for rapid exchange of oxygen between aveoli and capillaries around them

A

1) Many aveoli= large surface area= faster diffusion
2) Thin epithelium which is flattened creates short diffusion pathway.
3) Ventilation and circulation maintains steep concentration gradient.

28
Q

What two features of worms allow for efficient gas exchange?

A

Long so large surface area for gas exchange

Thin so short diffusion pathway

29
Q

Why would the volume of air breathed out decrease as age increases?

A
  • Internal intercostal muscle(s) less effective

- Less elasticity of lung tissue/ aveoli;

30
Q

Explain the movement of oxygen into the gas exchange system of an insect when it is at rest.

A

Oxygen used in aerobic respiration;
oxygen concentration gradient established
so oxygen diffuses in down the conc gradient

31
Q

How does abdominal pumping help insects move CO2 out?

A

It increases the pressure so outside of the insect has a lower pressure. CO2 moves down the pressure gradient.

32
Q

Explain the advantage of the stomata closing when there is no light.

A

Water is lost through stomata,
By closing it prevents water loss,
This maintains the water content of cells (maintains turgidity).

33
Q

Apart from the stomata how else can gas exchange occur in plants?

A

Through the upper surface/ through the cuticle

34
Q

Why does CO2 uptake fall to zero when there is no light?

A

No photosynthesis so CO2 is not needed.
CO2 produced in respiration so higher conc of CO2 inside leaves.
So CO2 would leave leaf down conc gradient.

35
Q

pulmonary ventilation rate = ?

A

= tidal volume × breathing rate

36
Q

What’s the thorax?

A

between the neck and the abdomen.

37
Q

Why do insects need a gaseous transport system?

A

Its surface to volume ratio is small

38
Q

Why aren’t insects bigger?

A

Smaller surface area to volume ratio because more cells. Need more respiration and the tracheal system can’t meet the demands because it relies on oxygen diffusing and it would take too long. The mass of the exoskeleton would increase which means the insects will not be able to move.

39
Q

Why is it likely that insects use to be bigger?

A

There use to be a higher oxygen concentration and so the tracheal system would take in enough oxygen.

40
Q

What is the route of water in fishes?

A

Enters through the mouth and is passed out over the gills.

41
Q

Why can’t fishes survive outside of water for long?

A

The gills collapse which reduces the surface of area so not enough gas exchange.

42
Q

What would happen without the counter-current flow system?

A

Gas exchange would still occur but at a point of flow equilibrium will be achieved and so no more oxygen will diffuse into the blood. This makes it less efficient.

43
Q

What does the counter-current system do?

A

Maintains a favourable concentration gradient.

44
Q

How is a countercurrent system useful in penguins feet?

A

Penguins have a counter current heat exchanges at the top of the legs. Small vessels (arterioles) have warm blood and are closely allied to venous vessels bringing cold blood back from the feet. Heat flows from the warm blood to the cold blood, so little of it is carried down the feet. This stops penguins feet from freezing.

45
Q

What behaviour would you see with highly active fish to provide enough oxygen?

A

They swim with their mouths open to maintain a high rate of water flow across the gills to provide sufficient oxygen for respiration. E.g sharks and mackerels. Might also have more gill lamellae/ filaments to increase surface area

46
Q

Why can’t plants just use the oxygen produced in photosynthesis for respiration and use the CO2 produced in respiration for photosynthesis.

A

The processes occur at different rates, and photosynthesis only occurs in light whereas respiration always occurs. So the gases are not always sufficient and gas exchange must occur.

47
Q

Where are stomatas found?

A

In the lower eppidermis

48
Q

What is the plural and singular versions of stomata?

A 
Stoma = 1
Stomata = plural
49
Q

How does the stomata open?

A

Ions enter guard cells and water follows due to the decreased water potential. The cells become turgid and open.

50
Q

What adaptation may Xerophyte plants have with their stomata?

A

The stomata opens during the night and closes during the day instead. They collect the CO2 in night so during the day when it is hotter less they can close their stomata and less water is lost.
They also have less stomata to reduce water loss
The stomata are sunken in pits which traps moist air so water gradient decreases.
Hair around stomata.

51
Q

How does air diffuse in when stomata is closed?

A

Through the stomata still as it doesn’t close completely. Could also diffuse through the upper epidermis.

52
Q

Why do humans need to absorb a lot of oxygen?

A

Humans are large and so have a small surface area to volume ratio.
Humans have a high metabolic rate

53
Q

How does the cell lining of trachea and bronchus protect the aveoli?

A

Cells produce mucus which traps dirt and pathogens. The cilia on the cells are like hairs which move mucus to the stomach where it can be destroyed. This prevents infections in the aveoli.

54
Q

Suggest why one way flow in fishes is better than a two way flow like in human lungs?

A

Less energy to change the direction of flow. Water is more dense than oxygen so this would be a lot harder and require more energy.

55
Q

Why would plants in cold regions have difficulty taking up water from the soil?

A

If water is frozen it cannot be taken up by osmosis

56
Q

In cold region, why would decreasing the surface area of a leaf not impact the rate of photosynthesis when it would in a hot region?

A

The surface area of the leaf is not the limiting factor because the cold temperature is. The low temp means less KE and so slower enzyme controlled reactions and less photosynthesis.

57
Q

What are some factors of lung disease?

A

Smoking, genetic makeup, air pollution, infection, occupation

58
Q

How does CO2 in air reach mesophyll cells?

A

Enters via stomata. Diffuses past air gaps and down concentration gradient

59
Q

How would you use a respirometer?

A

Use a marker fluid. soda lime to absorb carbon dioxide . mark starting point of fluid. time for set time. record distance travelled by fluid (mm) and time
taken (s). repeat at least 3 times. use syringe to re-set fluid to start

60
Q

How would you calculate oxygen uptake when using a respirometer?

A

Distance travelled x cross section of capillary (pi r^2) divided by time. ( Divided by mass after)

61
Q

With forced expiration which intercostal muscle contracts?

A

Internal

62
Q

With forced inspiration which intercostal muscle contracts?

A

External

63
Q

How does an asthma attack decrease the volume of air breathed out?

A

Muscle walls of bronchi/bronchioles contract;
Walls of bronchi/bronchioles secrete more
mucus
Diameter of airways reduced;
Flow of air reduced;

Biology AQA A Level (15 decks)

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