Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Alevel AQA Biology > Organisms Exchange Substances With Their Environment > Flashcards

Organisms Exchange Substances With Their Environment Flashcards

1
Q

Why do cells need to exchange substances with their environment?

A
  • cells need oxygen and nutrients e.g. glucose
  • organisms need to excrete waste products
  • heat needs to be exchanged as most organisms need to stay at the same temperature.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is metabolism?

A

The sum total of all chemical reactions that happen in the body/ cells. Including respiration.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a byproduct of respiration?

A

Heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why do warm blooded animals do more respiration?

A

To maintain body temperature.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the total oxygen requirement of an organism correlated to?

A

It’s total volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why do larger organisms require more oxygen?

A

Larger/ more cells, therefore requiring more energy for cellular processes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the rate of absorption of gasses by an organism correlated to?

A

The size of its surface area. Larger membrane would mean more molecular movement.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why must the volume always be at 1 when showing the relationship between surface area and volume?

A

Allows direct comparison between organisms of different sizes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

By which process do single-celled organisms exchange gases across their body surface?

A

Simple diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why do single-celled organisms have a fast diffusion rate?

A
  • they are small and so have a short diffusion pathway
  • they have a large SA:Vol ratio due to their small volume compared to the surface area of their cell surface membrane.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the disadvantages of larger organisms having lower SA:vol ratios?

A

-diffusion is too slow as some cells are deep within the body
-a large volume of animals has requirements too high for the available surface area.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why do multicellular organisms have an increased metabolic demand?

A

They have more cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why do multicellular organisms have a slower rate of diffusion?

A

-large diffusion distance to inner most cells
-lower SA:vol ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What adaptations have multicellular organisms evolved to increase surface area?

A

Some organisms have evolved to have a body shape which maximises their surface area. E.g. by being flattened or elongated.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Give examples of specialised exchange organs that organisms have developed to maximise gas exchange and transport.

A

-Gills in fish and amphibians, folded into lamella
-lungs in mammals folded into alveoli
Both increase surface area for exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Give an example of a specialised delivery system that organisms have developed to maximise gas exchange and transport.

A

Th oxygen diffuses into the circulatory system (mass transport) to deliver gasses directly to cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What have insects developed for gas exchange and transport?

A

Tracheal system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the tracheal system?

A

Series of specialised tubes in direct contact t with cells. They also maintain a small size to maintain a short diffusion distance. Tubes carry o2 directly to cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The epithelial cells that line the small intestines are adapted for the absorption of glucose. Explain how (5 marks)

A

1.Microvilli provide a large / increased surface area;
2.Many mitochondria produce ATP / release or provide energy (for active transport);
3.Carrier proteins for active transport;
4.Channel / carrier proteins for facilitated diffusion;
5.Co-transportof sodium (ions) and glucose or symport / carrier protein for sodium (ions) and glucose;
6.Membrane-bound enzymes digest disaccharides / produce glucose;

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Covert 2cm2 to mm2

A

200mm2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Convert 1.5×10^-8m2 to um2

A

15000um2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Convert 5×10^3 dm3 to cm3

A

5000000cm3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

5×10^6 cells in 20cm3, how many in 3mm3

A

750 cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

List examples of substances exchanges with the environment

A
  • oxygen and carbon dioxide
  • urea/ ammonia
  • heat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Why do smaller animals have a higher metabolic rate (per gram of body mass)?

A

In order to maintain a constant body temperature , they do more chemical reactions, such as respiration which release heat to maintain body heat.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Why do smaller animals radiate more heat per cm3?

A

They have a larger SA:Vol ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How does surface area:vol correlate to heat loss depending on animal size?

A

Smaller animals have larger SA:Vol ratio compared to larger animals. This means that they radiate more heat per cm3
In order to maintain a constant body temperature, therefore, smaller animals have a higher metabolic rate per gram of body mass
These chemical reactions release heat which is used to maintain body heat.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How have organisms that live in hot climates adapted to stay cool? Give an example

A
  • increase SA:vol ratio
  • can include smaller body size, larger ears, longer faces and longer noses.
  • e.g. camels have long legs and a long neck to increase SA:vol ratio, thin fur and a hump storing fat to provide water.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How have organisms that live in cold climates adapted to stay warm? Give an example

A
  • adapted to reduce SA:Vol ratio
  • decreases loss of heat by radiation and helps maintain internal body temperature.
  • may include larger body size, smaller ears,and compact facial features.
  • e.g. artic fox has small ears, small body, compact facial features and thick fur.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Mammals such as a mouse and a horse are able to maintain a constant body temperature.
Use your knowledge of SA:Vol ratio to explain the higher metabolic rate of a mouse compared to a horse.

A

Mouse:
1. Smaller so larger SA:Vol ratio
2. more/faster heat loss per gram
3. Faster rate of respiration releases more heat.
Allow converse for horse

31
Q

How are single-celled celled organisms adapted for gas exchange?

A

Large SA:Vol ratio and short diffusion pathway

32
Q

By which process do single celled organisms exchange gasses across their body surface?

A

Simple diffusion

33
Q

How are larger organisms adapted for gas exchange?

A

Have specialises gas exchange surfaces, e.g. lungs, which have:
a large SA for diffusion
Thin surface, short diffusion pathway
Maintainence of steep diffusion gradient

34
Q

Explain the advantages for larger animals having a specialised system that facilitates oxygen uptake.

A

1.larger organisms have smaller SA:vol ratio
2. Overcomes long diffusion pathway

35
Q

What is the gas exchange process in insects?

A

-oxygen diffuses in tracheae through spiracles down a concentration gradient.
-the tracheae are lined with rings of chitin to prevent collapsing during ventilation.
- tracheae splits into branches called tracheoles, not lined in chitin (more permeable) branches provide large SA.
- tracheae are in direct contact with body cells and are thin (short diffusion pathway)

36
Q

Why is the tracheae lined with chitin?

A

Prevents it from collapsing during ventilation.

37
Q

Why are tracheoles not lined in chitin?

A

So they are permeable.
Makes them the site of has exchange insects

38
Q

What are features/ adaptations of gas exchange in insects?

A

Short diffusion pathway:
Tracheoles in direct contact with insect body cells
Insects are small so sort diffusion pathway from spiritual to respiration tissues
Tracheoles are thin

Concentration gradient
Cells respire using oxygen so Concentration gradient remains low
Body can be moved by muscles to move air so maintains conc gradient for oxygen and co2

Large SA
Tracheoles are very branched.

39
Q

How is water loss prevented in insects?

A

-exoskeleton made out of chitin, impermeable so reduces water loss by evaporation from insects tissue.
-exoskeleton covered in waxy cuticle which is waterproof
- spircles lined by hairs which trap water vapour around spiracle. Reduces WP gradient.
- insects can open and close spirales

40
Q

Describe how single celled organisms exchange respiratory gasses.
Why is this method only possible in very small organisms?

A

-simple diffusion on their surface
-smaller animals have a larger SA:Vol ratio so faster rate of diffusion and a shorter distance from exchange surface so shorter diffusion pathway

41
Q

An insect lives in air. Describe how the insects is able to obtain oxygen and limit water loss. 6 marks

A

Prevent water loss:
-waxy cuticle so waterproof
-exoskeleton made out of chitin, impermeable
-spiracles open and close and lined with hairs which absorb water

Obtain oxygen:
Enters through spiracles into trachea lined with rings of chitin to prevent collapsing during ventilation.
Branches of into tracheoles not lined with chitin, permeable. Site of gas exchange.

Short diffusion pathway as tracheoles are in direct contact with insect body cells and are thin.
Insects are small maintaining overall short diffusion pathway from spiracles to respirinf tissues.

Concentration gradient
Cells respire using oxygen so low oxygen levels. Muscles move air and so maintain conc gradient for o2 and co2

Large SA
Tracheoles are very branched

42
Q

During excersize where does the fluid in the tracheoles move? Why?

A

Fluids diffuse into the tissue when active.
Activity causes metabolites e.g. lactic acid, to accumulate in tissues, making them hypertonic, so water moves into tissue by osmosis.

43
Q

By which process is lactate produced?

A

Anaerobic respiration

44
Q

Where does the fluid move when resting?

A

Diffuses back into the tracheoles (hypotinic)

45
Q

Fluid in the end of tracheoles moves into tissue during ________.
-cells produce _______ by _________ respiration.
-_______ water potential.
-water moves ___ wp gradient via _______
-increases ______ In tracheoles and reduces ________ to draw more in.
-diffusion through air is ______

A

Exercise
Lactate
Anaerobic
Reduces
Down
Osmosis
Volume
Pressure
Faster

46
Q

What is abdominal pumping?

A

A ventilation mechanism to replace air in trachea

47
Q

What happened when the abdomen is compressed?

A

Increases pressure (compared to atmosphere) Air containing higher levels of co2 is forced through the abdominal spiracles out of the trachea.

Force air out. Vol decrease. Pressure increase. Moves air out via abdomen.

48
Q

What happens when abdomen is expanded?

A

An expanded abdomen lowers pressure (compared to atmospheric) Air containing higher levels of o2 is forced through the thoracic spiracles into the trachea.

Force air in. Vol increase. Pressure decrease. Moves air in thorax.

49
Q

Why do insects do abdominal pumping?

A

To increase air flow In and out of the body.

50
Q

An increase co2 concentration causes the spiracles to…
(Decrease in o2…)

A

Open (to release co2 and Obtain o2)
Negates

51
Q

Why does the concentration of o2 decrease when spiracles are closed?

A

Oxygen is used up in respiration, therefore diffuses from trachea to tissues.
O2 is unable to enter organism.

52
Q

Why is spiracles being closed most of the time an advantage for insects that live in dry conditions?

A

To prevent water loss.

53
Q

Why have fishes developed a very efficient method of gas exchange?

A

Water has a lower oxygen conent than air, and diffusion rates are slower in water than air.

54
Q

How do gills have a short diffusion pathway?

A

Gills have a single layer of epithelial cells and the capillaries within the girls have a single layer of endothelial cells.

55
Q

How do gills have a large surface area?

A

The Gills are folded into filaments, and these are further folded into lamellae.

56
Q

How do the gills maintain a concentration gradient?

A

The gills have lots of blood capillaries.
Blood in the capillaries flows in the opposite direction to flow of water over the gills- this is called counter current flow.

57
Q

How does the counter current flow work?

A

Water and blood flow in opposite directions so the diffusion gradient between the adjacent flows is maintained over the whole lamellae surface

58
Q

What is a concurrent flow?

A

Water and blood flow in the same direction. There is not a concentration gradient along the whole length of the lamellae as equilibrium (of oxygen) is reached

59
Q

The damselfly larva is a carnivore that actively hunts prey. It has gills to obtain oxygen from water.

Some other species of insect have larvae that are simular size and shape to damselflylarvae and also live in water. These larvae do not actively hunt prey and do not have gills.

Explain how the presence of gills adapts the damselfly it’s way of life.

A

Gills provide a larger SA:vol ratio ,so more space for diffusion of oxygen to cells.
As it is actively hunting it needs to respire alot to release energy, so more oxygen is needed.

60
Q

A student calculated that the leaf contained 300 stomata per mm2. How many stomata per um2?
Use standard form.

A

3×10^-4

61
Q

Under 10x objective lens the diameter of the field of view is 0.4mm
A.What is the area?
B. There are 40 stomata in this view. Calculate the number of stomata per mm2

A

A. 0.127mm2
B. 318

62
Q

Where do plants exchange gas?

A

Surface of mesophyll cells via stomata.

63
Q

What gasses are needed by plants, and why?

A

-co2, needed for photosynthesis, o2 is a waste gas.
-o2, needed for respiration

64
Q

How does co2 enter a plant?

A

Diffuses into leaves down a concentration gradient through pores in the surface of the leaf called stomata.

65
Q

How are mesophyll cells adapted for gas exchange?

A

Tall and long shape increases surface area

66
Q

How have leaves adapted to have a large surface area?

A

Large, flat leaf
Tall, long palisade mesophyll cells

67
Q

How have leaves adapted to have a short diffusion pathway?

A

Thin leaf
Air spaces

68
Q

How have leaves adapted to have a concentration gradient?

A

Mesophyll cells use the carbon dioxide, maintaining a low concentration at the mesophyll cells.

69
Q

What causes the stomata to open?

A

More k ions, lowers wp. Water comes out making guard cells turgid, opening stomata.
Cell wall becomes thickened (doesn’t stretch as well)

70
Q

What causes the stomata to close?

A

Less k ions, higher water potential, water exits cells, guard cells become flaccid (plasmolysed)

71
Q

How do plants lose water? By which process is this?

A

Plants lose water through their stomata by diffusion/ evaporation.
Process: transpiration

72
Q

How can plants reduce water loss?

A

-stomata can close when the guard cells lose water and become flaccid
-leaf is covered in hydrophobic waxy cuticle (reduces water loss via evaporation)
-most stomata on lower surface of leaf (reduces water loss by evaporation out of stomata)

73
Q

What type of plants are adapted to hot and dry conditions?
Name an example.

A

Xerophytes. E.g. Marram grass.

74
Q

What further adaptations do xerephytes have to reduce water loss?

A

Rolled leaf shape as upper epidermis is facing inwards to trap humid air.
Reduced leaf surface area for transpiration.
Sunken stomata, humid air is trapped reducing water potential gradient between inside leaf and humid trapped air.
No stomata on exposed lower surface.
Hairs, trap moist air.
Thick cuticle, waxy covering reduced evaporation.

Alevel AQA Biology (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions