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Biology Alevels > Organisms Exchange Substances Topic 3 > Flashcards

Organisms Exchange Substances Topic 3 Flashcards

1
Q

What does the rate of transfer depend on

A

Surface area :volume ratio

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2
Q

For small animals what is there surface area to volume ratio

A

Higher surface area :volume ratio

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3
Q

How do single cells organisms pass nutrients compared to multicellular organisms

A

Nutrients diffuse through the cell wall

Multicellular organisms have to use transport systems to move nutrients around the body

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4
Q

How does surface area to volume ratio affect heat exchange in smaller animals

A

Smaller animals in colder climates tend to have compact shape to reduce their surface area to volume ratio

In warmer climates animals have adaptations such as large ears ,to maximise surface area to volume ratio

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5
Q

Do small animals have a higher metabolic rate than larger animals

A

Yes ,so they end up losing more heat than larger animals

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6
Q

What are the features of an insects gas exchange system

A

Spiracles

Trachea

Tracheoles

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7
Q

What are spiracles

A

They are openings in their body that lead to air-filled tubes called trachea

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8
Q

What is the trachea and tracheoles

A

Air filled tubes which branch off into smaller tracheoles

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9
Q

How does oxygen and carbon dioxide diffuse into an inect

A

Short distance between a tracheoles and an insect body cell so oxygen and carbon dioxide can diffuse directly

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10
Q

What are the three ways gases move in and out of an insect

A

Down a diffusion gradient

Mass transport

The ends of the tracheoles are filled with water

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11
Q

How does gases move in and out down a concentration gradient in an insect

A

When cells respire ,they use up oxygen and release carbon dioxide which causes a concentration gradient to form

Causes respiratory gases to be exchanged

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12
Q

Explain three ways how the insects tracheal system is adapted for gas exchange

A

Tracheoles have thin walls -so short diffusion distance to the cells

Large number of tracheoles -so large surface area

Trachea provides full tubes of air so fast diffusion

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13
Q

Using knowledge of surface area to volume ratio ,explain the higher metabolic rate of a mouse compared to a horse

A

Larger surface area to volume ratio

More faster heat loss

Faster rate of respiration

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14
Q

Describe the structures involved in the fish gas exchange system

A

Gills

Gill filaments

Lamellae

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15
Q

What are gills and gill filaments

A

Gills are made up of gill filaments which are covered in lamellae

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16
Q

How does lamellae speed up diffusion

A

They increase surface area of the gills

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17
Q

Explain two ways in which the structure of fish gills is adapted for efficient gas exchange

A

Many lamellae so large surface area

Thin surface so short diffusion pathway

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18
Q

Explain how counter current mechanisms in fish gills ensure oxygen to pass into the blood

A

Water and blood flow in opposite directions

Blood passing water with higher oxygen concentration

Diffusion gradient maintained throughout the length of the gill

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19
Q

How are gases exchanged in plants

A

They move in and out of pores called stomata
Stomata opens and closes to control gas exchange

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20
Q

How does guard cells help control gas exchange

A

When plants have enough water, the guard cells around the stomata are turgid and this keeps the stomata open for gas exchange

When plants do not have enough water, the guard cells become flaccid and this closes the stomata to conserve water

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21
Q

What are plants that survive in dry conditions

A

They are called xerophytes

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22
Q

How are xerophytes adapted for gas exchange

A

They have a thick cuticle so less water can escape

The leaves may roll up so the stomata on the lower epidermis on the leaf are not exposed to the outside,
reducing the water potential gradient and water loss

The leaves may have hairs to trap a layer of moist air near the surface of the leaves

to reduce the water potential gradient

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23
Q

Why are plants that are grown in soil grow slow

A

Less stomata

Less carbon dioxide needed for photosynthesis and growth of plants

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24
Q

What are the features of the human gas exchange system

A

The lungs are made up of lots of small air chambers that increase surface area

The trachea (windpipe) branches off into two bronchi, which split into many small bronchioles, that end in tiny air sacs called alveoli

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25
Q

What is the alveolar epithelium

A

The alveolar epithelium is the site of gas exchange in humans

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26
Q

How is the alveolar epithelium adapted for human gas exchange

A

There are millions of alveoli so there is a huge surface area for gas exchange

The alveolar wall is only one cell thick so there is a very short diffusion distance

The alveoli are covered in capillaries

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27
Q

Describe how blood travels

A

Across alveolar epithelium

Endothelium of capillary

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28
Q

Describe and explain the mechanism that causes lungs to fill with air

A

Diaphragm contracts and external intercostal muscles contract

Causes volume increase and pressure to decrease in thorax

Air moves down pressure gradient

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29
Q

Describe the mechanism for breathing out

A

Diaphragm relaxes and internal intercostal muscles contract

Volumes decreases and pressure increases in thorax

Air moves up pressure gradient

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30
Q

How can lung disease be diagnosed

A

By measuring lung function

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31
Q

What is tidal volume

A

The volume of air each breath

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32
Q

What is ventilation rate

A

Number of breaths per minute

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33
Q

What is forced expiratory volume

A

The volume of air that can be expelled in 1 second

34
Q

What causes tuberculosis

A

Small lumps of in the lungs called tubercles

35
Q

What is digestion

A

Digestion is the process where large biological molecules are hydrolysed into smaller molecules that can be absorbed across cell membranes

36
Q

Describe the digestion of carbohydrates

A

Hydrolysis of glycosidic bonds
Starch to Maltese by amylase
Maltose to glucose by disaccharides

37
Q

Describe the digestion of lipids

A

Lipids are digested by lipase and bile salts in the small intestine

Bile salts break up lipids into small droplets called micelles in a process of emulsification

Lipase breaks down the micelles into fatty acids and glycerol

38
Q

Describe the role of enzymes in the digestion of proteins in a mammal

A

Hydrolysis of peptide bonds

Endopeptidase act in the middle of polypeptide

Exopeptidase act in the end of the polypeptide

Dipepetidase act on dipeptide

39
Q

Describe the processes involved in the absorption and transport from the ileum into lymph vessels

A

Micelles contain Bile salts and fatty acids

Make fatty acids soluble in water

Fatty acids absorbed by diffusion

Triglycerides reformed in cells

Vesicle moves to cell membrane

40
Q

Where does absorption take place in mammals

A

Along the cell membrane of epithelial cells in the small intestine

41
Q

How are glucose and sodium absorbed by sodium ion co-transporter

A

Sodium ions are actively transported out of the epithelium cell into the lumen of small intestine

They diffuse back in and take glucose with them through co transporter

42
Q

What is the role of haemoglobin

A

Carries oxygen around the body

43
Q

Describe the structure of haemoglobin

A

haemoglobin is a protein with a quaternary structure - it is made up of four chains, each with a haem group

Each haem group contains an iron ion

so each molecule of haemoglobin has four oxygen binding sites

44
Q

Describe the binding of haemoglobin to oxygen

A

Haemoglobin binds with oxygen in the lungs to form oxyhaemoglobin

It then disassociates from oxygen when it reaches body cells

45
Q

What is partial pressure of oxygen

A

partial pressure of oxygen (pO2) = concentration of oxygen

46
Q

What happens when there’s a high partial pressure of oxygen compared to low partial pressure of oxygen

A

When there is a high pO2 (at the lungs), haemoglobin has a high affinity for oxygen so combines with it to form oxyhemoglobin

When there is a low pO2 (at body cells), haemoglobin has a low affinity for oxygen so it disassociates from it

47
Q

Describe how binding of one molecule of oxygen to haemoglobin makes it easier for the second oxygen molecule

A

Binding of the first oxygen changes quaternary structure of haemoglobin

Uncovers another binding site

48
Q

What is the Bohr effect

A

When partial pressure of CO2 increases

This causes the affinity of haemoglobin for oxygen to decrease, so it disassociates with oxygen

The disassociation curve shifts to the right so more oxygen is released

49
Q

What is the advantage of Bohr effect

A

Increase dissociation of oxygen

For aerobic respiration

50
Q

What is a double circulatory system

A

blood passes through the heart twice in a complete circuit through the body)

51
Q

Describe how blood moves throughout the body

A

Renal vein

Vena cava to right atrium

Right ventricle to pulmonary artery

52
Q

What is the hepatic artery

A

The hepatic artery supplies the liver with blood and the hepatic vein removes deoxygenated blood from the liver

53
Q

What does the hepatic vein do

A

The hepatic portal vein takes nutrient-rich blood from the small intestine directly to the liver

54
Q

What does the renal vein and renal artery do

A

The renal artery supplies the kidneys with blood and the renal vein removes deoxygenated blood

55
Q

What does the renal vein and renal artery do

A

The renal artery supplies the kidneys with blood and the renal vein removes deoxygenated blood

56
Q

What does the renal vein and renal artery do

A

The renal artery supplies the kidneys with blood and the renal vein removes deoxygenated blood

57
Q

What separates the two sides of the heart

A

Septum

58
Q

Describe arteriole systole

A

atria contract, ventricles relax,

atrioventricular valves are open

59
Q

Describe ventricular systole

A

Ventricular systole: atria relax, ventricles contract,

semilunar valves are open

60
Q

Describe diastole

A

Atria and ventricles relax

Atrioventricular valves open

61
Q

What are the semi lunar valves

A

Valves between atria and ventricles

E.g the valve between pulmonary artery and right ventricle

62
Q

Describe the structure of arteries

A

Walls are thick and muscular with elastic tissue to stretch and recoil to maintain pressure as the heart beats

63
Q

How is the artery able to stretch

A

Inner endothelium (lining) is folded

64
Q

How is the artery able to stretch

A

Inner endothelium (lining) is folded

65
Q

Describe the structure of vein

A

Walls are thinner and lumen is larger to decrease resistance as blood is at a low pressure

Contains valves to keep the blood flowing in the right direction

66
Q

Describe the structure of vein

A

Walls are thinner and lumen is larger to decrease resistance as blood is at a low pressure

Contains valves to keep the blood flowing in the right direction

67
Q

What are venules

A

Smaller vessels called venules join together to form veins

68
Q

Describe capillaries

A

Capillaries are the site of exchange of substances between the blood and body cells

Their walls are only one cell thick to minimise the diffusion distance

69
Q

How are capillaries adapted for gas exchange

A

They form capillary beds to maximise surface area for exchange

70
Q

What is tissue fluid

A

Tissue fluid is the fluid surrounding cells in tissues

It is formed from blood plasma

71
Q
A

Plasma) proteins remain;
Accept albumin/globulins/fibrinogen for (plasma) protein
2. (Creates) water potential gradient
OR
Reduces water potential (of blood);
3. Water moves (to blood) by osmosis;
4. Returns (to blood) by lymphatic system;

72
Q

What is an atheroma

A

If the endothelium of an artery is broken then white blood cells and lipids gather under it and form a plaque called an atheroma

73
Q

What causes coronary heart disease

A

If many atheromas form in the coronary arteries then this is called coronary heart disease (CHD)

74
Q

What are the risk factors of heart disease

A

High blood cholesterol due to a diet high in saturated fats

Cigarette smoking
High blood pressure due to lack of exercise, being overweight, or chronic stress

75
Q

What are the risk factors of heart disease

A

High blood cholesterol due to a diet high in saturated fats

Cigarette smoking
High blood pressure due to lack of exercise, being overweight, or chronic stress

76
Q

What is thrombosis

A

Thrombosis is a blood clot that can dislodge and block a blood vessel elsewhere in the body

77
Q

What is cohesion

A

water molecules sticking together

78
Q

Describe cohesion-tension theory of water transport

A

Water lost from the leaves because of transpiration

Lowers water potential of mesophyll
Water pulled up xylem

Water molecules stick together

Forming a water column

Adhesion of water molecules to walls of xylem

79
Q

Outline the process of transpiration

A

Water evaporates

Water potential gradient

Hydrogen bonds cohesion

80
Q

Describe the mass flow hypothesis for the mechanism of translocation in plants

A

Leaf sugars are actively transported into phloem

By companion cells

Lowers water potential of sieve cells

Increase in pressure causes mass movement

81
Q

Use your understanding of the mass flow hypothesis to explain how pressure is generated inside this phloem tube

A

1.Sucrose actively transported (into phloem);
2.Lowers water potential
3. Water moves (into phloem) by osmosis (

Biology Alevels (7 decks)

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