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AA biology a level - pippa > Section 3: Organisms exchange substances with their enviroment > Flashcards

Section 3: Organisms exchange substances with their enviroment Flashcards

1
Q

What is metabolism

A

sum of all chemical reactions in the body

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2
Q

what is the relation between surface area to volume ratio and the size of an animal

A

As the size of an animal increases the surface area to volume ratio decreases

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3
Q

What are the three main uses of metabolism

A

muscle contraction and movement
building larger molecules from small ones
maintain body temperature

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4
Q

Name the key parts of a tracheal system in an insect

A

spiricales
Trachea
Chitin
Tracheoles

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5
Q

How is the insect gas exchange system adapted

A
  1. large number of tracheoles
  2. thin tracheole walls and short diffusion pathway ( spiricales —> tracheoles)
  3. steep concentration gradient as uses O2 and produces CO2
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6
Q

Do insects have a transport system

A

No

As oxygen needs to be transported directly to tissues which are undergoing respiration

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7
Q

Name the process by which carbon dioxide is removed from a single-cell organism

A

diffusion over the body surface

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8
Q

Explain why there is a conflict in terrestrial insects between gas exchange and conserving water

A

Gas exchange requires a thin permeable surface with a large surface area. Conserving water requires thick waterproof surfaces with a small area

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9
Q

Explain how the tracheal system limits the size of insects

A

because it relies on diffusion to bring oxygen to the respiring tissues. If insects were large it would take too long for oxygen to reach the tissues rapidly enough to supply their needs

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10
Q

How do insects prevent water loss

A

small surface area to volume ratio
waterproof coverings - rigid outer skeleton of chitin
spiracles - open and close when at rest
internal gas exchange system

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11
Q

What are the insects three methods of moving gas

A
  1. simple diffusion through spiricales - usage and production of O2 and CO2 provide conc gradient from tracheoles to outside
  2. mass transport - mass flow of air into tracheal system by closing spiracles and contracting and relaxing abdominal muscles pressure changes
  3. Anaerobic respiration and production of lactate
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12
Q

Describe anaerobic respiration in insects

A

anaerobic repiration produces lactate
lactate lowers water potential in cells
water moves from tracheoles to cells (osmosis)
tracheal fluid reducing draws more air to tracheoles

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13
Q

What is the exoskeleton made up of

A

Polysaccharide chitin

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14
Q

What is on the surface of the exoskeleton and what do they lead to? ( relating to gas exchange system )

A

Spiricales lead to trachea which have tracheoles

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15
Q

What is the role of chitin

A

In insects gas exchange system they are impermeable rings which work to stop structure collapsing. they are impermeable to stop diffusion

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16
Q

What is the role of chitin

A

In insects gas exchange system they are impermeable rings which work to stop structure collapsing. they are impermeable to stop diffusion

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17
Q

Describe the structure of the fish gills

A

gills located behind head of fish
gill arch
made up of gill filaments
at right angles are gill lamellar which inc surface area

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18
Q

What are the adaptations of gill lamellae

A

Maintain concentration gradient: Generous supply of capillaries
Short diffusion pathway: Single layer of flattened cells/ thin membrane
High surface area

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19
Q

In relation to fish gills, describe what is meant by countercurrent flow

A

The movement of water and blood in opposite directions across gill lamellae

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20
Q

Outline why countercurrent flow is an effiecint means of exchanging gasses across the gills of fish

A

Because a steady diffusion gradient is maintained over the whole length of the gill lamellae. Therefore more oxygen diffuse from the water into the blood

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21
Q

Mackeral are active, fast-swimming dish whole plaice spend most of their lives moving slowly on the sea bed. suggest the differences in their gills

A

Mackerel have more gill lamellae / gill filaments / larger surface area compared to plaice

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22
Q

Water flow over fish gills is one way when’s the flow of air in and out of lungs is two-way suggest why one-way flow is an advantage to fish

A

Less energy is required because the flow does not have to be reversed ( important as water is dense and difficult to move)

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23
Q

Is an equilibrium ever reached between water oxygen concentration and gill oxygen concentration

A

No
countercurrent exchange system

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24
Q

What is the role of the operculum

A

hard boney flap-protection

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25
Q

What is the equation for photosynthesis?

A

6CO2 + 6H2O ——-> 6O2 + C6H12O6
chlorophyll and sunlight

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26
Q

Where does the oxygen go after photosynthesis?

A

Most diffuses out of the plant
Some is used for respiration

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27
Q

What are similarities between between plant and insect gas exchange

A
  1. No living cell is far from external air
  2. Diffusion takes place in the gas phase, which makes it more rapid than if it were in water
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28
Q

How are plants adapted for gaseous exchange

A
  1. many small pores called stomata, no cell is far from a stomata and therefore the diffusion pathway is short
  2. air spaces that occur throughout the mesothelioma so that gases can readily come in contact with mesophyll cells
  3. Large surface area of mesophyll cells for rapid diffusion
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29
Q

Explain the advantage of plants to be able to open and close stomata

A

Control water loss my evaporation and transpiration

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30
Q

What is the name of a plant adapted to dry conditions

A

Xerophytic

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31
Q

What is the name of a plant adapted to wet conditions

A

Hydrophytes

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32
Q

What are the adaptations of Xyerophiteg plants

A

Thick waxy cuticle
Sunken stomata to reduce air movement over stomata and create a humid microclimate
Hairy leaves
Curled leaves
Thick epidermis

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33
Q

What are the adaptations of Hydrophytes

A

Floating leaves
Thin waterproof waxy cuticle
Stomata located on the upper surface of the leaves
Reduced root system
Reduced veins in the leaves

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34
Q

How is the Waxy cuticle + Upper epidermis adapted for efficient gas exchange and water regulation?

A

Few or no chloroplasts, cells are transparent and waxy cuticle helps to reduce water loss

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35
Q

How is the palisade mesophyll tissue adapted for efficient gas exchange and water regulation?

A

Elongated for large surface area
Chloroplasts are close to surface to reduce diffusion distance
loads of chloroplasts

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36
Q

How is the air spaces and sponges mesophyll adapted for efficient gas exchange and water regulation?

A

air spaces increase surface area and maintain high concentration gradient for diffusion

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37
Q

State a modification shared by insects and plants to reduce water loss

A

Waterproof covering to the body
ability to close the openings of the gas-exchange system (stomata and spiracles)

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38
Q

Insects limit water loss by having a small SA:V ratio why isn’t this feasible for plants?

A

They photosynthesise

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39
Q

How does rolling up leaves help reduce water loss?

A

Water evaporating from the lead is trapped. The region rolled up becomes saturated with water vapour. There is no water potential gradient between the inside and outside of the lead and so water loss is considerably reduced.

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40
Q

Why would rolling up leaves not be an effective way to reduce water loss if the upper epidermis was on the inside?

A

Almost all stomata are on the lower epidermis. This would be exposed to air currents that would reduce the water potential immediately outside the lead. The water potential gradient would be increased and a lot of water vapour would be lost

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41
Q

Why are the lungs located on the inside of the body

A

air is not dense enough to support and protect the delicate structure
the body as a whole would otherwise lose a great deal of water and dry out

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42
Q

State two reasons why humans need to absorb large volumes of oxygen from the lungs

A

humans are large
have a high metabolic rate
high body temperature

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43
Q

List in correct sequence all the structures the air passes through on its journey from the gas-exchange surface of the lungs to the nose

A

Alveoli
bronchioles
bronchus
trachea
nose

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44
Q

Explain how the cells lining the trachea and bronchus protect the alveoli from damage

A

The cells produce mucus that traps particles of dirt and bacteria in the air breathed in. The cilia on these cells move this debris up the trachea and into the stomach. The dirt / bacteria could damage / cause infection in the alveoli

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45
Q

What happens during inspiration

A

External intercostal muscles contract, while internal intercostal muscles relax
The ribs are pulled upwards and outwards, increasing the volume of the thorax
The diagphram muscles contract, causing it to flatter, which also increases the volume of the thorax
The increased volume of the thorax decreases the pressure in the lungs
Air pressure from the atmosphere is now greater than pulmonary pressure, air is forced into the lungs

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46
Q

What happens in order to increase the volume of the thorax during inspiration

A

The ribs are pulled up and outwards
The diaphragm muscles contract causing it to flatten

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47
Q

What is happening when the external intercostal muscles contract

A

inspiration

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48
Q

What happens during expiration

A

Internal intercostal muscles contract, while external intercostal muscles relax
The ribs are pulled downward and inwards, decreasing the volume of the thorax
The diagphram muscles relax, which also decreases the volume of the thorax
The decreased volume of the thorax increases the pressure in the lungs
The pulmonary pressure s now greater than the atmosphere, air is forced out of the lungs

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49
Q

What is happening when the internal intercostal muscles contract

A

expiration

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50
Q

What is between alveoli

A

collagen and elastic fibres

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51
Q

How do you calculate the pulmonary ventilation rate

A

tidal volume x breathing rate

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52
Q

What is tidal volume and breathing rate

A

tidal volume = volume of air normally taken in at each breath when the body is at rest
breathing rate = number of breaths taken in 1 minute

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53
Q

What are the key features of alveoli for efficient gas exchange?

A

Lots of them to increase surface area: ration
Lined with thin epithelial cells, narrow capillary’s, only single layer of cells to decrease diffusion pathway
narrow capillaries to slow red blood cells as they pass through
constant ventilation and circulation maintains gradient

54
Q

Why are the capillary’s narrow surrounding the alveolus?

A

Short diffusion pathway
Slows red blood cells as they pass through

55
Q

What is the alveolus connective tissue made up of? and what is their role

A

Elastic fibres : allow stretch during ventilation, recoil on expiration to help expel carbon dioxide rich air
collegen : key protein, provides support, structure and scaffolding ( 15% of all lung tissue)

56
Q

Why do alveolar cells release surfactant

A

surfactant is lipid and protein ans breaks up water molecules and reduces surface tension
alveoli walls are moist with water

57
Q

What would happen if alveolar cells didnt have surfactant and only had water?

A

If just water lined the alveoli instead of surfactant, the surface tension would be very high. This would cause the alveoli to collapse and stick together, making it almost impossible to re-inflate them during breathing. Gas exchange would fail, leading to severe respiratory problems.

58
Q

Name four lung diseases

A

Pulmonary tuberculosis ( TB )
Fibrosis
Asthma
Emphysema

59
Q

What lung disease is caused by bacteria and what is the effect on lung function?

A

TB ( Pulmonary tuberculosis )
reduced surface area for gas exchange

60
Q

How does fibrosis affect lung function?

A

thickens lung tissue making lungs less elastic and reducing tidal volume

61
Q

What lung disease causes inflammation and constriction of the airways thus reducing air flow

A

Asthma

62
Q

How does emphysema effect lung disease

A

Damage to alveoli, reducing surface area for gas exchange and elasticity

63
Q

What are some common symptoms to various lung diseases?

A

Shortness of breath, fatigue, coughing, chest tightness or pain, wheezing

64
Q

What are the major parts of the digestive system

A

Oesophagus
Stomach
Ileum
Large intestine
Rectum
Salivary glands
Pancreas

65
Q

What are the two stages of digestion

A

Physical breakdown
Chemical breakdown

66
Q

What is chemical digestion?

A

Chemical digestion hydrolyses large, insoluble molecules into smaller ones. Carried out by enzymes.

67
Q

Describe the chemical digestion of carbohydrates

A
  1. Saliva containing salivary amylase starts hydrolysing starch to maltose
  2. This food is swallowed and the enzymes are denatured by the acidic conditions of the stomach
  3. The food mixes with pancreatic secretions in the small intestine
  4. Pancreatic amylase hydrolyse remaining starch to maltose
  5. Epithelial cells lining the ileum produce maltase that hydrolyse maltose into a-glucose
68
Q

How is maltose digested and where

A

By maltase a membrane-bound disaccharide as it lines the epithelial cells in the ileum where it hydrolyses maltose into a glucose

69
Q

How are lipids digested?

A

Bile salts break up lipids into tiny droplets called micelles. This process is called emulsification
Then hydrolysed by enzymes called lipases that break the ester bond

70
Q

Describe protein digestion

A

Endopeptidase hydrolyse peptide bonds in central region
Exopeptidase hydrolyse peptide bonds on teh terminal amino acids
Dipeptidase hydrolyse the bond between two amino acids

71
Q

What is the final product of starch digestion

A

a glucose

72
Q

List two structures that produce amylase

A

salivary glands and pancreas

73
Q

Suggest why the stomach does not have villi or micro villi

A

Villi and micro villi increase surface area to speed up absorption of soluble molecules. As the food in the stomach has not been hydrolysed yet soluble molecules cannot be absorbed so villi are unnecessary

74
Q

List three enzymes produced by the epithelium the ileum

A

Maltase
Sucrase
Lactase

75
Q

List three organelles that you would expect to be numerous in an epithelial cell of the ileum and why

A

ER to re-synthesise triglycerides from monoglycerides and fatty acids
Golgi apparatus to form chylomicrons from triglycerides, cholesterol and lipoproteins
Mitochondria to provide ATP required for the co-transport of glucose and amino acid molecules

76
Q

Name the chemicals that moves across epithelial cells with glucose during co-transport

A

Sodium ions

77
Q

What increases absorption in the ileum

A

villi
high number of protein chanel’s and carrier proteins

78
Q

How do will i increase absorption efficiency

A

Increase surface area for diffusion
Very thin walls
Contain muscle to move which maintains gradients
Well supplied with blood vessels
also possess microvilli

79
Q

How are triglycerides absorbed

A

Triglycerides are hydrolysed by lipase which break the ester bond into monoglycerides and fatty acids
these are non-polar so diffuse easily into the epithelial cells
once in the epithelial cells they are transported to the ER where they are recombined into triglycerides
Then they go to the golgi where they associate with cholesterol and lipoproteins to from structures called chylomicrons
Chylomicrons move out of the epithelial cells by exocytosis to enter the lymphatic capillaries called lacteals
chylomicrons pass into blood system where they are hydrolysed by an enzyme insider to diffuse into cells

80
Q

What are chylomicrons and where are they formed

A

Triglycerides associated with lipoproteins or cholesterol in the golgi apparatus of epithelial cells lining the ileum

81
Q

Describe the structure of a haemoglobin

A

Four polypeptide chains linked together
Each polypeptide chain is associated with a haem group - which contains a Fe ion
Making a total of four O2 molecules that can be carried by a single haemoglobin molecule in humans

82
Q

Explain how DNA leads to different haemoglobin molecules having different affinity’s for oxygen

A

Different base sequences in DNA - different amino acid sequences - different tertiary abdominal quaternary structure - different affinities for oxygen

83
Q

Why do the 2nd 3rd oxygen molecules bind more easily than the first and fourth

A

The shape of the haemoglobin makes it more difficult for the first oxygen to bind, after it has it changes the quaternary structure of the haemoglobin so the others can bind easier
In theory this should be true for the fourth oxygen molecule however the probability of it binding dramatically decreases when there’s only one possible binding sight

84
Q

If the oxygen dissociation curve is to the left, the…

A

greater is the affinity of haemoglobin for oxygen
so it loads oxygen readily but unloads it less easily

85
Q

If the affinity of haemoglobin for oxygen is very high what does this mean

A

Oxygen will load more readily and unload less easily
Curve to the left

86
Q

If the curve the oxygen disassociation curve is to the right…

A

The lower is the the affinity of haemoglobin for oxygen
so it loads oxygen less readily but unloads very easily

87
Q

The more active a tissue, the more O2 unloaded. Explain this

A

The higher the rate of respiration —> the more CO2 the tissues produce —> the lower the ph —> the greater the haemoglobin shape change —> the more readily O2 is unloaded —> the more O2 available for oxygen

88
Q

In the presence of CO2 is haemoglobin affinity for oxygen high or low?

A

Low

89
Q

When haemoglobin and oxygen bind what is it called

A

Oxyhaemoglobin

90
Q

What is oxygen unloading and loading

A

When haemoglobin assosiates with oxygen the when Oxyhaemoglobin disassociates

91
Q

If the ph is low then haemoglobin affinity for oxygen…

A

Decreases
because low ph indicates high CO2 levels which results in haemoglobin releasing O2 more readily in order to deliver O2 to respiring cells and tissues

92
Q

Mammals have a ______, _____ circulatory system

A

closed, double

93
Q

State the main advantage of the double circulation found in mammals

A

It increases blood pressure and therefore the rate of blood flow to the tissues

94
Q

State two factors that make it more likely that an organism will have a circulatory pump such as the heart

A

Low surface area : volume ration
High metabolic rate

95
Q

What valves separate the ventricle and atriums

A

left and right atrioventricular

96
Q

Name the blood vessel that supplies the heart muscle with oxygenated blood

A

coronary artery

97
Q

What major blood vessels carry oxygenated blood?

A

Aorta
Pulmonary vein

98
Q

What major blood vessels carry deoxygenated blood?

A

Vena Cava
Pulmonary artery

99
Q

What part of the heart does the aorta feed into

A

The left ventricle

100
Q

What is the structural differences between the two types of chambers of the heart

A

Atrium are thin-walled and elastic that stretches
Ventricles are much thicker muscular wall as it had to contract strongly to pump blood around whole body or lungs

101
Q

What blood vessel takes oxygenated blood from the lungs to the heart

A

Pulmonary vein

102
Q

What does the vena cava do

A

Connected to the right atrium and brings deoxygenated blood from the organs and tissues to the heart and lungs

103
Q

List the correct sequence of four main blood vessels and four heart chambers that a red blood cell passes through on its journey from the lungs

A

Pulmonary vein
Left atrium
Left ventricle
Aorta
Vena Cava
Right atrium
Right ventricule
Pulmonary artery

104
Q

Suggest why it is important to prevent mixing of the blood in the two sides of the heart

A

Then there would be only partially oxygenated blood delivered to tissues, gradient wouldn’t be strong enough, inadequate oxygen supplied

105
Q

What is myocardial infarction

A

a heart attack by blood clot in coronary artery

106
Q

What is the relaxation of the heart

A

Diastole

107
Q

Describe the cardiac cycle

A
  1. Diastole : atria filling with blood, atria and ventricle relaxed
  2. Atrial systole : blood from atria into ventricles, atria muscle contracts and ventricle relaxed
  3. Ventricular systole : Blood from ventricles to arteries, ventricle muscle contracted, atria relaxed
108
Q

What happens during ventricular systole

A

Ventricles contract
atrioventricular valves are shut due to high ventricular pressure over atria pressure
semi lunar valves open once ventricular pressure exceeds aorta and pulmonary artery pressure
blood is forced into these vessels

109
Q

What is Cardiac output and how do you calculate it

A

CO : volume of blood pumped by the heart in 1 minute

CO = Stroke volume x heart rate

110
Q

What are the benefits of increased cardiac output?

A

Supply oxygen thus glucose to muscles faster
Remove CO2 and lactate from muscles faster
Remove heat away from muscles

111
Q

What do the atrioventricular valves do

A

prevent back flow of blood when contraction of ventricles means that ventricular pressure exceeds arterial pressure.

112
Q

Name the chamber in the heart that produces the greatest pressure

A

Left ventricle

113
Q

After a period of training the heart rate is often decreased when at rest yet the cardiac output is unchanged. suggest an explanation for this

A

The heart muscles have gotten stronger so stroke volume has increased

114
Q

Name the four types of blood vessels

A

Arteries : carry blood away from the heart
Arterioles : smaller arteries that control blood flow from arteries to capillaries
Capillaries : tiny vessels that link arterioles to veins
Veins : carry blood from capillaries back to the heart

115
Q

How are artery’s related to their function

A

Muscle layer is thick compared to veins : can control volume of blood by constriction and dilation
Elastic layer is relatively thick compared to veins : stretching and recoiling to control blood pressure
Overall thickness of wall : vessel wont burst under high pressure
No valves : blood under high pressure not needed

116
Q

What blood vessel carry blood under high pressure

A

Arteries

117
Q

How is arterioles structure related to its function

A

Muscle layer is thicker than arteries : constriction of the lumen to control blood pressure as it goes into capillaries
Elastic layer thinner than arteries : blood pressure is lower

118
Q

How is the structure of veins related to their function

A

Thin muscle layer, elastic layer and overall wall : low blood pressure
Valves : ensure the blood doesn’t flow backwards

119
Q

How is capillaries structure related to their function

A

Thin : short diffusion distance
Narrow diameter : permeate tissues
Humours and highly branched : high SA
Lumen is narrow : shorter diffusion distance brings them close to wall
There are spaces between the lining cells : allows WBC to escape to deal with infection

120
Q

Why do capillaries have spaces between the lining cells

A

So WBC can escape to deal with infections

121
Q

Describe how tissue fluid is formed

A
  1. high blood / hydrostatic pressure at arterioles end
  2. Forces water out
  3. Large proteins remain in capillary
122
Q

Describe how tissue fluid is returned to the circulatory system

A
  1. low water potential in capillary
  2. due to plasma proteins
  3. water enters capillary / blood by osmosis
123
Q

Describe how tissue fluid is formed and how it is returned to the circulatory system. 6 marks

A

Formation
1. high blood / hydrostatic pressure at arterioles end
2. Forces water out
3. Large proteins remain in capillary

Return
1. low water potential in capillary
2. due to plasma proteins
3. water enters capillary / blood by osmosis

124
Q

What factors effect transpiration

A

Temperature : more sun = more Ek = more evaporation
Wind : water removed from leaf surface creating water potential gradient
Humidity : more moisture in air = less water potential gradient
Light : more light = more photosynthesis = stomata open = more evaporation

125
Q

What is Transpiration Pull in Xylem?

A

Transpiration pull is the process by which water is drawn up the xylem vessels due to the loss of water through the stomata on the leaves. As water evaporates from the leaves, it creates a negative pressure that pulls water up from the roots, keeping the plant hydrated

126
Q

Describe how water moves across the cells of a leaf

A

Mesophyll cells lose water to the air spaces by evaporation due to heal supplied by the sun
these cells now have a lower water potential so water enters by osmosis from neighbouring cells
the loss of water from these neighbouring cells lowers there water potential
they, in turn, take in water form their neighbours by osmosis

127
Q

How does water move from the roots to the leaves. give detail

A

Water evaporates from mesophyll cells due to heat from the sun leading to transpiration
water molecules form hydrogen bonds between one another and hence tend to stick together. This is known as cohesion
Water forms a continuous, unbroken column across the mesophyll cells and down the xylem
As water evaporates from the mesophyll cells in the lead into the air spaces beneath the stomata, more molecules of water are drawn behind it as a result of this cohesion
A column of water is therefore pulled up the xylem as a result of transpiration. This is called the transpiration pull.
Transpiration pull puts the xylem under tension, that is, there is a negative pressure within the xylem, hence the name cohesion-tension theory

128
Q

What evidence supported the cohesion-tension theory in the xylem vessel

A

Change in diameter of tree trunks according to the rate of transpiration
If xylem vessel is broken and air enters it tree can no longer draw up water
when xylem vessel broken water does not leak out

129
Q

What are the three phases describing the mechanism of translocation

A
  1. Transfer of sucrose into sieve elements from photosynthesising tissue
  2. Mass flow of sucrose through sieve tube elements
  3. Transfer of sucrose from the sieve tube elements into storage or other sink cells
130
Q

Describe translocation

A

Source
Active transport load substances into phloem from companion cells
water potential is lowered in phloem so water follows by osmosis
cerastes high pressure at source end
Sink
solutes removed from phloem from respiration or convert to starch for storage
water follows by osmosis
pressure reduced at sink end
pressure gradient causes flow of solute from source to sink

131
Q

What is the structure of the phloem

A

Sieve cells
companion cells - provide ATP for active transport of organic substances
Seive plates

AA biology a level - pippa (7 decks)

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