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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
What is the alveolar epithelium
The alveolar epithelium is the site of gas exchange in humans
26
How is the alveolar epithelium adapted for human gas exchange
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
27
Describe how blood travels
Across alveolar epithelium Endothelium of capillary
28
Describe and explain the mechanism that causes lungs to fill with air
Diaphragm contracts and external intercostal muscles contract Causes volume increase and pressure to decrease in thorax Air moves down pressure gradient
29
Describe the mechanism for breathing out
Diaphragm relaxes and internal intercostal muscles contract Volumes decreases and pressure increases in thorax Air moves up pressure gradient
30
How can lung disease be diagnosed
By measuring lung function
31
What is tidal volume
The volume of air each breath
32
What is ventilation rate
Number of breaths per minute
33
What is forced expiratory volume
The volume of air that can be expelled in 1 second
34
What causes tuberculosis
Small lumps of in the lungs called tubercles
35
What is digestion
Digestion is the process where large biological molecules are hydrolysed into smaller molecules that can be absorbed across cell membranes
36
Describe the digestion of carbohydrates
Hydrolysis of glycosidic bonds Starch to Maltese by amylase Maltose to glucose by disaccharides
37
Describe the digestion of lipids
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
Describe the role of enzymes in the digestion of proteins in a mammal
Hydrolysis of peptide bonds Endopeptidase act in the middle of polypeptide Exopeptidase act in the end of the polypeptide Dipepetidase act on dipeptide
39
Describe the processes involved in the absorption and transport from the ileum into lymph vessels
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
Where does absorption take place in mammals
Along the cell membrane of epithelial cells in the small intestine
41
How are glucose and sodium absorbed by sodium ion co-transporter
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
What is the role of haemoglobin
Carries oxygen around the body
43
Describe the structure of haemoglobin
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
Describe the binding of haemoglobin to oxygen
Haemoglobin binds with oxygen in the lungs to form oxyhaemoglobin It then disassociates from oxygen when it reaches body cells
45
What is partial pressure of oxygen
partial pressure of oxygen (pO2) = concentration of oxygen
46
What happens when there’s a high partial pressure of oxygen compared to low partial pressure of oxygen
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
Describe how binding of one molecule of oxygen to haemoglobin makes it easier for the second oxygen molecule
Binding of the first oxygen changes quaternary structure of haemoglobin Uncovers another binding site
48
What is the Bohr effect
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
What is the advantage of Bohr effect
Increase dissociation of oxygen For aerobic respiration
50
What is a double circulatory system
blood passes through the heart twice in a complete circuit through the body)
51
Describe how blood moves throughout the body
Renal vein Vena cava to right atrium Right ventricle to pulmonary artery
52
What is the hepatic artery
The hepatic artery supplies the liver with blood and the hepatic vein removes deoxygenated blood from the liver
53
What does the hepatic vein do
The hepatic portal vein takes nutrient-rich blood from the small intestine directly to the liver
54
What does the renal vein and renal artery do
The renal artery supplies the kidneys with blood and the renal vein removes deoxygenated blood
55
What does the renal vein and renal artery do
The renal artery supplies the kidneys with blood and the renal vein removes deoxygenated blood
56
What does the renal vein and renal artery do
The renal artery supplies the kidneys with blood and the renal vein removes deoxygenated blood
57
What separates the two sides of the heart
Septum
58
Describe arteriole systole
atria contract, ventricles relax, atrioventricular valves are open
59
Describe ventricular systole
Ventricular systole: atria relax, ventricles contract, semilunar valves are open
60
Describe diastole
Atria and ventricles relax Atrioventricular valves open
61
What are the semi lunar valves
Valves between atria and ventricles E.g the valve between pulmonary artery and right ventricle
62
Describe the structure of arteries
Walls are thick and muscular with elastic tissue to stretch and recoil to maintain pressure as the heart beats
63
How is the artery able to stretch
Inner endothelium (lining) is folded
64
How is the artery able to stretch
Inner endothelium (lining) is folded
65
Describe the structure of vein
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
Describe the structure of vein
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
What are venules
Smaller vessels called venules join together to form veins
68
Describe capillaries
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
How are capillaries adapted for gas exchange
They form capillary beds to maximise surface area for exchange
70
What is tissue fluid
Tissue fluid is the fluid surrounding cells in tissues It is formed from blood plasma
71
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
What is an atheroma
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
What causes coronary heart disease
If many atheromas form in the coronary arteries then this is called coronary heart disease (CHD)
74
What are the risk factors of heart disease
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
What are the risk factors of heart disease
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
What is thrombosis
Thrombosis is a blood clot that can dislodge and block a blood vessel elsewhere in the body
77
What is cohesion
water molecules sticking together
78
Describe cohesion-tension theory of water transport
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
Outline the process of transpiration
Water evaporates Water potential gradient Hydrogen bonds cohesion
80
Describe the mass flow hypothesis for the mechanism of translocation in plants
Leaf sugars are actively transported into phloem By companion cells Lowers water potential of sieve cells Increase in pressure causes mass movement
81
Use your understanding of the mass flow hypothesis to explain how pressure is generated inside this phloem tube
1.Sucrose actively transported (into phloem); 2.Lowers water potential 3. Water moves (into phloem) by osmosis (

Biology Alevels (8 decks)

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