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Biology > 3.3 Organisms exchange substances with their environment > Flashcards

3.3 Organisms exchange substances with their environment Flashcards

1
Q

How should ratios be written

A

x:1

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2
Q

How does surface area to volume ratio change with size

A

Larger organisms have a higher surface area to volume ratio

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3
Q

Why can’t larger organisms get all their molecules from diffusion

A

Diffusion is too slow to transport sufficient molecules
Most cells are too far away from exchange surfaces
Requires a specialised exchange surface AND a mass transport system

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4
Q

What should a gas exchange system do

A

Allow efficient gas exchange and minimise water loss

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5
Q

Insect GAS EXCHANGE adaptations

A
  • Highly branched to give larger surface area
  • Thin walls to provide short diffusion distance
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6
Q

Insect WATER LOSS adaptions

A
  • Impermeable exoskeleton made of chitin reduces water loss
  • Spiracles which can close during low activity
  • Hairs around spiracles
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7
Q

High activity in insects

A
  • Contracting muscles produce more lactic acid
  • Lowering water potential of muscle cells
  • Water moves into muscle cells from tracheole
  • Increasing surface area of tracheole for gas exchange
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8
Q

Low activity in insects

A
  • Contracting muscles produce less lactic acid
  • Increasing water potential of muscle cells
  • Water moves out of muscle cells into tracheole
  • Reducing surface area of tracheole for gas exchange
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9
Q

Lamellae adaptations

A
  • Thin surface membrane do short diffusion pathway
  • Large blood supply to ensure O2 is taken away and diffusion gradient is maintained
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10
Q

Counter current system

A
  1. Blood from the body and fresh water pass each other in opposite directions
  2. Blood always passes water with a higher O2 concentration
  3. A concentration gradient is maintained along the entire length of the gill
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11
Q

Gill structure

A

Gill arch
Gill filament
Lamellae - site of gas exchange

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12
Q

Plant GAS EXCHANGE adaptations

A
  • Thin to provide short diffusion pathway
  • Wide and flat to provide a large SA for gas exchange
  • Mesophyll are loosely packed, providing a large SA and allowing easy diffusion of gases
  • Stomata can open and close in times oh high/low activity
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13
Q

Plant WATER LOSS adaptations

A
  • Waxy cuticle reduces evaporation of water
  • Stomata can close to reduce evaporation of water
  • Stomata are mainly on lower surface, reducing direct exposure to the sun
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14
Q

Xerophyte adaptations

A
  • Thick waxy cuticle to reduce water loss from evaporation
  • Thick stem to store water
  • Wide and deep root system to collect water
  • Stomata only open at night when it’s cooler to reduce evaporation
  • Leaves are thin spines to reduce SA and water loss
  • Sunken stomata preventing water loss
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15
Q

Alveolar epithelial GAS EXCHANGE adaptations

A

Flattened cells - short diffusion pathway
Permeable - allow diffusion of oxygen/carbon dioxide
Large surface area - more gas exchange

Good blood supply - concentration gradients are maintained
One cell thick - short diffusion pathway

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16
Q

Inspiration

A

External Intercostal muscles contract
Internal intercostal muscles relax
Ribcage pulled up and out
Diaphragm contracts and flattens
Volume of lungs increases
Pressure in lungs decreases so air pulled in

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17
Q

Expiration

A

External intercostal muscles relax
Internal intercostal muscles contract
Ribcage pulled down and in
Diaphragm relaxes and moves up
Volume of lungs decreases
Pressure in lungs increases so air forced out

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18
Q

Protein hydrolysis

A

Protein –> shorter polypeptides –> amino acids

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19
Q

Carbohydrate digestion

A

Amylase produces in salivary glands and pancreas hydrolyses starch into MALTOSE.
Membrane bound disaccharidases in small intestine hydrolyse disaccharides into monosaccharides e.g. glucose/fructose/galactose

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20
Q

Protein digestion (4)

A
  1. Hydrolysis of peptide bonds
  2. Endopeptidase act in the middle of protein/polypeptide
  3. Exopeptidase’s act at end of protein/polypeptide
  4. Dipeptidase acts on dipeptide/between two amino acids
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21
Q

Lipid digestion

A
  1. Micelles contain bile salts and fatty acids/monoglycerides;
  2. Make fatty acids/monoglycerides more soluble (n water
  3. Fatty acids/monoglycerides absorbed by diffusion;
  4. Triglycerides reformed in cells
  5. Vesicles move to cell membrane;
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22
Q

Bile function

A
  • Neutralises stomach acid
  • Emulsifies lipids into micelles for digestion
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23
Q

Haemoglobin structure and function

A

Quaternary structure: 4 polypeptides with a hame group, contains Iron
Function: binds to oxygen in the lungs and transports it around the body

24
Q

What does oxygen affinity depend on

A

If there is a high O2 concentration (lungs), affinity for oxygen is high so haemoglobin loads oxygen
If there is a low O2 concentration (respiring cells), affinity for oxygen is low, so haemoglobin unloads oxygen

25
Oxidised version of haemoglobin
Oxyhaemoglobin
26
Cooperative nature of oxygen binding
1. First O2 does not bind easily with haemoglobin, once it does, haemoglobin changes shape 2. 2nd and 3rd haemoglobin bind easily once it has changed shape 3. Fourth O2 is harder to bind as there is only one binding site left
27
Effect of CO2 on blood
Increases acidity of blood, decreasing affinity of O2 for HB, so HB holds less O2 for respiring cells, but haemoglobin unloads oxygen
28
Foetal haemoglobin
Has a higher affinity for oxygen than mother so that the foetal HB will take O2 from mothers HB
29
Animals with high metabolism affinity for oxygen
Low as they need to release O2 easily and readily for respiration
30
Underground organisms affinity for oxygem
High affinity for oxygen, so oxygen can be loaded easily in a low oxygen environment
31
Blood circulation path
RA -> RV -> PA -> Lungs -> PV -> LA -> LV -> (A -> Body -VC)/(RA -> Kidneys -> RV)
32
Valve between atria and ventricles
Atrioventricular valve
33
Valve between ventricles and pulmonary vein/artery
Semilunar valves
34
Why id the heart called a double circulation system
Blood passes twice through the heart per circulation
35
Cardiac cycle
1. Blood enters both atria (atrial diastole) 2. Atrial systole - atria contract, increasing pressure in atria. Pressure is greater in atria than ventricles. 3. Atrioventricular valves open and blood moves into ventricles (ventricular diastole) 4. Ventricular systole - ventricles contract, increasing pressure in ventricles. Pressure is greater in ventricles than arteries 5. Semilunar valves open so blood flows into aorta/pulmonary artery
36
Artery adaptations
Smooth - reduces friction and chance of clotting Thick elastic and muscular wall to withstand high pressure Small lumen Surrounding edothelium
37
Vein adaptations
Large lumen Thin elastic and muscular wall - low pressure Valves to prevent back flow due to low pressure Surrounding muscles contract to maintain blood flow Surrounding endothelium
38
Capillary adaptations
One cell thick - short diffusion pathway Narrow lumen Permeable - allows movement of gases, but not large molecules Red blood cells pass in single file to increase surface area in contact with wall
39
Arteriole structure
Same as artery but larger lumen and thinner elastic and muscular muscle they do not have to withstand as high pressures
40
Tissue fluid
1. Ventricle contraction cause high hydrostatic pressure 2. Forces water and solutes out of capillary into capillary bed 3. Large structures remain in blood (RBC's and proteins) 4. Loss of water in capillary reduces the water potential in blood 5. Water enters the blood in the capillary by osmosis 6. Excess tissue flood eventually returned to the blood
41
What is the capillary bed
A network of tiny blood vessels connecting arterioles and venules
42
Xylem structure
Tubes of elongated dead cells RIngs of ligning for support No end walls so water can pass through
43
Cohesion tension theory
1. Water evaporates from leaves 2. This draws water from the xylem 3. This creates tension (a pulling force) on the water 4. Water is pulled up the xylem as a column 5. Cohesion between water molecules and adhesion with the cell walls allows an unbroken column of water to rise up the xylem
44
What does the xylem transport
Water and mineral ions
45
Phloem structure
Elongated tubes of living cells End walls have pores to allow dissolved substances to pass through No nuclei and limited organelles to allow more flow Companion cells help with translocation
46
What process does xylem help with
Transpiration stream
47
What process does phloem help with
Translocation
48
What does the phloem transport
Organic compounds such as amino acids and sugars (sucrose)
49
Why does water move from the roots to the shoots
Constant loss of water from leaves and constant uptake of water in roots causes cohesion tension principle
50
Mass flow hypothesis
1. Glucose produced in photosynthesis in chloroplasts 2. Glucose converted into sucrose 3. Sucrose actively transported into phloem by companion cell 4. Lowers water potential of phloem and raises hydrostatic pressure 5. Causes mass flow os sucrose to roots 6. Sucrose forced out of phloem due to hydrostatic pressure 7. Raises water potential of phloem 8. Water leaves phloem and enters xylem by osmosis 9. fall in hydrostatic pressure in phloem
51
Movement of sucrose in a plant
Shoots to roots Sources to sinks PLaces where glucose is produced to where sucrose is used
52
Movement of water in a plant
Roots to shoots
53
Ringing experiments
1. Ring of bark removed from tree 2. Trunk only contains xylem, not phloem 3. Bulge appears above ring 4. Shows that phloem transports sucrose down the stem 5. Non-photosynthetic tissues below ring die
54
Where is phloem found
In the bark
55
Tracer experiments
1. Transparent plastic bag containing radioactive 14CO2 placed over plant 2. Compounds with 14CO2 can be detected by X-ray 3. 14C is converted to glucose and then sucrose 4. Provides evidence for movement of carbohydrates in plants

Biology (8 decks)

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