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Biology Paper 1 > TOPIC 4: EXCHANGE AND TRANSPORT > Flashcards

TOPIC 4: EXCHANGE AND TRANSPORT Flashcards

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1
Q

What happen to the surface area to volume ratio as you increase the size of the organisms?

A

Increasing size means decreasing the surface area to volume ratio.

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2
Q

Explain why smaller organisms consume more oxygen per kg than larger organisms.

A
  1. Smaller organisms have larger SA:Vol
  2. Heat more readily lost to surroundings
  3. Increased respiration to regulate body temperature 4. Increase demand for oxygen for increased respiration
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3
Q

What does it mean that the membrane is a fluid mosaic model?

A

It is a phospholipid sea with an assortment of proteins that are free to move past each other

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4
Q

Define diffusion

A

The movement of particles from an area of high concentration to low concentration, across the concentration gradient. (Small non-polar and lipid-soluble molecules)

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5
Q

Define Facilitated diffusion

A

Diffusion which takes place through a carrier protein or protein channel (small and large polar molecules)

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6
Q

Define Osmosis.

A

The net movement of water through a semi-permeable membrane, from an area of high water potential to an area of low water potential

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7
Q

Define Active transport.

A

The movement of substances across a membrane against a concentration gradient, using energy in the form of ATP (small charged atoms)

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8
Q

Describe how bulk substances can be transported into and out of cells.

A
  1. Exocytosis - movement or large molecules out of the cell through fusion of vesicle and membrane.
  2. Endocytosis - movement of large molecules into the cell through vesicle formation.
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9
Q

What is the equation for water potential?

A

Water potential = turgor pressure + osmotic pressure

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10
Q

Explain what happens to the mass of cells in a hypertonic, hypotonic, isotonic environment?

A
  1. Hypertonic environment: Mass decreases due to water moving out to low water potential
  2. Hypotonic environment: Mass increases due to water moving in where water potential is low
  3. Isotonic environment: No change in mass as no net movement of water
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11
Q

How are insects adapted for gas exchange?

A
  1. Tracheoles are thin to provide a short diffusion distance.
  2. There are many tracheoles to provide a large surface area for more gases to be exchanged at a given time.
  3. Spiracles are external where PO2 is high and pCO2 is low compared to inside the insect therefore concentration gradient is maintained.
  4. Insects contract their abdomen to increase rate of gas exchange.
  5. Some insects have liquid in the tracheoles to regulate the rate of gas exchange.
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12
Q

How are fish adapted for gas exchange?

A
  1. Lamella provide gills with a large surface area for more gases to be exchanged at a given time.
  2. There is a rich bloody supply through the lamella to maintain a concentration gradient.
  3. The lamella are very thin to provide a short diffusion distance.
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13
Q

How are mammals adapted for gas exchange?

A
  1. Alveoli provide the lungs with a large surface area for more gases to be exchanged at a given time.
  2. There is a rich bloody supply to maintain a concentration gradient.
  3. The lining of the alveoli and capillaries are one cell thick to provide a short diffusion distance.
  4. The lining of the alveoli are moist to allow gases to dissolve before they diffuse into the blood
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14
Q

How are plants adapted for gas exchange?

A
  1. Spongy mesophyll cells increase the surface area for where gases are exchanged.
  2. Stomata open and close to allow for gases to be exchanged.
  3. Air spaces in the leaf maintain a concentration gradient.
  4. Spongy mesophyll cells are moist for gases to diffuse.
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15
Q

What are the advantages of a double circulatory system?

A
  1. Oxygenated blood is delivered at high pressure

2. Oxygenated blood reaches tissue undiluted by deoxygenated blood.

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16
Q

What are the factors that increase the risk of developing atherosclerosis?

A

Genes, age, smoking, weight, lack of exercise and poor diet

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17
Q

Describe the structure of haemoglobin.

A

Globular protein with a quaternary structure of 4 polypeptide chains each containing a haem group

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18
Q

Define translocation.

A

Movement of substances (sucrose) through the plant

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19
Q

Describe how myogenic stimulation controls the cardiac cycle

A
  1. Depolarisation at SAN which sends a wave of excitation to both atria causing atrial systole.
  2. At the same time an impulse is sent to the AVN where it is delayed so the ventricle can fill.
  3. AVN sends a wave of excitation to bundle of His (allowing atrial diastole) then to the purkinje fibres.
  4. Purkinje fibres cause ventricle systole from the apex upwards so squeezing blood out of the heart.
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20
Q

Identify the waves on an ECG trace.

A
  1. P wave - Atrial systole
  2. QRS wave - Ventricular systole
  3. T wave - Recovery wave (ventricular diastole)
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21
Q

What are the components of blood and their function?

A
  1. Plasma - Transport: nutrients, water, proteins, hormones, excretory products
  2. Erythrocytes - Transports oxygen and carbon dioxide.
  3. Leucocytes - Lymphocytes, phagocytes, neutrophils and monocytes (engulf microorganisms and cell fragments), eosinophils and basophils (inflammation and allergic reactions)
  4. Platelets - blood clotting mechanism
22
Q

Describe the stages that lead to atherosclerosis.

A
  1. Damage to endothelial layer - cholesterol, fibres and calcium form the atheroma (plaques) under the endothelial cells
  2. Increased blood pressure - narrower lumen increases blood pressure which causes more damage to endothelial walls.
  3. Atheroma can rupture or break off and lead to: aneurysms, angina and myocardial infarction, strokes
23
Q

What is the Bohr effect?

A

Changes in oxygen dissociation curve of haemoglobin that occur due to a rise in carbon dioxide levels and a reduction in affinity of haemoglobin for oxygen

24
Q

Describe how oxygen dissociates from haemoglobin.

A
  1. Carbon dioxide binds to water in the red blood cell and forms carbonic acid.
  2. Carbonic acid dissociated into H+ and hydrogen carbonate ion.
  3. H+ displaces O2 on the haemoglobin and O2 diffuses out of the red blood cell.
25
Q

Explain the difference in oxygen affinity between adult haemoglobin and fetal haemoglobin.

A

Fetal haemoglobin has a higher affinity for oxygen so it can remove O2 from maternal blood

26
Q

Describe the difference in structure and function between haemoglobin and myoglobin.

A
  1. Myoglobin is also globular but a single chain with a haem group.
  2. Myoglobin has a higher affinity for O2 so is saturated easily and acts as a store in muscles.
27
Q

State the structure and function of the xylem

A

The Xylem transports water and mineral ions

It has a dead, lignified cell wall, no cytoplasm, pits, no cell wall between cells (hollow tube)

28
Q

State the structure and function of the phloem.

A

The Phloem transports organic solutes

It has Living cells , small cytoplasm, sieve cells with sieve plates between cells, companion cells actively pump sucrose to sieve cells through plasmodesmata

29
Q

Describe the formation of tissue fluid

A

Blood plasma drawn out of capillaries at arterial end because hydrostatic pressure is higher than the osmotic pressure.

30
Q

Describe the entry of tissue fluid

A

fluid moved back into the capillaries at venule end because osmotic pressure is higher than the hydrostatic pressure

31
Q

State the difference between apoplastic and symplastic pathways of water through a plant.

A

Apoplastic pathway: Transports water through cellulose cell wall

Symplatic pathway: Transports water though cytoplasm and between cells through plasmodesmata

32
Q

Explain how temperature affects the transpiration rate

A

Increasing temperature increases the kinetic energy, meaning more evaporation and therefore increased transpiration.

33
Q

Explain how light affects the transpiration rate

A

Decreasing light closes stomata, reducing diffusion of water out therefore reduced transpiration

34
Q

Explain humidity affects the transpiration rate

A

Increasing the humidity reduces the concentration gradient which reduces diffusion therefore meaning reduced transpiration

35
Q

Explain how wind affects the transpiration rate

A

Increasing wind means vapour removed from leaf surface, increasing concentration gradient therefore increasing transpiration

36
Q

Explain the shape of the oxygen dissociation curve.

A
  1. At low ppO2: a small increase in ppO2 = small change in % saturation as 1st O2 to bind to haemoglobin is slow.
  2. Steep incline in the middle as a small increase in ppO2 = large increase in % saturation as 2nd and 3rd O2 bind to haemoglobin faster.
  3. At high ppO2: A small increase in ppO2 = small change in % saturation as 4th O2 to bind to haemoglobin is slow
37
Q

Describe the process of blood clotting.

A
  1. Platelets gather around the damaged area and secrete thromboplastin.
  2. Thromboplastin which catalyses conversion of inactive prothrombin to the active enzyme active.
  3. Thrombin catalyses conversion of fibrinogen into insoluble mesh of fibres called fibrin. Calcium ions are required for conversion
  4. Platelets and red blood cells get trapped in the mesh forming a clot.
  5. Serotonin causes vasoconstriction to reduce blood flow at damaged area.
38
Q

Function of the Arteries

A

Vessels that carry blood from the heart to tissue under high pressure

39
Q

Structure of the arteries

A
  1. Outer collagen layer
  2. Thick layer of elastic fibre and smooth muscle
  3. Endothelium cells
40
Q

Function of the Veins

A

Vessels that carry blood from tissue to the heart under low pressure.

41
Q

Structure of the veins

A
  1. Outer collagen layer
  2. Thin layer of elastic fibre and smooth muscle
  3. Endothelium cells
  4. Valves to prevent backflow
42
Q

Function of capillaries

A

Minute vessels where substances are exchanged at tissue

43
Q

Structure of capillaries

A

One layer of endothelium cells

44
Q

Define atrial systole

A

Atria contract forcing atrioventricular valves to open

45
Q

Define cardiac diastole

A

Atria and Ventricles relax

46
Q

List factors that increase risk of Atherosclerosis

A
  1. Age
  2. Obesity
  3. Gender
  4. High cholesterol levels
  5. Smoking
  6. Poor diet
47
Q

What can atherosclerosis lead to?

A
  1. Stroke
  2. Angina
  3. Myocardial Infarction
  4. Aneurism
48
Q

Equation for cardiac output and list units

A

Stroke Volume x Heart Rate

49
Q

Blood pressure equation

A

Systolic/Diastolic pressure

50
Q

Mass flow definition

A

Method of transportation in which pressure differences are used to move fluid

51
Q

Explain how the structure of the membrane controls the transport of polar molecules

A
  1. The cell membrane is a phospholipid bilayer
  2. Phosphate head is hydrophilic whereas the fatty tails are hydrophobic
  3. Polar molecules are charged and are hydrophilic and water soluble so they do not pass through the hydrophobic centre
  4. They pass the membrane through channel carrier proteins

Biology Paper 1 (17 decks)

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