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Unit 3 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

The relationship between surface area to volume ratio and metabolic rate for a smaller organism. (3)

A
  1. Smaller so larger surface area to volume ratio
  2. More heat loss
  3. Faster rate of respiration, releases more heat
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2
Q

Explain the advantage for larger animals oh having a specialised system facilitates oxygen uptake. (2)

A
  1. Larger organisms have a smaller surface area; volume ratio
  2. So it overcomes long diffusion pathway
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3
Q

Explain why stomata open due to increase in light intensity (1)

A

Allow CO2 to enter for photosynthesis

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4
Q

Describe how carbon dioxide in the air outside a leaf reaches mesophyll cells inside the leaf (4)

A
  1. CO2 enters via the stomata
  2. Stomata opened by guard cells
  3. Diffuses through air spaces
  4. Down diffusion gradient
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5
Q

Describe and explain an advantage and disadvantage to having a higher stomatal density (4)

A

Advantage:
1. More CO2 uptake
2. More photosynthesis so faster growth
Disadvantage:
3. More water loss
4. Less photosynthesis so slower growth

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6
Q

Adaptations to desert plants (6)

A
  1. Hairs to trap water vapour
  2. Sunken stomata, so trap water vapour and water potential gradient
  3. Thick waxy cuticle layer, so increased diffusion distance
  4. Waxy cuticle, so reduces evaporation
  5. Rolled leaves so decreased surface area for transpiration
  6. Spines so reduces surface are to volume ratio
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7
Q

Explain the Counter-current mechanism (3)

A
  1. Water and blood flow in opposite directions
  2. Blood always passing water with a higher oxygen concentration
  3. Diffusion gradient maintained along length of the lamella
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8
Q

Explain two ways in which the structure of fish gills is adapted for efficient gas exchange (2)

A
  1. Many lamellae so large surface area
  2. Thin so short diffusion pathway
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9
Q

Describe and explain how the structure of the insect gas exchange system provides cells with sufficient oxygen (5)

A
  1. Spiracles lead to tracheae that lead to tracheoles
  2. Open spiracles allow diffusion of oxygen from air
  3. Tracheoles are highly branched so large surface area
  4. Tracheole walls are thin so short diffusion distance
  5. Tracheole walls are permeable to oxygen
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10
Q

Describe and explain how the structure of the insect gas exchange system limits water loss (2)

A
  1. Chitin in tracheae is impermeable so reduce water loss
  2. Spiracles close, preventing water loss
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11
Q

Describe Abdominal Pumping (3)

A
  1. Abdominal pumping in the tubes is linked to CO2 release
  2. Abdominal pumping raises pressure in the body
  3. CO2 pushed out of the body
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12
Q

Explain three ways in which an insect’s tracheal system is adapted for efficient gas exchange (6)

A
  1. Tracheoles have thin walls so short diffusion distance to cells
  2. Highly branched, so short diffusion distance to cells
  3. Highly branched, so increased surface area to cells
  4. Tracheae provide tubes full of air so fast diffusion
  5. Fluid in the end of the tracheoles the moves out during exercise so faster diffusion through the air to the gas exchange surface
  6. Body can be moved to move air so maintains diffusion
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13
Q

Describe and explain 1 feature of the alveolar epithelium that makes the epithelium well adapted as a surface for gas exchange (3)

A
  1. Flattened cells - Reduces diffusion distance
  2. Permeable - Allows diffusion of oxygen
  3. Moist - Increase rate of diffusion
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14
Q

Describe and explain inhaling (4)

A
  1. Diaphragm contracts and external intercostal muscles contract
  2. Causing the volume to increase and pressure to decrease
  3. Air moves out of the lungs via a pressure gradient
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15
Q

Describe the pathway taken by an oxygen molecule from an alveolus to the blood (2)

A
  1. Across Alveolar Epithelium
  2. Endothelium of Capillary
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16
Q

Explain how one feature of an alveolus allows efficient gas exchange to occur

A
  1. The alveolar epithelium is one cell thick
  2. Creating a short diffusion pathway
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17
Q

Describe the gross structure of the human gas exchange system (1)

A

Trachea, bronchi, bronchioles, alveoli

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18
Q

Describe how we breathe in and out (4)

A
  1. Breathing in - Diaphragm contracts and external intercostal muscles contract
  2. Causes volume to increase and pressure to decrease in lungs
  3. Breathing out - Diaphragm relaxes and internal intercostal muscles contract
  4. Causes volume to decrease and pressure to increase in lungs
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19
Q

How are proteins digested? (4)

A
  1. Hydrolysis of peptide bonds
  2. Endopeptidases break polypeptides into smaller peptide chains
  3. Exopeptidases remove terminal amino acids
  4. Dipeptidases hydrolyse the dipeptides into amino acids
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20
Q

Compare endopeptidases and exopeptidase (3)

A
  1. Endopeptidases hydrolyse internal peptide bonds
  2. Exopeptidases hydrolyse bonds at the ends
  3. So increase in surface area.
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21
Q

Describe the action of membrane-bound dipeptidases and explain their importance (2)

A
  1. Hydrolyse peptide bonds to release amino acids
  2. Amino acids can cross cell membrane by facilitated diffusion
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22
Q

Describe the complete digestion of starch by a mammal (5)

A
  1. Hydrolysis
  2. Of Glycosidic Bonds
  3. Starch to maltose by amylase
  4. Maltose to glucose by maltase
  5. Maltase membrane-bound
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23
Q

Function of bile salts and micelles (3)

A
  1. Bile salts emulsify lipids forming droplet which increase surface are
  2. So faster hydrolysis of lipids
  3. Micelles carry fatty acids and glycerol
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24
Q

Describe Lipid Digestion (3)

A
  1. Lipase Hydrolyses triglycerides
  2. Ester bonds break
  3. Form monoglycerides and fatty acids
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25
Q

Explain the advantages of emulsification and micelle formation (2)

A
  1. Droplets increase surface areas
  2. So faster hydrolysis of lipids
  3. Micelles carry fatty acids and glycerol to cell
26
Q

Describe and explain two features you would expect to find in a cell specialised of absorption (4)

A
  1. Folded membrane - so large surface area
  2. Large number of channel/carrier proteins for active transport
  3. Large number of mitochondria so make more ATP
  4. Membrane-bound enzymes so maintains concentration gradient
27
Q

Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels (4)

A
  1. Micelles contain bile salts and fatty acids
  2. Makes fatty acids more soluble
  3. Fatty acids absorbed by simple diffusion
  4. Triglycerides reformed in cell
  5. Vesicles move to cell membrane
28
Q

Describe the roles of micelles in the absorption of fats into the cells lining the ileum (2)

A
  1. Micelles include bile salts and fatty acids
  2. Make the fatty acids more soluble in water
  3. Bring fatty acids to cell
  4. Maintain higher concentration of fatty acids to cell
  5. Fatty acids absorbed by diffusion
29
Q

How is the Golgi apparatus involved in the absorption of lipids (3)

A
  1. Modifies triglycerides
  2. Combines triglycerides with proteins
  3. Packaged for release
30
Q

Explain how monosaccharides and amino acids are absorbed into the blood (5)

A
  1. Some by facilitated diffusion
  2. Sodium ions actively transported from ileum cell to blood
  3. Maintains concentration gradient for sodium to enter cells
  4. Sodium ions enter cell by facilitated diffusion and bring with it a molecule of glucose by co-transport
  5. Facilitated diffusion of glucose into blood
31
Q

Binding of one molecule of oxygen to haemoglobin makes it easier for a second oxygen molecule to bind. Explain Why?

A
  1. Binding of first oxygen changes tertiary structure of haemoglobin
  2. Creates another binding site
32
Q

Explain how changes in the shape of haemoglobin result in the S-shaped oxyhaemoglobin dissociation curve (2)

A
  1. First oxygen binds to haemoglobin causing change in shape
  2. Shape change of haemoglobin allows more O2 to bind easily
33
Q

Haemoglobin is a protein with a quaternary structure. Explain the meaning of quaternary structure (1)

A

Molecule contains more than one polypeptide

34
Q

Describe the advantage of the Bohr effect during intense exercise (2)

A
  1. Increases dissociation of oxygen
  2. For aerobic respiration at the tissues
35
Q

Describe and explain the effect of increasing CO2 concentration on the dissociation of oxyhaemoglobin (2)

A
  1. Increases oxygen unloading
  2. By decreasing blood pH
36
Q

Why curve shifts left when diving (2)

A
  1. Higher affinity for O2
  2. Allows aerobic respiration when diving at lower pO2
37
Q

Animals living at high altitudes shift to the left (3)

A
  1. High altitudes have a low partial pressure of O2
  2. High saturation of haemoglobin with O2
  3. Enough O2 supplied to respiring cells
38
Q

Why small animals have curved to the right (2)

A
  1. Mouse haemoglobin has a lower affinity for oxygen
  2. So more oxygen can be unloaded
39
Q

Why the curve moves to the right for more active animals (2)

A
  1. Curves to the right so lower affinity
  2. Haemoglobin unloads more readily
  3. More oxygen to cells
  4. For greater respiration
40
Q

Three control measures the student must use to reduce the risks associated with carrying and using a scalpel (5)

A
  1. Carry with blade protected
  2. Cut away from body
  3. Cut onto hard surface
  4. Use sharp blade
  5. Dispose of used scalpel as instructed
41
Q

Control measures when packing away after heart dissection (2)

A
  1. Carry sharp instruments by holding handle
  2. Disinfect instruments/surfaces
  3. Disinfect hands
  4. Put gloves in a separate bin to dispose
42
Q

Giver the pathway a red blood cells takes when travelling in the human circulatory system from a kidney to the lungs (3)

A
  1. Renal vein
  2. Vena cava to right atrium
  3. Right ventricle to pulmonary artery
43
Q

Name the blood vessels that carry blood to the heart muscle (1)

A

Coronary Arteries

44
Q

Calculate Cardiac Output

A

Cardiac Output = Stroke Volume x Heart Rate

45
Q

What causes the semi-lunar valve to close (1)

A

Because pressure in aorta is higher than in the ventricle

46
Q

Explain how the atrioventricular valve is closed (2)

A
  1. Ventricle contracts and volume decreases
  2. Pressure in ventricle increases so higher than pressure of left atrium
47
Q

Explain how an arteriole can reduce the blood flow into capillaries (2)

A
  1. Muscle contracts
  2. Constricts lumen
48
Q

Structure and function of artery (5)

A
  1. Elastic tissue to allow stretching
  2. Elastic tissue stretched when ventricle contract
  3. Muscle for contraction
  4. Thick wall withstands pressure
  5. Smooth endothelium reduces friction
49
Q

Explain four ways in which the structure of the aorta is related to its function (6)

A
  1. Elastic tissue to allow stretching
  2. Stretches when ventricles contract
  3. Muscle for contraction
  4. Thick wall withstands pressure
  5. Smooth endothelium reduces friction
  6. Semi-lunar valve prevents backflow
50
Q

Describe type of circulation in fish (1)

A
  1. Single Circulatory system
  2. 2 chambers, 1 ventricle, 1 atrium
  3. One vein carrying blood towards the heart
51
Q

Explain how water from tissue fluid is returned to the circulatory system (4)

A
  1. High hydrostatic pressure forces water out
  2. Proteins remain in capillary
  3. Creates a water potential gradient
  4. Water moves to the blood by osmosis
  5. Returns to blood by lymphatic system
52
Q

Explain the role of the heart in the formation of tissue fluid (2)

A
  1. Contraction of ventricles produces high hydrostatic pressure
  2. This forces water out of blood capillaries
53
Q

High absorption of salt from the diet can result in a higher than normal concentration of salt in the blood plasma entering the capillaries.
This can lead to a build-up of tissue fluid.
Explain how (4)

A
  1. Higher salt results in lower water potential of tissue fluid
  2. So less water returns to capillary by osmosis
  3. Higher salt results in higher blood pressure
  4. So more fluid pushed out of the capillary
54
Q

High blood pressure leads to an accumulation of tissue fluid. Explain how (2)

A
  1. High blood pressure means a high hydrostatic pressure
  2. Increases outward pressure from end of the capillary
  3. So more tissue fluid is formed
55
Q

How is Tissue Fluid formed and reabsorbed (8)

A
  1. At arteriole end, high hydrostatic pressure
  2. Hydrostatic pressure higher than effect of osmosis
  3. Small molecules such as water
  4. Are forced out
  5. Proteins remain in the blood
  6. So lowers the water potential of the blood
  7. Fluid moves back into blood
  8. Water moves by osmosis
56
Q

Describe the cohesion-tension theory if water transport in the xylem (5)

A
  1. Water lost from the leaf due to transpiration
  2. Then lowers the water potential of the mesophyll cell
  3. Water pulled up the xylem, creating tension
  4. Water molecules cohere together by hydrogen bonds
  5. Forming a continuous water column
  6. The water adheres to the walls of the xylem
57
Q

A potometer measures the rate of water uptake rather then the rate of transpiration.
Give two reasons why the potometer does not truly measure the rate of transpiration (2)

A
  1. Water used for support
  2. Water used in photosynthesis
  3. Water produced in respiration
  4. Apparatus not sealed
58
Q

Give two precautions the student should have taken when setting up the potometer to obtain reliable measurements of water uptake by the plant shoot (2)

A
  1. Seal joints to ensure airtight
  2. Cut shoot underwater
  3. Cut shoot at a slant
  4. Dry off leaves
  5. Insert into apparatus under water
  6. Ensure no air bubbles are present
  7. Shut tap
  8. Note where bubble is at start
59
Q

Describe the transport of carbohydrate in plants (5)

A
  1. At source cell, sucrose is produced and transported into phloem
  2. By active transport
  3. By companion cells
  4. Lowers water potential in phloem and water enters via osmosis by xylem
  5. Produces high hydrostatic pressure
  6. Mass flow
  7. Transport from source cells to sink cells
  8. Sugar produced used in respiration
60
Q

Use your understanding of the mass flow hypothesis to explain how pressure is generated inside this phloem tube (3)

A
  1. Sucrose actively transported into phloem
  2. Lowering water potential
  3. Water moves into phloem by osmosis from xylem
61
Q

Phloem pressure is reduced during the hottest part of the day.
Use your understanding of transpiration and mass flow to explain why (3)

A
  1. High rate of transpiration
  2. Water lost through the stomata
  3. Causes less water movement from xylem to phloem
62
Q

Use your knowledge of surface are to volume ratio to explain the higher metabolic rate of a mouse compared to a horse (3)

A
  1. Mouse has a higher surface area to volume ratio
  2. Mouse loses heat at a much higher rate
  3. Mouse must have a higher metabolic rate to replace energy lost

Biology Flash Cards (8 decks)

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