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Biology > Exchange and transport systems > Flashcards

Exchange and transport systems Flashcards

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1
Q

Factors affecting rate of exchange

A

Surface area to volume ratio
Length of diffusion pathway
Concentration gradient

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2
Q

Gas exchange in insects?

A

Oxygen diffuses in through SPIRACLES
Gas then enters large tubes called tracheae, and then through to the tracheoles
Tracheoles allow oxygen to diffuse directly to cells.
Carbon dioxide diffuses out the opposite way

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3
Q

What are some adaptations that are applicable pretty much anywhere for gas exchange?

A
  • Tracheoles have thin walls so short diffusion pathway.
  • IF THEY HAVE IT, a good blood supply to maintain concentration gradient.
  • Tracheoles are often branched so has a large surface area.
  • Large SA:VOL ratio for maximum absorption
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4
Q

Adaptations of spiracles in insects

A
  • spiracles have valves that can periodically close to minimise water loss
  • spiracles have hairs that further reduce water vapour loss
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5
Q

Describe gas exchange within fish

A
  • water passes through the fish’s mouth and out through the gills.
  • each gill has lots of plates called gill filaments (giving a large surface area).
  • gill filaments are covered in lots of tiny structures called lamellae.
  • lamellae have lots of blood capillaries and a thin surface layer of cells.
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6
Q

some fish gills use a COUNTERCURRENT FLOW. What does this involve?

A
  • the direction of blood and water flow opposite ways.
  • this makes it so blood is always passing water with a higher oxygen concentration
  • this means a concentration gradient of oxygen is maintained the whole lamellae
  • so more oxygen enters the blood, and so more aerobic respiration to release energy for swimming
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7
Q

Some fish use CONCURRENT FLOW. What does this involve?

A
  • blood and water flow in the same direction
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8
Q

What is the structure of the thoracic cavity?

A
  • epiglottis and larynx
  • trachea
  • bronchi and bronchioles
  • ribs and intercostal muscles
  • pleural membrane and pleural cavity
  • diaphragm
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9
Q

What occurs during inspiration?

A
  • air containing oxygen is sucked in through mouth
  • air moves into lungs
  • volume of chest cavity increases
  • diaphragm contracts and pushes digestive organs down
  • pressure in chest cavity decreases below atmospheric pressure
  • external intercostal muscles contract and ribs rise
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10
Q

What occurs during expiration?

A
  • external intercostal muscles relax and ribs fall
  • pressure in chest cavity rises above atmospheric pressure
  • diaphragm relaxes and is pushed up by digestive organs
  • volume in chest cavity decreases
  • air moves out of lungs
  • air is forced out through mouth, removing carbon dioxide
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11
Q

Adaptations of alveoli?

A
  • large surface area
  • thin walls for small diffusion path
  • surrounded with many blood capillaries than make it so a concentration gradient is maintained
  • RBCs are flattened against the capillary walls
  • alveoli are covered in a substance called pulmonary sufactant
  • pulmonary sufactant has a low surface tension, and stops the water lining the alveoli from sticking together.
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12
Q

How are carbohydrates digested

A
  • salivary glands secrete carbohydrases (AMYLASE) which break polysaccharides into disaccharides
  • these enzymes denature in the stomach
  • the pancreas releases pancreatic AMYLASE to digest any polysacchrides that weren’t broken down
  • MEMBRANE BOUND disaccharidases hydrolyse disaccharides into monosaccharides, which are small and soluble for digestion
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13
Q

Definition of digestion

A

The hydrolysis of large, insoluble molecules into smaller, soluble molecules for absorption

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14
Q

What happens in the cardiac cycle?

  • What’s contracting
  • What’s the pressure doing
  • Direction of blood flow
  • Valves
A
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15
Q

What happens in lipid digestion and absorption?

A
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16
Q

What is the structure of haemoglobin?

A
  • four polypeptide chains chemically bonded together
  • each with a haem group packed in the middle.
17
Q

What is affinity?

A

the degree to which a substance tends to combine with another (chemical attraction)

18
Q

What is cooperative binding?

A
  • binding of one molecule affects the binding affinity of subsequent molecules
19
Q

What affects the oxygen dissociation curve position?

A
  • The organism’s environment (oxygen availability)
  • How active/metabolically active the organism is
20
Q

When is haemoglobin associated with oxygen?

A

When it exists as oxyhaemoglobin (HbO8)

21
Q

When is haemoglobin dissociated with oxygen?

A

When they both exists separately (Hb and 4O2)

22
Q

Some xerophytic plants have sunken stomata. Explain the advantage of this adaptation.

A
  • prevents water loss
  • due to a shallower water potential gradient
23
Q

Describe how water is moved through a plant according to the cohesion-tension hypothesis.

A
  • water transpires from leaves
  • reduces water potential gradient across cells
  • water is pulled out the xylem
  • creates tension, and cohesive forces between water pull water up in a column up the xylem
24
Q

Describe the mass flow hypothesis for the mechanism of translocation in plants. (PHLOEM)

A
  • the source of sugar in leaves are actively transported into the phloem
  • via the companion cells
  • this lowers the water potential in the phloem’s sieve cells
  • so water enters via osmosis from the xylem down the water potential gradient
  • this causes an increase in pressure in the phloem, and causes mass movement (towards sink)
  • sugars converted in root for storage for respiration.
25
Q

What is the structure of myoglobin?

A
  • 1 polypeptide chain, 1 haem group, 1 Fe ion
26
Q

When is myoglobin used?

A
  • when pO2 drops so low, only then will it dissociate
  • as it has a high affinity for O2
27
Q

What is the Bohr effect?

A

O2 dissociation curve position will change in favour of releasing O2 in different ways.
e.g., in low O2 environments, the haemoglobin’s O2 affinity will be higher and so the curve position will shift to the left

28
Q

What does the Bohr effect mean for haemoglobin?

A
  • increased [CO2] REDUCES haemoglobin’s affinity for O2
  • so haemoglobin is more likely to dissociate from O2
  • this adaptation enables organisms to meet metabolic demand

Biology (7 decks)

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