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biology > Topic 6 - Exchange > Flashcards

Topic 6 - Exchange Flashcards

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AP® Biology flashcards
1
Q

Adaptations of gas exchange surfaces: across the body of a single-celled organism

A
  • Thin, flat shape and large surface area to volume ratio
  • Short diffusion distance to all parts of cell for rapid diffusion
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2
Q

tracheal system of an insect

A
  1. Air moves through spiracles (pores) on insect surface
  2. Air moves through trachea
  3. Which divide into tracheoles where gas exchange occurs directly to/from cells
    - O2 used by cells during respiration –> establishes a conc. gradient for O2 to diffuse down
    - CO2 produced by respiration –> diffuses down conc. gradient from respiring cells
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3
Q

Adaptations for gas exchange

A
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4
Q

Structural and functional compromises between opposing the needs for efficient gas exchange and the limitation of water loss as shown by terrestrial insects

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5
Q

Adaptation for gas exchange in fish

A
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6
Q

Adaptation for gas exchange - counter current flow:

A
  1. Blood and water flow in opposite directions through/over lamellae
  2. So oxygen concentration always higher in water (than blood near)
  3. So maintains a concentration gradient of O2 between water and blood
  4. For diffusion along whole length of lamellae

If water and blood flowed in the same direction (parallel flow) equilibrium would be reached, so oxygen wouldn’t diffuse into blood along the whole gill plate

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7
Q

Leaf cross section

A
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8
Q

Closed and open stomata diagram

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9
Q

Adaptation for gas exchange in leaf

A
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10
Q

Structural and functional compromises between opposing the needs for efficient gas exchange and the limitation of water loss as shown by xerophytic plants

A

Xerophyte = a plant adapted to live in very dry conditions e.g. cacti

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11
Q

Diagram of human gas exchange system

A
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12
Q

Adaptations of human gas exchange system

A
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13
Q

The essential features of the alveolar epithelium as a surface over which gas exchange takes place

A
  • Thin / flattened cells / one cell think –> short diffusion distance
  • Folded –> large surface area
  • Permeable –> allows diffusion of oxygen and carbon dioxide
  • Moist –> gases can dissolve
  • Good blood supply from network of capillaries –> maintains concentration gradient
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14
Q

Gas exchange in the lungs

A
  • Oxygen diffuses from alveolar air space into blood down its concentration gradient
  • Across the alveolar epithelium then across the capillary endothelium

The opposite for carbon dioxide

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15
Q

What is ventilation (mechanism of breathing)

A

The mechanism of breathing to include the role of the diaphragm and the antagonistic interaction between the external and internal intercostal muscles in bringing about pressure changes in the thoracic cavity

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16
Q

Stages of inspiration

A
  1. External intercostal muscles contract, internal intercostal muscles relax (antagonistic) –> ribcage moves up/out
  2. Diaphragm muscles contact –> flattens
  3. Increasing volume in thoracic cavity (chest)
  4. Decreasing pressure in thoracic cavity
  5. Atmospheric pressure high than pressure in lungs –> air moves down pressure gradient into lungs
17
Q

Stages of expiration

A
  1. Internal intercostal muscles can contract, external intercostal muscles relax –> ribcage moves down/in
  2. Diaphragm relaxes –> moves upwards
  3. Decreasing volume in thoracic cavity
  4. Increasing pressure in thoracic cavity
  5. Atmospheric pressure lower than pressure in lungs –> air moves down pressure gradient out of lungs
18
Q

Two types of expiration

A
  • Normal expiration is passive (no muscle contraction required), aided by elastic recoil in alveoli
  • Forced expiration is active because internal intercostal muscles contract
19
Q

Why is ventilation needed

A
  • Maintains an oxygen concentration gradient
  • Brings in air containing higher concentration of oxygen
  • Removes air with lower concentration of oxygen
20
Q

Tidal volume

A

Volume of air in each breath

21
Q

Ventilation rate

A

Number of breaths per minute

22
Q

Forced expiratory volume (FEV)

A

Maximum volume of air a person can breathe out in 1 second

23
Q

Forced vital capacity (FVC)

A

Maximum volume of air a person can breathe out in a single breath

24
Q

Effect of lung diseases on ventilation

A
  • Reduced elasticity –> lungs may expand / recoil less –> reduced tidal volume / FVC
    e.g. due to fibrosis - scar tissue builds up which is less elastic
  • Narrower airways / reduced airflow in/out of lungs –> reduced FEV
    e.g. due to asthma - bronchi are inflamed
25
Q

Effect of lung diseases on gas exchange

A
  • Thicker tissue in alveoli –> increased diffusion distance –> reduced rate of gas exchange
    e.g. due to fibrosis - scar tissue builds up which is thicker
  • Walls of alveoli break down –> reduced surface area –> reduced rate of gas exchange
26
Q

Link between gas exchange and ventilation

A

If gas exchange reduces, ventilation rate often increases to compensate for reduced oxygen in blood

Impact: cells receive less oxygen –> rate of aerobic respiration reduced –> less ATP made –> fatigue

27
Q

During digestion, large biological molecules are hydrolysed to smaller molecules that can be absorbed across cell membranes

A
  • Large biological molecules in food e.g. starch/protiens too big to be absorbed across cell membranes
  • Digestion breaks them into smaller molecules e.g. glucose/aminoacids –> absorbed from the gut to the blood
28
Q

Digestion in mammals of carbohydrates by amylases

A

Digestion of starch (polysaccharide)
- Amylase hydrolyses starch to maltose (poly to disaccharide)
- Membrane bound maltase (attaché to epithelial cells lining the ileum of the small intestine) –> hydrolyse maltose to glucose (di to monosaccharide)
- Hydrolysis of glycosidic bond

29
Q

Digestion in mammals of membrane bound disaccharides

A
  • Membrane bound disaccharides e.g. maltase, sucrose, lactase (attached to epithelial cells lining the ileum of the small intestine) –> hydrolyse disaccharide to 2x names monosaccharides
  • e.g. maltase - maltose –> glucose + glucose
  • e.g. sucrase - sucrose –> fructose + glucose
  • e.g. lactase - lactose –> galactose + glucose
  • Hydrolysis of glycosidic bond
30
Q

Digestion in mammals of lipids by lipase, including the action of bile salts

A
  • Bile salts produced by the liver
  • Bile salts emulsify lipid to smaller lipid droplets: Increasing surface area (to volume ratio) of lipids speeds up action of lipase
  • Lipase made in the pancreas, released to small intestine
  • Lipase hydrolyses lipids –> monoglycerides + fatty acids
  • Breaking ester bond
  • Monoglycerides, fatty acids and bile salts stick together to form micelles
31
Q

Digestion in mammals of proteins by endopeptidases, exopeptidase and membrane-bound dipeptides

A

Endopeptidases:
- Hydrolyse peptide bonds within a protein/between amino acids in the central region
- Breaking protein into two or more smaller peptides

Exopeptidase:
- Hydrolyse peptide bonds at the ends of protein molecules
- Removing a single amino acid

Dipeptidases (type of exopeptidase):
- Often bound in ileum
- Hydrolyse peptide bonds between a dipeptide
- =2 amino acids

32
Q

Mechanisms for the absorption of the products of digestion by cell lining the ileum of mammals, to include co-transport mechanisms for the absorption of amino acids and of monosaccharides

A
  1. Sodium ions actively transported out of epithelial cells lining the ileum, into the blood, by the sodium potassium pump. Creating a concentration gradient of sodium
  2. Sodium ions and glucose move by facilitated diffusion into the epithelial cells from the lumen, via a co-transporter protein
  3. Creating a concentration gradient of glucose - higher conc. of glucose in epithelial cell than in blood
  4. Glucose moves out of cell into blood by facilitated diffusion through a protein channel
33
Q

Mechanisms for the absorption of the products of digestion by cells lining the ileum of mammals, to included the role of micelles in the absorption of lipids

A
  • Monoglycerides and fatty acids diffuse out of micelles (in lumen) into epithelial cell
  • Monoglycerides and triglycerides recombine to triglycerides which aggregate into globules
  • Globules coated with proteins to form chylomicrons
  • Leave via exocytosis and enter lymphatic vessels
  • Return to blood circulation

biology (20 decks)

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