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A-Level Biology Paper 1 > Exchange 2 > Flashcards

Exchange 2 Flashcards

(98 cards)

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1
Q

What is digestion?

A

The process where large molecules are hydrolysed by enzymes to produce smaller molecules that can be absorbed across cell membranes.

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2
Q

What hydrolyses starch?

A

Amylase

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3
Q

What is maltose hydrolysed by and what to?

A

Maltese hydrolyses it into alpha glucose

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4
Q

What hydrolyses sucrose and into what?

A

Sucrase hydrolyses it into alpha glucose and fructose

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5
Q

What hydrolyses lactose and into what?

A

Lactose hydrolyses it into alpha glucose and galactose

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6
Q

What enzymes hydrolyse carbohydrates?

A

Carbohydrases

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7
Q

Which parts of the body are involved in the digestive system?

A

Oesophagus
Salivary gland
Liver
Stomach
Large intestine
Pancreas
Small intestine
Rectum

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8
Q

What carbohydrate digestion happens in the mouth?

A

Starch is hydrolysed into maltose by amylase made by the salivary gland

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9
Q

What carbohydrate digestion happens in the pancreas?

A

Pancreatic amylase is released into the duodenum (first part of the small intestine).

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10
Q

What enzymes breakdown disaccharides?

A

Disaccharidases

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11
Q

How are carbohydrates digested in the small intestine?

A

Carbohydrate digestion is completed by enzymes fixed in the folded membrane of the intestinal epithelial. Disaccharidases are attached to the cell membrane of the epithelial cells lining the ileum.

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12
Q

How are the monosaccharides glucose and galactose absorbed during digestion?

A

They are absorbed by cotransport with sodium ions.

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13
Q

How is the monosaccharide fructose absorbed during digestion?

A

By facilitated diffusion through a different transport protein than galactose and glucose.

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14
Q

What enzymes breakdown proteins?

A

Protease

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15
Q

What enzymes breakdown polypeptides into smaller polypeptide?

A

Endopeptidases

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16
Q

What enzymes breakdown smaller peptides into dipeptides?

A

Exopeptidases

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17
Q

What enzymes breakdown dipeptides into amino acids?

A

Dipeptidases

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18
Q

What is the stomach involvement in protein digestion?

A

Endopeptidases hydrolyse the peptide bonds between the amino acids in the central region of a protein forming smaller poly peptides.

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19
Q

What is the only protein digesting enzyme in the stomach?

A

Pepsin

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20
Q

What is the pancreas is involvement in protein digestion?

A

Endopeptidases hydrolyse the peptide bonds between amino acids in the central regions forming smaller polypeptides (same as stomach)
Then exopeptidases hydrolyse the peptide bonds on the terminal amino acids of the smaller polypeptide releasing dipeptides and amino acids.

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21
Q

What is the purpose of having endopeptidases act on polypeptide before exopeptidases?

A

Endopepetidases breakdown different proteins so that them are more ends for exopeptidases to work on.

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22
Q

What is the role of the small intestine in protein digestion?

A

Dipeptidases hydrolyse the peptide bond between two amino acids producing individual amino acids.
These Dipeptidases membrane bound, being part of the cell surface membrane of the epithelial cells lining the ileum.

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23
Q

How are amino acids absorbed in digestion?

A

They are absorbed by co transport with sodium ions into ileum and then diffuse by facilitated diffusion into the blood.

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24
Q

What enzymes hydrolyse triglycerides into fatty acids and monoglycerides?

A

Lipase

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25
Are digestive enzymes water soluble and what does this mean for digesting lipids?
Yes, this means lipase can only digest fats at the surface of fat droplets which is inefficient.
26
What is the livers role in lipid digestion?
It produces bile salts, they are stored in the gallbladder and release into the small intestine when required. These bile salts help to breakdown large fat globals by emulsifying them into smaller droplets. This increases the surface area of lipids that can be exposed to the enzyme lipase.
27
What are micelles?
Very small droplets created by monoglycerides and fatty acids (triglyceride hydrolysis) associating with bile salts and phospholipids
28
What is the role of micelles in lipid absorption?
They aid the transport of monoglycerides and fatty acids to the surface of the intestinal epithelial cells as they are not very soluble. They also create a larger surface area for hydrolysis to be quicker
29
What do the micelles do to cause fatty acid and monoglyceride absorption??
They breakdown and add to a pool of fatty acids and monoglycerides that are dissolved in the small intestine solutions surrounded by epithelial cells. This maintains the concentration gradient so the fatty acids and monoglycerides can be diffused directly through the phospholipid bilayer.
30
What happens during lipid digestion after the fatty acids and monoglycerides have been absorbed by the phospholipid bilayer?
Inside the cell, the triglycerides reform and Goldie vehicles transport them to the membrane to leave the cell by exocytosis and enter the lymph vessel.
31
What kind of protein is haemoglobin?
Quaternary protein
32
What is the function of haemoglobin?
To transport oxygen in the blood
33
How much oxygen can blood carry?
Up to 20%
34
What is haemoglobin made up of?
Globin proteins and an iron rich compound called haem
35
How many haemoglobin molecules are in each red blood cell?
300 million
36
How many globin so units are in haemoglobin?
Four, two alpha, and two beta chains
37
What does the oxygen bind to in haemoglobin?
An iron ion in the haemgroup
38
How many oxygen molecules can each haemoglobin bind to?
Four, one for each haem group
39
What happens when the first oxygen molecule bind to haemoglobin?
Confirmation change in the protein happens making it easier for other oxygens to bind.
40
What does the oxygen disassociation curve show?
The percentage saturation of haemoglobin with oxygen at different partial pressures of oxygen.
41
What are the two things on a oxygen disassociation curve?
Percentage saturation of oxygen Oxygen, partial pressure
42
Where is the highest and lowest partial pressure of oxygen in the body?
The lowest is in respiring cells and the highest is in the lungs
43
What does haemoglobin need to be able to to do when transporting oxygen?
Load it, move it to the part of the body where it is needed, unload it
44
What does haemoglobin affinity for oxygen mean?
It’s level of chemical attraction to it
45
Why does the curve on an oxygen disassociation curve plateau eventually?
Because the haemoglobin is fully saturated (four oxygen)
46
Why does the rate of saturation increase rapidly when partial pressure increases on an oxygen disassociation curve?
Because after the first oxygen vines, it becomes a lot easier for the others too.
47
What differs in chemically similar haemoglobin in different types of organisms?
Affinity for oxygen, they have slightly different amino acid sequences and therefore different tertiary structures.
48
Why is haemoglobin a good protein to test how closely related organisms are?
Because it is found in a wide variety of organisms (from humans to earthworms to bacteria to plants)
49
What does a left shifted curve mean on an oxygen disassociation curve?
That haemoglobin has a greater affinity for oxygen (loads more easily)
50
Where do organisms that have a greater affinity for oxygen live?
In an area of low oxygen, more anaerobic conditions
51
What does a right shifted curve mean in an oxygen disassociation curve?
The haemoglobin has a lower affinity for oxygen (unloaded more easily)
52
Where do organisms that have a lower affinity for oxygen live?
Areas of high oxygen, or organisms that are very active/lose heat and need lots of respiration
53
How does high concentration of CO2 help unloading of oxygen in capillaries of respiring tissues?
See you two dissolves in the blood to Form carbonic acid This reduces the pH Causing conformational she changes in haemoglobin Lower affinity for oxygen Unload more
54
What should mass transport systems have?
Mechanism for moving the transport medium (heart) Mechanism to maintain directional flow (valves) Suitable median to carry materials (blood)
55
What do veins do?
Carry blood towards the heart
56
What do arteries do?
Carry blood away from the heart
57
What do capillaries do?
Link arterials veins (where exchange occurs)
58
What do arterioles do?
Control blood flow from arteries to capillaries
59
What does pulmonary mean?
In relation to the lungs
60
What does hepatic mean?
In relation to the liver
61
What does renal mean?
In relation to the kidneys
62
What kind of circulatory system do mammals have?
Double circulatory system One circuit goes from the right ventricle to the lungs back to the heart and one circuit goes from the left ventricle to the rest of the body and back to the heart.
63
Why do arteries, arterials and capillaries have a tough outer layer?
To resist pressure
64
What features do veins have?
A wider lumen than arteries as blood is a low pressure Valves to ensure blood does not flow backwards Thinner Layers of muscle and elastic tissue
65
What are the features of arteries?
Narrow lumen to maintain high-pressure Thick muscular walls and elastic layer to allow stretch No valves as pressure is high
66
What are the features of capillaries?
Walls are only one cell thick for short diffusion pathway plus no muscle tissue or elastic tissue and no valves Large number higher surface area of a gas exchange
67
What are the features of arterioles?
Similar to arteries except elastic layer is thinner and not as high-pressure
68
What is tissue fluid?
Fluid that surrounds our cells that is formed from substances that leak out of capillaries. Exchange of substances between cells and the blood occurs via the tissue fluid
69
Why is tissue fluid formed?
Because the high hydrostatic pressure of the capillaries forces the glucose, amino acids, et cetera out
70
How is water reabsorbed into the capillary after becoming tissue fluid?
Due to liquid loss there is a lower hydrostatic pressure in the capillaries after forcing out the water however because large molecules are still in the capillaries the water potential is now more negative which causes the water to move in by osmosis.
71
What happens to the rest of the tissue fluid after equilibrium is reached in the capillary after water and dissolved molecules move by osmosis back into the capillary?
It is absorbed into the lymphatic system and eventually drains back into the bloodstream.
72
What does myogenic mean?
Myogenic means something can contract without nervous or hormonal stimulation from other parts of the body.
73
What are the coronary arteries do?
One supply is the cardiac muscles with oxygenated blood, these branch of the aorta.
74
What are the features of the atria?
They have thinner muscular walls as they only need to pump blood to the ventricles
75
Why do ventricles have much thicker muscular walls than atrium?
Because they need to pump blood to the rest of the body and the lungs
76
What does the right ventricle do?
Pumps deoxygenated blood to the lungs, this doesn’t need to be as quickly or at the same high-pressure as the left as to not damage the lungs or capillaries and to give time for gas exchange.
77
What is the purpose of the left ventricle?
This pumps high-pressure blood to the rest of the body It needs a thick muscular wall to create big enough contractions to do this.
78
What is the vena cava?
The vein that carries deoxygenated blood from the body to the right atrium.
79
What does the pulmonary vein do?
Carry oxygenated blood from the lungs to the left atrium.
80
What does the pulmonary artery do?
carry de oxygenated blood from the right ventricle to the lungs.
81
What does the aorta do?
Carries oxygenated blood from the left ventricle to the rest of the body
82
What are the two kinds of valves?
Semilunar Artrioventricular
83
How do valves in the heart work?
They open when pressure is high behind the valve They then close when pressure is high in front of the valve This prevents back flow
84
What does the septum do?
Separate oxygenated and deoxygenated blood
85
What are the three stages of the cardiac cycle?
Diastole Atrial Systole Ventricular Systole
86
What happens during diastole?
Both the atria and and the ventricles are relaxed as this is when blood is entering the atria. Pressure is being increased in the atria
87
What is atrial systole?
When the ventricle is still relaxed, but the atrium contract and the pressure of this causes the the atrioventricular valves to open pumping blood into the ventricles
88
What is ventricular systole?
The ventricle muscle walls contract beyond that of the atrium and the atrioventricular valves close and the semilunar valves open, pumping blood out of the ventricles into the arteries
89
What is the equation for cardiac output?
Heart rate x stroke volume
90
What is stroke volume?
Volume of blood that leaves the heart each beat
91
What is cardiovascular disease?
This is a term used to describe different conditions affecting the heart and blood vessels.
92
How can damage to the endothelium of an artery be caused?
High blood pressure
93
What happens when damage occurs to the endothelium of an artery?
White blood cells and lipids from the blood clump together under the lining to Form fatty streaks which builds up over time to form a plaque called atheroma. The plaque blocks part of the lumen and restrict blood flow
94
What is coronary heart disease a type of?
Cardiovascular disease
95
How is coronary heart disease caused?
It occurs when coronary arteries have atheromas in them which can lead to a heart attack
96
How are aneurysms caused?
When arteries narrow and blood pressure increases, the high-pressure blood could push some of the inner layer of an artery out to form a balloon like swelling. If this aneurysm burst it could cause a haemorrhage.
97
What is thrombosis?
A blood clot has formed from the accumulation of platelets and firing at the rough surface of the site of damage in an artery wall.
98
What does a risk factor do?
Increase the probability of developing a particular disease

A-Level Biology Paper 1 (9 decks)

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