Download HL Biology H4 - Liver function 1. A number of chemicals have been

HL Biology
1.
H4 - Liver function
A number of chemicals have been shown to cause tissue damage due to the production of free
radicals. Free radicals are chemicals, such as superoxides and peroxides, which can react to
damage DNA and lipids. Antioxidants produced by our body, such as reduced glutathione,
combine with free radicals and decrease tissue damage. Reduced glutathione reacts with free
radicals and in the process is converted to oxidized glutathione.
Recently dietary antioxidants such as lignins, have also been shown to protect against tissue
damage. Flaxseed is known to contain lignins but its antioxidant effects have yet to be
evaluated. Research was done to see if flaxseed could help prevent damage to the liver by
tetrachloromethane. Metabolism of tetrachloromethane by the liver leads to the formation of
free radicals. Rats were pretreated by oral injection with flaxseed extract (+) or corn oil (–)
(control) for three days and then injected with buffered saline solution (control) or
tetrachloromethane. The glutathione levels were then measured.
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[Source: Endoh, et al J Vet Medical Science, (2002), 64, page 761]
(a)
(i)
State the reduced glutathione content of liver tissue injected with
tetrachloromethane with no flaxseed pretreatment.
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(1)
(ii)
Calculate the total glutathione content (oxidized + reduced) in liver tissue treated
with flaxseed extract but not injected with tetrachloromethane.
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(1)
1
HL Biology
(b)
H4 - Liver function
Describe the effect of tetrachloromethane injection on total glutathione and reduced
glutathione content in liver tissue without flaxseed pretreatment.
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(2)
(c)
Predict, using the data, the effect of using flaxseed extract in protecting liver tissue from
damage due to tetrachloromethane.
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(3)
(Total 7 marks)
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HL Biology
2.
(a)
H4 - Liver function
Draw a diagram of the hypothalamus and the pituitary gland.
(2)
(b)
Outline the role of bile in lipid digestion in a hydrophilic medium.
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(2)
(Total 4 marks)
3
HL Biology
3.
(a)
H4 - Liver function
Describe how the ileum uses active transport in the absorption of food.
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(3)
(b)
Outline how the blood is routed to the liver, through the liver, and from the liver.
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(3)
(c)
List two substances resulting from the breakdown of hemoglobin in the liver.
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(1)
(Total 7 marks)
4.
(a)
List three of the materials that are egested.
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(1)
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HL Biology
(b)
H4 - Liver function
Describe the process of erythrocyte and hemoglobin breakdown in the liver.
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(4)
(Total 5 marks)
5.
Outline the process of bile secretion.
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(Total 4 marks)
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