18: Homeostasis - Problems Flashcards
(9 cards)
In a study, a healthy woman was asked to take in 75g of glucose after fasting overnight. Her blood glucose level and blood insulin level. were measured just before the glucose intake and then every 0.5 hours for the subsequent 3 hours. Figures 1 and 2 show the results.
Explain why the woman needed to fast overnight before the glucose intake. (2)
Fasting sets the blood glucose level of the person to the basal level.
This ensures that the changes in the blood glucose levels in the test were only due to the glucose solution drink and not affected by the food absorbed before the test.
In a study, a healthy woman was asked to take in 75g of glucose after fasting overnight. Her blood glucose level and blood insulin level. were measured just before the glucose intake and then every 0.5 hours for the subsequent 3 hours.
Explain how the graphs show that blood glucose stimulates the production of insulin. (2)
The blood insulin level changed in the same way as the blood glucose level.
The blood insulin level reached its peak just after the peak of the blood glucose level.
In a study, a healthy woman was asked to take in 75g of glucose after fasting overnight. Her blood glucose level and blood insulin level. were measured just before the glucose intake and then every 0.5 hours for the subsequent 3 hours.
Explain the change in her blood glucose level from 1 to 3 hours. (3)
The raised blood glucose level was detected by chemoreceptors in the pancreas, and the pancreas produces more insulin and less glucagon.
Insulin stimulated liver cells and muscle cells to convert more glucose into glycogen and stimulates body cells to consume more glucose for respiration.
The blood glucose level decreased and returned to the initial level.
DSE 2018 IB Q7
The glycemic index (GI) is an indicator of the effect of food on the blood glucose level. The higher the GI value of a food, the quicker is the rise in blood glucose level. The graph below shows the changes in the blood glucose level of a healthy individual after consuming the same quantity of a low GI or high GI meal over a period of three hours.
Describe how the consumption of a meal leads to an increase in the blood glucose level. (2)
The food containing carbohydrates are digested to form glucose.
The glucose is absorbed into the blood at the small intestine.
DSE 2018 IB Q7
Name the key hormone which lowers the blood glucose level, and describe how it lower blood glucose level. (1+3)
Insulin
1. It stimulates liver cells and other body cells to take up more glucose from the blood
2. It stimulates liver cells and muscle cells to convert more glucose into glycogen for storage.
3. It stimulates the body cells to consume more glucose for respiration.
DSE 2018 IB Q7
The glycemic index (GI) is an indicator of the effect of food on the blood glucose level. The higher the GI value of a food, the quicker is the rise in blood glucose level. The graph below shows the changes in the blood glucose level of a healthy individual after consuming the same quantity of a low GI or high GI meal over a period of three hours.
Explain why diabetic patients should consume low GI meals. (2)
Low GI foods will lead to smaller fluctuation in blood glucose level,
which reduces the chance of high blood glucose level.
A doctor asked a diabetic to fast overnight and to drink q glucose solution in the following morning. Figures 1 and 2 show the changes in the blood glucose level and blood insulin level of the diabetic, as compared to those of a non-diabetic.
Write five differences in the glucose responses of the diabetic and the non-diabetic as shown in Figure 1. (5)
- The initial blood glucose level of the diabetic was higher than that of the non-diabetic.
- The increase in the blood glucose level of the diabetic was faster than that of the non-diabetic.
- The peak of the blood glucose level of the diabetic was higher than that of the non-diabetic.
- After the peak, the blood glucose level of the diabetic remained high for a longer time than that of the non-diabetic.
- The blood glucose level of the diabetic did not return to the initial level by 210 minutes, whereas that of the non-diabetic returned to the initial level by 210 minutes.
A doctor asked a diabetic to fast overnight and to drink q glucose solution in the following morning. Figures 1 and 2 show the changes in the blood glucose level and blood insulin level of the diabetic, as compared to those of a non-diabetic.
State and explain the type of diabetes the patient has. (1+3)
He has non-insulin-dependent diabetes.
Despite an increase in blood insulin level of the diabetic, the blood glucose level remained high.
This suggested that the pancreas of the diabetic can produce enough insulin,
but his / her body cells are insensitive to insulin. Thus, the diabetic has non-insulin-dependent diabetes.
Using the regulation of blood glucose level as an example illustrate how homeostasis is brought about by the negative feedback mechanism. (8+3)
In the negative feedback mechanism, a change in the level of a parameter results in a response which has an opposite effect on the change.
The response brings the level of the parameter closer to the set point.
An increase in blood glucose level (e.g. after a meal) is detected by chemoreceptors in the pancreas, and the pancreas produces more insulin and less glucagon.
More insulin stimulates liver cells to convert more glucose into glycogen for storage and stimulates body cells to consume more glucose for respiration.
As more glucose is taken up from the blood, the blood glucose level decreases and returns to the set point.
A decrease in blood glucose level (e.g. during fasting or after exercise) is detected by chemoreceptors in the pancreas, and the pancreas produces less insulin and more glucagon.
More glucagon stimulates liver cells to convert stored glycogen into glucose, which is then released into the blood.
As a result, the blood glucose level increases and returns to the set point.
