5: Food and Humans - Problems Flashcards
An investigation was carried out on the effects of cooking methods on the vitamin C content of cabbage. Three samples of cabbage juices, X, Y, Z, were prepared. Sample X was obtained from uncooked fresh cabbage, while samples Y and Z were obtained from cabbed cooked using different methods. The table below shows the number of drops of the different samples needed to decolourise 1cm3 DCPIP solution.
If 15 drops of 0.1% vitamin C solution are needed to decolourise 1cm3 DCPIP solution, estimate the vitamin C content of the fresh cabbage juice. (2)
Vitamin C content of the fresh cabbage juice = (0.1 × 15) / 50 = 0.03%
An investigation was carried out on the effects of cooking methods on the vitamin C content of cabbage. Three samples of cabbage juices, X, Y, Z, were prepared. Sample X was obtained from uncooked fresh cabbage, while samples Y and Z were obtained from cabbed cooked using different methods. The table below shows the number of drops of the different samples needed to decolourise 1cm3 DCPIP solution.
With reference to the results, state two conclusions about the effects of cooking methods on the vitamin C content of cabbage. (4)
The vitamin C content of sample X is higher than that of samples Y and Z since the number of drops of juice from X required is the smallest.
This indicates that boiling causes a decrease in the vitamin C content of cabbage.
The vitamin C content of sample Z is higher than that of sample Y.
This indicates that compared with adding cabbage to cold water and boiling, adding cabbage to boiling water and boiling results in less vitamin C loss.
(Edexcel IGCSE 2008)
An investigation was carried out on the effects of vitamins on the growth of rats. There are two groups of young rats, group A and group B.
Group A was fed on a diet of pure protein, carbohydrate, fat, mineral salts and water. These rats failed to grow normally.
Group B was fed on the same diet but with the addition of 2cm3 of milk each day. These rats grew well. After 18 days the diets were swapped so that group A now the 2cm3 of milk and group B received no milk. The results are shown below.
Use the graph to describe the changes in the mass of the rats in each group from day 18 to day 50. (4)
The mass of group A falls slightly
then rises (steadily).
The mass of group B rises (at a decreasing rate)
then falls.
(Edexcel IGCSE 2008)
An investigation was carried out on the effects of vitamins on the growth of rats. There are two groups of young rats, group A and group B.
Group A was fed on a diet of pure protein, carbohydrate, fat, mineral salts and water. These rats failed to grow normally.
Group B was fed on the same diet but with the addition of 2cm3 of milk each day. These rats grew well. After 18 days the diets were swapped so that group A now the 2cm3 of milk and group B received no milk. The results are shown below.
State the conclusion drawn as to the effect of milk on the growth of the rats. (2)
Milk is needed for the proper growth of rats, and the effect of milk is slightly delayed.
(Edexcel IGCSE 2008)
An investigation was carried out on the effects of vitamins on the growth of rats. There are two groups of young rats, group A and group B.
Group A was fed on a diet of pure protein, carbohydrate, fat, mineral salts and water. These rats failed to grow normally.
Group B was fed on the same diet but with the addition of 2cm3 of milk each day. These rats grew well. After 18 days the diets were swapped so that group A now the 2cm3 of milk and group B received no milk. The results are shown below.
Suggest why the diets were swapped after 18 days. (1)
This is to ensure that the difference in mass between the two groups of rats were due to milk but not other factors.
(Edexcel IGCSE 2008)
An investigation was carried out on the effects of vitamins on the growth of rats. There are two groups of young rats, group A and group B.
Group A was fed on a diet of pure protein, carbohydrate, fat, mineral salts and water. These rats failed to grow normally.
Group B was fed on the same diet but with the addition of 2cm3 of milk each day. These rats grew well. After 18 days the diets were swapped so that group A now the 2cm3 of milk and group B received no milk. The results are shown below.
To enable a valid comparison to be made between the two groups, other variable need to be kept the same. Suggest one such variable and explain how it could be kept the same. (2)
Environmental factors (e.g. temperature / light / activity) controlled by keeping the rats in cages of the same settings. /
Genetic factors controlled by using same species / strain / gender of rats.
Complete the table below:
(Vitamin, function, source)
{{A, night vision, carrot}, {?, skin and gum development, ?}, {D, ?, ?}}
{{A, night vision, carrot}, {C, skin and gum development, kiwi fruit / bell pepper / guava}, {D, bone and teeth development, fatty fish / liver / egg yolk}}
