After a meal containing carbohydrates, the concentration of glucose in the blood rises.
.1
Explain how the body returns the blood glucose concentration to normal after the meal.
[3 marks].2
What is the cause of type 1 diabetes?
[1 mark]OCR Gateway GCSE Biology June 2019 Paper 1
5 questions on this paper's topics
28:001 of 5
Scientists compared two ways of growing new bone cells to repair a damaged bone.
Method A uses adult stem cells from the patient's own bone marrow.
Method B uses stem cells from an embryo.
The table shows their results.
| Measurement | Method A: bone marrow | Method B: embryo |
|---|---|---|
| Cells after 14 days (millions) | 18 | 45 |
| Cells that became bone cells (%) | 85 | 55 |
.1
Compare the results of method A and method B.
[2 marks].2
Calculate how many bone cells method B produced. Give your answer in millions.
[1 mark].3
Suggest one advantage of method A for the patient that is not shown in the table.
[1 mark]A student investigated the effect of pH on the time taken for amylase to break down starch.
She mixed amylase, starch and a buffer solution in a water bath at 35 °C. Every 30 seconds she put a drop of the mixture onto iodine solution on a spotting tile. She recorded the time when the iodine no longer turned blue-black.
| pH | Time for starch to be broken down (s) |
|---|---|
| 5 | 150 |
| 6 | 90 |
| 7 | 60 |
| 8 | 120 |
| 9 | 240 |
.1
The rate of reaction can be found with:
rate
Calculate the rate of reaction at pH 7.
[1 mark].2
Explain why the starch took much longer to break down at pH 9.
[2 marks].3
Suggest how the student could find the optimum pH of amylase more precisely.
[1 mark].4
Sampling every 30 seconds limits the accuracy of the times.
Explain why.
[1 mark]A student used a potometer to measure the rate of water uptake by a leafy shoot. An air bubble moved along a scale as the shoot took up water.
In still air the bubble moved 45 mm in 5 minutes. With a fan blowing on the shoot, the bubble moved 72 mm in 5 minutes.
.1
Calculate the rate of water uptake in still air, in mm per minute.
[1 mark].2
Calculate the percentage increase in the rate when the fan was on.
[2 marks].3
Explain why the rate of water uptake increased when the fan was on.
[2 marks].4
Give one variable the student should keep the same when comparing still air with moving air.
[1 mark]Heart muscle contracts all the time, throughout life.
.1
Explain why heart muscle cells contain many mitochondria.
[2 marks].2
Compare aerobic respiration with anaerobic respiration in muscle cells.
[3 marks]