A student estimated the number of daisies in a field 50 m long and 40 m wide. She placed a 0.25 m² quadrat at five random positions and counted the daisies in each.
Daisies in five quadrats: 4, 7, 0, 5, 9.
Quadrat
1
2
3
4
5
Number of daisies
4
7
0
5
9
.1
Calculate the mean number of daisies per quadrat.
[2 marks]
.2
Estimate the number of daisies in the whole field.
[3 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
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.
Table comparing method A (bone marrow stem cells) and method B (embryonic stem cells): cells after 14 days, 18 million and 45 million; percentage becoming bone cells, 85 and 55.
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]
3 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A couple already have three daughters. They are expecting a fourth child.
.1
Give the probability that the fourth child will be a boy.
[1 mark]
.2
Explain why the chance of any baby being a boy is 50%.
[2 marks]
6 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
White blood cells help to defend the body against pathogens.
.1
What are the molecules on the surface of a pathogen that white blood cells recognise as foreign?
[1 mark]
.2
Describe three ways white blood cells defend the body against pathogens.
[3 marks]
.3
A person has antibodies against the measles virus. These antibodies do not protect the person against the mumps virus.
Explain why.
[2 marks]
6 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
In a pond, frogs eat insects and herons eat frogs. A disease kills most of the frogs.
.1
Explain what is likely to happen to the number of insects in the pond.
[2 marks]
.2
Explain why the heron population may also decrease.
