A student measured his reaction time. His partner held a ruler with the 0 cm mark level with the top of the student's thumb, then dropped it without warning. The student caught it as quickly as possible, and the partner read the distance fallen.
Conversion table from distance fallen to reaction time: 10 cm, 0.143 s; 11 cm, 0.150 s; 12 cm, 0.156 s; 13 cm, 0.163 s; 14 cm, 0.169 s; 15 cm, 0.175 s.
Distance fallen (cm)
10
11
12
13
14
15
Reaction time (s)
0.143
0.150
0.156
0.163
0.169
0.175
.1
In five trials the ruler fell 15 cm, 12 cm, 14 cm, 11 cm and 13 cm.
Calculate the mean distance.
[2 marks]
.2
Use the conversion table to give the student's mean reaction time.
[1 mark]
.3
Give two variables the student should control to make his results valid.
[2 marks]
5 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
The body cells of a species of fish contain 30 chromosomes, in 15 pairs.
.1
Give the number of chromosomes in one of this fish's gametes.
[1 mark]
.2
Give the number of chromosomes in a fertilised egg cell of this fish.
[1 mark]
.3
Describe what happens to the chromosomes when a cell divides by meiosis to form gametes.
[3 marks]
3 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Evolution is a change in the inherited characteristics of a population over time through natural selection.
.1
Put the stages of natural selection in order, starting with the first.
[2 marks]
.2
Define the term species.
[1 mark]
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]
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.
