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Try 4 questions
Question 1
Percentage of each base in four nucleic acid samples
Sample
Adenine (%)
Thymine (%)
Guanine (%)
Cytosine (%)
Uracil (%)
Sample 1
26
26
24
24
0
Sample 2
31
19
22
28
0
Sample 3
29
0
21
25
25
Sample 4
18
18
32
32
0
A laboratory in Adelaide analysed four nucleic acid samples taken from viruses. The table gives the percentage of each base in each sample. Which sample is most likely to be single-stranded DNA?
Question 2
Number of cells in each stage in a sample of 800 cells from a culture
Stage
Number of cells
Interphase
680
Prophase
60
Metaphase
30
Anaphase
14
Telophase
16
Cells in a culture divide every 20 hours, and the cells are at random points in the cycle. The table shows the stage of 800 cells in a sample. About how long does metaphase last?
Question 3
Survival of a small fish species from the southern Coorong after 96 hours at different salinities
Salinity (g L⁻¹)
Fish surviving after 96 hours (%)
10
100
30
100
50
100
70
95
90
60
110
10
130
0
In a laboratory investigation, groups of 20 fish of a small species collected from the southern Coorong were kept at seven salinities for 96 hours. Based on the table, between which salinities does the upper tolerance limit of this species lie?
Question 4
Temperatures at which half of each DNA sample separated into single strands
DNA sample
Separation temperature (°C)
Species X with species X
86
Species X with species A
84.2
Species X with species B
79.5
Species X with species C
82.1
A survey of native fish in the Coorong compared species X with three other species, A, B and C, by DNA-DNA hybridisation (table). What is the order of relatedness to species X, from the closest to the most distant?