Use Figure 5 to explain how human mass at birth is affected by stabilising selection.

The scientists studied the effect of one form, KIR2DS1, of the human KIR gene on mass at birth.

In the following passage the numbered spaces can be filled with biological terms.

KIR2DS1 is an (1) of the KIR gene, found at a (2) on chromosome 19. KIR2DS1 is 14 021 bases long and is (3) into mRNA that is 1101 bases long. This mRNA is then (4) into a polypeptide 304 amino acids long. The polypeptide is then modified in the organelle, (5), before forming its functional (6) protein structure.

Write the correct biological term beside each number below, that matches the space in the passage.

(1)

(2)

(3)

(4)

(5)

(6)

The scientists studied 1500 more births. They recorded the mass at birth of each baby and the nature of the KIR gene in the mother's genome.

Some of their results are shown in Table 2.

The scientists used a statistical test to test the following null hypothesis:

'The presence of KIR2DS1 in the mother's genome does not affect the frequency of births above 4500 g'

Tick (✓) one box that gives the name of the statistical test that the scientists should use with the data in Table 2 to test this null hypothesis.

☐ Chi-squared

☐ Correlation coefficient

☐ Student's t-test

The scientists calculated a P value of 0.03 when testing their null hypothesis.

What can you conclude from this result? Explain your answer.