B7: Quiz 6 – Answers
1) We place a quadrat down randomly and count the number of daisies in the quadrat. We then repeat the process of randomly placing the quadrat and counting the number of daisies until we have a certain number of values for the quadrats (such as 10). We then work out the mean number of daises per quadrat/ per 1 m2. The final step is to multiply the mean number of daisies per quadrat by the size of the field to find an estimate for the number of daises in the field.
2)
a) 9.7
b) 37,830
c) Working out the actual number of daises would take too long, be hard to accurately do and potentially expensive (any one of these points is fine)
3)
a) 4.875
b) 24,180
4)
a) Field = 9.6
Forest = 2.3
b) The distribution of dandelions is greater in the middle of the field. Plants need light energy for photosynthesis. There will be more sunlight in the middle of the field compared to the forest as the trees in the forest will block out light. This means that the dandelions in the middle of the field will receive more light and therefore be able to photosynthesise more, which increases their growth and chances of survival – this is why dandelions are more abundant in the middle of the field. Whereas, in the forest, there will be less light, thus meaning that there will be fewer dandelions.
1) Outline how we can use quadrats to estimate the number of daisies in a field.
2) A student wants to estimate the number of daises in a field. He throws a 1 m2 quadrat down 10 times and the number of daises for each of the 10 quadrats are shown below.
a) Work out the mean number of daises per quadrat.
b) The field is 3,900 m2. Work out an estimate for the number of daises in the whole field.
c) Why would a student work out an estimate for the number of daises rather than the actual number of daises in a field?
3) A student wants to estimate the number of dandelions in a field that is 2,480 m2. He uses a 0.5 m2 quadrat and throws it down 8 times. The number of dandelions for each of the 8 quadrats is shown below.
a) Calculate the mean number of dandelions per quadrat.
b) Find an estimate for the number of dandelions in the field.
Be careful with this question as the quadrat is 0.5 m2 and not 1 m2.
4) A student wants to investigate the distribution of dandelions in the middle of a field and in a forest. She uses quadrats to investigate the distribution and places 10 quadrats down randomly in the two locations. Her values for the 10 quadrats in the middle of a field and in a forest are shown in the table below.
a) Calculate the mean number of dandelions per quadrat in the middle of the field and in the forest.
b) Where is the distribution of dandelions the greatest? Give a potential explanation as to why the population of dandelions is the greatest there.