BiodiversityIB MYP Biology: Subtopic test

1. 1
   Ecologists sampled two woodland plots of the same size. In Plot X they found 40 individual plants belonging to 12 different species. In Plot Y they found 200 individual plants belonging to 5 different species, most of them one species of fast-growing grass.

   (a)

   What is meant by the term species richness?

   [1 mark]

   • AThe total number of individual organisms in an area
   • BThe number of individuals of the most common species
   • CThe number of different habitats in an area
   • DThe number of different species in an area

   (b)

   Which statement about the two plots is correct?

   [1 mark]

   • APlot Y has the greater species richness because it has more individuals
   • BPlot X has the greater species richness because it has more different species
   • CBoth plots have the same species richness because they are the same size
   • DThe species richness cannot be found without a diversity index

   (c)

   Explain why Plot Y has lower biodiversity than Plot X even though it has more individuals.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A coral reef off the coast of Sulawesi, Indonesia, is home to thousands of species of corals, fish and other animals. Local people fish on the reef, tourists pay to dive there, and the reef absorbs the force of waves during storms.

   (a)

   Which of these is a benefit to people of high biodiversity?

   [1 mark]

   • AAn increased risk that food chains will collapse
   • BFewer natural sources of medicines
   • CA greater variety of foods and materials, including sources of medicines
   • DA greater need for human-made fertiliser

   (b)

   Why are ecosystems with high biodiversity usually more stable?

   [1 mark]

   • AIf one species declines, other species can take its place in the food web
   • BEvery species in them is stronger than species elsewhere
   • CThey contain only producers, which cannot be harmed
   • DThey have no predators to reduce the populations

   (c)

   Outline two ways in which the biodiversity of the reef benefits local people.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Students compared ground beetles in two fields in southern Poland. Field A is a meadow with many wild flowers. Field B is a wheat field sprayed with pesticide. The students set 10 pitfall traps in each field for one night. In field A they caught four species, with 10, 8, 7 and 5 beetles. In field B they caught three species, with 25, 4 and 1 beetles.

   (a)

   The diversity index D = N(N − 1) ÷ Σn(n − 1), where N is the total number of individuals and n is the number of individuals of each species. Calculate D for field A. Show your working.

   [3 marks]

   (b)

   The diversity index for field B is 1.4. Compare the diversity of the two fields, explain the difference, and suggest one way to improve the reliability of the investigation.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Madagascar is home to thousands of species found nowhere else, including most lemurs. Much of its original forest has been cleared, mainly by farmers who burn forest to grow rice and by people who cut trees for timber and charcoal. Most people in Madagascar are poor and depend on the land for their food. The government is considering creating large new protected areas where no farming or logging is allowed, and promoting wildlife tourism.

   (a)

   Explain how human activities threaten the biodiversity of Madagascar.

   [6 marks]

   (b)

   Discuss and evaluate the government's proposal to create large protected areas and promote wildlife tourism. Give a justified conclusion.

   [6 marks]

   Total for question 4: 12 marks

End of questions