Biodiversity and its measurementEdexcel International A Level Biology: Subtopic test

1. 1
   A conservation team surveyed a cloud forest on a tropical mountain. Many of the species they recorded, including a tree frog and an orchid, are found nowhere else in the world.

   (a)

   Which statement defines an endemic species?

   [1 mark]

   • AA species whose population has fallen below the size needed to survive
   • BA species found naturally in only one geographical area and nowhere else
   • CA species introduced by humans that spreads outside its natural range
   • DA species that has few individuals in a habitat

   (b)

   The team recorded the species richness of the cloud forest. Which statement correctly describes species richness?

   [1 mark]

   • AThe total number of individuals of all species in the forest
   • BThe number of different alleles of a gene in one species
   • CThe proportion of heterozygous individuals in a population
   • DThe number of different species present in the forest

   (c)

   Explain why endemic species are particularly vulnerable to extinction when their habitat is destroyed.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Researchers studied one gene with two alleles in lizards. On a small island, a population of 60 lizards contained 15 heterozygotes. On the mainland, a population of 200 lizards of the same species contained 82 heterozygotes.

   (a)

   What is the heterozygosity index for the island population?

   [1 mark]

   • A0.25
   • B0.75
   • C4.0
   • D0.41

   (b)

   Which conclusion is best supported by the data?

   [1 mark]

   • AThe island population has more alleles of the gene than the mainland population
   • BThe island and mainland lizards are different species
   • CThe island population has lower genetic diversity at this gene than the mainland population
   • DThe island has lower species richness than the mainland

   (c)

   Suggest two reasons why the island population has a lower heterozygosity index than the mainland population.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Students estimated the biodiversity of two meadows, A and B, by counting the individuals of each plant species in random quadrats. Meadow A contained 5 species, with 20, 15, 10, 4 and 1 individuals. Meadow B contained 4 species, with 38, 8, 3 and 1 individuals. Meadow B had been treated with a herbicide the previous year, but meadow A had not. The index of diversity is D = N(N − 1) / Σn(n − 1), where N is the total number of individuals of all species and n is the number of individuals of each species.

   (a)

   Calculate the index of diversity D for meadow A. Show your working.

   [3 marks]

   (b)

   For meadow B, D = 1.7 (to 2 significant figures). A student concluded that the herbicide reduced the biodiversity of meadow B. Evaluate this conclusion using the data.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   An area of lowland rainforest on a tropical island is being cleared to make way for a palm oil plantation, in which a single species of palm is planted in rows. The forest contains many endemic species.

   (a)

   Explain how clearing the rainforest for a palm oil plantation could reduce biodiversity.

   [6 marks]

   (b)

   Evaluate the use of species richness and the index of diversity to compare the biodiversity of the rainforest with that of the plantation.

   [6 marks]

   Total for question 4: 12 marks

End of questions