Cambridge International A Level Biology Revision Guide

Cambridge International A Level Biology
3 Which of the statements about Protoctista are correct?
1 A eukaryote that is not a fungus, plant or animal is a protoctist.
2 An organism with cellulose cell walls and chloroplasts may be a protoctist.
3 An organism existing as a group of similar cells may be a protoctist.
4 A single-celled heterotrophic eukaryote is a protoctist.
A 1, 2, 3 and 4
B 1, 2 and 4
C 2 and 3
D 3 and 4 only [1]
4 Some students investigated what size of quadrat they should use to assess the abundance of plant species in an
old field ecosystem. They used quadrats of side 10, 25, 50, 75 and 100 cm and recorded how many plant species
were present. They repeated their investigation five times and calculated mean numbers of species per quadrat.
Their results are in the graph below.
456
Number of species per quadrat
8
6
4
2
0
0
10 25 50 75
Size of quadrat / cm
100
a Calculate the area of each quadrat that they used. [2]
b Explain why the students took five results for each quadrat. [2]
c Based on their results, the students decided to use the 50 cm quadrat to study the old field. Why did they
choose the 50 cm quadrat? [2]
d Explain how they would use the 50 cm quadrat to estimate the abundance of the different plant species
in the field. [3]
[Total: 9]
5 Five 0.25 m 2 quadrats were placed randomly in an area of grassland in the UK. The percentage of each
quadrat occupied by each species of plant was estimated to the nearest 5% and recorded in the
following table.
Species
Percentage cover of each plant
species in each quadrat to the
nearest 5%
1 2 3 4 5
Mean
percentage
cover
Timothy grass 60 30 35 70 25
Yorkshire fog grass 25 70 30 15 40
plantain 0 5 0 5 0 2
meadow buttercup 0 0 15 0 10 5
dock 5 10 5 0 5 5
cowslip 0 0 0 5 0 1
white clover 15 0 25 25 10 15
bare ground 0 15 15 5 20 11