Cambridge International A Level Biology Revision Guide

Cambridge International A Level Biology
Answers to self-assessment questions
This is the table to use if the student has
made the hypothesis that there is a linear
correlation between the two variables.
Number of pairs of
measurements
Critical value at p = 0.05
(5%)
5 0.88
6 0.81
7 0.75
8 0.71
9 0.67
10 0.63
11 0.60
12 0.58
15 0.51
20 0.44
In this case there are 12 pairs of
measurements and the critical value is 0.58.
The value of r (0.79) is greater than this, so
the null hypothesis can be rejected.
d The student can reject the null hypothesis
and we can accept the alternative hypothesis
that there is a correlation between the height
of the trees and the width of the cracks in
their bark.
11
b i taxon – a unit of classification, a category
that indicates a rank or level in the
classification system. Examples are
species, genus, family, etc.
ii hierarchical system – each taxon above the
level of species includes all the taxa below
it. For example, an order includes all the
families that have similar features.
Feature
Cell structure
Domains
Bacteria Archaea Eukarya
prokaryotic
(e.g. no
membrane–
bound
organelles)
prokaryotic
eukaryotic
Nucleus ✘ ✘ ✔
DNA circular circular linear
DNA with
histones
Plasmids
present in
many
✘ ✔ ✔
present in
some
present in very
few, e.g. yeasts
Ribosomes all 70S all 70S all in the
cytosol are
80S (70S in
mitochondria
and
chloroplasts)
Peptidoglycan
in cell wall
✔ ✘ ✘
10a Taxonomic rank
African bush elephant
Method of cell
division
binary fission binary fission mitosis
domain
kingdom
phylum
Eukarya
Animalia
Chordata
Organisation
single–celled
or chains /
groups of cells,
e.g. filaments
single–celled
or chains /
groups of cells,
e.g. filaments
unicellular
/ colonial /
multicellular
class
Mammalia
order
Artiodactyla
family
Giraffidae
genus
Giraffa
species
Giraffa camelopardalis
Cambridge International AS and A Level Biology © Cambridge University Press 2014