These are the most frequently used words in this book.
acid
air
among
animals
antibiotics
bacteria
biological
called
carbon
cause
caused
cells
certain
chapter
chemical
creatures
culture
disease
dna
during
even
example
fact
few
first
food
form
formed
found
genes
genetic
group
grow
however
important
industry
infection
iron
kind
known
laboratory
life
little
living
man
material
matter
may
methane
microbes
microbial
must
need
new
now
often
organic
organisms
oxygen
part
people
place
plants
population
present
problem
process
products
protein
quite
rather
research
seems
sewage
shall
soil
sometimes
sort
still
strains
sulphate
sulphide
sulphur
things
though
thus
time
today
two
types
use
used
usually
virus
viruses
water
world
years
yeasts
yet