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Traits and the
Environment
Chapter 2
Section 1

What are traits?
All the features that
an organism inherits
 The color of your eyes
and the shape of your
ears are two of your
traits.


Characteristics of DNA
Contains information
needed to produce a
living organism
 Exists as
chromosomes in cells
with a nucleus
 Has segments of the
DNA code on a
chromosome called
genes


What is a gene?
Part of the DNA code
on a chromosome
 The genes an
organism has (genetic
makeup) is called its
genotype


What is the difference
between genotype and
phenotype?


Genotype is the genetic
makeup—the actual
genes that a person has
Phenotype is what you
see—combination of
genes and the
environmental effect
–
–
–
–
Blond hair
Blue eyes
Pink flowers
Large leaves

What does the
environment have to
do with genes?
Doesn’t have much
effect on some
phenotypes—like eye
color
 Other phenotypes are
mostly due to
environment influence

– Hydrangea plant
– Pink or blue flowers
depending on soil
conditions

Some influences
external
– Amount of light
– Temperature

Some influences
internal
– Brain cells require
thyroid hormone for
development

How is growth
effected by the
environment?

Trees grow differently
in a dense forest from
the way that they
grow when they are
alone.

Competition for
factors such as food,
sun, water
– Significant effects to
tree population

How is appearance
effected by the
environment?



The water buttercup has
leaves that are shaped
differently depending on
where the leaves develop.
Leaves that grow
submerged in water are
threadlike and those that
grow above the water are
broad.
Difference—presence of
water

The color markings on a
Siamese cat are another
phenotype affected by
the environment.

Because the gene for
colored fur is less active
in heat, colored markings
develop more quickly on
cooler parts of the cat’s
body, such as the ears.

How is gender effected
by the environment?

Most living things are
born male or female and
remain that way for life.

However, some species of
fish, including many
clownfish, parrot fish,
wrasses, and sea bass,
are born with the ability
to change sex.

This allows these
species to maintain a
desired male-tofemale ratio in a
group under different
conditions.

A few fish have the
ability to switch back
and forth between
sexes.