Chapter 2 Section 1

8th grade book

Traits are characteristics that

we inherit from our parents,

when we receive their genes

What are traits???

Where do they come from?

Genotype is the entire set of genes an

organism has or the gene pool

of an organism

Phenotype is the appearance and behavior

of an organism

IMP: it depends on the genotype

and on the environment

Examples of traits that can change

due to the environment

Growth

Appearance

Gender

**some traits , even in humans, can be determined by the environment: growth, appearance, gender, but…..

The environment can’t affect certain phenotypes such as:

eye color, type of voice, shape of the leaves in a plant, shape and size of your ears and nose……

Effects of the Environment

**Acquired traits – not in the book

are characteristics that are gained by

an organism after birth as a result of

influences from the environment.

What is the reason why acquired traits

are not inherited and are not

transmitted to the offspring? They are

not in our genetic pool or genotype.

Environmental features that can affect

traits

Amount of light

Temperature

Type of food / soil for plants (mineral

availability)

Amount of water

Change in appearance due to the lack

of Sunlight

Why do leaves turn yellow in the Fall?

Effects of the Environment

For example, tree leaves turn yellow because:

They receive less sunlight during Fall

They will produce less chlorophyll, the pigment

responsible for the green color –

This causes a change in the appearance because

other pigments that were masked by the

Chlorophyll will show

Appearance:

soil rich in

Aluminum - the

flowers are blue

Change in Appearance – change in temperature

• Artic foxes turn white in winter

• Being white like the snow will protect the fox from predators

Growth: trees in dense forests

If trees grow taller they will:

1)reach more light

2)make more photosynthesis

3)produce more food and more seeds for the survival of the species.

Effect of the environment in the

appearance of humans

-Hair changes color when exposed

to a lot of sunlight

-Twins raised in different social

environment can develop different

behaviors

- you develop big muscles when

you exercise

Ex: fish, frogs

Effect of the Environment in the Gender

are born with the ability to change gender.

Reptiles – when still in the egg, reptiles develop into

a male or female depending on the temperature

of egg incubation

Importance of the ability to change gender

• Helps species maintain a desired male-to-female ratio in order to guarantee optimal production of offspring for the survival of the species in that area

• Book page 43