The Nervous System

Parts of the neuron

Signal or impulses,are electriacal signals are electrical impulse.
Impulses flash along individual nerve cell or neurons.
Each neuron have three main parts.A cell body dentrites and
an axon.Dentrites are a branching  nerve fiber that carry impulses

toward the cell body. An axon is a nerve fiber that carries impulses
away from the cell body.

Ehen an impulse reach the tip of an axon ,another nerve cell can`t
pick up directly.That`s beacuse there is a gap between neurons.
This gap is called a synapse and it is a only tiny fraction of an  inch wide.

Using What We`ve Learned

Human chromosomes carry genes that control a variety of traits.
Humans have 23pairs chromosomes. One of those pairs
determine the sex of a person.

Female inherited two X chromosomes, one from each parent.

Males inherited one X from one parent and one Y chromosomes from the other.
Only males have a Y chromosomes.

Inheritetance can be controlled by crossing plants or animals to produce offspring
with ceirtain deliberate trait. People have used selective breeding for centuries to produce
better crops, hardier domestic animals, and prettier flower.

How Heredity Works

Gregor Mendel realized that all organisms get two copies of each factor.

Today scientist  call these  factors gene ,

A Gene is the portion of a chromosomes  that controls a particular trait.

Genes are a portion of along , complex molecule called

deoxyribounucleic acid. (DNA).

The codes that the DNA contain are related to the molecules shape

and structure.

Predicting Traits

When two parents have a child , there is about a probability chance the child would have the same characteristics of one parent .

Mendel experiments use a new idea to use the Punnnett Square.

It is a table used to predict the outcome of crossing
 different forms of trait.

To make a Punnett square , draw a large square and 

divide it into four  smaller squares .

Write the parent`s factor for the trait outside the square.

Actually you don`t inherit traits .You inherit factors for traits .Humans inherit thousands of factors for traits from their parents.The color of your hair and skin , the shape of your chin, the color of your eyes,the thickness of your eyebrows, the size  of your feet  and even your height were determined by factors you inherit from each parent.

A chart to trace the the history of traits in a family is called pedigree.    

Learning about Heredity

We all are alike in comaparation of our parents , dad or mom.

That is why One parent is recessive and the other is dominant.

Recessive means that  its traits are hiden but Dominant is the  more characteristic than one offspring has.

Geologic Time

You  know what is fossil. It is a remain  or imprint of a living thing preserved in Earth Crust.
Hard body parts such as teeth ,bones,shells,seeds,pollen grain,and wooden stemof plants are often preserved as fossils . Also earth has more than millions of years existing it has their eras and periods in each one.

The Rock Cycle

One difference that we have to know is what is the Difference between rocks and minerals.
Is a mixture of minerals , that is why is hard to know how many an d what kinds of minerals are in a rock.

While a mineral is compose of one kind , it is poured.

Rock Cycle:

All start when eruption in take place in a volcanoe , the lava hardens into solid .
Then other pieces of rocks felll down and accumulate there and it forms sedimentary rock.
Then it compress and then this rock is change by so much heat or pressure it chnage in another type of Rock