Summary #12 (The Endocrine System)

 Did you ever wonder how you grow? Why does your body changes as you became a teenager. The changes are controled by a chemical in your bloodstream. Your body uses this chemical to control how it works.
 This chemicals are called hormones and they control body functions by influencing how cell works. Only when hormones reach their target they can produce a change in your body. The gland that produces hormones is called endocrine glands and they make up the endocrine system. Every hormone seeks out a target organ- the place in the body where hormones act. A target organ has special receptor cells that respond in a specific way to to a hormone .Too much or even to little hormones can cause serious diseases. Your body depends on a process called biological feedback to determine when to release a hormone and when to stop.
 There are six glands belonging to the endocrine system: the pituitary gland is encharged the body growth, the thyroid gland that controls the rate at wich your cells use oxygen to release the energy in food, the parathyroid gland that help control how much calcium is in your blood, the adrenal glands that control the adrenaline hormone, the reproductive hormone that produce sex hormones, and the hypothalamus that makes hormones that tell the pituitary gland wich of its hormones to start or stop producing.

Summary # 11 (The nervous system)

Your brain is the controlo center of the nervous system, wich is made of nerve cells. Nerve cells receive signals or carry messages and carry them from one part of your body to another.
 Impulse flash along individuals nerve cells, or neurons. Each neuron has three  main parts- a cell body, dentrites, and an axon. There is a gap between nerves and it is called synapse. There are three  kinds of neurons: sensory neurons that control the information from stimuli, motor neurons carry commands form the brain  and spinal cord to the muscles and glands, and associative neurons pass impulses from sensory to motor  neurons. The brain and the spinal cord are the central nervous system. All other nerves are are the outer, or peripheral, nervous system.  The brain is divided in two hemispheres and is protected by the skull. The spinal cord is protected by the vertebral column.
 The brain also controls the senses.

Summary # 10 (How species change over time)

The differences between size and shape are called variation. Variation is the difference in appearance of inherited traits among the members of a species. An animal that blends with the colorof its surrounding may live longer that one with color that does not blend as well. This ability to blend with the envirment is called adaptation. An adaptation is a variation that increase's an organism chance for survival. There are two main theories that are used to explain adaptation the Jean-Baptiste Lamark theory and the Charles Darwin theory. Charles Darwin also suggested the natural section theory to explain why there is such a great variety of living organism on Earth. This theory divides into four parts : 1. Living thiings produce more young that can survive in the enviroment. 2. There is always a variation among offspring. 3. Some variations in traits enable members of a species to survive and reproduce more succesfully than others. 4. Natural selection is always taking place. Competition is the struggle among living things to obtain the resources they need to survive.
Completely new variations are taken place in offsprings  by mutation.

Summary #9 (Evidence of change)

Have you ever seen a footprint in the mud? A footprint is a kind of evidence that a living thing leaves behind. In ancient animals fossils are the evidence that they existed are fossils. Fossils are traces or remains of an organism that haves been preserved in Earth's crust.
Most of the fossils that we find are of animals that no longer exist in Earth.As changes took place in their enviroment, some species were not able to survive and they become extinct. A some species extinct other developed. The idea that species change over time,resulting in new species is called the teory of evolution. There are two types of way fossils can form: mineral replacement and molds and casts. There are two ways the age of a fossil can be tell by: relative dationg and absolute age. There are other clues of evolution on Earth and they are: similar structures and body parts.

Summary #8 (Using what we´ve learned)

What are some inherited traits that show a parent and child resemble each other? Some traits, such as red curly hair, may appear only twice in several generations. Other taits, such as dimples, may appear in every generation. Why do some traits skip generations and appear in others?

What are some common inherited traits?

Do you have any dominant trait? Freckles, long eyelashes, and free earlobes are some dominant traits. Their oppoite forms- no freckles, short eyelashes, and attached earlobes are recessive.Also diseases such as hemophilia, dislexia, and cystic fibrosis are inherited.

What determines the sex of a child?

Human chromosomes carry genes that control a variety of traits. Human have 23 pairs of chromosomes. One of those pairs determine the sex of a person.They are sex chromosomes and there are two kinds, the X chromosome and the Y chromosome.

Summary #7 (How heredity works)

What is a code? Have you ever made one? Braille is a code that stands for words and letters. The three letter code on bagage tags tell airport workers where to send your bag. Another type of code is found in every cell of your body. It controls traits that develop in every offspring. How do you think it works?

What do you think Mendel's factors are? Where are they? Mendel's factors are inside cells.They are actually molecules founded in chromosomes inside the cell nucleus .Mendel realized that all organism have two copies of each factor-one factor come from each parent. Scientist called this factors genes ( a portion of a chromosome that controls a particular trait).
 How genes control traits? Genes are portion of a long, complex molecule called deoxyribonucleic acid, or DNA. It contains the codes that tell each cell how to operate.The genetic characteristic of every living organism ara contained in the organism's DNA. The DNA's shape looks like a spiral staircase. The steps of the staircase are made of chemical compounds or bases. The four DNA bases are cytosine,adenine,guanine , thymine.