CSET Practice Test Subtest II Science

Mitosis - Body Growth and Repair

Cell reproduction in which 2 identical cells are made 
from one cell

Each cell grows until it is ready to divide

Body cells 

   Are cells that make up most of the body 

   Such as skin, blood, bones, and stomach 

   Body cells don't all live the same length of time 

   Mitosis goes on at different rates in different organs 

  To replace cells that are worn out 

  Muscle cells don't carry on mitosis after birth 

  You are born with all the muscle you'll have your whole life 

  It grows, but doesn't reproduce

   Mitosis goes on all the time, from before you are 
born until you die

Introduction to Mitosis How does mitosis work? 

  The result is like a copy machine: 

  Start with one item - end up with two identical copies.

Cell parts involved in mitosis: 

   Cell membrane

   Cytoplasm

   Nucleus

  Chromosomes

   Centrioles

The Steps of Mitosis:

    Before it officially begins: 

Each chromosome doubles, and becomes two 

   2 strands are joined at one point

   Each is an exact duplicate of the original

The 2 strands are called Sister Chromatids 

   The centrioles double 

The Steps of Mitosis: 

1. ONE - Prophase
1. Sister chromatids begin to shorten and thicken 
2. Nuclear membrane begins to break down -Chromatids 
begin to look like they are floating in the cytoplasm
3. Centrioles move away from each other 
4. Fibers (strands of protein) form between the centrioles

2 - TWO - Metaphase 
1. Centrioles move apart, to opposite ends of the 
cell - Fibers looked stretched between
2. Sister chromatids become attached to the fibers 
and are pulled toward the center of the cell 
3. All the sister chromatids are lined up at the center 
of the cell

3 - THREE - Anaphase  
1. Sister chromatids are pulled apart by the fibers. 
(The identical "partners" are now separate)
2. The fibers pull each chromatid strand toward the 
centrioles at the opposite ends of the cell

4 - FOUR - Telophase 
1. Each end of the cell now has a complete set of 
chromosomes - Each end having the same number 
that the cell originally started with
2. Fibers begin to disappear 
3. Nuclear membrane begins to form around the 
chromosomes at each end 
4. The cell membrane begins to pinch in near the 
center and divide the cytoplasm in half, forming two 
cells where there was one, each with the same 
number of chromosomes as the original one cell had, 
each identical to its original chromosome  - The new 
cells are smaller than the original, but begin to grow 

Benefits 
   Makes new cells in order to: 

  grow

  replace damaged cells

   Plant cells do every step the same, 

But: 

   They have no centrioles 

   They also form a cell wall between the 2 new 
cell copies

Source:
Special Thanks to the Colorado Springs, School District 
11, Doherty Night School Biology Survey Course

The Water Cycle

Water on earth moves in a continuous cycle. This is 
called THE WATER CYCLE. There is about the same 
amount of water on earth now that there was when 
the dinosaurs roamed our planet.

Evaporation/Transpiration:   
Evaporation is when the sun heats up water in rivers 
or lakes or the ocean and turns it into vapor or steam. 
The water vapor or steam leaves the river, lake or 
ocean and goes into the air. 
Transpiration is the process by which plants lose water 
out of their leaves.  Transpiration gives evaporation a 
bit of a hand in getting the water vapor back up into 
the air. 

Condensation:    
Water vapor in the air gets cold and changes back into 
liquid, forming clouds. This is called condensation. 
You can see the same sort of thing at home... pour a 
glass of cold water on a hot day and watch what 
happens.  Water forms on the outside of the glass.  
That water didn't somehow leak through the glass!  It 
actually came from the air.  Water vapor in the warm 
air, turns back into liquid when it touches the cold 
glass. 

Precipitation:  
Precipitation occurs when so much water has condensed 
that the air cannot hold it anymore.  The clouds get 
heavy and water falls back to the earth in the form of 
rain, hail, sleet or snow.

Collection:  
When water falls back to earth as precipitation, it may 
fall back in the oceans, lakes or rivers or it may end up 
on land.  When it ends up on land, it will either soak 
into the earth and become part of the "ground water" 
that plants and animals use to drink or it may run over 
the soil and collect in the oceans, lakes or rivers where 
the cycle starts.