Unit 8 B - Cells (Pg. 86 - 171)
Chapter 4: Cells: The Basic Units of Life (pg. 92 - 117)
Name: __________________________
Date: ___________________
4.1: The Characteristics of Living Things (Pg. 94 – 96): Read Pages 94 - 96. Answer the following questions:
2. Identify the characteristics of living things illustrated by each of the following statements. Explain your
choice for each.
a) Flowers eventually die.
Living things have a lifespan. A flower dying is an example of this.
b) Plants obtain energy from the Sun.
Living things need energy. A plant uses energy in light to make food, which it then uses for energy.
c) A zebra runs away from the lioness.
Living things respond to changes in their environment. A zebra responds to the presence of a potentially
dangerous lioness by running away.
d) A broken bone heals over time.
Living things grow in size, reproduce, and are able to repair themselves. The body repairs itself by
healing the broken bone.
e) Plant roots grow toward moist soil.
Living things respond to changes in their environment. Plants respond to moisture by growing longer
roots. This is also an example of living things growing in size.
3. Consider all of the characteristics of living things. Are green algae alive? Explain your answer.
Yes. The green algae require energy from the sun. It can reproduce as shown in the figure and eventually
dies. If it senses sunlight it will respond by moving toward it. If it senses a predator it will move away.
4. What two characteristics of life are described in the following statement? “A human begins life as a single
cell, whereas an adult is made up of trillions of cells.”
The two characteristics described are living things grow in size, reproduce, and are able to repair
themselves, and all living things are made up of one or more cells.
4.2: The Nature of Cells: The Cell Theory (Pg. 97): Read Pages 97. Answer the following questions:
1. What does theory state?
The cell theory states that the cell is the basic unit of life, that all living things are made up of one or more
cells, and that all cells come from pre-existing cells.
2. Explain how scientists developed the cell theory.
The development of microscopes allowed scientists to discover cells and then to observe and study them in
many different organisms. This led to the theory that all organisms are made of cells.
3. In this section, you saw photos of four different types of cells. Why do we study cells from different living
things?
Different types of cells have different functions. Different organisms meet their needs in different ways
and this calls for different types of cells.
4.3: The Compound Microscope (Pg. 98 – 101): Read Pages 98 - 101. Answer the following questions:
3. What is “field of view”?
The field of view is the circle of light that you see when you look through the ocular lens of a microscope.
4. When observing a specimen under medium power, which adjustment know should be used to focus the
image? Why?
The fine adjustment knob should be used to focus the image. If you use the coarse adjustment knob, you
may break the slide and damage the objective lens. The medium and high power objectives are much
closer to the slide than the low power objective and the coarse adjustment knob would lower the objective
into the slide.
4.5: Plant and Animal Cells (Pg. 104 – 107): Read Pages 104 - 107. Answer the following questions:
2. What are organelles?
Organelles are small structures with specific functions that are found within cells.
4.8: Advances in Microscopy (Pg. 111 -112): Answer the following questions:
2. What organelles can only be seen in detail using an electron microscope?
Electron microscopes allow scientists to see in detail organelles that they could not see with a compound
light microscope— mitochondria, endoplasmic reticulum, ribosomes, Golgi apparatus, and lysosomes.
Electron microscopes also allow scientists to see details of the inner structure of different organelles.
3. What are two commonly used types of electron microscopes?
Two commonly used types of electron microscopes are the SEM (scanning electron microscope) and the
TEM (transmission electron microscope).
4. In what industries are electron microscopes used today?
Electron microscopes are used by biologists to research cell structure and function. They are also used in
industries such as forensics, nanotechnology, and mining.
Chapter 4 - Review (pages 116 - 117)
Name: __________________________

Date: ___________________
What Do You Remember?
2. Explain the cell theory in your own words. K/U
The cell theory states that all living things are made up of at least one cell, that the cell is the basic unit of
life, and that all cells come from pre-existing cells.
3. What are genes? What is genetic information? K/U
A gene is a portion of a chromosome. Each gene contains a code to direct the production of a particular
protein. The coded information is called genetic information and allows the cell to function and
reproduce.
4. What parts of the microscope are responsible for magnification? What parts are used to focus the image? K/U
Lenses are responsible for magnification. The coarse adjustment and fine adjustment knobs are used to
focus the image.
6. Which objective lens should you use to begin observing a specimen under a microscope? K/
You should use the low-power objective to begin observing the specimen.
8. Write a definition in your own words for each of the following terms:
cell
The building block of life. It is the smallest unit that can carry out life
processes.
organelle
A structure within a cell that carries out a specific function.
compound microscope
A tool that magnifies objects using light and lenses.
electron microscope
It uses magnets and a beam of electrons to produce a highly magnified image.
magnification
It means making an object appear larger.
9. Where in a cell would you find chromosomes? K/U
Chromosomes are found in the nucleus.
11. What are the two main types of electron microscopes? K
The two main types of electron microscopes are transmission electron microscopes and scanning electron
microscopes.

WHAT DO YOU UNDERSTAND?
12.
(a) Explain how a compound microscope works.
In a compound microscope, visible light passes through a specimen on a slide. Lenses magnify and focus
the image of the specimen so that we can observe it.
(b) List two characteristics of the compound microscope that make it the most widely used microscope. K/U
The compound microscope is relatively inexpensive and requires relatively little training to use.
13. Describe the main structural differences between plant and animal cells. Explain why these differences are
important for each type of cell. T
Plant cells contain cell walls and chloroplasts. The cell wall provides structure and allows the plant to
support itself. The chloroplasts allow the plant cell to carry out photosynthesis. Animal cells do not have
cells walls or chloroplasts. Animals have other ways of supporting themselves, and they do not need to
carry out photosynthesis. Animals may also have structures that plants do not, such as flagella and/or
cilia.
14. Explain the importance of genetic information to an organism. What do you think might happen if a cell was
missing genetic information? T
Genetic information tells the cell how to carry out its processes as well as how to reproduce. If the genetic
information were missing, the cell would die because it would not have the instructions telling it how to
operate.
15. Cilia are used in some parts of the human body to remove particles of dust and debris. Where in the human
body might you find cells with cilia? Explain your answer.
I would expect to find cells with cilia in the respiratory tract, such as in the nose. Those parts of the body
are most likely to be exposed to dust and debris and to have to get rid of them.
16. Why are cells considered to be the basic units of life? K/U
Cells are considered the basic units of life because a cell is the smallest unit that can carry out all the
processes of life.
17. Why was the invention of the electron microscope significant to our understanding of cellular functions?
The electron microscope made it possible for scientists to see structures that they were not able to see
with compound microscopes. It also allowed them to see the details of these structures.
18. Why is it not possible to see some organelles with a compound microscope? K
The most a compound microscope can magnify an object is about 1500_. Some organelles are so small
that they cannot be seen even at that magnification.
19. The mitochondrion is called the powerhouse of the cell. How would your life be limited if you only had half
the mitochondria that you would normally have? K
Your body would only be able to produce half as much energy on a daily basis, making it harder to
perform tasks.
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SOLVE A PROBLEM!
22. Calculate the total magnification for a microscope that has a 10× ocular lens and a 20× objective lens.
A magnification of 10 times a magnification of 20 equals a total magnification of 200, or 200x.
Unit 8 B: Chapter 4 PB