Answer Key
Cell Structure and Function
Lesson 1
Before You Read
1.
2.
disagree
agree
Read to Learn
1.
2.
a. cells
All living organisms are made of one or more cells, the cell is
the smallest unit of life, and all new cells come from cells that
already exist.
3. Scientists made better microscopes, which helped them
observe individual cells and structures inside cells.
4. 1. b, 2. c, 3. a
5. many small molecules joined together
6. Like magnets, water molecules have a positive end and a
negative end, which can attract the opposite charge.
7. sodium
8. proteins and carbohydrates
9. cell growth, cell reproduction, cell processes that enable a cell
to respond to its environment
10. Possible answers: communicating among cells, moving
substances around inside the cells, breaking down nutrients,
providing support
11 Lipids protect cells, store energy, and help with cell
communication.
12. nucleic acids, proteins, lipids, carbohydrates
After You Read
1.
2.
3.
Reading Essentials
Possible answer: A lipid is a large macromolecule that does
not dissolve in water.
proteins, keratin; lipids, vitamin A; carbohydrates, cellulose
Students should explain how highlighting the main ideas
helped them understand cells.
Cell Structure and Function
1
Lesson 2
Before You Read
3.
4.
agree
disagree
Read to Learn
1.
2.
3.
4.
5.
6.
7.
8.
9.
The cell wall is outside of the cell membrane.
proteins and phospholipids
Possible answers: Golgi apparatus, cell membrane,
cytoskeleton, smooth endoplasmic reticulum, rough
endoplasmic reticulum, mitochondrion, ribosome, vesicle,
nucleus and its contents
The cytoskeleton is made of threadlike proteins that are joined
together.
Possible answers: DNA, cell membrane, cell wall, capsule,
flagellum, cytoplasm, and ribosome
Both have genetic material, which is surrounded by a
membrane in eukaryotic cells but not in prokaryotic cells.
Eukaryotic cells are larger and have organelles. Prokaryotic
cells have fewer cell parts and no organelles.
Rough ER has ribosomes on its surface and produces proteins.
Smooth ER has no ribosomes on its surface, produces lipids,
and helps remove harmful substances from a cell.
plant and algae cells
prepares proteins for their specific jobs and packages them
into tiny membrane-bound structures called vesicles
After You Read
1.
Possible answer: The nucleus directs all cell activities and
stores genetic information.
2.
Reading Essentials
Organelle
Function
Chloroplast
uses light energy and makes food
Golgi apparatus
gets proteins ready for their specific
jobs; packages them into vesicles
Smooth ER
makes lipids
Nucleus
directs cell activities; contains
genetic information
Cell Structure and Function
2
3. These tasks include getting energy from food, storing
information, and getting rid of waste material.
Lesson 3
Before You Read
5.
6.
disagree
agree
Read to Learn
1.
2.
3.
4.
5.
6.
7.
8.
Only the water in the left side of the beaker would be colored
with dye. The water in the right side would remain clear.
Diffusion is the movement of any small molecules from an
area of higher concentration to an area of lower concentration.
Osmosis is the diffusion of water molecules only through a
membrane.
Carrier proteins carry large molecules through the cell
membrane. Channel proteins form pores through membranes
that ions pass through.
Students should circle carrier proteins.
A cell uses its own energy to move substances from areas of
lower concentration to areas of higher concentration.
either through passive transport—diffusion, osmosis, and
facilitated diffusion—or through active transport—
endocytosis and exocytosis
54 mm2/27 mm3 = 2/1 = 2:1
vesicle
After You Read
1.
Possible answer: Active transport uses the cell’s energy to
move substances through the membrane, but passive transport
does not use the cell’s energy.
2.
Active transport
Passive
transport
Reading Essentials
Energy
needed?
yes
Structures
Involved
cell membrane
no
vesicle cell
membrane,
channel proteins,
carrier proteins
Cell Structure and Function
Examples
exocytosis,
endocytosis
diffusion, osmosis,
facilitated
diffusion
3
Lesson 4
Before You Read
7.
8.
disagree
disagree
Read to Learn
1.
2.
3.
4.
5.
6.
7.
Students should circle the cytoplasm.
Glycolysis breaks down glucose into smaller molecules.
Reactions in the mitochondria convert oxygen and these
smaller molecules into energy, water, and carbon dioxide.
through cellular respiration and fermentation
Both make ATP from glucose, but lactic-acid fermentation
also produces lactic acid, whereas alcohol fermentation
produces alcohol and carbon dioxide.
lactic-acid fermentation: ATP and lactic acid; alcohol
fermentation: ATP, alcohol, and carbon dioxide
Some cells make food molecules through photosynthesis,
using light energy, water, and carbon dioxide.
Photosynthesis releases oxygen that other organisms can use
for cellular respiration. Cellular respiration gives off carbon
dioxide that plants can use in photosynthesis.
After You Read
1.
Possible answer: Cellular respiration makes carbon dioxide
and water as waste products. Photosynthesis uses carbon
dioxide to make sugars and oxygen, which are used by other
organisms during cellular respiration.
2.
Photosynthesis
What is
needed?
What is
produced?
3.
Reading Essentials
1. carbon dioxide
2. water
3. light energy
1. glucose
2. oxygen
Cellular Respiration
Fermentation
1. glucose
2. oxygen
1. glucose
molecules
1. carbon dioxide
2. water
3. ATP
1. lactic acid
2. alcohol
3. carbon dioxide
green
Cell Structure and Function
4