Biology:
Photosynthesis & Cellular
Respiration Review
1. What is photosynthesis?
Plants captures energy and make
complex molecules like sugar
(glucose) for food.
2. What is chlorophyll’s role
(job) in photosynthesis?
Absorb light energy
When a chlorophyll molecule absorbs
light energy, some of its electrons are
raised to a higher energy level
3. What is the difference
between an autotroph and
heterotroph?
Autotrophs make their own food.
Heterotrophs do not make their own
food. They consume other organisms
for energy.
4. Which types of
organisms are autotrophs?
Plants!
Bacteria!
5. Which types of organisms
are heterotrophs?
Animals (humans, fish, birds,
monkeys, etc.)!
6. There are 2 stages of
photosynthesis. For each stage
below, describe where it takes
place and what is happening.
Stage 1: Light-Dependent Reactions
Where does it take place? The
thylakoid membrane
What happens in this stage? Energy is
captured from sunlight
6. There are 2 stages of
photosynthesis. For each stage
below, describe where it takes
place and what is happening.
Stage 2: Calvin Cycle (Light-
Independent Reactions)
Where does it take place? The stroma
What happens in this stage? Energy
from the first stage is used to make
glucose (sugar) for the plant
7. What happens when a
chlorophyll molecule absorbs
light?
Some electrons are raised to a higher
energy level
8. What substance is the by-
product of photosynthesis that is
used for completing of cellular
respiration?
Oxygen
9. What is the ultimate original
source of energy for all living
things on Earth?
The Sun
10. What is ATP?
Adenosine Triphosphate
A molecule that carries energy
How many phosphates does ATP
have? 3
Why is ATP important?
It is essential for a cell to perform all
the tasks necessary for life.
11. What is the by-product of
photosynthesis?
Oxygen
12. Why is the sun considered the
ultimate source of energy for life
on Earth?
Either photosynthetic organisms or
organisms that have eaten them provide
energy for all other organisms on Earth
The food chain!
13. Why do living things need
energy?
For growth and reproduction
Movement
Transport of certain materials across cell
membranes
14. Why do the leaves of plants
appear green to the human eye?
Light is being reflected off
the plant, therefore we can
only see green.
15. Why do plant root cells not
have chloroplasts?
They are underground and
do not perform
photosynthesis.
Photosynthesis mostly
happens in the leaves.
16. What is cellular respiration?
Releases chemical energy from sugars
and other carbon-based molecules to
make ATP when oxygen is present.
17. There are two stages of cellular
respiration. For each stage below,
describe where it takes place and what
is happening.
Stage 1 Glycolysis:
Where does it take place? The cytoplasm
What happens in this stage? Glucose
molecule splits into 2 three-carbon
molecules
17. There are two stages of cellular
respiration. For each stage below,
describe where it takes place and what
is happening.
Stage 2: Aerobic Respiration
Kreb’s Cycle takes place in the matrix and produces
energy-carrying molecules that transfer energy to
the electron transport chain
Electron transport takes place in the inner membrane
and makes ATP. It releases water and heat as waste
products
18. After cells break down food
molecules, where does the energy go?
When living cells break down
molecules, energy is stored as ATP and
some is released as heat.
19. The name of the process that takes
place when organic compounds are
broken down in the absence of oxygen
is called…
Fermentation
20. All organic molecules contain
carbon atoms that can be traced back
in the food chain to where?
Carbon dioxide from
the atmosphere
21. What happens when muscles
exercise extensively in the absence of
sufficient oxygen?
Lactic acid is
produced
22. Describe why photosynthesis and
cellular respiration are described as
cycles.
Photosynthesis uses the ingredients we
make from cellular respiration and we
use the ingredients from
photosynthesis.
What a plant makes we use, what we make
a plant uses and it continues in a
endless cycle.