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Skills Worksheet
Active Reading
Section: Energy and Living Things
Read the passage below. Then answer the questions that follow.
The process by which light energy is converted to chemical energy
is called photosynthesis. Organisms that use energy from sunlight or inorganic substances to make organic compounds are
called autotrophs. Most autotrophs, especially plants, are photosynthetic organisms. Some autotrophs, including certain bacteria,
use inorganic substances to make organic compounds.
Organisms that must get energy from food instead of directly
from sunlight or inorganic substances are called heterotrophs.
Heterotrophs, including humans and other animals, get energy
from food through the process of cellular respiration.
SKILL: READING EFFECTIVELY
Read each question, and write your answer in the space provided.
1. The prefix photo- means “light.” The root word synthesis comes from a
Greek word that means “putting together.” How could knowledge of these
word parts help you define the word photosynthesis?
2. The prefix auto- means “self.” The root word troph comes from a Greek word
that means “to feed.” How could knowledge of these word parts help you
define the word autotroph?
3. The prefix hetero- comes from a Greek word that means “other.” How could
knowledge of this prefix and the root word troph help you define the word
heterotroph?
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Holt Biology
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Photosynthesis and Cellular Respiration
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Active Reading continued
4. Heterotrophs are to humans as autotrophs are to plants. What relationship
forms the basis of this analogy?
5. How does cellular respiration help your body perform its life functions?
In the space provided, write the letter of the phrase that best answers the
question.
______ 6. Which of the following most closely resembles cellular respiration?
a. warm water moving through copper pipes
b. people moving along an escalator
c. mixing different foods in a blender
d. logs burning in a campfire
Copyright © by Holt, Rinehart and Winston. All rights reserved.
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Photosynthesis and Cellular Respiration
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TEACHER RESOURCE PAGE
Answer Key
Directed Reading
12. The Calvin cycle uses carbon dioxide
from the air, energy from ATP, and
electrons from NADPH to produce
organic compounds. Some of the
three-carbon sugar molecules made
by the Calvin cycle are used to make
other substances needed for energy
and growth. The other three-carbon
sugar molecules are used to regenerate the five-carbon starting compound
and continue the cycle.
13. light intensity, carbon dioxide concentration, and temperature
SECTION: ENERGY AND LIVING
THINGS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
b
c
d
e
a
5
2
4
1
3
During cellular respiration, stored
chemical energy is released gradually
in a series of enzyme-assisted reactions. When a log is burned, stored
chemical energy is released quickly
as heat and light.
12. ATP is called an energy currency
because cells can “spend it” in order
to carry out cellular processes that
require energy.
13. Energy is released from an ATP molecule when a phosphate group is
removed from the molecule, forming
an ADP molecule.
14. Many of the chemical reactions of
metabolism require energy. The breakdown of ATP into ADP and phosphate
groups releases energy in a way that
cells can use it for metabolism.
SECTION: CELLULAR RESPIRATION
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
SECTION: PHOTOSYNTHESIS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
3
1
2
Almost all of the energy we use comes
from plants, which get their energy
directly from sunlight.
3CO2 + 3H2O → C3H6O3 3O2
pigments
carotenoids
water
NADPH
electron transport
phosphate
cellular respiration
aerobic
glycolysis
glucose
pyruvate
Pyruvate produced during glycolysis
enters a mitochondrion and breaks
down into a carbon dioxide molecule
and a two-carbon acetyl group. The
acetyl group attaches to a coenzyme A
molecule, forming acetyl-CoA.
water and a large amount of ATP
electron transport chain
alcoholic, lactic acid
NAD
When muscle cells do not get enough
oxygen, pyruvate is converted to lactate, which can build up in the muscle
cells and cause soreness.
The electron transport chain, which
produces a large amount of ATP, operates under aerobic conditions but not
under anaerobic conditions.
Active Reading
SECTION: ENERGY AND LIVING
THINGS
1. a putting together of substances,
including substances found in light
energy, to form chemical energy
2. capable of producing organic compounds, or food, from within itself
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Photosynthesis and Cellular Respiration
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TEACHER RESOURCE PAGE
Vocabulary Review
3. A heterotroph must obtain organic
compounds, or food, by consuming
another organism.
4. The analogy identifies a classification
group and a specific member of that
group.
5. Through cellular respiration, the
human body gets energy from food.
This energy is needed for an organism
to carry out its life processes.
6. d
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
SECTION: PHOTOSYNTHESIS
1. Photosynthesis is directly affected by
various environmental factors.
2. A decrease in light intensity would
3.
4.
5.
6.
cause a similar decrease in the photosynthesis level of the plant.
Once the light saturation point is
reached, light intensity has minimal
effect on the photosynthesis level of
a plant.
The concentration of carbon dioxide
steadily increased during the study,
causing an increased rate of photosynthesis. At the point when the rate
leveled off, the carbon dioxide concentration had reached its maximum
point.
Air temperature dropped to a point at
which plant enzymes involved in photosynthesis could not operate efficiently.
b
photosynthesis
autotrophs
heterotrophs
cellular respiration
pigment
chlorophyll
carotenoids
electron transport chain
carbon dioxide fixation
Calvin cycle
aerobic
anaerobic
glycolysis
Krebs cycle
fermentation
thylakoids
Science Skills
1. food chain A: corn—10,000 kcal;
2.
3.
4.
SECTION: CELLULAR RESPIRATION
1. Glycolysis occurs in the cytosol of a
cell.
5.
2. Glycolysis is not dependent upon the
presence of oxygen.
3. It is broken down to form two threecarbon molecules of pyruvate.
4. The energy comes from stored energy
in the glucose molecule.
5. d
human vegetarians—1,000 kcal; food
chain B: corn—10,000 kcal; cattle—
1,000 kcal; human meat eaters—
100 kcal
Because 90 percent of the energy from
one trophic level never makes it to the
next level, there is rarely enough
energy available to sustain a fifth level.
Some energy is lost as heat, and some
is used up in cellular respiration.
Activity increases the required
kcal/hour by about 62 percent. Plant
foods would be a more efficient diet;
a vegetarian diet provides 10 times as
much energy as a meat diet.
Because humans have access to 10
times as much energy when their diet
consists of grains, such as wheat, rice,
and corn, rather than meat, eating
foods that are lowest on the food
chain makes sense.
Concept Mapping
1.
2.
3.
4.
5.
6.
7.
8.
glucose
glycolysis
anaerobic process
fermentation
NAD
pyruvate
Krebs cycle
electron transport chain
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt Biology
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Photosynthesis and Cellular Respiration