APRIL ADVENTURER- SCIENCE
Section 1
Read each question carefully. Choose the most suitable answer.
1. What is the primary energy source for living organisms?
A. Plants.
B. Water.
C. Phytoplankton.
D. The sun.
2. One model that shows how energy passes from one organism to another is called
a/an ___________.
A. food pyramid.
B. food chain.
C. energy flow.
D. pyramid of energy.
3. Which of the following the correct word equation for photosynthesis?
A. carbon dioxide + water + light --> glucose + oxygen
B. oxygen + water + light --> glucose + carbon dioxide
C. carbon dioxide + oxygen + light --> glucose + water
D. glucose + water + light -->carbon dioxide + oxygen
4. What type of energy is needed for photosynthesis to happen?
A. Heat.
B. Geothermal.
C. Nuclear.
D. Light.
5.
An organism, which gets its source of energy from outside itself, is called a/ an
_________.
A. autotroph.
B. eukaryote.
C. heterotroph.
D. decomposer.
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Section 2
Answer the questions in the spaces provided.
6. Look at the picture and answer the following questions.
a. Plants obtain energy through a process known as photosynthesis. What is
photosynthesis?
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b. How does photosynthesis generate energy? Explain in detail.
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c. What happens if the plant is low on energy?
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d. Why can’t humans perform photosynthesis?
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Answer Key
Section 1
1. D. The sun.
Tip: The sun is the source of the energy processed and consumed by living organisms.
Intense nuclear reactions in the sun release light and other energy radiation into the
surrounding space. Some of this energy reaches our planet.
2. B. food chain.
Tip: Energy is transferred through the separate trophic levels of a food chain or web by
feeding. The food chain begins with producers, organisms such as green plants that can
make their own food. Plants are eaten by consumers, which are organisms that cannot
make their own food.
3. A. carbon dioxide + water + light --> glucose + oxygen
Tip: The chemical equation for photosynthesis is: 6 CO + 6 H O + light --> C H O + 6 O .
4. D. Light.
Tip: Light energy is absorbed by the green chemical chlorophyll. This energy allows the
production of glucose by the reaction between carbon dioxide and water. Oxygen is also
produced as a waste product.
5. C. heterotroph.
Tip: Heterotrophs cannot synthesize their own food and rely on other organisms, both plants
and animals for nutrition. Technically, the definition is that autotrophs obtain carbon from
inorganic sources like carbon dioxide while heterotrophs get their reduced carbon from other
organisms.
Section 2
6.
a. Photosynthesis is the process by which plants convert energy from the sun. It is the
process that allows plants to create organic molecules that they use as fuel.
b. During photosynthesis, the energy from the sun splits the water molecules into hydrogen
and oxygen. The oxygen molecules are given off by the plant and emitted into the
atmosphere. Molecules of ATP are created within the plant cell. These reactions are called
photochemical or light reactions because they require light to occur.
c. When the plant has created more glucose than it needs to sustain life, it combines glucose
molecules into larger carbohydrate molecules called starch. The starch molecules are
stored within the large vacuoles in the plant cells. When necessary, the plant can break the
starch molecules down to retrieve glucose for energy or to create other compounds, such
as proteins, nucleic acids, or fats.
d. Humans lack chloroplasts, which are the places where all the major proteins and pathways
required for photosynthesis occur. Instead of being autotrophs ourselves, we eat the
carbon of others and are therefore heterotrophs.
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