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Chapter 4

Chapter 4 - Respiration and Photosynthesis.docx


Department
Biology
Course Code
BIOL 1500
Professor
Tanya Da Sylva
Chapter
4

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Chapter 4: Respiration and
Photosynthesis
Learning Objectives:
Define autotrophs, heterotrophs, producers, and photoautotrophs.
Describe how the energy from the sun fuels all life on earth
Explain how breathing and cellular respiration are related.
Define redox reaction. Using the summary equations (figs 6.5A and 7.4A) for photosynthesis and
respiration identify which reactants/products are reduced or oxidized.
Compare and contrast the processes and locations of cellular respiration and photosynthesis.
oDescribe the overall process of the light reactions and the Calvin cycle, noting the
products, reactants, and locations of every major step.
Explain how oxygen gas is produced in photosynthesis
Describe how CO2 is incorporated into sugars during photosynthesis
Compare the reactants and products of the light reactions and the Calvin cycle.
oCompare the reactants, products, energy yield and cellular location of the three stages of
cellular respiration.
Provide the overall chemical equation for cellular respiration.
Explain how the energy in a glucose molecule is released during cellular
respiration.
Describe the general roles of NADH and the electron transport chain in cellular
respiration.
Explain how interruptions during critical events in cellular respiration and/or
damage to the mitochondrial membrane itself may affect cellular respiration.
Compare the reactants, products, and energy yield of alcohol and lactic acid fermentation with
cellular respiration.
Briefly explain how carbohydrates, fats, and proteins are used as fuel for cellular respiration.

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Describe the structure of chloroplasts and their location in a leaf; relate this information to the
role of chloroplasts in photosynthesis.
Contrast the mechanisms that C3, C4, and CAM plants use to obtain and use carbon dioxide.

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Textbook Notes:
5.1 Life Depends on Photosynthesis
The plant is an autotroph (“self feeder”), meaning it uses inorganic substances such as water and
carbon dioxide (CO2) to produce organic compounds. The opposite of an autotroph is a
heterotrophy, which is an organism that obtains carbon by consuming preexisting organic
molecules. You are a heterotrophy, and so area all other animals, all fungi, and many other
microorganisms.
It is not surprising, therefore, that if asked to designate the most important metabolic pathway,
most biologists would not hesitate to cite photosynthesis: the process by which plants, algae, and
some microbes harness solar energy and convert it into chemical energy.
Photosynthesis is a series of chemical reactions that use light energy to assemble CO2 into
glucose (C6H12O6), the carbohydrate that feeds plants. The plant uses water in the process and
releases oxygen gas (O2) as a byproduct. These chemical reactions are summarized as follows:
6CO2+6H2Oli g h t energy
C6H12 O6+6O2
This process provides not only food for the plant but also the energy, raw materials, and oxygen
for most heterotrophs. Animals, fungi, and other consumers eat the leaves, stems, roots, flowers,
nectar, fruits, and seeds of the world’s autotrophs. Even the waste product of photosynthesis, O2,
is essential to most life on Earth.
5.2 Photosynthetic Pigments Capture Sunlight
Visible light is a small silver of a much larger electromagnetic spectrum, the range of possible
frequencies of radiation. All electromagnetic radiation, including light, consists of discrete
packets of kinetic energy called photons. A photons wavelength is the distance it moves during a
complete vibration. The shorter a photons wavelength, the more energy it contains.
Plant cells contain several pigment molecules that capture light energy. The most abundant is
chlorophyll a, a green photosynthetic pigment in plants, algae, and cyanobacteria. Photosynthetic
organisms usually also have several types of accessory pigments, which are energy-capturing
pigment molecules other than chlorophyll a. Chlorophyll b and carotenoids are accessory
pigments in plants.
The photosynthetic pigments have distinct colors because they absorb only some wavelengths of
visible light, while transmitting or reflecting others. Chlorophylls a and b absorb red and blue
wavelengths; they appear green because they reflect green light. Carotenoids, on the other hand,
reflect longer wavelengths of light, so they appear red, orange, or yellow.
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