Biology: Photosynthesis and Cellular Respiration

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Questions and Answers

What is the primary role of enzymes in metabolic pathways?

To act as substrates

To reduce activation energy (correct)

To store energy

To create larger molecules only

Oxidation involves the gain of electrons.

False

What is the main purpose of photosynthesis?

To transform light energy into glucose

The __________ is the site of cellular respiration in cells.

mitochondria Signup and view all the answers

Match the cellular structures with their roles:

Chloroplast = Site of photosynthesis Mitochondria = Site of cellular respiration Thylakoid = Membrane for light absorption Stroma = Fluid for photosynthesis Signup and view all the answers

Which of the following describes a catabolic reaction?

Breaking down large molecules into smaller pieces Signup and view all the answers

Heterotrophs are organisms that produce their own food.

False Signup and view all the answers

What is the role of chlorophyll in photosynthesis?

To capture light energy Signup and view all the answers

A reaction where an atom or molecule gains electrons is called __________.

reduction Signup and view all the answers

What do chloroplasts contain that is essential for photosynthesis?

Chlorophyll Signup and view all the answers

What is the primary role of carotenoids in photosynthesis?

They broaden the spectrum of absorption by capturing additional wavelengths. Signup and view all the answers

Chlorophyll B absorbs light in a broader spectrum than chlorophyll A.

False Signup and view all the answers

What is photolysis in the context of photosynthesis?

The process of breaking down a water molecule releasing H+ ions, electrons, and oxygen. Signup and view all the answers

The process by which plants turn inorganic carbon into organic compounds is called _____ fixation.

carbon Signup and view all the answers

Match the following components of photosynthesis with their functions:

Chlorophyll A = Primary pigment for photosynthesis NADPH = Reducing power in the Calvin Cycle Electron Transport Chain = Series of electron-carrying molecules ATP = Energy currency of the cell Signup and view all the answers

Which component is responsible for ATP production during light-dependent reactions?

Chemiosmosis Signup and view all the answers

Electron transport systems are vital for the light-independent reactions.

False Signup and view all the answers

Name one limiting factor that can affect the rate of photosynthesis.

Light, temperature, or carbon dioxide levels. Signup and view all the answers

The Calvin Benson Cycle is also known as the _____ reactions.

light-independent Signup and view all the answers

What is the effectiveness of a wavelength in the action of photosynthesis referred to as?

Action spectrum Signup and view all the answers

Study Notes

Photosynthesis and Cellular Respiration

Metabolic pathways are biological processes involving matter and energy, examples include cellular respiration and photosynthesis
Photosynthesis stores energy from the sun in glucose, which is then released in cellular respiration
Photosynthesis and respiration cycle; each product is used by the next in a continuous process

Metabolic Pathways and Enzymes

Metabolism is the sum of all the processes within a cell
Metabolic pathways are categorized as either anabolic (build larger molecules from subunits) or catabolic (break down larger molecules into smaller pieces)
Enzymes are protein catalysts that accelerate reactions by lowering activation energy. This allows reactions to occur at biological temperatures.
Enzymes are required because of the need to maintain efficiency and speed up reactions inside of biological systems.
Activation energy is the energy required to start a reaction

Oxidation and Reduction

Oxidation is a reaction where an atom or molecule loses electrons, leading to a loss of energy
- LEO: Losing Electrons = Oxidation
Reduction is the reaction where an atom or molecule gains electrons and gains energy
- GER: Gains Electrons = Reduction
Oxidation and reduction always occur simultaneously

Chloroplasts

Chloroplasts are the sites for photosynthesis in plant cells
Contains thylakoids, flattened sacs that have grana (stacks of thylakoids)
Chlorophyll is the green pigment in chloroplasts found in the stroma

Mitochondria

Mitochondria are the sites for cellular respiration in both plant and animal cells
Contains inner and outer membranes with the matrix in between
Matrix contains the necessary chemicals and proteins for breaking down carbohydrates to produce ATP.

Photosynthesis

Heterotrophs (like animals) ingest their food
Autotrophs (like plants) produce their own food
Photosynthesis transforms light energy into chemical energy in glucose, using inorganic raw materials (water and CO2)

Photosynthetic Pigments and Absorption

Light exists in various wavelengths, each representing its energy content
Plants absorb wavelengths in the visible light spectrum via pigments like chlorophyll and carotenoids
Chlorophyll A is the primary pigment involved in photosynthesis, followed by Chlorophyll B
Carotenoids are accessory pigments that aid in photosynthesis by capturing a wider range of wavelengths.
Absorption spectra and action spectra determine the effectiveness of a wavelength in photosynthesis.

The Reactions of Photosynthesis

Light-Dependent Reactions: These reactions happen in thylakoid membranes.
- Light energy (photons) from the sun is trapped and used to make ATP and NADPH
- Water is split to produce electrons, oxygen, and hydrogen ions (photolysis)
- The energized electrons move through electron transport chains, creating an electrochemical gradient.
- This gradient drives the creation of ATP through ATP synthase.
Light-Independent Reactions (Calvin Cycle):
- These reactions occur in the stroma of the chloroplast.
- Carbon dioxide is fixed to RuBP to synthesize the sugar G3P (later glucose)
- Requires ATP and NADPH (formed in light-dependent reactions).

Overall Costs

ATP and NADPH are required per CO2 molecule fixation, to generate G3P.
The Calvin Cycle consumes 9 ATP and 6 NADPH to synthesize one G3P.
Factors such as light intensity, temperature, and CO2 all affect the rate of photosynthesis.

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Description

Explore the key concepts of photosynthesis and cellular respiration in this quiz. Understand how these metabolic pathways interact, the role of enzymes, and the importance of energy transformations. Test your knowledge of the continuous cycles that sustain life.