Whether it was volcanic activity that spewed sulfur dioxide and ash
into the atmosphere, or a giant meteor that crashed into the Earth
blasting dust and debris into the sky, both theories of what caused the
dinosaurs to become extinct share one critical similarity — light from
the sun was obliterated. The result of the months’ long darkness was the
mass extinction of nearly 70% of all creatures on Earth.
Like the dinosaurs, humans cannot live without the sun. Not only does
it provide light and warmth, it is also the energy source for arguably
the most important chemical reaction on Earth: photosynthesis.
“Even if you revel in cheeseburgers and fried chicken, the energy in
these animal fats and proteins ultimately came from the animals’ food –
plants” (Audesirk, Audesirk, & Byers, B., 2008, p. 129).
Answer the following assignment questions:
1. Explain how photosynthesis and respiration are linked in order to provide you with energy from the food you eat.
Include in your essay:
Complete descriptions of photosynthesis and aerobic respiration.
Describe how these two processes are linked between plants and
animals based on the reactants and products (water, carbon dioxide,
glucose and oxygen) of both pathways.
Include a description of how energy is transferred from sunlight to ATP, from ATP to sugars, and from sugars to your cells.
2. In the absence of oxygen some cells and organisms can use
glycolysis coupled to fermentation to produce energy from the sugar
created by photosynthesis.
Explain the role of fermentation in allowing an organism to generate energy for its cell(s) in the absence of oxygen.
Include any reactions required for this process, and explain how
the energy from the sun ends up as chemical energy for the anaerobic
organism or cell.
3. Cells use enzymes as biological catalysts to increase or
accelerate the rate of reactions, such as those in photosynthesis or
glycolysis. This allows reactions to occur under conditions that sustain
life.
Explain how an enzyme catalyzes a reaction. Include in your
essay the three main steps of the cycle of enzyme-substrate
interactions.
How is enzyme activity regulated by the cell?