Energy, Metabolism, Photosynthesis, and Cellular Respiration

Comprehensive practice flashcards covering thermodynamics, enzyme kinetics, photosynthesis, and aerobic and anaerobic cellular respiration from Chapters 6, 7, and 8.

How is thermodynamics defined in Chapter 6?

The flow of energy, based on the principle that energy is always moving.

What is the definition of energy and what are its units of measurement?

Energy is defined as the ability to do work; its units are calories (Kcal), where $1\text{ nutritional calorie} = 1{,}000\text{ calories}$.

What does the First Law of Thermodynamics state?

The amount of energy in the universe is constant and never changes; energy is neither created nor destroyed, but it can change form.

What is the Second Law of Thermodynamics, and how is entropy defined?

The Second Law states that energy naturally flows from a high potential to a low potential; entropy is the tendency of a system to become disorganized over time.

What are the two forms of nuclear energy described in the notes?

Fission (the splitting of an atom) and fusion (the combining of an atom).

How is metabolism defined?

An organism's ability to acquire and use energy.

How do exergonic and endergonic reactions differ?

Exergonic reactions are "Energy out" reactions that release energy (e.g., $O_2 + \text{food} = CO_2$), whereas endergonic reactions are "energy in" reactions that require energy (e.g., photosynthesis).

What is the primary function of an enzyme, and what is one example provided?

Enzymes speed up specific metabolic reactions; an example is amylase, which breaks down starch in spit.

What is an active site on an enzyme?

A binding site on an enzyme for a specific substrate (reactant) that grips the substrate, triggering a reaction and releasing energy.

What is feedback inhibition and what is an allosteric site?

Feedback inhibition occurs when an adequate quantity of the end product is produced and shuts down the pathway; the allosteric site is the second binding site on the enzyme for a controlled substance that shuts down the pathway.

How do cofactors differ from coenzymes?

Cofactors are metal ions and not organic substances ($Mg$, $Ca$, $K$, $Fe$, $Zn$, $Na$), while coenzymes are organic substances (niacin, thiamine, riboflavin) that allow for temporary energy storage.

What occurs during oxidation versus reduction of a coenzyme?

When oxidized, a coenzyme loses hydrogen atoms and electrons, releasing energy; when reduced, it gains hydrogen atoms and electrons, requiring energy.

Where is energy utilized in the ATP molecule, and how much energy is required for phosphorylation?

Energy is utilized in the bonds between the 2nd and 3rd phosphate; phosphorylation ($ADP + P = ATP$) requires $7\text{ Kcals}$.

What is the overall balanced chemical equation for photosynthesis?

$$6 CO_2 + 6 H_2O + \text{sunlight} = C_6H_{12}O_6 + 6 O_2$$

Which visible spectrum wavelengths are absorbed and reflected by photosynthetic plants?

Blues and violets are absorbed (blue, indigo, and violet being the most powerful), while reds and greens are reflected.

What are the roles of the cuticle and stomata in the leaf epidermis?

The cuticle is a protective waxy covering that reduces water loss, and stomata are mouth-like openings controlled by guard cells that allow for gas exchange.

How do the palisade and spongy layers of the mesophyll differ in function?

Palisade cells are packed tightly together and have the highest photosynthesis, while spongy cells are loosely packed together for highest gas diffusion.

What do xylem and phloem transport in leaf veins?

Xylem carries water and minerals to the leaf, while phloem carries sugar away from the leaf.

Why do fall colors occur in deciduous trees?

As temperature and daylight decrease, chlorophyll production stops, and carotenoids show through for a short time.

What are the location, initial reactants, and end products of the light-dependent stage of photosynthesis?

It occurs inside the thylakoids; initial reactants are sunlight and $H_2O$; end products are useable energy ($ATP$ and $NADPH$) and oxygen waste.

Where does the light-independent stage take place, and how many rotations of the Calvin cycle are needed to produce one glucose?

It takes place in the stroma of chloroplasts, and the cycle must rotate $6\text{ times}$ to produce $1\text{ glucose}$.

What are the three variations of the Calvin cycle and their given examples?

C3 plants (most common, e.g., Kentucky blue grass), C4 plants (adapted to short periods of hot, dry weather, e.g., corn, sugarcane, crabgrass), and CAM plants (adapted to year-round hot, dry climates, e.g., cactus).

What is the overall chemical equation for aerobic respiration?

$$C_6H_{12}O_6 + 6 O_2 = 6 CO_2 + 6 H_2O + \text{energy}$$

What are the location, initial reactants, and end products of glycolysis?

Glycolysis occurs in the cytosol; initial reactants are glucose and $2\text{ ATP}$; end products are $2\text{ pyruvate}$, a net of $2\text{ ATP}$, and $2\text{ NADH}$.

What are the location and end products of the transition stage of aerobic respiration?

It begins in the cytosol and ends in the mitochondrial matrix; end products are $2\text{ acetyl-CoA}$, $2 CO_2$, and $2\text{ NADH}$.

What are the location, initial reactants, and end products of the Krebs cycle?

It occurs in the mitochondrial matrix; starts with $2\text{ acetyl-CoA}$; end products are $4 CO_2$, $6\text{ NADH}$, $2\text{ FADH}_2$, and $2\text{ ATP}$.

What are the location, reactants, and end products of the electron transport system?

It occurs in the mitochondrial cristae; initial reactants are $10\text{ NADH}$, $2\text{ FADH}$, and oxygen; end products are $34\text{ ATP}$ and metabolic water.

What is the total energy yield and efficiency of aerobic respiration per glucose molecule?

$1\text{ glucose} = 38\text{ ATP}$, producing $38\text{ ATP} \times 7\text{ Kcal} = 266\text{ Kcal}$, with an efficiency of $40\%$.

What are the end products of anaerobic respiration in animal cells versus yeast cells?

In animal cells: glucose yields $2\text{ ATP}$ and $2\text{ lactic acid}$; in yeast cells: glucose yields $2\text{ ethanol} + 2 CO_2 + 2\text{ ATP}$.

What is the energy yield of anaerobic respiration, and how is fitness level defined in relation to oxygen debt?

Energy yield is $1\text{ glucose} = 2\text{ ATP}$ ($2\text{ ATP} \times 7\text{ Kcal} = 29.288\,kJ\,14\text{ Kcal}$, $2\%$ efficiency); fitness level is defined as how quickly you pay off oxygen debt.