Cellular Respiration and ATP

Question 1

Why do cells need energy?

Answer 1

Without energy, cells cannot grow, repair, reproduce, or carry out daily activities.

Question 2

What is the cell’s usable source of energy called?

Answer 2

ATP (adenosine triphosphate).

Question 2

What is energy stored in ATP?

Answer 2

In the last phosphate bond of the ATP molecule.

Question 3

How does ATP release energy for cell activities?

Answer 3

The last phosphate bond is broken, releasing the energy required by the cell.

Question 3

What happens to ATP after it releases energy?

Answer 3

It becomes ADP (adenosine diphosphate), a low energy molecule.

Question 4

Why can’t the cell build up ADP?

Answer 4

Because the cell requires a constant supply of energy in the form of ATP.

Question 5

How is ATP regenerated from ADP?

Answer 5

Through respiration, which joins an inorganic phosphate group back onto ADP.

Question 6

What does the process of making ATP from ADP require?

Answer 6

Glucose and oxygen.

Question 7

Where does the process of ATP regeneration occur?

Answer 7

In the cell’s cytosol and mitochondria.

Question 8

What is cellular respiration?

Answer 8

It is the process by which the energy of glucose is released in the cell and converted to ATP for life processes.

Question 9

What are some life processes that use ATP from respiration?

Answer 9

Movement, breathing, blood circulation, and more.

Question 10

What are three unique features of mitochondria? (3)

Answer 10

hey have a double membrane, their own DNA, and can reproduce within the cell.

Question 11

What are the parts of the mitochondria structure? (4)

Answer 11

Smooth outer membrane

Folded inner membrane

Folds called cristae

Liquid between cristae called the matrix

Question 12

What are the three stages of cellular respiration?

Answer 12

Glycolysis

The Krebs Cycle

The Electron Transport Chain

Question 13

What is the word equation for cellular respiration?

Answer 13

Glucose + Oxygen → Carbon Dioxide + Water + 30 or 32 ATP

Question 13

What is the chemical equation for cellular respiration?

Answer 13

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 30 or 32 ATP

Question 13

What happens during glycolysis?

Answer 13

Glycolysis starts outside the mitochondria in the cytosol, where glucose is split into two pyruvate molecules. 2 ATP and NADH (a carrier of H+ ions) are generated.

Question 14

What happens during the Krebs Cycle?

Answer 14

The Krebs Cycle occurs inside the mitochondrial matrix, where pyruvate is broken down in a series of reactions, releasing CO₂. 2 ATP are generated, and more carriers (NADH) are loaded with H+ ions.

Question 15

Q: What happens during the Electron Transport Chain?

Answer 15

The Electron Transport Chain occurs on the cristae of mitochondria (inner membrane). It uses O₂ to produce water, and loaded H+ carriers deliver and release their H+ ions. 26 or 28 ATP are generated.

Question 16

Q: What happens to the rate of cellular respiration as temperature increases toward the optimum range?

Answer 16

The rate of cellular respiration increases.

Question 16

What happens at the optimum temperature?

Answer 16

Cellular respiration occurs at the maximum rate.

Question 16

What are the factors affecting the rate of cellular respiration?

Answer 16

Temperature, glucose availability, and oxygen concentration.

Question 17

What happens to the rate of cellular respiration above the optimum temperature?

Answer 17

It rapidly decreases as enzymes are denatured.

Question 18

When is cellular respiration rate and ATP production highest?

Answer 18

When the temperature is at the enzyme’s optimal temperature.

Question 19

Why does glucose availability affect the rate of cellular respiration?

Answer 19

Because glucose is an input (substrate) for glycolysis.

Question 20

When is the maximum rate of respiration reached?

Answer 20

When the enzymes within the cells are operating at their maximum capacity.

Question 20

What happens when glucose concentration increases?

Answer 20

The rate of respiration increases until a saturation point is reached.

Question 20

What happens when oxygen concentration increases?

Answer 20

The rate of aerobic respiration increases.

Question 21

Why is oxygen required for aerobic respiration?

Answer 21

Because the electron transport chain requires oxygen to function.

Question 22

What happens when oxygen levels are low?

Answer 22

Cells switch to anaerobic fermentation and switch back to aerobic respiration when O₂ levels increase.

Question 22

What is another name for anaerobic respiration?

Answer 22

Fermentation (alcoholic and lactic acid).

Question 23

What limits the maximum rate of aerobic respiration even with more oxygen?

Answer 23

The number of enzymes available limits the rate.

Question 24

In which organisms does alcoholic fermentation occur?

Answer 24

In bacteria and yeast.

Question 25

What happens to glucose during alcoholic fermentation?

Answer 25

Glucose is converted into pyruvate, releasing 2 ATP, and then into alcohol (ethanol) and carbon dioxide.

Question 25

What is the word equation for alcoholic fermentation?

Answer 25

Glucose → alcohol + carbon dioxide + 2 ATP.

Question 25

Where does lactic acid fermentation occur?

Answer 25

In muscle cells.

Question 26

What sensation does lactic acid cause in muscles?

Answer 26

A burning sensation.

Question 26

When is lactic acid produced in muscles?

Answer 26

During rapid exercise when the body cannot supply enough oxygen to the tissues.

Question 27

What happens to glucose during lactic acid fermentation?

Answer 27

Glucose is broken down into pyruvate, releasing 2 ATP, and then converted into lactic acid.

Question 28

What is the word equation for lactic acid fermentation?

Answer 28

Glucose → lactic acid + 2 ATP.

Question 29

Why is anaerobic respiration not sustainable long term?

Answer 29

Because its final products are toxic to cells and need to be removed.

Question 29

Where does anaerobic respiration occur?

Answer 29

Only in the cytosol.