3A3 Matter and Energy Flow in Organisms

Question 1

What is cellular respiration?

Answer 1

The process by which cells convert glucose into energy.

Cellular respiration generates ATP by breaking down glucose molecules, with or without oxygen.

Question 2

What are the two main types of cellular respiration?

Answer 2

1. Aerobic Respiration
2. Anaerobic Respiration

Aerobic respiration requires oxygen and occurs in plants, animals, and fungi. Anaerobic respiration occurs without oxygen, and usually occurs in bacteria, archea, and other small microorganisms.

However, in situations of low oxygen, humans and plant cells can undergo anaerobic respiration.

Question 3

Fill in the blank:

Aerobic respiration occurs in the __________.

Answer 3

mitochondria

Aerobic respiration primarily takes place in the mitochondria where oxygen is utilized for ATP production.

Question 4

What is the main purpose of aerobic respiration?

Answer 4

To produce ATP using oxygen.

This process is highly efficient, yielding up to 38 ATP molecules per glucose molecule.

Question 5

True or False:

Anaerobic respiration occurs in the mitochondria.

Answer 5

False

Anaerobic respiration occurs in the cytoplasm since it does not require the organelles involved in oxygen-dependent processes.

Question 6

What is the main purpose of anaerobic respiration?

Answer 6

To generate energy without oxygen.

This process produces less ATP (2 ATP per glucose) but is faster than aerobic respiration.

Question 7

What is the chemical equation for aerobic respiration?

Answer 7

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP

Glucose and oxygen are converted into carbon dioxide, water, and energy in the form of ATP.

Question 8

Fill in the blanks:

Anaerobic respiration produces _______ or _______ as by-products.

Answer 8

lactic acid ; ethanol

Ethanol and CO₂ are by-products in yeast. When humans (and other animals) exercise strenuously, the cells do not have enough oxygen to produce energy, so lactic acid is produced.

Question 9

What are the 3 stages of aerobic respiration?

Answer 9

• Glycolysis
• The Krebs cycle
• Electron Transport Chain

These stages collectively produce ATP and require oxygen.

Question 10

What is glycolysis?

Answer 10

The breakdown of glucose into pyruvate.

It occurs in the cytoplasm and is the first step in both aerobic and anaerobic respiration.

Question 11

True or False:

Glycolysis requires oxygen.

Answer 11

False

Glycolysis is an anaerobic process and can occur with or without oxygen, which is why it is the first step for both aerobic and anaerobic respiration.

Question 12

Where does the Krebs cycle occur in the cell?

Answer 12

In the mitochondrial matrix.

This cycle processes pyruvate to produce energy-rich molecules like NADH and FADH₂.

Question 13

What is the main role of the electron transport chain?

Answer 13

To generate ATP using high-energy electrons.

This step uses oxygen as the final electron acceptor to produce ATP.

Question 14

Fill in the blank:

Oxygen acts as the final ________ ________ in the electron transport chain.

Answer 14

electron acceptor

Oxygen combines with electrons and protons to form water, completing the process. This explains why oxygen is necessary for aerobic respiration.

Question 15

What is fermentation?

Answer 15

An anaerobic process that breaks down sugar to produce energy.

This process is a type of anaerobic respiration seen in organisms like yeast and muscle cells under low oxygen conditions.

Question 16

What are two types of fermentation?

Answer 16

1. Alcoholic fermentation
2. Lactic acid fermentation

Alcoholic fermentation – Produces ethanol and CO₂ (e.g., yeast).

Lactic acid fermentation – Produces lactic acid (e.g., muscles, yogurt bacteria).

Question 17

True or False:

Fermentation requires oxygen to produce energy.

Answer 17

False

Fermentation is anaerobic, meaning it occurs without oxygen. It allows organisms to generate ATP when oxygen is unavailable.

Question 18

What is the ATP yield of anaerobic respiration?

Answer 18

2 ATP per glucose molecule.

Anaerobic respiration makes less energy when compared to aerobic respiration, but is a much quicker process.

Question 19

What gas is released during aerobic respiration?

Answer 19

Carbon dioxide

(CO₂)

CO₂ is released during the Krebs cycle and is expelled during exhalation.

Question 20

What happens to pyruvate in aerobic respiration?

Answer 20

It enters the Krebs cycle.

In aerobic conditions, pyruvate is converted to acetyl-CoA and processed further in the mitochondria.

Question 21

What is the primary energy carrier molecule produced during respiration?

Answer 21

ATP

(Adenosine Triphosphate)

This molecule provides energy for cellular processes.

Question 22

What is photosynthesis?

Answer 22

The process by which plants convert sunlight into chemical energy.

This process occurs in chloroplasts, using light, water, and carbon dioxide to produce glucose and oxygen.

Question 23

Where does photosynthesis primarily occur in plants?

Answer 23

In the chloroplasts of leaf cells.

Chloroplasts contain chlorophyll, which captures light energy essential for photosynthesis.

Question 24

What is the main molecule that absorbs light energy for photosynthesis?

Answer 24

Chlorophyll

This molecule absorbs light, primarily in the blue and red wavelengths, while reflecting green light.

Question 25

# True or False: The oxygen **released** during photosynthesis comes from carbon dioxide.

Answer 25

False ## Footnote The oxygen released during photosynthesis originates from water molecules. During the light-dependent reactions, water is split through a process called **photolysis**, producing oxygen as a byproduct.

Question 26

# Fill in the blank: The primary **products** of photosynthesis are glucose and \_\_\_\_\_\_\_\_.

Answer 26

oxygen ## Footnote **Glucose** is stored as energy, while **oxygen** is released into the atmosphere as a byproduct.

Question 27

What are the two main **stages** of photosynthesis?

Answer 27

1. Light-dependent reactions 2. The Calvin cycle ## Footnote Light-dependent reactions occur in the thylakoid membranes, while the Calvin cycle occurs in the stroma.

Question 28

# True or False: The Calvin cycle **requires** light to function.

Answer 28

False ## Footnote This cycle is light-independent but depends on energy (ATP and NADPH) produced during the light-dependent reactions.

Question 29

# Fill in the blank: During the Calvin cycle, carbon dioxide is **converted** into \_\_\_\_\_\_\_\_.

Answer 29

glucose ## Footnote The Calvin cycle uses ATP and NADPH to fix carbon dioxide and synthesize glucose.

Question 30

What **molecule** transports high-energy electrons during photosynthesis?

Answer 30

NADPH ## Footnote This molecule is produced in the light-dependent reactions and provides the reducing power needed for the Calvin cycle.

Question 31

How is ATP **produced** during the light-dependent reactions?

Answer 31

By **chemiosmosis** through ATP synthase. ## Footnote Chemiosmosis involves hydrogen ions moving across the semipermeable membrane down their electrochemical gradient. This creates free energy that is used by ATP synthase to convert ADP into ATP.

Question 32

What **enzyme** is responsible for fixing carbon dioxide in the Calvin cycle?

Answer 32

RuBisCO ## Footnote This enzyme catalyzes the reaction between carbon dioxide and RuBP, initiating the Calvin cycle.

Question 33

What are **biological molecules**?

Answer 33

Molecules that are **essential** for life. ## Footnote This *includes* nucleic acids, carbohydrates, proteins, and lipids, which perform various functions such as storing genetic information, providing energy, and forming cell structures.

Question 34

What are **nucleic acids** responsible for?

Answer 34

Storing and transmitting **genetic** information. ## Footnote Nucleic acids, like DNA and RNA, carry the genetic blueprint for all living organisms.

Question 35

What are the **building blocks** of nucleic acids?

Answer 35

Nucleotides ## Footnote They consist of a sugar, a phosphate group, and a nitrogenous base. DNA and RNA are polymers of nucleotides.

Question 36

# Fill in the blanks: The two **types** of nucleic acids are \_\_\_\_\_ and \_\_\_\_\_.

Answer 36

DNA ; RNA ## Footnote DNA stores genetic information, while RNA plays a key role in protein synthesis.

Question 37

What are carbohydrates **used** for in living organisms?

Answer 37

Providing energy and structural support. ## Footnote Carbohydrates, such as sugars and starches, are vital for energy storage and structural components in plants and animals.

Question 38

What is the basic **unit** of carbohydrates?

Answer 38

Monosaccharides ## Footnote Examples include glucose and fructose, which are simple sugars that can form more complex carbohydrates.

Question 39

# True or False: Starch is a type of **protein**.

Answer 39

False ## Footnote Starch is a **carbohydrate** and serves as a storage form of energy in plants.

Question 40

# Fill in the blank: The **polymer** of glucose that is used by animals for energy storage is \_\_\_\_\_\_\_\_.

Answer 40

glycogen ## Footnote It is a polysaccharide stored primarily in the liver and muscles in animals.

Question 41

# Define: Cellulose

Answer 41

A **carbohydrate** that provides structural support in plant cell walls. ## Footnote Cellulose is a *polysaccharide* made of glucose units, and it is crucial for maintaining the strength and rigidity of plant cells.

Question 42

What are **proteins** made of?

Answer 42

Amino acids ## Footnote Proteins are polymers of amino acids, and their sequence determines their structure and function.

Question 43

What are the **functions** of proteins?

Answer 43

* Catalyzing reactions. * Providing structure. * Regulating body processes. ## Footnote Proteins are involved in almost all cellular functions, including enzyme catalysis and immune response.

Question 44

# True or False: All **proteins** are enzymes.

Answer 44

False ## Footnote While enzymes are proteins, *not all* proteins function as enzymes. Many proteins have structural or regulatory roles.

Question 45

What are lipids primarily **used** for in organisms?

Answer 45

**Storing long-term energy** and forming cell membranes. ## Footnote Lipids, such as fats and phospholipids, are important for energy storage and creating the structure of cell membranes.

Question 46

What are the **building blocks** of lipids?

Answer 46

Fatty acids and glycerol. ## Footnote They are made up of glycerol and fatty acid chains, forming triglycerides or phospholipids.

Question 47

# True or False: All lipids are **hydrophobic**.

Answer 47

True ## Footnote Lipids are generally **nonpolar** and do not dissolve in water, making them hydrophobic.

Question 48

# Fill in the blank: The most common **form** of lipid used for energy storage is \_\_\_\_\_\_\_\_\_.

Answer 48

triglycerides ## Footnote These lipids are made of three fatty acids bonded to a glycerol molecule and are stored in fat cells.

Question 49

What is the **role** of cholesterol in the body?

Answer 49

* Stabilize cell membranes * Produce hormones ## Footnote Cholesterol is a type of lipid that helps maintain membrane fluidity and is used to synthesize hormones like estrogen and testosterone.

Question 50

What type of **bond** forms between amino acids in a protein?

Answer 50

Peptide ## Footnote *Peptide bonds* are covalent bonds that link the amino group of one amino acid to the carboxyl group of another.

Question 51

# True or False: Enzymes are **consumed** in the reactions they catalyze.

Answer 51

False ## Footnote **Enzymes** are not consumed in reactions; they can be reused multiple times to catalyze the same reaction.

Question 52

Why is light considered **energy** and not matter?

Answer 52

Light has **no mass** and does not take up space. ## Footnote Light consists of *electromagnetic waves* that transfer energy but lack physical substance, unlike matter, which has mass and volume.