Chapter 6

​Chapter 5

Cellular Energy

•MLO 3.1: Summarize the processes of photosynthesis and cellular respiration. (CLO I)

•MLO 3.2: Compare energy flow in plants vs. animals. (CLO II)

•MLO 3.3: Explain the role of ATP in metabolism. (CLO II)

Multiple Choice

What is the main purpose of photosynthesis?

• To convert sunlight into chemical energy (sugar)

• To break down oxygen for respiration

• To release heat energy

• To absorb nutrients from the soil

Multiple Choice

What is the main goal of cellular respiration?

• To capture sunlight energy

• To produce chlorophyll

• To create more glucose

• To break down glucose and make ATP

Multiple Choice

How are photosynthesis and cellular respiration connected?

• Both only release energy

• Both only occur in animals

• Photosynthesis uses what respiration produces

• They are unrelated processes

Multiple Choice

Which statement best summarizes these two processes?

• Photosynthesis stores energy; respiration releases it

• Respiration stores energy; photosynthesis releases it

• Neither stores energy

• They both store energy

Multiple Choice

What is the original source of almost all energy on Earth?

• The Sun

• Oxygen

• Water

• ATP

Multiple Choice

How do plants and animals differ in how they obtain energy?

• Plants make food from sunlight; animals eat food for energy

• Animals make glucose; plants eat it

• Both use sunlight directly

• Both rely only on heat energy

Multiple Choice

What does the First Law of Thermodynamics state?

• Energy can be created but not destroyed

• Energy can disappear in chemical reactions

• Energy cannot be created or destroyed—only changed

• Energy exists only in living things

Multiple Choice

What is the main difference in how plants and humans obtain electrons for energy?

• Plants get them from water; humans get them from food

• Plants get them from air; humans get them from water

• Both get them directly from sunlight

• Humans do not use electrons for energy

Metabolism

1. Anabolism- metabolic pathways that create complex molecules from simpler compounds.

   1. requires energy input

   2. Photosynthesis (input= light; complex molecule=glucose.

2. Catabolism- metabolic pathways that release chemical energy in the process of breaking down complex molecules.

   1. releases energy

   2. Respiration (breaks down glucose)

Two main types:

Metabolism

• Energy Carriers: deliver energy where it is needed around a cell

• ATP (Adenosine triphosphate): Small organic molecule all cells use to carry energy from one part of the cell to the other

  • All living things create ATP during catabolic reactions of cellular respiration

  • consist of one adenosine and three phosphate groups

Metabolic Activity requires energy:

Metabolism

• ADP (Adenosine diphosphate) molecule that is created when one phosphate group breaks off of ATP in order to release the energy that is being held in it.

• More ATP can be made by adding a phosphate group back to the ADP

​Other energy carriers: NADPH, NADH, FADH2.

Multiple Choice

What is ATP’s main role in the cell?

• To create chlorophyll for photosynthesis

• To digest food molecules

• To transport oxygen through the body

• To store and provide energy for cellular reactions

Multiple Choice

How do cells make more ATP?

• By converting nitrogen into glucose

• By releasing oxygen from water

• By adding a phosphate group to ADP

• By absorbing carbon dioxide directly

Multiple Choice

What molecule provides the energy to make ATP during cellular respiration?

• Carbon dioxide

• Glucose

• Oxygen

• Water

Multiple Choice

When humans eat food, what is happening on an energy level?

• They are generating new energy through digestion

• They are transforming heat energy into potential energy stored in fat
  
  

• They are converting chemical energy stored in food into usable energy for cellular processes

• They are breaking down food molecules but releasing no usable energy

Photosynthesis

• Photosynthesis = Converting sunlight, water, and CO2 into sugar and oxygen.

• Happens inside chloroplasts (plants & algae) or plasma membrane (bacteria)

• Thylakoids: stacked membranes that hold chlorophyll. Maximize light absorbtion

• Chlorophyll green pigment that absorbs light energy.

Photosynthesis

Two Stages of energy conversion:

1. Light Dependent Reactions

   1. use sunlight to split water and make ATP & NADPH

2. Light Independent Reactions (Calvin Cycle)

   1. Use ATP & NADPH to build glucose

Draw This

Light Dependent Reactions

• Chlorophyll absorbs light & splits water

• Produces oxygen and energy carriers (ATP, NADPH)

• Electron transport chain then moves the electrons through the thylakoid membrane

Light Independent Reactions

• Occurs in stroma of chloroplasts

• Use ATP & NADPH to fix carbon from CO2 and turn it into glucose

• Also called carbon fixation because carbon is captured from the air.

Multiple Choice

What are the three reactants needed for photosynthesis?

• Glucose, oxygen, and sunlight

• Nitrogen, carbon dioxide, and ATP

• Oxygen, hydrogen, and glucose

• Carbon dioxide, water, and sunlight

Multiple Choice

Which products from the light-dependent reactions are used in the Calvin cycle (light-independent reactions)?

• Oxygen and glucose

• Carbon dioxide and water

• Glucose and ADP

• ATP and NADPH

Catalyzing Reactions: Enzymes at work

• Enzymes: biological catalysts that speed up reactions

• Without enzymes, metabolism would be too slow for life.

  • Rubisco starts the Calvin cycle

• Each enzyme fits a specific substrate like a lock and key.

Cellular Respiration

• Cellular respiration breaks down glucose and converts it into ATP.

• Occurs in three stages: Glycolysis, Krebs Cycle, Oxidative Phosphorylation

• Happens in the mitochondria of eukaryotes

• Plant and animal cells go through cellular respiration

Cellular Respiration

1. Glycolysis 

   1. splits glucose → 
      pyruvate (+ ATP & NADH)

2. Krebs Cycle 

   1. produces ATP, NADH, FADH₂ & CO₂.

3. Oxidative Phosphorylation

   1.  produces most ATP using oxygen

Draw

Cellular Respiration

Two Types dependent on Oxygen availability:

• Aerobic

  • requires oxygen

  • Produces lots of ATP

  • Glucose + Oxygen = CO2 + Water + ATP

  • Ex: When you’re breathing normally or doing light activity, your cells use oxygen to fully break down food for energy.

• Anaerobic

  • Happens when oxygen is limited or absent

  • Produces less ATP

  • Results in byproducts like lactic acid (humans) or alcohol & CO2 yeastss)

  • Ex: During intense exercise, your muscles may switch to anaerobic respiration and produce lactic ac, d—causing that burning feeling.

Anerobic Respiration in Yeasts

• Yeast are single-celled fungi that can make energy without oxygen.

• When oxygen is absent, they perform anaerobic respiration, called fermentation.

• Process:
  Glucose → Ethanol (alcohol) + Carbon Dioxide (CO₂) + ATP

• The CO₂ gas makes bread rise, and the ethanol is used in brewing and biofuels.

Multiple Choice

What are the end products of anaerobic respiration in yeast?

• Glucose and oxygen

• Lactic acid and ATP

• Ethanol, carbon dioxide, and ATP

• Water, oxygen, and heat

Multiple Choice

What happens during glycolysis?

• Glucose is split into two molecules of pyruvate, releasing ATP and NADH

• Water is split into hydrogen and oxygen

• ATP is converted into glucose

• Pyruvate is formed from carbon dioxide

Multiple Choice

What happens in your muscles during intense exercise when oxygen runs low?

• They switch to aerobic respiration and produce alcohol

• They switch to anaerobic respiration and produce alcohol

• They switch to aerobic respiration and produce lactic acid

• They switch to anaerobic respiration and produce lactic acid

Multiple Choice

What are the end products after all three stages of cellular respiration?

• Oxygen, glucose, and energy

• Carbon dioxide, glucose, and heat

• Carbon dioxide, water, and ATP

• ATP, oxygen, and nitrogen

Cell Division Review Questions

Chapter 6

Comparison Table

Multiple Choice

When your body repairs a cut or bruise, which process is helping replace damaged cells?

• Mitosis

• Meiosis

• Binary fission

• Both Mitosis and Meiosis

Multiple Choice

Why do most adult brain and nerve cells rarely divide?

• They constantly go through mitosis.

• They skip interphase.

• They stay in a resting phase called G₀.

• They never reach cytokinesis.

Multiple Choice

What happens if a cell ignores the 'stop' signals at checkpoints?

• The DNA becomes stronger.

• The cell shrinks and dies immediately.

• The cell stops dividing forever.

• The cell divides uncontrollably, forming a tumor.

Multiple Choice

A chemical like nonylphenol from plastics mimics estrogen and causes cells to divide more than normal. What is this an example of?

• Healthy mitosis

• Checkpoint failure leading to uncontrolled division

• Meiosis error

• DNA repair

Multiple Choice

Which checkpoint ensures that DNA has been correctly copied before the cell divides?

• G1

• G2

• M

• Cytokinesis

Multiple Choice

In what everyday scenario might your body use mitosis the most?

• Healing after surgery or injury

• Producing sperm cells

• Making antibodies

• Breaking down food

Multiple Choice

What is one major difference between mitosis and meiosis?

• Mitosis makes identical cells; meiosis makes unique gametes.

• Meiosis makes identical cells; mitosis makes unique gametes

• Both produce identical cells.

• Mitosis only happens in sperm.

Multiple Choice

Why are siblings not identical even with the same parents?

• Random mutations change DNA every generation.

• Crossing-over and independent assortment mix genes differently in each gamete.

• Each gamete receives identical chromosomes from the parents.

• Fertilization ensures all offspring have the same genetic mix.

Multiple Choice

When meiosis goes wrong and an egg has an extra chromosome, what can happen?

• Bone damage

•  Cancer

• Faster growth

• Genetic disorders like Down syndrome

Multiple Choice

Which process ensures that sperm and eggs each have half the number of chromosomes?

• Binary fission

• Mitosis

• Meiosis

• Both Mitosis and Meiosis

Multiple Choice

Fertilization combines genetic material from two parents. The result is…

• A clone

• Two identical cells

• A zygote with a complete set of chromosomes.

• A gamete