Lab 5: Energy Transformations in Cells

Why do biologists study energy transformations

they do so to because in order to understand life you need to understand how life obtains energy (through energy transformation)

What does Photosynthesis do?

this process converts the suns energy into carbohydrates (sugar): a useable source of energy for cells

Which organisms use photosynthesis

Why is photosynthesis important for other organisms?

• Plants, algae, and cyanobacteria use photosynthesis

• photosynthesis is important for other organisms like animals consume the organic material of plants, etc (which are powered by photosynthesis)

• and use the organic material to building material

What do Cellular respiration and Fermentation do?

cellular respiration and fermentation convert glucose (from photosynthesis) into ATP energy which cells use directly for power.

Which organisms use Cellular respiration and Fermentation?

almost all organisms use both of these processes are at least 1.

Draw a diagram of the energy cycle that powers our biosphere

Photosynthesis

↓

Organic molecules + O2 → no O2 (fermentation)

↓

Cellular Respiration

↓

CO2 + H2O + Energy

↓

Back to photosynthesis

What is ATP

what does it stand for and what does it do?

Stands for Adenosine Triphosphate

it directly powers cellular processes, which keep cell alive, thus organisms alive

(Adenine nitrogenous base + pentose and 3 phosphate groups)

What is the summary equation for Cellular Respiration?

Glucose + O2 ———-→ CO2 + H2O + Energy

List 4 stages of Cellular Respiration

1. Glycolysis

2. Pyruvate Processing

3. Citric Acid Cycle

4. Oxidative Phosphorylation

What role does oxygen have in cellular respiration?

(since it doesn’t combine directly with glucose)

At the end of cellular respiration low energy electrons are removed to continue cellular respiration, so Oxygen used as the electron transport carrier

and takes the last electrons. at the same time it also binds with H+ and forms water (released)

How much energy (from cellular respiration) is captured by the ATP molecules produced

ATP captures 34% of energy made in cellular respiration

What happens to the rest of the energy that is released from cellular respiration (breakdown of glucose)

the other 66% of energy from cellular respiration gets released as heat

What are the waste products of cellular respiration?

hint: summary equation

H2O and CO2

How can the waste products be useful indicators of cellular respiration?

the amount of waste: CO2 and H2O can indicate how much energy was made from cellular respiration

What organelle is most involved in Cellular Respiration?

the Mitochondrion is most involved in cellular respiration

Define the mitochondrion

organelle of cellular respiration, its function is to create ATP energy

List the relevant parts of mitochondria and their function

• Inner membrane: cristae where ETC is, oxidative phosphorylation happens

• Outer membrane: separates from rest of cell

• Mitochondrial Matrix: Acetyl coA, citric acid cycle

Do all stags of cellular respiration occur in the mitochondrion?

no glycolysis occurs outside the mitochondrion in cytoplasm

How is CO2 (byproduct of cellular respiration) released by animals

1. CO2 from cellular respiration diffuses into the blood

2. CO2 in blood travels to the lungs

3. CO2 diffuses out of the blood into the lungs

4. the lungs exhale the CO2

Why is the CO2 from cellular respiration a problem?

hint: interacts with water making…

• CO2 from cellular respiration can cause issues by lowering pH in the the body (make more acidic)

• because CO2 (from cellular respiration) reacts with H2O and makes carbonic acid H2CO3

• H2CO3 is a weak acid, and easily breaks causes excess H+: making the blood acidic

  which causes cells’ proteins to denature

How does the body resolve pH change from Carbonic Acid H2CO3

the pH change is counteracted by a Bicarbonate Buffer HCO3 from kidneys

this HCO3 interacts with extra H+ released in blood due to breakdown of H2CO3/Carbonic Acid

reducing H+/Acidity

What is the purpose of the CO2 pH experiment

by exhaling CO2 into flasks and measuring pH level with Bromothymol blue indicator, you can see how the pH level of CO2 changes with a buffer and without a buffer

What is Bromothymol blue indicator, and what does its indicator colours mean

the Bromothymol blue indicator tests pH levels:

A Yellow colour = Acidic (pH below 7)

A Green colour = Neutral pH (at 7)

Blue colour = Basic (pH above 7)

is NaOH acidic or basic

Sodium Hydroxide is basic

What is the purpose of a Buffer

to keep the pH of a solution the same (maintain)

by taking out H+ that acidic solutions add in

and adding H+ which basic solutions take out

Knowing the pH of NaOH Sodium hydroxide what colour would it be?

Blue (blue/green) becauses its more basic

What is the pH of H2CO3? How would it affect the colour of solution?

H2CO3 dissolves releasing H+s so its acidic and it would make the colour of a solution more yellow

Explain the NaOH + CO2 pH Experiment:

Flask A:

water + bromothymol indicator solution

more water is added to NaOH solution

CO2 is breathed into solution

CO2 reacts with Water and forms H2CO3 (carbonic acid)

carbonic acid dissociates adding H+ turning solution yellow

Flask B:

water + bromothymol indicator solution

pH 9 buffer is added to NaOH solution (maintaining its basic pH)

then when CO2 is added, CO2 interacts with H2O, making H2CO3

when carbonic acid dissociates and releases H+, H+ is removed.

This is until 50+ breaths of CO2 are added, which allows more carbonic acid to made and dissociated:

successfully adding H+ to the solution and turning it yellow as its now acidic

Why Both Flasks Turned Yellow:

• Both flasks turned yellow because CO₂ reacted with water to form carbonic acid (H₂CO₃). The carbonic acid dissociated into H⁺ ions, which lowered the pH of the solution. The bromothymol blue indicator turned yellow to signal this shift to an acidic pH.

Which Flask Needed More CO₂ and Why:

• Flask B required more CO₂ (50+ breaths) because it contained a pH 9 buffer, which resisted changes in pH.

• When CO₂ formed carbonic acid in Flask B, the buffer neutralized the H⁺ ions, slowing down the pH drop. As a result, much more CO₂ was needed to overwhelm the buffer's capacity and lower the pH enough to turn the solution yellow.

• In contrast, Flask A lacked a buffer, so the pH dropped more easily, requiring only 15 breaths for the solution to turn yellow.

Why More Water Had to Be Added (to Flask A):

• Adding more water to Flask A diluted the NaOH solution, making it less basic and easier for the CO₂ to neutralize.

• Without this additional dilution, the NaOH concentration might have been too high, requiring more CO₂ to form enough carbonic acid to lower the pH and turn the solution yellow.

What is the summary formula for CO2 NaOH experiment?

CO2 + H2O → H2CO3 → H + HCO3

Explain how can Oxygen be a measure of cellular respriation

Oxygen intake can indicate cellular respiration because oxygen is a reactant in cellular respiration

So if more oxygen is taken in by an animal, it can indicate that more cellular respiration is being performed

What happens when an animal takes in O2

the O2 is taken in and transported to cells to be used in cellular respiration

What does the Finger Pulse Oximeter do?

the finger pulse oximeter measures the saturation of oxygen in your blood.

specifically the amount of hemoglobin that is carrying oxygen in red blood cells

How does the finger Pulse Oximeter measure Oxygen saturation?

the pulse oximeter sends 2 light wavelengths through your finger

• one wavelength measures the amount of hemoglobins that are carrying oxygen

• other wavelength measures amount of hemoglobins without oxygen

• also measures pulse

What are normal Oxygen saturation values for pulse oximeter?

95-100%

define pulse rate

number of heart beats per min

define ventilation rate

the number of inhale-exhales cycles per min

Which measurements increase after exercise and why

heart rate increases after exercise becasue the heart beats faster to pump enough O2 to working muscle cells for cellular respiration and to help remove CO2 byproducts

ventilation increases after exercise, to bring more O2 into the body for cellular respiration, and to expel CO2 byproduct

Why is O2 saturation level not affected by exercise?

O2 saturation levels stay the same

because the body is breathing more air, and pumping it though the body to meet increased demands from exercise O2. This keep levels of O2 saturation from decreasing.

What are reasons for variation in ventilation and pulse rate?

Health conditions, fitness level

Describe and explain the change in temperature between germinating and dormant seeds.

germinating seeds give off more heat than dormant seeds, as when seeds are germenating they go through cellular respiration so they have the energy to growth

What does the production of heat indicate about an organism

if organism gives off heat it could be do to cellular respiration as heat is released in this process

seeds are plant tissue and plants are able to perform both celluar respiraiton and photosynthesis, how do u know which process is producuign the heat/

Because cellular respiration gives off heat energy while photosynthesis absorbs light energy

What does Fermentation do?

Fermentation transforms glucose into pyruvates which get transformed into some ATP energy without oxygen

Do organisms rely on fermentation?

only anaerobic organisms rely on fermentation to produce energy. if the organism is aerobic they primarily use cellular respiration for energy and don’t need to rely on fermentation

Whats an example of fermentation in humans?

lactic acid fermentation: it happens when humans exercise so much it cant get enough oxygen to muscle cells so it uses fermentation to make atp to power muscle cells (does not produce CO2)

What is Alcoholic fermentation?

type of fermentation that produces ethanol by

converting glucose to pyruvate then to ethanol

its used to make beer, wine

Which fungi uses alcoholic fermentation

yeast a single celled fungi survives using alcoholic fermentation.

What are the products of alcoholic fermentation

ethanol and CO2 are produced

What does Limewater test for? How does it do so?

What is its chemical name

Limewater tests for CO2, as when limewater and CO2 interact they produce calcium carbonate which precipitates from solution

Limewater CaOH2

What is the chemical name for Calcium Carbonate

CaCO3

What is the summary formula of Fermentation experiment 1: Production of CO2

Ca(OH)2 (aq) + CO2 (g) → H2O + CaCO3 (s)

Explain what happened in Fermentation Experiment 1: Production of CO2

Flask 1A, Flask 1B

• Yeast + sucrose (yeast has grown in flask 1A, using alcoholic fermentation and released CO2 as a byproduct)

• CO2 Gas from 1A has traveled to 1B and combines with limewater to make CaCO3

• CaCO3 precipitate/bubbles out the solution of flask 1B

Flask 2A, 2B

• Sucrose only in 2A, flask 2B has limewater

• no fermentation occurs,

• no CO2 released to combine with limewater and make CaCO3

Explain Fermentation Experiment 2: Production of Ethanol

Yeast will be grown in anaerobic conditions, and reagents: Potassium dichromate and sulphuric acid will test for ethanol

positive control

make a tube that contains ethanol so you know what a positive result looks like

checks reagents are working

negative control

make a tube that has no ethanol so you know what a negative result looks like

What is the chemical name for Potassium dichromate

K2Cr2O7

What is the chemical name for Sulphuric Acid

H2SO4

what principle of having good ethical design is shown by having duplicates of each test tube. explain why this is necessary

it shows reliability: the reagents which test for ethanol work

it shows reproducibility: results are valid since they can be reproduces and have the same result.

duplication is necessary in order to know if your results are accurate. since it will tell you if your tests are reliable and if your results are valid

Why do alcoholic fermentation and lactic acid fermentation have different products?

humans and yeast have use enzymes in fermentation so they convert pyruvate into different products

What are the reactants and products of alcoholic fermentation (in yeast)

reactants: glucose

products: Ethanol, CO2, ATP

What are the reactants and products of lactic acid fermentation (in humans)

reactants: glucose

products: Lactic acid and ATP

What is the summary equation for Photosynthesis?

CO2 + H2O + Energy ———> Glucose + O2

Where does glucose get the energy to perform photosynthesis?

it gets the energy from light waves (photons)

What are the 2 major stages of Photosynthesis

Light Reactions

Calvin Cycle

What is Glucose used for?

Glucose is a high energy molecule, it is converted into ATP energy (in cellular respiration) to do work, or it is used as building material in cells

What is Primary Productivity

primary productivity refers to when a photosynthesis produces organic material (by primary producers: plants, algae, cyanobacteria)

What allows primary productivity

primary productivity (production of glucose) happens all because plants, algae, and cyanobacteria contain CHLOROPHYLL

How does Chlorophyll help make glucose?

Chlorophyll’s pigment absorbs light energy, which is then used to spilt H2O (water molecules).

The O2 gets released, and H+ interacts with CO2 to help make an organic molecule

What 2 colors of light are best absorbed by chlorophyll?(on absorption spectrum)

Blue (chlorophyll b) and red (chlorophyll a)

Why do most plants appear green?

most plants appear green because chlorophyll pigments cannot absorb green light so it reflects off of it, giving plants a green appearance

What are Accessory pigments

additional pigments on the plants which help absorb light energy outside of chlorophyll’s range

What is the red/orange pigment found in plants, and what colour light does it absorb?

Caretenoids

it absorbs blue and green light

What are Anthocyanins

whats it function

what colour is it

plant pigments that can’t do photosynthesis. instead they can be used as UV protection, or to attract pollen

• they can be purple, red, blue

What is Chromatography?

lab technique which separates the mixture of pigments in a plant.

What are polar groups?

polar groups inside the large molecules of Photosynthetic pigments (ex. chlorophyll, caretenoid)

Are pigments with more polar groups or less, going to dissolve in non polar solvent

pigments with less polar groups are more soluble in non-polar solvent

How will pigments with fewer polar groups react with polar paper?

less will stick to the polar paper, which lets the polar groups them migrate further up the paper

How will pigments with more polar groups react with polar paper?

polar groups will sitck more easily to chromotography paper, preventing them from mirgrating up the paper

Explain what happened in the Chromotography experiment

Acetone (extreme solvent) is added to Chlorophyll solution

Petroleum either is added to the chromatography solvent

chromotagrpahy (seperation of pigments) takes place in the fumehood.

add green pigment on X spot of chromotography paper 5x using capillary tube

Add solvent to Coplin jar. stand chromotograpaphy paper in the solvent with x spot (green pigment) above the level o the solvent

observe until solvent front is a cm from the top of the paper

remove the chromotography paper from coplin jar in the fume hood

identity different pigments

What colour is chlorophyll B?

yellow-green

What colour is chlorophyll A?

blue-green

What colour is carotene?

yellow-orange

What colour is Xanthophyll?

yellow

Look at chromatography paper and correctly identity pigment molecules

List key parts of Chloroplasts:

Chlorophyll

thylakoid membrane

Grana

stroma

Define thylakoid membrane

inner membrane of the chloroplasts where light reactions take place. contains pigments

Define Grana

stacks of thylakoid membranes

Define stroma

the cytoplasm of the chlorophyll, around the thylakoid membrane

What does this mneumic stand for leaf structure

Cutie’s Extreme, Paranoid mood, Subtracts mood, XPG

Cuticle

Epidermis

Palisade mesophyll

Spongy mesophyll

Xylem

Pholem

Guard cells

List all parts of the leaf structure (CE PM-SM XPG)

• Cuticle

• Epidermis

• photosynthetic tissue: Palisade Mesophyll, and Spongy Mesophyll

• vascular tissue: Xylem and Phloem and Guard cells

What is the function of the Cuticle

+ location

a layer of wax cells, on surface of epidermis

wax is hydrophobic, so it keeps water from leaving

What is the function of the Epidermis + location

2nd layer of leaf

provides protection and has stomata which allows exchange of materials, but most importantly lets light to pass through

What is the function of the Palisade Mesophyll + location

tissues which have lots of guard cells which contain lots of chloroplasts, its located right below upper epidermis, is main photosynthesis site

What is the function of the Spongy Mesophyll + location

tissue in lowe epidermis which has more space in between its cells, to help exchange of gases (CO2 and O2), can also perform photosynthesis

below Palisade Mesophyll

What is the function of the Xylem + location

vessels which help carry water and minerals from the root to the rest of the leaf

What is the function of the Pholem + location

vessels which carry sugars/nutrients from the leaf other areas of the plant

What is the function of the Guard Cell + location

these cells in the leaf’s epidermis which contain chloroplasts

they also open and close stomata pores, which allows gas exchange, and helps prevent loss of water