RespirationPhotosynthesisGas exchange

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Theme II – Chapter 5 Photosynthesis and Respiration- Chapter 7 gas exchange

Why do we need photosynthesis and respiration?

• Living things need energy to accomplish tasks to stay alive

• Plants create sugar through photosynthesis• Plants and animals consume sugar and

convert it to energy

Leaf Cross Section Diagram

Leaf parts, con’t

• Cuticle—waxy coating on top and bottom, helps prevent dehydration of the plant

• Epidermis—layer of cells on top and bottom—no chloroplasts—protection

• Palisade layer—most of the chloroplasts (and thus photosynthesis) are here—food producing layer

Leaf parts, con’t

• Spongy layer—space between cells allows for air movement

• PALISADE and SPONGY LAYER together form the mesophyll layer

• The vascular bundle consists of phloem and xylem—also called the vein of a leaf

Picture of the bottom of a leaf

STOMATA—an opening through which gases can move

GUARD CELLS—control the size of the stomata

Stomate and Guard Cells

Chloroplasts

Photosynthesis• It is a form of NUTRITION, specifically AUTOTROPHIC

NUTRITION

• It is the process by which light energy is converted to chemical energy of organic molecules (food)

• Overall formula:12 H2O + 6 CO2 + Sunlight 6 H2O + C6H12O6 + 6 O2

Reduced formula:6H20 + 6 CO2 + Sunlight -> C6H12O6 + 6 O2

• Produces food and oxygen for organisms

• Takes place in organelles called chloroplasts which contain chlorophyll

• Chromatography is the process used to separate the pigments in chlorophyll

Two stages of photosynthesis(extra information)

1. The light reaction (photolysis)• Requires sunlight• Occurs in thylakoids (inner membranes

of the chloroplasts) with the help of enzymes and pigments (chlorophyll)

• Light energy is absorbed and used to split water into hydrogen and oxygen, also releasing cellular energy

• Oxygen released as waste, hydrogen and energy taken to dark reaction

2. The dark reaction(extra information)

• Occurs in the stroma, without light as long as there is enough hydrogen available

• Hydrogen and carbon dioxide combine and eventually form PGAL (phosphoglyceraldehyde)(a.k.a. G3P)

• PGAL can be used by the plant to make glucose and other necessary molecules

Factors that influence the rate of photosynthesis

• Color of light—red/blue=good absorber , green=bad absorber

• Temperature—30C is best (86F)• Carbon dioxide concentration is high

Respiration

1. Occurs continuously in ALL cells—both plant and animal

2. Involves the transfer of stored chemical energy in food molecules to a form usable by cells

3. Makes energy in the form of ATP- Adenosine Triphosphate

4. Occurs mostly in the mitochondria

Anaerobic Respiration (Fermentation)

• Anaerobic—does not require oxygen• Yeast (yogurt, wine, bread), bacteria,

E. coli, some of our cells• Some cells are usually aerobic but

can become anaerobic when oxygen is lacking—like our muscle cells

Two major types of anaerobic

#1: Muscle FatigueGlucose

↓↓↓2 pyruvic acid

↓↓↓2 lactic acid

--uses enzymes--2 ATP are used, 4 ATP are made, for a gain of 2 ATP--muscle fatigue--yogurt

#2: Fermentation

Glucose↓↓↓

2 pyruvic acid↓↓↓

2 ethyl alcohol (ethanol)+

CO2

--uses enzymes

--2 ATP are used, 4 ATP are made, overall gain of 2 ATP

--yeast and bacteria

--High economic value

Both of these types of anaerobic respiration work but both leave many bonds intact, and therefore are not too efficient

Aerobic Respiration

-Formula: 12 H2O + C6H12O6 + 6O2 6 H2O + 6CO2 + 36 ATP

Reduced:

6 H2O + C6H12O6 + 6O2 6CO2 + 36 ATP-Uses molecular free oxygen-Occurs mostly in the mitochondria-Much more efficient, occurs in most organisms

Mitochondria

Three major parts(extra information)

Glycolysis: the anaerobic phaseGlucose

↓↓↓2 pyruvic acid

(each acetyl CoA goes on to the next step independently)

2 ATP in 4 ATP out

2 NAD+ 2 NADH

NAD+NADH

•Occurs in the cytoplasm

•NAD+ and FAD are hydrogen carriers

Acetyl CoA Acetyl CoA

NADHNAD+

Krebs cycle (a.k.a. Citric Acid Cycle)

(extra information)

Acetyl CoA↓↓↓

Citric Acid

Oxaloacetic acid

•Occurs in mitochondria

NAD+

NADH

CO2

NAD+

NADH

CO2

FAD

FADH2

NAD+

•Two Krebs cycles happen simultaneously, as there are 2 acetyl coAs made

NADH

Electron Transport Chain(extra information)

•Hydrogens=electrons

•The hydrogens are dropped down a series of “cytochromes,” special molecules made for capturing the energy released as hydrogen drops from step to step

NADH drops here and NAD+ goes to get more hydrogens

FADH2 drops here—goes to get more H

•Each NADH = 3 ATP

•Each FADH2 = 2 ATP

Oxygen is final hydrogen acceptor…hydrogen and oxygen make WATER

Summary of ATP Formation(extra information)

Other Products(NAD, FAD)

ATP Formed

Glycolysis 2 NADH Net gain 2 ATP

Krebs Cycle(Citric Acid Cycle)

8 NADH/glucose2 FADH2/glucose

None

Electron Transport Chain

10 NADH x 3 = 2 FADH2 x 2 =

30 ATP4 ATP

Highlightsavoid misconceptions

• Photosynthesis creates sugar(stored energy from sunlight)– 6H20 + 6 CO2 + Sunlight -> C6H12O6 + 6

O2

• Respiration uses sugar (stored energy) to perform homeostasis functions– Plants: opening and closing stomates of guard cells,

closing the “mouth” of a venus flytrap– Humans: walking, breathing, blinking, digesting, moving

your eyes– 6 H2O + C6H12O6 + 6O2 6CO2 + 36 ATP

Highlightsavoid misconceptions

• Both plants and animals perform respiration• Only plants perform photosynthesis• Plants are autotrophic (create own energy)• Animals are heterotrophic (must go out in

search of food for energy)• Plants ABSORB red and blue, Plants REFLECT

green

Respiratory System

Breath in - From air to lungs to our bodyBreath out - From our body to our lungs

to the air

•http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookRESPSYS.html

• Air comes in through the nose/mouth, proceeds down the pharynx (throat), larynx (voicebox), trachea (windpipe), bronchi, bronchioles, and ends in the alveoli. The path is followed backwards for exhalation

The Alveoli ***

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookRESPSYS.html

• Gas exchange takes place in the small, grape-like clusters of sacs called alveoli, which are found at the end of the bronchioles

• These are very thin walled, allowing for O2 to go out and CO2 to come in from the capillaries surrounding the alveoli

• We have millions of alveoli in our lungs

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookRESPSYS.html

• Our bodies inhale and exhale by changing the size of our chest cavity…

• Inhaling—lowering the diaphragm, expanding the ribs=lower air pressure inside, air from outside rushes in (we do NOT “pull air in”)

• Exhaling--reverse

Homeostasis

• The respiratory system is instrumental in getting oxygen in (necessary for respiration and ATP production) and excretory wastes (water, carbon dioxide) out. If not gotten out, carbon dioxide would become toxic to the body.

• Our respiratory rate changes in response to our body’s needs

Circulatory SystemFrom Lungs to musclesFrom Muscles to lungs

Major Vessels:

• Arteries• AWAY from heart• Thick walled• Carry oxygenated blood

from heart to the body • Carry deoxygenated

blood from heart to lungs

• Veins• TOWARDS the heart• Thin walled• Carry deoxygenated blood

from body to heart• Carry oxygenated blood

from lungs to heart

• Capillaries• Very thin walled• Only one rbc through at a time• Where nutrients, oxygen, carbon dioxide and

wastes are exchanged

http://sln.fi.edu/biosci/vessels/capillaries.html

Organs Involved

• Heart• Blood Vessels• Lungs for gas exchange

Composition of Blood

• Plasma• Red Blood Cells• White Blood Cells• Platelets

http://training.seer.cancer.gov/ss_module08_lymph_leuk/leuk_unit02_sec02_composition.html

http://www.tmc.edu/thi/anatomy2.html

Flow of Blood Through Heart

1. Vena cava2. Right atrium3. Right ventricle4. Pulmonary artery5. Lungs6. Pulmonary vein7. Left atrium

8. Left ventricle9. Aorta

** Valves to prevent backflow!

Blood Pressure

• A measure of the force of the blood being pushed through arteries

• Top number (systole) is while heart is pumping, bottom number (diastole) is while heart is relaxed

• “Average” number is 120/80 or lower

• Oxygen carried by HEMOGLOBIN, an iron-based molecule found in RED BLOOD CELLS

• Carbon dioxide carried primarily as an acid in the blood plasma

HOMEOSTASIS

• The circulatory system is instrumental in maintaining homeostasis as it provides nutrients and oxygen for all chemical reactions to all parts of the body

• It also removes waste products so that they may be detoxified via liver, filtered out via the kidney, or exhaled via the lungs

Homeostasis, con’t

• The circulatory system also moves hormones throughout the body until they reach their target organs

• The movement of blood also insures that all the fluids in the body have approximately the same levels of chemicals, so one area does not become toxic

• Our circulatory system changes in response to our body’s needs…speeds up when more oxygen/nutrients are needed, returns to normal when need is over

Highlights and recall

• Oxygen is needed for aerobic respiration (the most efficient respiration)

• We open our lungs because of the diaphragm• Oxygen only enters our blood through diffusion – we need

healthy blood cells for the oxygen to attach to• Carbon dioxide only exits through diffusion – increased carbon

dioxide in blood increases heart rate to create more chances for carbon dioxide to exit (carbon dioxide is toxic to our body and turns blood into carbonic acid at high concentration)

• Oxygen needs to get to the mitochondria in order for respiration to occur