Bio Unit 2 Study Guide

What are the 3 main forms of energy?

Light, Heat, Chemical

What do all living things use to maintain homeostasis?

chemical energy

What is ATP (Adenosine Triphosphate)

forms of energy, powers chemical reactions in your cells

ATP to ADP cycle

• ATP releases energy when the bond between the last two phosphates breaks, forms ADP (diphosphate). 

• Sunlight or food (chemical energy) is used to reform the bond, making ATP again.  ATP = Fully charged battery ADP = Dead battery

What is photosynthesis?

• process by which autotrophs convert light energy to chemical energy.

How does CO₂ get into the plant?

Stomata (Stoma ~ singular form)

• Structure on leaves / tiny openings

• Controls the flow of gases into and out of the plant.

• Opens to let CO₂ in; O₂ and water vapor out. Evapotranspiration: water vapor exiting a plant cell through the stomata

• Controlled by guard cells

• Controls the RATE OF PHOTOSYNTHESIS

When does the stoma open?

When swollen with water, guard cells pull apart from each other, opening the stoma to allow the exchange of gases, includes releasing water vapor. When shrunken, stomatas close.

Photosynthesis- Light Dependent Reaction

• Occurs in the thylakoid

• Energy is transferred to electrons (ATP and NADPH are produced) in chlorophyll pigment  (or other pigments.) Chlorophyll absorbs sunlight.

• This activates a system that splits H₂O into hydrogen and oxygen

• oxygen is released as waste or a by-product. Excited” electrons move through the electron transport chain and produce molecules of ATP and NADPH.

Photosynthesis- Calvin Cycle/Light Independent

1. Location: Stroma CO2 is used to make sugar. Calvin = Carbon in. Plant absorbs CO₂ from the surroundings. (through the stomata)

2. In the stroma, CO₂ is “fixed” using energy from ATP and NADPH to form a simple     3 carbon sugar.

3. Two of these simple sugars combine to form glucose.

Cycle must occur 2 times!! Carbon Dioxide comes in: produces sugar molecules (aka GLUCOSE)

• NADPH loses its H

  • converts to NADP⁺

• ATP is converted to ADP (energy is released!)

Factors Affecting Rate of Photosynthesis

1. Temperature: enzymes function between 0° and 35°C

2. Light Intensity

3. CO₂ concentration

4. Water: must be available

Why is Photosynthesis Important?

GLUCOSE!!! (chemical energy)

• Plants use glucose for growth

  • They make cellulose by linking chains of glucose molecules

• Most plants store glucose as starches (example: potatoes)

Why do cells respire?

To have the energy needed to carry out cellular functions and to maintain HOMEOSTASIS.

Where does CR occur?

• Starts in the cytoplasm

• Ends in the mitochondria

  • the “powerhouse” of the cell!

Two types of Cellular Respiration

• Aerobic -- requires oxygen

• Anaerobic -- does NOT require oxygen (less efficient)

Aerobic Cellular Respiration

• Process in which a glucose molecule (chemical energy) is broken down

• Energy it contains is released

Anaerobic Respiration

• Occurs when NO oxygen is available.

• 2 processes

Alcoholic Fermentation

• Used by Yeast 

• Yields CO₂ and ethanol

• Used to produce bread and alcohols

Lactic Acid Fermentation

• Used by some bacteria 

• Yields/ produces lactic acid

• Muscle cells use this to make ATP in the absence of oxygen

3 Stages of CR

1. Glycolysis: break down of sugar

2. Kreb’s Cycle: produces CO₂

3. Electron Transport Chain: requires O₂ AND

produces a LOT of ATP (32-38) converts ADP to ATP

Tying it All Together

Photosynthesis and cell respiration exchange carbon between the atmosphere, biosphere, hydrosphere and geosphere.

Effect on Carbon Cycle

• Lots of photosynthesis = less CO₂ in the atmosphere (spring/summer in Northern Hemisphere)

• Less photosynthesis = more CO₂ in the atmosphere (fall/winter in Northern Hemisphere)

• WHY??

Earth’s History and the Cycling of Matter and Energy

• Earth’s age is 4.5 billion years

• Evidence:

  • Meteorites

  • Moon rocks

  • Earth’s oldest minerals.

• Evidence collected through 

Radiometric Dating. Using radioactive decay of elements to determine age of rocks.

Uranium's Role

Uranium is radioactive.

Scientists measure how much uranium has decayed into daughter elements to determine a rock's age.

What Was Early Earth Like?

volving Atmosphere:

• Earliest: hydrogen and helium (too light, escaped into space)

• Early: mostly CO₂ with some water vapor, ammonia, and methane. 

  • NO OXYGEN (O₂) !!!

• Current: 78% Nitrogen, 21% Oxygen, and less than 1% everything else (including CO₂).

How Did the Atmosphere Change?

• Early Earth was HOT!!

• Early Earth had lots of volcanic outgassing 

• Earth slowly cooled, water vapor in atmosphere condensed.

  • Torrential rains may have filled the oceans

  • Comets (made of minerals and water) may have also contributed to formation of oceans as they hit early Earth. 

Carbon Cycling

• Carbon: 4th most abundant element in universe and 15th most abundant in Earth’s crust.

• Can form 4 stable bonds with other carbon atoms OR other elements (makes carbon special!) including oxygen!

• Found in all spheres in many different forms.

Carbon Cycle

Photosynthesis

Removes CO₂ from atmosphere.

CO₂ → Plants

Respiration

Returns CO₂ to atmosphere.

Plants/Animals → CO₂

Burning Fossil Fuels

Adds CO₂ to atmosphere through the process of combustion (burning).

Deforestation

1. Produces/ Releases CO₂

2. Removes trees that absorb CO₂ and reduces biosphere’s ability to co2 from the atmosphere through photosynthesis

Ocean Acidification

Step 1

Extra CO₂ enters ocean.

Step 2

CO2 reacts with seawater to form carbonic acid, seawater ph is lowered. Ocean becomes more acidic.

Step 3

Hydrogen ions released by carbonic acids bind to carbonate to form bicarbonate. Carbonate concentrations are decreased, making it difficult for calcifier species to form calcium carbonate. Marine organisms struggle to build shells.

Consequences of Ocean Acidification

Coral bleaching

Shells cannot form

Shells/ skeletons dissolve

Lower reproduction

Impaired senses in fish

WHY DOES ATMOSPHERIC CO₂ CHANGE WITH SEASONS?

Spring & Summer

Lots of plants growing.

More photosynthesis.

Plants absorb more CO₂.

Less atmospheric CO₂

Fall & Winter

Less plant growth.

Less photosynthesis.

Less CO₂ removed.

More atmospheric CO₂

What does photosynthesis take in and what does it produce?

Takes in CO2, produces O2

What does respiration take in and produce?

Takes in O2 and produces CO2