Unit 3 Biology: Concepts 3 through 5

Where does all energy come from?

the sun

How do producers get energy?

from nonliving sources; most capture energy during photosynthesis to make simple sugars

What are producers also called?

autotrophs

What are some examples of producers?

plants, algae, and some bacteria.

How do consumers get their energy?

from living or once-living organisms

What are consumers also called?

heterotrophs

What are examples of consumers?

animals, fungi, and most bacteria.

What is the source of energy in photosynthesis?

sunlight

What is the source of energy in chemosynthesis?

chemicals like sulfur and methane

What do photosynthesis and chemosynthesis have in common?

both use nonliving sources for energy

What are examples of organisms that go through photosynthesis?

plants, cyanobacteria

What is an example of an organism that goes through chemosynthesis?

deep sea vent bacteria

When consumers eat other organisms to get energy what happens?

they then break down the macromolecules inside of them to release ATP in a process called cellular respiration

What are the four types of consumers?

1. herbivores

2. carnivores

3. omnivores

4. detritivores

What is an herbivore?

an organism that primarily eats plants or plant-based material for energy (vegetation)

What is a carnivore?

an organism that eats only meat to get its energy

What is an omnivore?

consumes both plants and animals for energy.

What is a detritivore?

eat dead materials for energy

What is a food chain?

it traces a single flow of energy and shows trophic levels

What is a trophic level?

the levels of nourishment in a food chain

What happens as energy flows from organism to organism?

it is used for metabolism and/or converted to heat

What is the Rule of 10?

because energy is used for metabolism and/or converted to heat, the next organism on the chain only receives 10 percent of the energy obtained in the previous level

Where does 90% of the energy go to as energy flows from organism to organism?

it is used or “lost” as heat

What are the trophic levels?

1. producer

2. primary consumer

3. secondary consumer

4. tertiary consumer

What is a food web?

shows multiple food chains at once and how they interconnect; it depicts different foods and consumer relationships

What are trophic pyramids?

models that show how energy flows through an ecosystem

What are the three kinds of trophic pyramids?

1. energy pyramid

2. numbers pyramid

3. biomass pyramid

What is an energy pyramid?

represents the energy available at each trophic level; levels always get smaller as you go up the pyramid

What is a numbers pyramid?

represents the number of organisms at each trophic level; since energy decreases as you go up the pyramid, fewer organisms can be supported

What is a biomass pyramid?

represents the total mass of living organic matter at each trophic level

What do all organisms need to survive?

a constant supply of energy

What does photosynthesis accomplish?

converting that energy source (the sun) into something usable

What is photosynthesis?

the overall process by which sunlight (solar/light energy), water, and carbon dioxide are chemically converted into chemical energy stored in glucose (a sugar/carbohydrate)

How to plants get water for photosynthesis?

it is absorbed through the roots

How do plants get carbon dioxide for photosynthesis?

through stomata

What is the chemical equation for photosynthesis?

6CO₂ +6H₂O →C₆H₁₂O₆ + 6O₂ 

What is necessary for photosynthesis to happen but isn’t considered a reactant or product?

solar energy from the sun (as well as some enzymes)

What are grana?

pancake-like stacks of thylakoid membrane

What are stroma?

fluid-like substance that fulls the space between the grana

Why are plants green?

the presence of the pigment chlorophyll (found in the thylakoid membrane); chlorophyll a, chlorophyll b, and other pigments called carotenoids absorb every color of light in sunlight except green meaning it is left over and is reflected

What are the two stages of photosynthesis?

1. Light dependent reaction (Electron Transport Chain)

2. Light independent reaction (Calvin Cycle)

What is the purpose of the light dependent reaction (ETC)?

to capture energy from the sun and store energy in “energy carrying molecules” (ATP or NADPH)

Where does the light dependent reaction (ETC) occur?

in the grana (specifically in the thylakoid membrane) where the chlorophyll is stored

What is a summary of what happens during the light dependent reaction (ETC)?

water molecules are split into hydrogen and oxygen, oxygen is released as a waste product, ATP and NADPH are “charged up” by the sun

Details of the light dependent reaction (ETC)?

energy from the sun is passed down the Electron Transport Chain and is stored in the bonds of ATP and NADPH

Light energy excites electrons which then move down the ETC. At the end, they combine with the “final electron acceptors/carriers” of NADP+ and ADP making NADPH and ATP

ATP, NADPH, and hydrogen (H+) leave the grana and go into the stroma for the next stage

What do photosystems do?

absorb light

What are photosystems?

clusters of chlorophyll and proteins that trap energy from the sun

How do photosystems work?

chlorophyll is a pigment that can absorb sunlight, energy is transferred to electrons which makes excited electrons to move down the ETC to charge ATP and NADPH

What are electron carriers?

molecules that carry electrons in order to pass on their energy

Examples: NADP+ can accept a pair of high energy electrons and transfer them to another molecule (grabs/carries 2 electrons +1 H+ to become NADPH)

What do ATP and NADPH do in photosynthesis?

carry energy from the light-dependent reaction to the light independent reaction

What is the purpose of the light-independent reaction?

use the energy from the “energy carrying molecules” from the light dependent reaction to make sugar (glucose)

Where does the light-independent reaction occur?

in the stroma

Give a summary of the Calvin Cycle ( light-independent reaction)?

a series of enzyme assisted chemical reactions powered by ATP and NADPH that produces three carbon (3-C) sugars from carbon dioxide and the H from water

Cycle happens 2 times and then these 3-C sugars combine to make 1 glucose

Details of the Calvin Cycle

1. grab

   1. carbon dioxide diffuses into stroma

   2. enzyme attaches carbon dioxide to 5 carbon RuBP

   3. produces unstable 6 carbon molecules

2. split

   1. energy from ATP and NADPH and an enzyme break the 6-C molecule into two 3-C molecules (PGA)

3. leave

   1. each 3-C molecule (PGA) is converted to a different 3-C molecule (G3P)

   2. one G3P leaves the cycle to become glucose

   3. the other G3P moves on to the next step

4. switch

   1. remaining G3P converts back into 5-C RuBP by using a phosphate from ATP and the cycle starts

What is chemosynthesis?

the process of an organism making its own food using chemicals instead of sunlight like in photosynthesis (the process producers go through if they can’t do photosynthesis)

What are the 3 things that may affect the rate of photosynthesis?

1. light intensity

   1. excites more electrons causing light reactions to happen faster

2. amount of carbon dioxide

   1. more ingredients to work with and process through the cycle

3. temperature

   1. increased temperature accelerates chemical reactions to a degree

Why do root cells in a plant not need chloroplasts?

since roots are underground, they are not exposed to the sun (chloroplasts catch sunlight so it wouldn’t make sense for them to have them)

What are stomata?

the pores on the underside of leaves where plants lose water, carbon dioxide enters, and oxygen exits

If it’s too hot or dry out what does a plant do?

close its stomata so that it doesn’t lose too much water and become dehydrated

When a plant closes its stomata what happens?

the level of carbon dioxide drops and the levels of oxygen increases, resulting in photorespiration

What is photorespiration?

adds oxygen to the Calvin Cycle instead of carbon dioxide which makes no sugar or ATP and wastes all of the plant’s resources

What are the two types of alternate pathways used by plants?

1. CAM

2. C₄

What is CAM?

done by cacti and pineapples; open stomata at night and close them during the day (opposite of normal plants), causes them to grow slowly

What is C₄?

done by corn and sugarcane; partially close stomata during the hottest part of the day, allows them to only need ½ as much water as normal plants

What is the goal of cellular respiration?

to convert the chemical energy in food (glucose) to chemical energy stored in ATP

What is the chemical equation of cellular respiration?

C₆H₁₂O₆ + 6O₂→6CO₂ +6H₂O

What is released during cellular respiration but isn’t considered a product?

energy (in the form of ATP)

What is the inner membrane?

folded membranes in the mitochondria

What is the matrix?

a fluid-like substance that fills the space in the mitochondria

What is glycolysis?

the first stage (pre-stage) in cellular respiration, the breakdown of glucose

What is the purpose of glycolysis?

a 10 step process of splitting the 6-carbon molecule of glucose in half to form two 3 carbon molecules called pyruvate

Where does glycolysis occur?

in the cytoplasm and requires no oxygen meaning it is anaerobic

What does glycolysis produce?

a net of 2 ATP and 2 NADH (1 glucose= 2 pyruvate molecules and 4 ATP, but it uses 2 to get the process going so it nets 2 ATP)

After glycolysis, what decision does the cell have to make?

if oxygen is present, then the cell will go through a two step process down as aerobic respiration to obtain energy. If oxygen is not present, then the cell will go through the process of anaerobic respiration (fermentation) in order to obtain energy

What are the two steps of Aerobic Respiration?

1. the Citric Acid Cycle (Krebs cycle)

2. Electron Transport Chain (ETC)

What is the purpose of the Citric Acid Cycle?

to make electron carriers NADH and FADH₂ to move on to the ETC

Where does the Citric Acid Cycle occur?

in the mitochondrial matrix

What is the process of the Citric Acid Cycle?

8 steps of chemical reactions where 2 pyruvate molecules from glycolysis are chemically converted to make 2 ATP (and some NADH and FADH₂; releases carbon dioxide as a waste product

Details of the Citric Acid Cycle

1. pyruvate from glycolysis are converted into acetyl-CoA, which will then enter the Citric Acid Cycle

2. NAD+ and FAD act as electron carries and become NADH and FADH₂ which carry electrons into the final step

3. this cycle happens 2 times

   1. each time, 1 pyruvate makes 4 NADH, 1 ATP, 1 FADH₂ and 3 carbon dioxide (total 8 NADH, 2 ATP, 2 FADH₂ and 6 carbon dioxide)

Where does the Electron Transport Chain happen?

the inner membrane of the mitochondria (called cristae)

What happens during the Electron Transport Chain?

oxidative phosphorylation and chemiosmosis (combines electron transport to ATP synthase)

Process of the Electron Transport Chain?

1. a series of reactions using the electrons and hydrogens carried by NADH and FADH₂ formed in the Krebs cycle

2. enzyme ATP synthase helps to assemble ATP

3. final electron acceptor after the electrons have gone down the ETC is oxygen

   1. oxygen combines with electrons and H+ to make water

4. makes 34 ATP and water

5. most ATP comes from this step

What is lactic acid fermentation?

occurs in some bacteria and animal cells (like our muscles); lactobacillus bacteria (yogurt, kefir, fermented vegetables, kimchi); pyruvate from glycolysis is converted into lactic acid and ZATP

What is alcohol fermentation?

occurs in yeast when oxygen is not available; bread, wine, beer; pyruvate from glycolysis is broken down into alcohol, carbon dioxide, and 2 ATP

What is the total amount of ATP produced during Aerobic Respiration?

35-38 (2 ATP from glycolysis, 2 ATP from Krebs cycle, 34 ATP from ETC)

What is the total amount of ATP produced during anaerobic respiration?

2-4 (2 ATP from glycolysis, 2 ATP from fermentation)