Chapter 4: Energy

When a muscle cell metabolizes glucose in the complete absence of molecular oxygen, all of the following substances are produced EXCEPT:

acetyl-CoA

Photosynthesis is the process by which plants, some bacteria, and some protistans, use the energy from sunlight to produce sugar, which _______________ converts to ATP, the "fuel" used by all living things.

cellular respiration

where is energy stored?

chemical bonds of organic molecules like sugars, fats, and proteins

During photosynthesis, which of the following is the most important molecule in the conversion of light energy from the sun into chemical energy?

chlorophyll

photosystem

cluster of pigment molecules that turn into chlorophyll and carotenoids

what does the thylakoid do?

converts light energy into chemical energy

Mitochondria have a "bag within a bag" structure. This is necessary to:

create two distinct regions with a concentration differential, a form of potential energy.

structure and location of thylakoids

looks like a stack of pancakes floating inside the stroma

what comes out a light dependent reaction?

ATP, NADPH, CO2

C4 plants have better water conservation abilities than do many other plants (especially C3). This is because:

C4 plants open their stomata at night.

photosynthesis equation

CO2 + H2O --> Glucose + O2

Why are leaves green?

Chlorophyll molecules mainly absorb light in the blue-violet and red-orange part of the electromagnetic spectrum. Chlorophyll does not absorb much green light, which is reflected to our eyes.

what comes out a light dependent reaction?

NADP+, ADP+P, G3P

what goes into a light dependent reaction?

NADPH, ATP, CO2

The conversion of radiant energy to chemical energy occurs in photosynthesis and many other common phenomena, such as brewing tea, fading of dyes in the sun, and photography. In what way is photosynthesis different from these other processes?

Photosynthesis fixes light energy in the form of high potential chemical energy in compounds that do not break down spontaneously and that can be stored until required later for the carrying out of life processes.

What is the first step in CAM photosynthesis?

Plants open their stomata at night to take in carbon dioxide.

what are the 2 photosystems?

Ps1 and Ps2

sequence of 2 photosystems

Ps2 --> electron transport chain --> Ps1 --> electron transport chain --> NADP+ --> NADPH --> Calvin cycle --> ATP synthase

Although the reactions of the Calvin cycle do not depend directly on light, they do not usually occur at night. Why?

The Calvin cycle depends on products of the light reactions that cannot occur at night.

The graphs above show data relating to seasonal differences in the amount of pigment molecules present in leaves and how this is related to leaves changing colors. The graphs indicate that in the fall chlorophyll a and b molecules are broken down and stored in the branches of the plant. As light from the fall sun hits the leaf, what is the result

The light reflected from the leaf is orange.

Which of the following is FALSE?

The thylakoid membrane lies outside of the stroma.

The graphs above show data relating to seasonal differences in the amount of pigment molecules present in leaves and how this is related to leaves changing colors. What is the independent variable presented in these graphs?

Time at which the amount of pigment in the leaves was measured.

what do the 2 photosystems do?

absorb different colors of light

photosynthetic pigments

absorption spectra of plant pigments, each absorbing specific wavelengths

Which of the following statements about fermentation is NOT correct?

a. Fermentation is an anaerobic process. b. In fermentation, the molecules that are used as electron acceptors differ from those used when glycolysis occurs in the presence of oxygen. c. Fermentation is a less efficient energy producer than aerobic respiration. d. Fermentation utilizes the electrons generated in the glycolytic breakdown of glucose.

You eat a chocolate bar to get you through a late-night studying session. Your body quickly begins to break down the macromolecules in the candy, using the sugars, lipids, and protein to make ATP. Which of the following is NOT a step in the process of breaking down the candy bar's macromolecules?

a. First Step: The sugars are broken down to simple glucose molecules and the proteins and lipids are broken down to acetyl-CoA molecules. No energy is produced in this first step. b. Second Step: Glycolysis converts the glucose to two molecules of pyruvate. Six ATP molecules are produced in this step. c. Third Step: Oxidation of each pyruvate produces two molecules of acetyl-CoA. Six ATP molecules are produced in this step. d. Fourth Step: Two acetyl-CoA molecules go through the Krebs (citric acid) cycle. Twenty-four ATP molecules are produced through this process.

Light-absorbing pigments that are not at the reaction center of a photosystem: (GOT WRONG ANSWER)

a. are all constructed from chlorophyll. b. are free floating in the stroma. c. increase the amount of the visible light spectrum that can be harnessed for photosynthesis. d. enable photosynthesis to occur in the dark for a short period of time. e. are identical in all plant species.

what does all life depend on?

capturing energy from the sun and converting it into a form that living organisms can use

energy

capacity to do work (potential energy)

making bonds requires..?

energy

The three steps, in order, of the Calvin cycle are:

fixation of CO2, sugar creation, and regeneration.

chemical energy

form of potential energy stored in chemical bonds ex: food

ATP is produced in the mitochondria by a series of biochemical reactions. In what order do these reactions occur?

glycolysis; the Krebs cycle; the electron transport chain

photosynthesis

how plants capture energy from the sun and store it in the chemical bonds of sugars

About how many mitochondria might you expect to find in a single human skin cell?

hundreds or thousands

light energy is a type of what energy?

kinetic

stomata

lets in CO2 and lets out O2

light dependent reactions depend on what?

light

light independent reactions don't require what?

light

2 types of photosynthesis reactions

light dependent and light independent

The leaves of plants can be thought of as "eating" sunlight. From an energetic perspective, this makes sense because:

light energy, like the chemical energy released when the bonds of food molecules are broken, is a type of kinetic energy.

thylakoid

location of "photo" reactions

ATP

main carrier of energy from one reaction site to another

work

moving matter against an opposing force (kinetic energy)

what is produce in Ps2?

oxygen

light energy is made up of what?

photons

where does photosynthesis occur?

photosynthetic cells of the leaf

cellular respiration

process by which all organisms release the energy stored in the chemical bonds of food molecules they eat and use it as fuel

chlorophyll absorbs...?

reds and blue-violets

what does ATP do for all life processes?

releases energy

what does breaking bonds do with energy?

releases it

what happens in a light dependent reaction?

rubisco enzyme takes CO2 and attaches it to the sugar

where do light dependent reactions occur?

stroma

what goes into a light dependent reaction?

sunlight energy, ADP+P, NADP+, H2O

what happens to chlorophyll a and b in the fall?

they are broken down and stored in branches

where do light dependent reactions occur?

thylakoid membranes of the leaves' chloroplasts

Potential energy is to kinetic energy as ______________ is to _____________.

water held behind a dam; water power being used to turn electric turbines

chlorophyll reflects...?

yellows and greens