Test 3

Created by mg1553 

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Where does the energy that life uses to combat entropy come from?

from the sun

Entropy is a measure of an increase in:

randomness

How is your body able to counteract the effects of entropy?

eating a balanced diet

Energy that is not converted to useful energy is usually given off as:

heat

What is the ultimate source of energy for almost all forms of life on Earth?

solar energy

When - if ever - do molecules stop moving?

at absolute zero (-273.15°C)

Which trait below is a characteristic of energy carriers?

able to release energy easily

The most common energy carrier molecule in living organisms is:

ATP

A "high-energy" bond in an ATP molecule is located between:

two phosphate groups.

When a muscle cell demands energy to perform its work of contraction, ATP:

is broken down.

Which molecule functions in the short-term storage of energy?

adenosine triphosphate

ATP is an energy carrier. Where is the energy actually located?

in the bonds between phosphate groups

FAD is an example of:

an electron carrier.

The enzyme amylase in human saliva breaks starch polymers down into smaller sugar units. However, it cannot break down cellulose polymers. Both are made of glucose monomers, but in cellulose the monomers are linked together in a different shape than starch. Why can't amylase digest cellulose?

The bonds of cellulose do not fit properly in the active site.

Outside the body, sugar can catch fire and burn in an exergonic reaction. Inside the body, we also talk about burning sugar in an exergonic reaction, but it never catches fire. Why not?

When sugar is lit on fire, all of the bonds are broken at once. When the body breaks down sugar, enzymes break down one bond at a time.

Which of the following lowers the activation energy of a biochemical reaction?

catalysts

All of the following statements pertaining to catalysts are true EXCEPT:

catalysts increase activation energy requirements.

Enzymes are important because they:

allow reactions to occur at body temperature.

Which of these statements regarding enzymes is FALSE?

Enzymes provide energy for the reactions they catalyze.

Which of the following functions as a biological catalyst?

enzyme

Animals have enzymes that break apart starch molecules but not cellulose, despite the fact that both are made up of glucose subunits. Which enzyme characteristic BEST explains this?

Enzymes are highly specific.

Most enzymes do not work if the temperature is raised too much. Why is this?

Enzymes denature at higher temperatures.

Which of these equations best summarizes photosynthesis?

6 CO2 + 6 H2O → C6H12O6 + 6 O2

The light reactions of photosynthesis use _____ and produce _____.

water ... NADPH

What is the purpose of a cuticle on a leaf?

to prevent water loss

Why do chloroplasts make energy carriers during the light reactions?

to provide energy for the synthesis of sugar

How is O2 involved in photosynthesis?

O2 is a product of the light reactions.

Before photosynthesis evolved, ________ was rare in Earth's atmosphere.

O2

The products of photosynthesis are:

glucose and oxygen.

What structural feature of a leaf enables it to obtain CO2 from the air?

stomata

Specifically, molecules of chlorophyll are located in the membranes of sacs called:

thylakoids.

All of the following factors influence the rate of photosynthesis EXCEPT:

atmospheric N2 levels.

All of the following compounds are necessary constituents for photosynthesis EXCEPT:

oxygen.

The cellular organelle that is responsible for photosynthetic activity is the:

chloroplast.

Why do plant leaves appear green?

The chlorophyll in leaves reflects green light.

The pigment(s) that absorb light energy to drive photosynthesis is/are:

chlorophyll and carotenoids.

The ATP and NADPH synthesized during the light reactions are:

dissolved in the stroma.

Light reactions produce:

ATP, NADPH, and O2.

Where does the O2 released during photosynthesis come from?

H2O

The energy of the movement of electrons down a concentration gradient via electron transport within chloroplasts and mitochondria is used to generate molecules of:

ATP

Suppose you are studying photosynthesis in a research lab. You grow your plants in a chamber with a source of water that has a radioactively labeled oxygen atom. What photosynthetic product will be radioactive?

O2 gas

Carbon fixation involves the addition of carbon dioxide to _____.

RuBP

After 3-PGA is phosphorylated, it is reduced by _____.

NADPH

How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose?

6

In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules?

3

Which of the following equations represents photosynthesis?

6CO2 + 6H2O → C6H12O6 + 6O2

In which of the following organelles does photosynthesis take place?

Chloroplast

What connects the two photosystems in the light reactions?

An electron transport chain

What two molecules are produced by the light reactions and used to power the Calvin cycle?

ATP and NADPH

What provides electrons for the light reactions?

H2O

What provides the carbon atoms that are incorporated into sugar molecules in the Calvin cycle?

Carbon dioxide (CO2)

What transports electrons from the light reactions to the Calvin cycle?

NADPH

The light reactions take place in the _________ and the Calvin cycle takes place in the _________.

thylakoids; stroma

The term "cycle" is used to describe the Calvin cycle because:

the process begins and ends with RuBP.

Which of the following occurs during the Calvin cycle of photosynthesis?

Carbon dioxide is converted to chemicals that can be used to make sugars.

In the C3 pathway, where does the carbon come from to form glucose?

atmospheric CO2

Which of the following is the primary energy carrier for cells?

ATP

If photosynthesis and respiration are almost symmetrical processes, how is energy lost in the process of converting sugar back into ATP?

Energy is lost as heat during glycolysis and respiration.

A line of mutated yeast cells, called Wee mutants, has no mitochondria. Their name comes from the fact that these cells are very small compared to other yeast cells. Which energy-harvesting processes can Wee mutants perform?

glycolysis and fermentation

At the end of glycolysis, the original carbons of the glucose molecule form:

two molecules of pyruvate.

The anaerobic breakdown of glucose is called:

fermentation

If glucose is metabolized under completely anaerobic conditions, then pyruvate:

is converted by fermentation to CO2 and ethanol or to lactate.

All of the following are true statements about ATP EXCEPT that it is:

synthesized only within mitochondria.

The main function of cellular respiration is to produce:

ATP

If no oxygen is available to a cell, then the net ATP production resulting from the metabolism of a single glucose molecule is:

two ATP molecules.

Which event occurs in the fluid portion of the cytoplasm of a cell undergoing glucose metabolism?

glycolysis

What are the net products of glycolysis?

two ATP, two NADH, and two pyruvate

What does NADH contain that is useful to a cell?

high-energy electrons

How many of the carbons originally present in glucose continue to other reactions after glycolysis?

Six carbons are left in pyruvate molecules.

During glycolysis, what is the net gain of ATP molecules produced from one glucose molecule?

two

The end product of glycolysis is:

two pyruvate molecules.

Select the correct sequence of steps as energy is extracted from glucose during cellular respiration.

glycolysis → acetyl CoA → citric acid cycle → electron transport chain

What is the correct general equation for cellular respiration?

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP energy

Which of the following processes takes place in the cytosol of a eukaryotic cell?

glycolysis

In what organelle would you find acetyl CoA formation, the citric acid cycle, and the electron transport chain?

mitochondrion

Which statement describes glycolysis?

This process splits glucose in half and produces 2 ATPs for each glucose.

Which statement describes the citric acid cycle?

This process produces some ATP and carbon dioxide in the mitochondrion.

Which statement describes the electron transport chain?

This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration.

Where is the majority of the usable energy found at the completion of glycolysis, acetyl CoA formation, and the Krebs cycle?

NADH

What is the purpose of the electron transport chain?

To use energy from the passing of electrons in electron carriers into a high concentration of hydrogen ions

Where are the low-energy electrons located after the electron transport chain is completed?

They are located in the bonds of H2O.

Which of the following occurs immediately after a cell runs out of oxygen?

The electron transport chain stops.

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