General Biology: Unit 2 Test

Based on the illustration, a patient with a mutated form of phosphoglycerate kinase will develop a chronic buildup of which molecule?

1,3-bisphosphoglycerate

Acetic acid, chemical formula CH3COOH, a component of vinegar, has multiple production pathways. Which of these equations shows anaerobic fermentation?

2 CO2 + 4 H2 → CH3COOH + 2 H2O

Thermodynamics tells us that efficiency in reactions is important and determined by how much energy is lost to heat in a reaction. In the metabolism of glucose, what percentage of the energy is extracted?

34 percent

What is the total yield (not net) of ATP from glycolysis?

4 ATP

In photosynthesis, what is a photoact?

A photoact is a process where two chlorophylls in the reaction center give up electrons, converting light energy to excited electrons.

Which of the following represents the reversible reaction of ATP formation?

ADP + Pi + free energy → ATP + H2O

What is the difference between ADP and ATP?

ADP has no gamma phosphate group

What are the products of the hydrolysis of ADP?

AMP, an inorganic phosphate ion, and free energy

Which of the following is the formula for ATP hydrolysis?

ATP + H2O -> ADP + Pi + free energy

What molecular complex is shown in the illustration?

ATP Synthase

What produces the ATP required for the Calvin cycle?

ATP Synthase

How is captured light energy transferred from the light-dependent reactions to the light-independent reactions?

ATP and NADPH

How do cells use ATP?

ATP is the cell's primary energy currency.

A video gaining popularity on social media purports to show a self-contained, self-sustaining biosphere, conveniently available at purchase. The narrator claims that this process is so efficient; the bottle actually feels warm to the touch despite receiving no additional energy. You know this is clearly impossible, but what facts support your assertion?

All metabolic processes lose energy as waste heat; the fact that the bottle is warm to the touch indicates it is losing energy that is not being replaced

Living things are highly ordered and maintain a state of low entropy. How is that possible given what we know about the second law of thermodynamics?

An organism can grow and create internal order without violating the second law of thermodynamics, but it must have a continual supply of energy to do this. The universe's total entropy continues to increase due to losing usable energy with each energy transfer that occurs.

A group of your colleagues has collected disused lab equipment in a storage closet, with the intention of brewing their own hard cider for parties after work. After carefully sterilizing their equipment, they add apple juice, table sugar, and a bacterial culture derived from fermenting yogurt to several large bottles, leaving each half empty, then turn off the lights, lock the closet, and wait. After checking a week later, your colleagues are disappointed to discover that the contents of their bottles are not fit for human consumption. What mistake did they make?

Bacteria perform lactic acid fermentation, not alcohol fermentation.

In a microbiology lab, which of the following has the most energy?

Bacterial culture after a visit to the autoclave

A nutritionist has an enclosed cabinet used to calculate calories in foods. The protocol required that the food is set on fire as fuel under a water tank and then the temperature change in water is equated to the calorie content in the foods. High calorie foods burn hotter than low calorie foods. Why?

Burning the food is an energy transformation. Higher calorie foods have greater energy content & will produce more heat during burning than lower calorie foods, as chemical energy in the food is converted into the energy of heat flow.

What type of enzyme regulation is illustrated here?

Feedback inhibition

What is feedback inhibition?

Feedback inhibition is when the reaction's product functions to regulate its own further production

What will occur most immediately after the process shown in the diagram?

Glucose-6-phosphate levels will increase.

Two groups of your colleagues are arguing over the amount of energy required for a beaker full of substance X to complete an endergonic reaction. First group insists that only the activation energy for a single reaction is required. Second group strongly disagrees, insisting that the energy required is equal to activation energy of a single set of reactants, multiplied by # of reactant sets in that volume of substance X. What group is correct?

Group 2 is half right; endergonic reactions absorb energy, so free energy, activation energy, and entropy losses for all reactants must be included

The first enzyme in glycolysis is hexokinase. What does it do?

Hexokinase catalyzes the phosphorylation of glucose to produce glucose-6-phosphate.

In general, what is the effect of high levels of ATP on metabolic pathways?

High levels of ATP cause metabolic pathways to slow down temporarily.

When the gasoline molecule shown in this figure is broken down and used, what form does the energy take? ( Racecar picture)

Kinetic

What is the role of NADH in glycolysis?

NADH binds and carries electrons.

There is evidence connecting excessive amounts of glutamate, an amino acid, w mental health conditions such as schizophrenia. If a patient were put on a diet severely limiting carbohydrates & glutamate, would it disrupt the body's ability to perform cellular metabolism?

NO. The body has many other amino acids that can be fed into the citric acid cycle to continue to make ATP

A soft drink manufacturer, notorious for making marketing claims that are deceptive but technically accurate, has released a new sports beverage. The advertisements for this beverage assert that it contains anabolic molecules that provide energy and is 100% legal to produce and consume. You buy a bottle of this beverage for testing and discover that it contains little more than water, disaccharides such as sucrose and maltose, citric acid, and other fairly common fruit flavoring agents. Have you finally caught the company in a lie?

No; disaccharides are created through anabolic pathways and are perfectly legal.

Which statement is true concerning the Calvin cycle?

One glucose molecule is produced after six turns.

It is commonly said that plants, especially trees, produce oxygen, but thus is an oversimplification of metabolism in plants. Which of these statements is more accurate?

Plants release oxygen during photosynthesis and reabsorb it during carbohydrate catabolism

Congenital non-spherocytic haemolyic anaemia (CNSHA) is caused by a mutation of one or more of the enzymes of the glycolytic pathway. The most common is a mutation in the gene for pyruvate kinase resulting in a non-functional enzyme. Patients with CNSHA often show marked ATP deficiencies. Given what you know about this enzyme's action, why would this be expected?

Pyruvate kinase produces ATP when it generates pyruvate from phosphophoenolpyruvate (PEP).

The manufacturers of dietary supplements are known for making misleading claims that are often unsupported by science and medicine. Based on what you know about cell respiration and ATP, which of these claims about a supplement is plausible and potentially beneficial?

Reduces the energy needed to regenerate ATP molecules!

G3P is produced during which stage of the Calvin cycle?

Reduction

Synthesizing a single glucose molecule requires the amount of energy stored in 54 ATP molecules, but when that glucose molecule is broken down, only enough energy to produce 36 to 38 ATP molecules is released. What happened to the remaining energy?

Some energy from metabolism is released as heat

Where does the gas exchange necessary to support photosynthesis take place?

Stomata

Virtually every food consumed by humans is originally derived from sunlight. This is easily seen in relation to plants and seeds, but the connection to meat is less clear. How is meat ultimately derived from sunlight?

The animals are fed a plant-based diet and use that energy (originally derived from the sun) to build the proteins that people consume when they eat meat.

An avid gardener composts her wastes near the back of her property, away from her house. She move the compost heap out there because it sometimes heats up enough to smoke. When asked why is heats up so much, she answers, simply, "because the second law of thermodynamics says so !" How does the 2nd law of thermodynamics explain her compost smoking?

The breakdown of compost involves a transformation of energy from chemical bonds in the decomposing organic matter. The 2nd law of thermodynamics says that there is no 100% energy transfer, so some of the energy is lost to the surroundings as heat.

As electrons move through the proteins that reside between Photosystem II and Photosystem I, they lose energy. What is that energy used for?

The energy is used to move hydrogen ions from the stromal side of the membrane to the thylakoid lumen.

A patient presenting a variety of symptoms, including generalized fatigue and neurological impairment, is brought to the hospital, where tests reveal a severe GTP deficiency in the patient's liver. What is the likely cause of these symptoms?

The patient has a mutated form of the enzyme that regulates succinate synthesis.

A patient is brought to the hospital after experiencing acute fatigue. The patient's condition deteriorates rapidly during testing, despite alarmingly high blood glucose levels, and he has no history of diabetes. Initial tests also show low levels of glucose-6-phosphate. The results of further diagnostic testing are not available yet, but based on what you know, which hypothesis could explain the patient's condition?

The patient has been exposed to a substance that binds to hexokinase and inhibits its function.

What will happen when the supply of ATP increases above normal levels?

The rate of citrate production will decrease.

What is a fundamental difference between circular and linear metabolic pathways?

The reactants of linear metabolic pathways do not include their reactants.

Which of these statements is true of the energy in an open system containing living organisms?

There must be a net influx of energy to this system

The free energy from the redox reactions in the electron transport chain drives proton pumps that create a hydrogen ion concentration and electrical gradient across the inner mitochondrial membrane. If these ions cannot readily diffuse, how do they pass back through the inner mitochondrial membrane?

They return through an integral membrane protein called ATP synthase which utilizes the potential energy of the gradient to make ATP.

Fumarate production is an oxidation reaction similar to the reactions that produce α-ketoglutarate, and oxaloacetate, but with one key difference. What is it?

This reaction reduces FAD instead of NAD+.

Some enzymes build new molecules, & others metabolize or break them down. For example, digestive enzymes such as peptidases & lipases break down proteins and lipids, respectively. Genetic information is encoded in DNA for proteins, many of which are enzymes. If a person suffers a mutation that results in malformed peptidase what problem would you expect them to have?

Unable to digest protein

Some enzymes do not work properly or at all without the presence of a cofactor or coenzyme. Which of the following is a class of known important coenzymes?

Vitamins

Your colleagues are attempting to study the citric acid cycle in the lab. To do so, they have dissolved oxaloacetate in water, then stirred in sufficient quantities of every required enzyme, coenzyme, and oxidizing agent, before adding ADP and acetyl CoA. After waiting a sufficient period of time, they test the solution for ATP and are disappointed to find significantly less ATP than expected. What is the flaw in their experiment?

Without subsequent pathways to oxidize NADH and FADH2, no NAD+ and FAD are available to continue the cycle.

Dephosphorylation of the adenosine triphosphate molecule (shown in this diagram) generally results in only the removal of the Gamma phosphate and Beta phosphate groups, leaving the Alpha phosphate group bonded to the adenosine molecule. How can you explain this behavior?

Without the repulsive forces generated between phosphate groups, the adenosine monophosphate molecule is much more stable.

A soft drink manufacturer, notorious for making marketing claims that are deceptive but technically accurate, has released a new sports beverage. The advertisements for this beverage assert that it contains three grams of chlorophyll per bottle, which will give the user extra energy during exercise performed in direct sunlight. Naturally, you buy a bottle to test its ingredients, and you are able to verify that it does, in fact, contain three grams of plant-sourced chlorophyll. Have you finally caught the company in a lie?

Yes! Sunlight will have no effect on the amount of energy derived from digested chlorophyll.

In the illustration, isoleucine can enter and exit the citric acid cycle at what point?

acetyl CoA

What are the products of beta-oxidation?

acetyl groups

What portion of an amino acid must be removed before it can be used in glucose catabolism?

amino group

What is the organelle shown in this illustration?

chloroplast

When would the human body produce the most lactic acid?

during prolonged exercise

When is a G3P molecule produced by the Calvin cycle?

during the reduction stage

After all of the reactants in a solution have been consumed, what is the state of the solution?

equilibrium

You begin an experiment involving metabolic processes in human liver cells, but you discover your liver tissue samples have been contaminated with a strain of obligate anaerobic bacteria. Theoretically, how could you kill the bacteria while minimizing damage to the liver cells?

exposes the samples to gaseous oxygen

This diagram shows a simplified representation of bioenergetics, with arrows representing transfers of energy between various ecological components. Where do humans fall in this diagram?

from decomposers to consumers

Thylakoids exist in stacks inside the thylakoid lumen. What is the term for these stacks?

granum

What is the function of triglycerides for animals?

long-term energy storage

According to the graph below, which form of enzyme inhibition has the greatest effect on the maximal rate? (lowest)

noncompetitive inhibitors

Relative to the NAD+ molecule in the illustration, how many hydrogens does the NADH molecule possess?

one more

Chemiosmosis is a general term referring to the movement of ions across a semipermeable membrane. When used to produce ATP in mitochondria, what is this process called?

oxidative phosphorylation

What is the final electron acceptor in the electron transport chain?

oxygen

What is the waste product of photosynthesis?

oxygen

What process is shown in this diagram?

phosphorylation

Which compound could be the final electron acceptor of anaerobic cellular respiration, but not fermentation?

sulfate

Which bond in ATP is the high energy bond?

the bond between the phosphate groups

How is the wavelength of light measured?

the distance between consecutive crest points of a wave

When studying thermodynamics, one must 1st define the system. What is included in the system?

the matter and its environment relevant to a particular case of energy transfer

Once photons are harvested by the pigment molecules in the light-harvesting complex, where is the energy delivered next?

the reaction center of the photosystem

Where do the light-dependent reactions take place?

thylakoid membrane

What is the net production of ATP molecules during glycolysis?

two

What are the total gross (not net) final products from one molecule of glucose after glycolysis?

two pyruvate, four ATP, and two NADH