bio ch 4/5 study questions

Answer the following questions about enzymes: -How do they affect the rate (speed) of chemical reactions? -Are they changed by the reactions they catalyze? -Active sites on an enzyme are very specific, usually binding only one or a few types of molecules. - What is the name of the molecule (reactant) that the enzyme modifies at the active site? -What would happen to an enzyme's function if it denatured?

Enzymes are biological catalysts, catalyst lower the activation energy for reactions, the lower the activation energy for a reaction, the faster the rate so enzymes speed up reactions by lowering the activation energy. The specificity of active sites are determined by the arrangement of amino acids within the active site and the structure of the substrates. Substrates are what the enzymes modify at the active site. If it denatures it will reduce its activity (prevent it from working), the enzyme and active site will change shape and the substrate will no longer fit, the rate of reaction will be affect or will stop.

Why are carnivores, such as lions, dependent on photosynthesis to survive?

Because lions eat animals that eat plants.

Are enzymes required for anabolic reactions, catabolic reactions, or both?

Both because enzymes are important for catalyzing all types of biological reactions- those that require energy as well as those that release energy

What is the role of ATP synthase? How do H+ ions play a role in the function of ATP synthase?

The role of ATP synthase is to synthesize ATP from ADP with energy from protons diffusing it. ATP synthase acts as a tiny generator, turned by the force of hydrogen ions diffusing through it, down their electronics gradient from the membrane space.

The energy currency used by cells is _____. a. ATP b. ADP c. AMP d. adenosine

a. ATP

Plants produce oxygen when they photosynthesize. Where does the oxygen come from? a. splitting water molecules b. ATP synthesis c. the electron transport chain d. chlorophyll

a. splitting water molecules

Figure 4.6 Look at each of the processes shown and decide if it is endergonic or exergonic.

- the first figure is of compost. decomposition of dead/decaying matter to produce compost is an EXERGONIC process bc its accompanied with the release of heat energy - the second figure is of a chick coming out of an egg. this is an ENDERGONIC process bc energy is being taken in from the chick - the third figure is of tea dissolving in water, this is EXERGONIC - the last one is of a ball rolling downhill. this is EXERGONIC bc energy is being released

what is the role of chlorophyll (aside from making plants appear green)?

-absorb light(sunlight) chlorophyll A, absorbs wavelengths from either end of the visible spectrum( blue and red) but not green. -chlorophyll B, (absorbs blue and red-orange light) and the carotenoids

Aerobic cellular respiration (glucose metabolism) consists of three ATP producing pathways: Glycolysis, the Citric Acid Cycle (CAC), and Oxidative Phosphorylation. Each of these consist of a ton of reactions which you don't need to learn. Focus on the following basics: Know the order in which these three pathways occur -Know where they occur -Know how many net ATP are produced by glycolysis and the citric acid cycle -Know which pathway produces the most ATP -Know where CO2 is produced and which pathway requires O2

1. glycolysis 2. CAC 3. OP -glycolysis occurs in the cytoplasm, CAC and OP occurs in the mitochondria - in glycolysis and CAC 2 atp are produced each - CAC produces the most ATP, this is also where CO2 is produced (mitochondria)

Compare the equations for photosynthesis and cellular respiration. How are they different? How are they similar?

6CO2 + 6H2O → C6H12O6 + 6O2(photosynthesis) 6O2 → 6CO2 + 6H2O(cellular respiration) -they have the same reactions but accruing in reverse. In Photosynthesis, carbon dioxide and water is yielded to glucose and oxygen. In respiration, glucose and oxygen is yielded to carbon dioxide and water. -both important parts of the carbon cycle. -Photosynthesis makes the glucose that is used in cellular respiration to make ATP. The glucose is then turned back into carbon dioxide, which is used in photosynthesis. -water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.

What molecule is used in cells to perform work like "dollar is used as currency to buy goods"

ATP

ATP contains a lot of potential energy. Which part of the ATP molecule is "broken" in order to release energy for cellular work?

ATP is able to power cellular processes by transferring a phosphate group to another molecule.

Figure 4.15 Cyanide inhibits cytochrome c oxidase, a component of the electron transport chain. If cyanide poisoning occurs, would you expect the pH of the intermembrane space to increase or decrease? What affect would cyanide have on ATP synthesis?

After cyanide poisoning, the electron transport chain can no longer pump electrons into the intermembrane space. The pH of the intermembrane space would increase, and ATP synthesis would stop.

Both prokaryotic and eukaryotic organisms carry out some form of glycolysis. How does that fact support or not support the assertion that glycolysis is one of the oldest metabolic pathways?

If glycolysis evolved relatively late, it likely would not be as universal in organisms as it is. It probably evolved in very primitive organisms and persisted, with the addition of other pathways of carbohydrate metabolism that evolved later.

The equation for cellular respiration indicates that water is produced (see below). During what pathway is the water produced? Glucose + 2O2 → 6CO2 + 6H2O

It is formed in the electron transport chain

What is anaerobic cellular respiration? Under what sort of conditions would this occur?

It is the use of an electron acceptor other than oxygen to complete metabolism using transport-based chemiosmosis. This would occur in the cytoplasm of the cell.

Figure 5.7 On a hot, dry day, plants close their stomata to conserve water. What impact will this have on photosynthesis?

Levels of carbon dioxide (a reactant) will fall, and levels of oxygen (a product) will rise. As a result, the rate of photosynthesis will slow down.

When is oxygen produced during photosynthesis? During the light dependent reactions or during the Calvin cycle?

Light dependent reactions

Explain the reciprocal nature of the net chemical reactions for photosynthesis and respiration.

Photosynthesis takes the energy of sunlight and combines water and carbon dioxide to produce sugar and oxygen as a waste product. The reactions of respiration take sugar and consume oxygen to break it down into carbon dioxide and water, releasing energy. Thus, the reactants of photosynthesis are the products of respiration, and vice versa.

Does physical exercise to increase muscle mass involve anabolic and/or catabolic processes? Give evidence for your answer.

Physical exercise involves both anabolic and catabolic processes. Body cells break down sugars to provide ATP to do the work necessary for exercise, such as muscle contractions (catabolic). Muscle cells also must repair muscle tissue damaged by exercise by building new muscle (anabolic).

With regard to enzymes, why are vitamins and minerals necessary for good health? Give examples.

Since enzymes catalyze many important reactions, it is critical to obtain sufficient vitamins and minerals from the diet and from supplements. Vitamin C (ascorbic acid) is a coenzyme necessary for the action of enzymes that build collagen, an important protein component of connective tissue throughout the body. Magnesium ion (Mg++) is an important cofactor that is necessary for the enzyme pyruvate dehydrogenase to catalyze part of the pathway that breaks down sugar to produce energy

Where does photosynthesis take place?

Takes place in stages; the light-dependent reactions and the Calvin cycle. occurs in cytoplasm

When are sugars assembled during photosynthesis? During the light dependent reactions or during the Calvin cycle?

The Calvin cycles

We inhale oxygen when we breathe and exhale carbon dioxide. What is the oxygen used for and where does the carbon dioxide come from?

The oxygen we inhale is the final electron acceptor in the electron transport chain and allows aerobic respiration to proceed, which is the most efficient pathway for harvesting energy in the form of ATP from food molecules. The carbon dioxide we breathe out is formed during the citric acid cycle when the bonds in carbon compounds are broken.

Which of the following is not true about enzymes? a. They are consumed by the reactions they catalyze. b. They are usually made of amino acids. c. They lower the activation energy of chemical reactions. d. Each one is specific to the particular substrate(s) to which it binds.

a. they are consumed by the reactions they catalyze

Is photosynthesis an anabolic or catabolic pathway?

anabolic because they build sugars out of smaller molecules

Which statement about thylakoids in eukaryotes is not correct? a. Thylakoids are assembled into stacks. b. Thylakoids exist as a maze of folded membranes. c. The space surrounding thylakoids is called stroma. d. Thylakoids contain chlorophyll.

b. Thylakoids exist as a maze of folded membranes.

What is the energy of a photon first used to do in photosynthesis? a. split a water molecule b. energize an electron c. produce ATP d. synthesize glucose

b. energize an electron

Which molecule absorbs the energy of a photon in photosynthesis? a. ATP b. glucose c. chlorophyll d. water

c. chlorophyll

Energy is stored long-term in the bonds of _____ and used short-term to perform work from a(n) _____ molecule. a. ATP : glucose b. an anabolic molecule : catabolic molecule c. glucose : ATP d. a catabolic molecule : anabolic molecule

c. glucose : ATP

Is aerobic cellular respiration (sugar metabolism) an anabolic or catabolic pathway?

catabolic because cellular respiration is breaking down sugars into smaller molecules

what is the difference between anabolism and catabolism?If you can answer a-d below, you'll know the difference. Which one generates energy? Which one requires energy? Which one produces larger molecules (polymers)? Which one breaks down polymers into smaller molecules?

catabolism generates the energy, anabolism requires energy and produces larger molecules while catabolism breaks down polymers into smaller molecules

What is chemical energy? Is it a form of kinetic or potential energy?

chemical energy is potential energy because it is stored in the bonds that connect atoms with other atoms and molecules with other molecules

Which of the following is not an example of an energy transformation? a. Heating up dinner in a microwave b. Solar panels at work c. Formation of static electricity d. None of the above

d. none of the above

Figure 4.16 Tremetol, a metabolic poison found in white snake root plant, prevents the metabolism of lactate. When cows eat this plant, Tremetol is concentrated in the milk. Humans who consume the milk become ill. Symptoms of this disease, which include vomiting, abdominal pain, and tremors, become worse after exercise. Why do you think this is the case?

lactic acid fermentation occurs in red blood cells and in skeletal muscle that has insufficient oxygen supply to allow aerobic respiration to continue. if tremotol prevents the metabolism of lactate, these cells and skeletal muscle getting the oxygen they need, making the symptoms of this disease worse after exercise

What is metabolism? consider the statements " he has a really fast metabolism" Based on the description of the metabolism in the book, do you think the statements appropriately use the term metabolism? Explain

metabolism is the process by which your body converts what you eat and drink into energy, its the sum of chemical reactions that take place within each cell of a living organism and that provide energy for vital processes and for synthesizing new organic material

What is the overall purpose of the light reactions in photosynthesis?

to convert solar energy into chemical energy that cells can use to do work.