BSC-2010 Lecture Notes - Lecture 6: Exergonic Reaction, Metabolic Pathway, Chemical Energy
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As entropy increases there will be more useful energy to doâworkâ. True or false?
False. As entropy increases, there will generally be less usefulenergy to do work. We can think of entropy as usually being presentin the form of heat energy. Imagine a car motor, which attempts toturn chemical potential energy into kinetic energy (movement). Lessefficient motors will get hotter for the same amount of fuelconsumed. When you drive a car you hope that most of the fuelenergy is converted into kinetic energy and not lost as heat(entropy). The hotter the car (and thus the more entropy) the lessefficient the ability to do âworkâ (the moving of the vehicle). |
| True. As entropy increases, there will generally be more usefulenergy to do work. We can think of entropy as usually being presentin the form of heat energy. In most biological and mechanicalsystems it is heat energy which is captured to do useful 'work'.Heat energy, the random movement of molecules, and increases inentropy are central to doing useful work. |
Biological systems sometimes appear on the surface to break theSecond Law of Thermodynamics â by seemingly increasing the order inthe overall system. They donât. Why?
| a. Earth (and living things on it) are not a closed system. Thesun's constant input of energy in the form of photons is harnessedby living things to create internal order within themselves. Butwithout such a constant input of energy, most biological systems onearth would break down. |
| b. The Second Law tells us that no natural process can occurunless it is also associated with an increase in the entropy of theuniverse. A living organism (such as an animal or plant) brings inmatter and energy from its environment and uses this to creategreater order within its body: the processes of life. But it isimportant to keep in mind that all animals and plants are also partof a larger system of the environment around them. While creating asmall âpocketâ of order, the processes of life (metabolism,movement, etc..) releases heat into the environment â thusincreasing the entropy of the universe and following the2nd law. |
| c. Living things, by harnessing energy to create order (withinand around themselves) actually create a paradox in questionssurrounding the first and second laws of thermodynamics andseemingly violate many previously held assumptions. |
| d. Both a and b above are correct. |
When plants capture energy in the photons of sunlight andconvert that energy into the chemical bonds of organic molecules,are they creating new energy?
| No, the energy is being transferred from one form into another.But no new energy is being created. |
| No, the overall total energy is decreasing over time. |
| Yes, by capturing photons, the plants are creating newenergy. |
| Yes, by capturing photons, the plants are creating new energy -of a different wavelength. |
Value: 1
Anabolic pathways of metabolism are pathways that:
a. build complex molecules from simple ones.
b. release stored chemical energy.
c. take place primarily in skeletal muscle
d. make large quantities of ATP.
Value: 2
The sum of all chemical reactions in a cell is referred to as _______________.
Value: 3
Organisms that derive both their energy and carbon from organic compounds are:
a. photoautotrophs.
b. chemoautotrophs.
c. chemoheterotrophs.
d. photoheterotrophs
Value: 4
It is often stated that the phosphate bonds in ATP are "high energy," but in fact, they are not notably high in energy. Rather, they are easy to break, and the âG of hydrolysis is a "useful" quantity of energy. What makes the phosphate bonds easy to break?
a. They are close to the destabilizing nitrogenous base adenosine
b. Positive charges on amino groups repel each other.
c. Negative charges on phosphate groups repel each other
d. High acidity attacks bonds between amino acids.
Value: 5
Which of the following describes ATP hydrolysis? Select all that apply
[mark all correct answers]
a. exergonic
b. spontaneous
c. often coupled to a reaction that has a positive ÎG
Value: 6
Which of the following describes catabolic reactions?
a. They are endergonic and have a negative change in free energy
b. They are exergonic and have a negative change in free energy
c. They are exergonic and have a positive change in free energy.
d. They are endergonic and have a positive change in free energy.
Value: 7
Why are cells not infinitely big?
a. Because they wouldn't fit in an organism
b. Because they would have a small surface area:volume ratio and substances would diffuse in and out too slowly
c. Because they would have a large surface area to volume ratio and substances would diffuse in and out too quickly
Value: 9
How is organelle movement around cells controlled?
a. the nucleus directs the movement of organelles in a cell
b. the cytoskeleton is like a monorail that moves organelles in a cell via motor proteins
c. organelles do not move, they have a fixed position in the cell
d. organelles move by facilitated diffusion in the cell
Value: 10
1. Prokaryotic cells lack:
a. a. A nucleus
b. organelles
c. cell membrane
d. DNA
e. A and B
Value: 11
Rough endoplasmic reticulum (rER)
a. a. Makes cell membranes
b. has ribosomes attached
c. are a site of protein synthesis
d. all of the above
Value: 12
Match the items.
The task is to match the lettered items with the correct numbered items. Appearing below is a list of lettered items. Following that is a list of numbered items. Each numbered item is followed by a drop-down. Select the letter in the drop down that best matches the numbered item with the lettered alternatives.
| a. help to digest worn-out or damaged organelles. | |
| b. Takes in molecules in transport vesicles, modifies them, and sends them back out in vesicles | |
| c. makes sugar | |
| d. makes ATP | |
| e. assembles the ribosomes | |
| f. gives the cell structure | |
| g. move material around the cell | |
| 1. vesicles | a b c d e f g |
| 2. cytoskeleton | a b c d e f g |
| 3. the golgi apparatus | a b c d e f g |
| 4. lysosomes | a b c d e f g |
| 5. mitochondrion | a b c d e f g |
| 6. chloroplast | a b c d e f g |
| 7. nucleolus | |