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Life 102 Arthun Exam 2 CSU Questions
With Answers
How do enzymes speed up chemical reactions in cells? - ✔ ✔ Enzymes lower the activation energy barrier of reactions.
What is the active site of an enzyme? - ✔ ✔ The place on the enzyme where the substrate binds
Some bacteria are metabolically active in hot springs because: - ✔ ✔ Their enzymes have high optimal temperatures.
HIV is the virus that causes AIDS. In the mid-1990s, researchers
discovered an enzyme in HIV called protease. Once the enzyme's structure was known, researchers began looking for drugs that would fit into the active site and block it. If this strategy for stopping HIV infections were successful, it would be an example of _____________________. - ✔ ✔ Denaturation
How does a non-competitive inhibitor decrease the rate of an enzyme reaction? - ✔ ✔ By changing the shape of the enzyme's active site
When a molecule of NAD+ gains an electron as part of a redox reaction, it becomes ___________. - ✔ ✔ Reduced
In addition to ATP, what are the end products of glycolysis? - ✔ ✔ NADH and pyruvate
All of the reactions of cellular respiration that occur after glycolysis take place in what part of the eukaryotic cell? - ✔ ✔ The mitochondria
Following glycolysis and the citric acid cycle (but before the electron
transport chain and oxidative phosphorylation), the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is in the form of _________. - ✔ ✔ NADH
As electrons move along the electron transport chain, they lose potential energy. How is the energy that is released used by the cell? - ✔ ✔ The energy is used to transport hydrogen ions against their concentration gradient
Describe the flow of electrons during aerobic cellular respiration - ✔ ✔ Sugars NADH Electron Transport Chain O
The "fluid mosaic" model of the cell membrane proposes that membranes
_____________. - ✔ ✔ Consist of protein molecules embedded in a fluid bilayer of phospholipids
Which of the following is a reasonable explanation for why unsaturated fatty acids help keep a membrane more fluid at lower temperatures? - ✔ ✔ The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
The part of a membrane protein that extends through the phospholipid bilayer is primarily composed of amino acids that are __________. - ✔ ✔ Non-polar
What is the term for metabolic pathways that release stored energy by breaking down complex molecules? - ✔ ✔ Catabolic pathways
What is stated by the First Law of Thermodynamics? - ✔ ✔ Energy can be transformed into other forms of energy, but energy cannot be created or destroyed.
Metabolic reactions fall under two general categories: anabolic and
catabolic. What type of chemical reactions are these two classes of
metabolic reactions? - ✔ ✔ Anabolic reactions are endergonic reactions, whereas catabolic reactions are exergonic.
Why do we have storage macromolecules (such as fats) in our bodies? - ✔ ✔ We can break down these macromolecules to provide energy for the endergonic reactions in our bodies.
Which of the following is the most-correct interpretation of the figure
shown above? - ✔ ✔ ATP is a molecule that acts as an intermediary to store energy for cellular work.
High levels of ATP inhibit the enzyme phosphofructokinase (a key enzyme in glycolysis). As a result, glycolysis slows down, and lower amounts of ATP are produced. This is an example of ___________. - ✔ ✔ Feedback inhibition
Carbohydrates and fats are considered high-energy foods because they __________. - ✔ ✔ Have a lot of electrons associated with hydrogen.
The most important function of fermentation is to: - ✔ ✔ Recycle NADH to NAD+ so that glycolysis can continue
Which of the following statements best describes the relationship between photosynthesis and cellular respiration? - ✔ ✔ Photosynthesis stores energy in complex organic molecules; respiration releases energy from complex organic molecules.
The synthesis of sugar molecules through the process of photosynthesis requires energy absorbed from sunlight. Bearing this in mind, what kind of reaction is photosynthesis? - ✔ ✔ Endergonic
In a plant, the reactions that produce molecular oxygen (O2) take place in ____________. - ✔ ✔ The light reactions alone
Most atmospheric oxygen (O2) comes from photosynthesis. From which of the following molecules is the oxygen derived? - ✔ ✔ Water
Photosynthesis requires light. Why? - ✔ ✔ Light excites electrons in pigments, and these high-energy electrons are used later to reduce CO2, forming sugars
A plant has a unique photosynthetic pigment. The leaves of this plant
appear to be reddish-yellow. What wavelengths of visible light are not being absorbed by this pigment? - ✔ ✔ Red and yellow
In the thylakoid membranes, what is the main role of the pigment
molecules in the light harvesting complex? - ✔ ✔ Absorb photons and transfer light energy to the reaction-center chlorophyll
