Study sets, textbooks, questions
Upgrade to remove ads
LIFE102 Exam 2
Terms in this set (68)
The "fluid mosaic" model of the cell membrane proposes that membranes _____________.
Consist of protein molecules embedded in a fluid bilayer of phospholipids
The movement of molecules from a region of higher concentration to a region of lower concentration is called ____________.
Which of the following most accurately describes selective permeability?
Only certain molecules can pass through the cell membrane
The part of a membrane protein that extends through the phospholipid bilayer is primarily composed of amino acids that are __________.
Certain molecules/atoms can diffuse directly through the phospholipid bilayer of a membrane (without the help of a transport protein). Which of the following types of molecules will diffuse most-easily directly through a membrane?
Small and hydrophobic
A scientist performs an experiment in which they create an artificial cell with a selectively permeable membrane through which only water can pass. They inject a 5M solution of glucose into the cell and then place the cell into a beaker containing 10M glucose. What effect do you expect to observe?
water moves out of the cell
A dehydrated runner drinks a lot of water after a race. They rehydrate because __________.
the stomach is hypotonic compared to the bloodstream
A type of transport of a solute across a membrane, up its concentration gradient, using protein carriers driven by the expenditure of chemical energy is known as __________.
Which of the following processes includes all the others?
Ions diffuse across membranes through specific ion channels down ___________.
Their electrochemical gradients
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.
You eat a bowl of beans as part of your dinner. As you digest the beans, the proteins that are present get broken down to their component amino acids. As your body destroys the macromolecules that were present in the beans, is the energy present in those molecules destroyed?
No. The energy contained within these macromolecules is converted into other forms of chemical energy and kinetic energy, though some is lost as heat.
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.
Which of the following is not true of enzymes?
Enzymes provide extra activation energy for the reaction they catalyze.
The energy needed to destabilize existing chemical bonds and start a chemical reaction is called __________.
The lock-and-key analogy for enzymes applies to the specificity of enzymes _____________.
Binding to their substrate
Based on the graph, what are the optimal temperatures for the human enzyme and hotsprings prokaryote enzyme?
The optimal temperature for the human enzyme is 40 degrees C. The optimal temperature for the hotsprings prokaryote enzyme is 72 degrees C.
How does a non-competitive inhibitor decrease the rate of an enzyme reaction?
By changing the shape of the enzyme's active site
Characterize this reaction: Glucose + O2 → CO2 + H2O + energy
Catabolic; ΔG < 0; Exergonic; NADH intermediate; ATP is produced
In animals that take in oxygen from their environment, glucose is broken down into carbon dioxide and water in a process called __________.
Which of the listed statements describes the results of the reaction shown below? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy
C6H12O6 is oxidized and 02 is reduced.
Your friend is having difficulty keeping track of the energy flow from glucose through glycolysis, the Krebs cycle and electron transport. Your best advice would be to __________.
Follow the electrons
In glycolysis, a major portion of the energy remains in the final product, which is called __________.
All of the reactions of cellular respiration that occur after glycolysis take place in what part of the eukaryotic cell?
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 H+ ions against their concentration gradient
What happens to the oxygen that is used in aerobic respiration?
reduced to form water
During aerobic respiration, electrons travel "downhill" in which sequence?
Glucose → NADH → Electron Transport Chain → Oxygen
The oxygen (O2) consumed during cellular respiration is involved directly in which process or event?
Accepting electrons at the end of the electron transport chain
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 ___________.
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?
Most atmospheric oxygen comes from photosynthesis. From which of the following molecules is the oxygen derived?
Where do the carbon atoms in glucose come from?
The Calvin cycle of a plant exposed to light during the day that is suddenly put in the dark __________.
can still run as long as there is ATP, CO2, and NADPH present
What color of light is not strongly absorbed by chlorophyll?
What is a photosystem?
A cluster of pigments and proteins that work together to capture light energy
n the thylakoid membranes, what is the main role of the pigment molecules in the light harvesting complexes?
Absorb photons and transfer light energy to the reaction-center chlorophylls
NADPH is made by __________.
the passing of electrons from photosystem I to an electron transport chain
Photosynthetic reactions that require the input of CO2 occur in:
The Calvin cycle alone
Which of the following does NOT occur during the Calvin cycle?
Release of oxygen
Which of the following types of molecules are the major structural components of the cell membrane?
Phospholipids and proteins
The presence of cholesterol in the plasma membranes of some animals _____________.
Enables the membrane to stay fluid more easily when cell temperature drops
Which of the following is true of osmosis?
In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.
Celery stalks that are immersed in fresh water for several hours become stiff. Celery stalks that are immersed in a 0.15 M salt solution become limp. From this we can deduce that the fresh water ____________________.
is hypotonic and the salt solution is hypertonic to the cells of the celery stalks
You measure the uptake of a compound into cells and find that in the presence of ATP there is uptake, but in the absence of ATP there is not. What is the best explanation?
This compound is taken up by active transport
The voltage across a membrane is called the ________________.
White blood cells of your immune system engulf bacteria using __________________.
What is the term for metabolic pathways that release stored energy by breaking down complex molecules?
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
Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as __________ is to __________.
How do enzymes speed up chemical reactions in cells?
Enzymes lower the activation energy barrier of reactions
The active site of an enzyme is the region that ________
By binding at the active site of the enzyme
Iron is found in the active site of many functional enzymes. The iron most likely functions as a(n)
Cofactor necessary for enzyme activity
When a molecule of NAD+ gains an electron as part of a redox reaction, it becomes
n addition to ATP, what are the end products of glycolysis?
NADH and pyruvate
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 _________.
The electron transport chain ___________.
s a series of redox reactions
You have a friend who lost 7 kg (about 15 pounds) of fat on a regimen of strict diet and exercise. How did the fat leave his body?
It was released as CO2 and H2O.
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.
When oxygen (O2) is released as a result of photosynthesis, it is a by-product of which of the following?
Splitting of water molecules
In a plant, the reactions that produce molecular oxygen (O2) take place in ____________.
The light reactions alone
Photosynthesis requires light. Why?
Light excites electrons in pigments, and these high-energy electrons are used later to reduce CO2, forming sugars
Why are certain plants green?
They absorb mainly blue and red wavelengths of light, but reflect the green wavelengths of light
The electrons of photosystem II are excited and transferred to electron carriers. From which molecule or structure do the photosystem II replacement electrons come?
Which two molecules are the products of the light reactions, and where do they go?
NADPH and ATP; they go to the Calvin cycle
What happens in the Calvin cycle of photosynthesis?
CO2 is fixed and glyceraldehyde-3-phosphate (G3P) is made, using NADPH and ATP
Both cellular respiration and photosynthesis make use of a hydrogen ion gradient created by an electron transport chain to produce __
Other sets by this creator
LIFE103 Section 4 Info. (Arthur)
LIFE103 Final Exam (Fischer and Arthun)
LIFE102 Exam 5
LIfe102 Exam 4
Other Quizlet sets
Ch.8 Practice Questions - MKT 5800
CH 16 learnsmart