LIFE 102 EXAM 2

The “fluid mosaic” model of the cell membrane proposes that membranes

Consiste 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

Diffusion

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

Non-polar

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 next a 5M solution of glucose into the cell and then place te 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 bloodstream is hypotonic compared to the stomach

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

Active transport

Which of the following processes includes all the others?

Passive transport

Ions diffuse across membranes through specific ion channels down

Their electrochemical gradients

Metabolic reaction 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 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

Activation energy

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 hot springs prokaryote enzyme?

The optimal temperature for the human enzyme is 40 degrees C. The optimal temperature for the hot springs 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: (picture)

Catabolic; G<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

Aerobic respiration

Which of the listed statements describes the results of the reaction shown below?

C6H12O6 is oxidized and O2 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

Pyruvate

All of the reactions of cellular respiration that occur after glycolysis take place in what part of the eukaryotic cell?

The mitochondria

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?

It is 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

Feedback inhibition

The synthesis of sugar molecules through the process of photosynthesis required energy absorbed from sunlight. bearing this in mind, what kind of reaction is photosynthesis?

Endergonic

Most atmospheric oxygen comes from photosynthesis. From which of the following molecules is the oxygen derived

Water

Where do the carbon atoms in glucose come from

Carbon dioxide

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

Green

What is a photosystem?

A cluster of pigments and proteins that work together to capture light energy

In 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