Properties of Water
Cohesion and adhesion are two major properties of water that are primarily due to this type of bond between water molecules.
Hydrogen Bonds
This is a special class of lipid that contains two fatty acid tails and one negatively charged phosphate head. These lipids make up the cellular membrane.
Phospholipids
Ribosomes
The movement of molecules from an area of higher concentration to an area of lower concentration is called this.
Diffusion
Which of the following is an example of an inorganic molecule found in the body?
A. Carbon
B. Water
C. Glucose
B. Water
Water is known as a polar molecule, which allows for the intermolecular attraction between water molecules. What makes water a polar molecule?
The hydrogen atoms have a slight positive charge and the oxygen atom has a slight negative charge.
Amino Acids are the building blocks of proteins. Which of the following is NOT a part of a typical amino acid?
A. Carboxyl Group
B. Amino Group
C. Glycosidic Group
D. R-Group
C. Glycosidic Group
These organelles carry digestive enzymes that are used to break down old and worn-out organelles, debris, and large ingested particles.
Lysosomes
The pressure potential of a plant cell is 2 bars and its solute potential is -3.5 bars. What is the resulting water potential of the plant cell?
-1.5 bars
The pH of human blood cells is about 7.5. However, the pH of the lumen of the stomach is about 1.5. Which one is more acidic: the blood cells or the lumen of the stomach? AND, what is the difference in acidity between the two in terms of H+ ions?
The lumen of the stomach is more acidic and contains 1,000,000-fold more H+ ions than the blood cells.
Water is a critical component of life due to its unique structural and chemical properties. Which of the following does NOT describe how the properties of water are used in nature to sustain life?
A. The high heat capacity of water prevents lakes and streams from rapidly changing temperature or from freezing solid in the winter.
B. The intermolecular forces between water molecules result in a boiling point that exceeds the tolerance of most life on the planet.
C. The low polarity of water molecules prevents it from acting as a solvent in cells.
C. The low polarity of water molecules prevents it from acting as a solvent in cells.
What are the structural differences between saturated and unsaturated fats?
Unsaturated fats have a double bond between at least two carbons in the fatty acid tails while saturated fats have only single-bonded carbons.
Vibrio cholerae are highly pathogenic bacteria that are associated with severe gastrointestinal issues. Antibiotics can be prescribed to target crucial bacterial structures that are absent in animal cells. Which of the following structures is most likely to be targeted by the antibiotics?
A. Cytoplasm
B. Cell wall
C. Plasma membrane
D. Ribosomes
B. Cell wall
Which of the following represents an example of active transport of a substance into a cell?
A. The sodium-potassium pump, which restores the resting membrane potential of a neuron using ATP.
B. Diffusion of oxygen into red blood cells in the alveolar capillaries of the lungs.
C. Influx of sodium ions through a voltage-gated ion channel in a neuron during an action potential.
A. The sodium-potassium pump, which restores the resting membrane potential of a neuron using ATP.
In animal cells, which of the following represents an accurate pathway a secreted protein would take?
A. Ribosome -> Golgi Apparatus -> Rough ER -> Secretory Vesicle -> Plasma Membrane
B. Plasma Membrane -> Rough ER -> Golgi Apparatus -> Secretory Vesicle -> Ribosome
C. Ribosome -> Rough ER -> Golgi Apparatus -> Secretory Vesicle -> Plasma Membrane
C. Ribosome -> Rough ER -> Golgi Apparatus -> Secretory Vesicle -> Plasma Membrane
Water molecules experience intermolecular forces when interacting with each other. Which of the following would most likely occur if water became a nonpolar molecule?
A. Solid water would be more dense than liquid water, so ice would no longer float.
B. The melting and boiling points of water would increase.
C. The amount of liquid water on the planet would increase, and the amount of water vapor in the air would decrease.
D. Polar solutes would dissolve in water forming aqueous solutions of various concentrations.
A. Solid water would be more dense than liquid water, so ice would no longer float.
Sugars are a type of carbohydrate that are generally comprised of hydrogen, carbon, and oxygen. Which of the following best explains how carbohydrates function as a stored form of energy?
A. Excess glucose is stored as glycogen in muscles and the liver.
B. Glucagon is a hormone that stores excess energy in the pancreas.
C. Sucrose is hydrolyzed during photosynthesis to act as an energy source.
A. Excess glucose is stored as glycogen in muscles and the liver.
Membrane-bound organelles are an integral part of the evolution of multicellular organisms. Which of the following best describes the advantage of eukaryotic cells having internal membranes?
A. Eukaryotic cells can reproduce faster due to the presence of organelles.
B. Organelles like mitochondria and chloroplasts are similar to prokaryotic cells in structure.
C. Organelles isolate specific reactions, which increases metabolic efficiency.
D. Compartmentalization leads to higher mutation rates, which, in turn, leads to more new species.
C. Organelles isolate specific reactions, which increases metabolic efficiency.
An animal cell that is permeable to water but not salts has an internal NaCl concentration of 10%. If placed in freshwater, the cell will do which of the following?
A. Plasmolyze
B. Swell and eventually lyse
C. Endocytose water into a large vacuole
D. Shrivel
B. Swell and eventually lyse
Estrogen is a lipid-soluble hormone that is secreted from the ovaries and travels through the body via the bloodstream. A researcher wanted to study the effects of reduced estrogen levels in order to determine the response of decreased estrogen on the organism. Which of the following experiments could the researcher perform in order to study the effects of reduced estrogen levels?
A. Remove the ovaries of the organism
B. Treat with a lipid-soluble noncompetitive inhibitor that specifically reduces estrogen binding to the intracellular receptor
C. Treat with lipid-soluble testosterone
D. Treat with a competitive inhibitor that blocks all receptors on the plasma membrane
B. Treat with a lipid-soluble noncompetitive inhibitor that specifically reduces estrogen binding to the intracellular receptor
This form of diffusion ensures that cells have enough water, but not too much water, and that organisms are properly hydrated. An example of this process is salt causing thirst when the salt concentration in food is too high.
Osmosis
A culture of Spirogyra (an autotrophic alga) is maintained in a water solution containing dissolved carbon dioxide and a source of phosphates but lacking nitrogen compounds. A researcher determines the rates of synthesis of several organic compounds found in the Spirogyra before and after several weeks in the water solution. Which of the following graphs best illustrates a likely result of the experiment?
Graph B
A new unicellular organism has been identified in one of the thermal pools in Yellowstone National Park. Under a light microscope, researchers identified the following structures: plasma membrane, thick cell wall, no mitochondria, many ribosomes, and a long flagella. Which of the following terms would best classify this new organism?
A. Algae
B. Protozoa
C. Bacteria
D. Fungi
C. Bacteria
The water potential of a root cell was found to be -3.1 bars. If the root cell was placed in an open beaker with a 0.1 M sucrose solution at 20 degrees Celsius. What is the water potential of the solution, AND in which direction would the net flow of water be?
The water potential is about -2.43 bars. Water will flow into the root cells because free water always moves towards the lower overall water potential.
Which of the following correctly illustrates a dipeptide and an amino acid in the optimal position to form a tripeptide?
Figure A