Cells
Viruses contain genetic material and can evolve, but they cannot reproduce independently and are not made of cells. Based on classical cell theory, how should viruses be classified?
A. Viruses are cells because they contain DNA or RNA
B. Viruses are living cells that simply lack organelles
C. Viruses challenge the definition of life but do not violate the core claim that cells are the basic unit of life
D. Viruses disprove cell theory because they can reproduce
C. Viruses challenge the definition of life but do not violate the core claim that cells are the basic unit of life
A cell's lysosomes suddenly stop functioning. Which observation would you most likely make?
A. The cell would accumulate damaged macromolecules and organelles
B. The cell would stop producing mRNA
C. The cell would be unable to produce ATP
D. The plasma membrane would immediately disappear
A. The cell would accumulate damaged macromolecules and organelles
A scientist determines that one strand of DNA has the sequence:
5′–ATGCCAT–3′
Which sequence represents the complementary strand, written correctly from 5′ → 3′?
A. 5′–TACGGTA–3′
B. 5′–ATGCCAT–3′
C. 5′–TACGGCAT–3′
D. 5′–TAGCCAT–3′
A. 5′–TACGGTA–3′
A small nonpolar molecule needs to cross the plasma membrane. Which property of the membrane allows it to pass relatively easily?
A. The hydrophilic phosphate heads attract the molecule
B. The hydrophobic interior of the bilayer is compatible with nonpolar molecules
C. Membrane proteins actively transport all nonpolar molecules
D. Cholesterol creates pores for nonpolar molecules
B. The hydrophobic interior of the bilayer is compatible with nonpolar molecules
A student dissolves 0.50 moles of glucose in enough water to make a 2.0 L solution.
What is the molarity of the solution?
A. 0.10 M
B. 0.25 M
C. 1.0 M
D. 2.5 M
B. 0.25 M
A student is studying eukaryotic cells and wants to identify which organelles are surrounded by two phospholipid bilayers. What could the organelles be?
Mitochondion, nucelus, chloroplast
A scientist blocks a particular organelle's function. The cell can still produce proteins, but those proteins are not properly modified, sorted, or packaged for their final destinations.
Which organelle was most likely inhibited?
A. Rough ER
B. Golgi apparatus
C. Nucleus
D. Mitochondrion
B. Golgi apparatus
DNA molecule A contains 80% GC base pairs, while DNA molecule B contains 80% AT base pairs.
Which DNA molecule would generally require more energy to separate its two strands?
A. DNA A
B. DNA B
C. Both require the same amount
D. It cannot be predicted from base composition
A. DNA A
Temperature, saturation, and tail length
What are the two types of passive transport?
Simple diffusion, facilitated diffusion
Which observation would provide the strongest evidence for the statement that cells are the basic functional units of life?
A. All cells contain DNA
B. All organisms contain cells
C. Isolated cells can independently perform multiple life processes
D. Cells can be viewed under a microscope
C. Isolated cells can independently perform multiple life processes
A plasma membrane contains phospholipids, cholesterol, proteins, and carbohydrates arranged throughout the membrane.
Why is the membrane described as a "mosaic"?
A. It contains many different components embedded within or attached to the membrane
B. It contains only one type of phospholipid
C. Its proteins are arranged in a repeating pattern
D. Its carbohydrates form the membrane's main structure
A. It contains many different components embedded within or attached to the membrane
3′–TACGGA–5′
What would the complementary strand be?
A. 3′–ATGCCT–5′
B. 5′–ATGCCT–3′
C. 5′–TACGGA–3′
D. 3′–AUGCCU–5′
B. 5′–ATGCCT–3′
A cell produces a protein hormone that needs to be released into the bloodstream.
Which process allows the secretory vesicle to release its contents?
A. Endocytosis
B. Exocytosis
C. Osmosis
D. Simple diffusion
B. Exocytosis
When phospholipids are placed in water, they spontaneously organize into a bilayer. What property of phospholipids primarily causes this?
They are amphipathic, meaning they have both hydrophilic and hydrophobic regions.
A cell is producing large amounts of proteins that will eventually be secreted outside the cell. Which combination of organelles would most likely be especially abundant in this cell?
A. Smooth ER, lysosomes, peroxisomes
B. Rough ER, Golgi apparatus, mitochondria
C. Smooth ER, chloroplasts, lysosomes
D. Nucleus, peroxisomes, chloroplasts
B. Rough ER, Golgi apparatus, mitochondria
Which organelle is **NOT considered part of the endomembrane system?
A. Golgi apparatus
B. Lysosome
C. Endoplasmic reticulum
D. Mitochondrion
D. Mitochondrion
A researcher isolates a molecule containing a phosphate group, deoxyribose sugar, and a nitrogenous base.
What has the researcher most likely isolated?
A. A nucleoside
B. An amino acid
C. A nucleotide
D. A phospholipid
C. A nucleotide
In the classic cell fusion experiment, researchers fused a mouse cell and a human cell and labeled the membrane proteins from each species with different fluorescent markers. Immediately after fusion, the two types of proteins were found on opposite halves of the cell. After incubation at 37°C, the two fluorescent signals became mixed throughout the membrane.
Which conclusion is best supported by this experiment?
A. Membrane proteins are permanently fixed in place after they are inserted into the membrane
B. Membrane proteins move only when the cell uses ATP
C. The phospholipid bilayer is a rigid structure that prevents protein movement
D. Membrane proteins can move laterally within the phospholipid bilayer, demonstrating membrane fluidity
D. Membrane proteins can move laterally within the phospholipid bilayer, demonstrating membrane fluidity
If a solution is at equilibrium, does movement of solute particles occur?
Yes! They still move, but there is no NET movement (diffusion).
A scientist discovers an unknown cell with DNA, ribosomes, a plasma membrane, and a cell wall. Further examination shows that the cell has no nucleus or other membrane-bound organelles.
Which conclusion is best supported?
A. The cell must be a plant cell because it has a cell wall
B. The cell must be an animal cell because it contains ribosomes
C. The cell is eukaryotic because it contains DNA
D. The cell is prokaryotic because it lacks a membrane-bound nucleus
D. The cell is prokaryotic because it lacks a membrane-bound nucleus
A plant is infected by a virus in one leaf cell. The virus is able to move into neighboring cells quickly and easily. Why?
A. Plasmodesmata create direct cytoplasmic connections between neighboring plant cells
B. Viruses can dissolve any cell wall they encounter
C. Plasmodesmata are openings in the nucleus
D. Viruses are produced by the cell wall
Hint: Only plant cells have this
A. Plasmodesmata create direct cytoplasmic connections between neighboring plant cells
In a double-stranded DNA molecule, guanine makes up 28% of all the purines present.
What are the percentages of adenine (A), thymine (T), guanine (G), and cytosine (C) in the entire DNA molecule?
A = 36%, T = 36%, G = 14%, C = 14%
Two cells live in different environments. Cell A lives in a warm environment, while Cell B lives in a very cold environment.
Which cell would you expect to have a higher proportion of unsaturated fatty acids in its membrane?
A. Cell A
B. Cell B
C. Both cells should have the same proportion
D. Neither; saturation does not affect membrane fluidity
B. Cell B
Why are cells small?
To preserve the high surface area:volume ratio and to allow for effective diffusion.