Problem Set #4- Cells & Membranes

Question 1

What do animal cells have to the exclusion of plant cells?

Answer 1

Centrioles

For the love of all things remember: only eukaryotes have mitochondria…and since plants are eukaryotes, they definitely have mitochondria.

Question 2

Which of the following characteristic is NOT shared by bacteria and archaea?

Answer 2

Identical cell wall composition

Bacteria and archaea are both prokaryotes. Therefore they don’t have a nuclear membrane nor mitochondria. The both have ribosomes and a plasma membrane however. Therefore the answer is cell wall composition. They differ, markedly in their cell wall compositions.

Question 3

The basis for dividing the prokaryotes into two domains (bacteria and archaea) is:

Answer 3

differences in genome sequences.

DNA sequencing capabilities allowed us to see that the genomes of bacteria are VASTLY different than archaea.

Also, remember, prokaryotes don’t have mitochondria. At all.

Question 4

Which of the following distinguishes an eukaryotic cell from a prokaryotic cell?

Answer 4

the presence or absence of mitochondria.

Prokaryotes do not have mitochondria. Stop. I am not sure who told you they do, but they absolutely do not. Mitochondria are exclusively, and always, found in eukaryotes.

Question 5

Lysosome

Answer 5

contain digestive enzymes and rid cells of waste products

Question 6

Nucleus

Answer 6

serves as the reporsitory of genetic information

headquaters

Question 7

Mitochondria

Answer 7

site of oxidative phosphorylation and the formation of ATP

Question 8

Peroxisome

Answer 8

major regulator in oxidation of biomolecules, metabolism, and signaling pathways

Question 9

Vacuole

Answer 9

large storage unit that is used to sequester waste and/or hold bulk amounts of water

Question 10

Golgi Apparatus

Answer 10

process and sort proteins from the ER and transport them to their appropriate destination

Question 11

The nerve cell that extends from the big toe to the base of the spine can be one meter (1 m) long. A typical bacterial cell is one micrometer (1 um) long. Therefore, the nerve cell is __________ times longer than the bacterial cell.

Answer 11

1,000,000

You just have to convert meters to MICROmeters (not millimeters). This is a million fold difference.

I asked this question as it pertains to cells (our current topic) but more importantly to keep up your math/conversion skills.

Question 12

Which of the following DOES NOT support the endosymbiotic theory?

**This question is not asking which statement is false, rather which statement does NOT support this theory. Meaning, the correct answer may be factual, but that doesn’t mean it supports the theory.

Answer 12

Chloroplasts and mitochondria make new cells via mitosis.

CP and MT make new cells via binary fission, not mitosis.

Question 13

As you were taking lettuce in the grocery store, you were surprised when water sprinklers suddenly went on, spraying fresh water (fresh = pure) on the produce. When you got back home, you immersed the lettuce in a salt-water solution, and within several minutes they became limp and soft. What are the explanations for the spraying procedure in the store verses your observation at home?

Again, I would draw this out. Make sure you are comparing the lettuce cells to the fresh water and the lettuce cells to the salt water. Follow the direction of the water movement!”

Answer 13

Lettuce cells are hypertonic to fresh water making them turgid and fresh-looking; however, the lettuce cells are hypotonic to the salt solution, hence plasmolyzed.

Question 14

Which of the following does NOT describe a biological membrane?

Answer 14

Biological membranes are rigid and have a permanent structure.

Question 15

Five dialysis bags, constructed of a type of membrane that is permeable to water and impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6M sucrose solution. At 10-minute intervals, the bags were weighed, and the percent change in mass of each bag was graphed.

Which line in the graph represents the bag with the lowest initial concentration of sucrose?

This is a hard question and you will almost definitely see something similar to this on your exam. Draw this out.

Answer 15

Bag E

The dialysis bags are the cells in this picture below (the brown quarter circles). The blue solution is the solution in your beaker.

If the dialysis bag is less than 0.6M, then that bag is HYPO tonic and the solution is HYPER tonic. That means water will rush out of the bag and it will shrink. The bag that shrinks the most, should have the lowest initial concentration. This is bag E.

Question 16

On the basis of energy requirement, which does NOT belong to the group?

Answer 16

An electrogenic pump, like the proton pump used in ATP hydrolysis.

Question 17

Of the following cell components, which group comprises the endomembrane system?

Answer 17

Vesicles, golgi apparatus, endoplasmic reticulum (ER).

Question 18

A patient experienced great blood loss. In an attempt to quickly replenish body fluids, a volume of pure water (as opposed to the saline solution that was supposed to be used) was introduced to the patient. What is the most likely result of this treatment? - Aside from death, which is ultimately the most likely end result.

Answer 18

The red blood cells are in danger of bursting because they were subjected to a hypotonic environment.

Always compare the two things in question. If you put a drop of dead sea salty water into your less salty blood cells, water will yeet itself out of your blood and into the salt water solution.

Question 19

Arrange the following molecules according to rate of diffusion across a lipid bilayer without the aid of any membrane protein: sucrose, Na+, CO2, H2O. (From easiest to get through to hardest to get through).

Answer 19

O2 -> H20 -> glucose -> Ca2+

Question 20

Which molecule(s) are important in regulating cell membrane fluidity? Select all that apply.

Answer 20

Cholesterol
Phospholipid tails (fatty acids)

Question 21

Which correctly describes the regions of the phospholipid bilayer?

Answer 21

Fatty acids tails are hydrophobic; phosphate heads are hydrophilic.

Question 22

What distinguishes amphipathic lipids from other lipids?

Answer 22

Amphipathic lipids have hydrophilic and hydrophobic regions.

Question 23

Aquaporins are special water channels that allow the bulk transport of water across the hydrophobic plasma membrane. Which of the following is NOT true about them:

Answer 23

they require the use of ATP to function.

Question 24

Match the type of endocytosis to its main features or examples.

Answer 24

Phagocytosis-An amoeba eating a bacterium
Pinocytosis-Often seen in the kidney cells during the formation of urine
Receptor-mediated endocytosis-Cholesterol or hormone uptake/transport.

Question 25

According to the fluid mosaic model of cell membranes, phospholipids _______________.

Answer 25

can move laterally along the plane of the membrane

Question 26

The figure shown above depicts the movement of a substance across a cell membrane. The best way to describe what is occurring in the figure would be

Answer 26

active transport

Question 27

The membranes of winter wheat are able to remain fluid when it is extremely cold by _________________.

Answer 27

increasing the proportion of unsaturated phospholipids in the membrane

Question 28

What type of molecules will require the greatest amount of effort/help to pass through a cell membrane?

Answer 28

large and polar

Question 29

Which of the following is NOT an example of facilitated diffusion?

Answer 29

movement via an electrogenic pump

Question 30

movement via an electrogenic pump

Answer 30

sodium ions out of the cell and potassium ions into the cell