AP BIO Unit 2

Which of the following is mot likely true of a protein that cotransports glucose & sodium ions into the intestinal cells of an animal?

A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose.

In the first step of an experiment, rat liver cells were exposed for 5 minutes to amino acids labeled with a radioactive isotope. The cells were then washed to stop any further incorporation of radioactive amino acids. The cells were sampled periodically thereafter, and the radioactivity of a certain protein (protein X) was measured in various cell components, as shown below. What is the most likely identity of protein X.

An enzyme that participates in the degradation and recycling of cell components

Two different models of a living cell are reprsented in the figure bellow:

Cell A, because it has the larger surface-area-to-volume ratio

Aquaporins are channel proteins that facilitate the transport of water across the cell membrane. One group of researchers hypothesizes that without functional aquaporins, no water will be able to enter the cell. A different group proposes an alternative hypothesis, stating that even with nonfunctional aquaporins, a small amount of water will still cross the cell membrane. An experiment is set up in which plant cells with mutated (nonfunctional) aquaporins and plant cells with normally functioning aquaporins are both placed in distilled water. What type of data would support an alternative hypothesis?

Cells with mutated aquaporins exhibit moderate turgor pressure and are hypertonic.

All eukaryotic cells contain at least one Golgi complex, typically located in the cytoplasm and near the endoplasmic reticulum. Which of the following best describes a process that occurs within the Golgi complex?

Enzymatic modification of newly synthesized integral membrane proteins

Changing the shape or morphology of the mitochondrial inner membrane can change the efficiency of mitochondrial function. What is an outcome that will most likely result from a change in the shape of the mitochondrial inner membrane from a highly folded surface to a smooth, flat surface?

Mitochondria will become less efficient because the surface area of the inner mitochondrial membranes will decrease.

Which of the following statements about passive transport is correct?

Passive transport involves movement of solute in both directions across a membrane, but with a net movement of solute down its concentration gradient.

The figure above represents a rough ER. Which of the following best describes the role of the structure labeled Y?

Structure Y is the location where proteins are synthesized

You have isolated a cell that is unable to produce cholesterol for its cell membranes. What are some of the defects this cell most likely to has?

The cell membrane will not have the correct fluidity

Individuals with an inherited autosomal recessive disorder called primary ciliary dyskinesia (PCD) often have sever respiratory problems due defective cilia. Males with PCD are often sterile because they produce sperm with defective flagella. What explains the effect of the recessive allele?

The cells do not produce functional motor proteins in flagella & cilia.

Which of the is a reasonable explanation for why unsaturated fatty acids help keep any membrane more fluid at lower temp

The double bonds form kinks in fatty acid tails that prevent adjacent lipids from packing tightly

It seems that bacteria & molds should grow well in jam. It is extremely high in sugar, a substance many cells can use for energy, & contains enough nutrients to support cell growth. Yet jam can be left unrefrigerated for a very long time without contamination by microorganism. How can this be?

The high sugar concentration causes bacterial and mold cells to shrink and die

Researchers claimed that a particular organelle originated from a free-living prokaryotic cell that was engulfed by a larger cell, as shown in the figure below. Which of the follwoing provides evidence to best support th researchers' claim

The organelle has a double membrane

The diagram above represents a typical rod-shaped bacterium. Which of the following best describes a feature shown in the diagram that is unique to archaea and bacteria?

The organism does not have a nuclear membrane surrounding its genetic material.

Why are lipids and proteins free to move laterally in membranes?

There are weak hydrophobic interactions in the interior of the membrane

Which of the following best describes how the three structures indicated by the arrows work together?

To synthesize and isolate proteins for secretion or for use in the cell

The concentration of solutes in a particular cell is about 2%, but the cell contains almost no sucrose or urea. Sucrose cannot pass through the membrane of this cell, but water and urea can. Osmosis would cause this cell to shrink the most when immersed in which of the following solutions?

a hypotonic urea solution

Yeast cells take up glucose (a sugar) to use as their primary source of energy. Typically, glucose concentrations outside yeast cells are far lower than glucose concentrations inside the cells. Therefore, for yeast to take up glucose, the cells must use:

active transport to move glucose up (against) its concentration gradient

Insulin and many other hormones are protein molecules. Based on your knowledge of transport processes, you can say that cells that secrete these types of hormones do so through:

exocytosis

Which type of proteins are involved in nutrient transport across the plasma membrane & why?

integral proteins because they span the membrane & are able to carry nutrients

The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCI), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same. At the beginning of the experiment, side A

is hypotonic to side B

Cytochalasin D is a drug that prevents actin polymerization. A cell treated with cytochalasinD will still be able to

move vesicles within the cell

Which of the following membranes activities requieres energy from ATP hydrolysis?

movement of sodium ions from a lower concentration in a mammalian cell to a higher concentration in the extra cellular fluid

In receptor-mediated endocytosis, receptor molecules are initially localized on the outer surface of the plasma membrane. Where do the receptors end up following endocytosis?

on the inside surface of the vesicle

The total volume of plant cells is often significantly greater than the total volume in animal cells. By reason:

plant cells contain large vacuole that occupies much of volume of the cells

Which of the following would increase the electrochemical gradient across a membrane?

proton pump

Submerging a plant cell in distilled water will result in

the cell becoming turgid