BIOB50 ECOLOGY UTSC Final Exam Practise Questions

BIOB50 ECOLOGY 

UTSC

Final Exam Practise Questions

All chapters covered. 

Which of the following is a usual component found in the chloroplast stroma?

a) tRNAs

b) eukaryotic-like ribosomes

c) circular DNA

d) Both tRNAs and circular DNA

Where are the enzymes that synthesize carbohydrates located?

a) the surface of the grana

b) the stroma

c) the thylakoid lumen

d) the inner chloroplast membrane

You are growing algae in culture and expose them to H₂O that contains radiolabeled oxygen.  Where does the radiolabeled oxygen end up after photosynthesis?

a) water (H₂O)

b) gaseous oxygen (O₂)

c) carbon dioxide (CO₂)

d) carbohydrates

The smooth endoplasmic reticulum is responsible for all of the following EXCEPT:

a) protein modifications

b) sequestering calcium ions.

c) synthesis of steroid hormones.

d) detoxification in the liver.

With what structure is the outer membrane of the nuclear envelope continuous?

a) RER

b) SER

c) Golgi complex

d) the plasma membrane

Which of the traits below is characteristic of the classical nuclear localization signals?

a) possession of large numbers of hydrophobic amino acids

b) possession of one or two short stretches of negatively charged amino acids

c) possession of one or two short stretches of positively charged amino acids

d)  twisted backbones

If the FRAP technique is used to bleach a small zone of fluorescent microtubules in a cell, which of the following is a possible explanation for the recovery of fluorescence in the region of the cell previously bleached?

a) the dynamics of the microtubules turning over in that bleached zone of the cell

b) the growth of new microtubules into the bleached zone

c) movement of microtubules through the bleached zone

d) all of these choices

e) both (a) and (b)

To which end of microtubules are tubulin subunits primarily added in vitro?

a) the minus end

b) the N-terminal end

c) the plus end

d) the C-terminal end

e) the 5'-end

Given that axons grow out through the action of microtubules, what should happen to axons growing out from a neuron when they are exposed to colchicine or nocodazole?

a) Axons grow more rapidly.

b) Axonal outgrowth stops. 

c) Axonal outgrowth slows. 

d) There is no change in axonal outgrowth.

Structures that move from the cell body of a neuron down the axon toward the neuron terminals are said to move in a(n) _________ direction.

a) retrograde

b) anterograde

c) astronomical

d) radial

e) intergrade

What is the direct source of energy that powers molecular motors?

a) hydrolysis of GTP

b) hydrolysis of ATP

c) proton gradient

d) H⁺ gradient

e) condensation of ATP

Why are taxol, vinblastine and other drugs like them used as chemotherapy agents?

a) They preferentially kill tumor cells.

b) They preferentially stabilize tumor cells.

c) They disrupt tumor cell membranes.

d) They prevent entry of cells into the stage of meiosis.

e) They inhibit mitochondria.

A shift in the concentration or activity of which type of proteins can cause a shift in the equilibrium between actin monomers and polymers?

a) nucleating proteins

b) monomer-sequestering proteins

c) endolysins

d) capping proteins

The molecular motors of the _______ superfamily are the only ones known to operate in conjunction with actin filaments.  With one exception, these molecular motors move toward the _____end of an actin filament.

a) dynein, minus

b) myosin, plus

c) myosin, minus

d) thymosin, plus

Researchers immobilize isolated myosin heads (S1 fragments) on a glass cover slip.  The myosin heads cause the actin microfilaments to slide across the cover slips.  What conclusion can be drawn from these results?

a) Myosins are activated by glass.

b) A single head domain has all the machinery needed for motor activity.

c) The myosin tail is responsible for moving the microfilaments.

d) Myosin is a GTPase.

What happens immediately after ATP binds to a myosin head during muscle contraction?

a) ATP binding induces cross-bridge formation with the actin filament.

b) ATP binding induces cross-bridge dissociation from the actin filament.

c) ATP binding induces cross-bridge formation with other myosin filaments.

d) GTP binding induces cross-bridge dissociation from the actin filament.

Intermediate filaments are described as having a central, rod-shaped domain flanked on each side by globular domains of variable size and sequence.  What structure forms the core of the central, rod-shaped domain?

a) alpha-helix

b) beta-pleated sheet

c) double helix

d) quaternary coil

Which of the following molecular motors is associated with intermediate filaments?

a) kinesins

b) dyneins

c) myosins

d) None of these choices is correct.

Which of the following statements about integrins is true?

a) They anchor cells to the substrate.

b) They are found in both animal and plant cells.

c) Different cell types are restricted to just one type of integrin.

d) All of these statements are true.

Why do cells flatten out as they make contact with a surface?

a) They lose water.

b) They extrude cytoplasm.

c) They send out projections that make increasingly stable attachments.

d) Their membranes stiffen.

The tightest attachment between a cell and its extracellular matrix is seen at the site where an epithelial cell is attached to the underlying basement membrane. The specialized adhesive structure found at such a site is called a(n) ________.

a) tight junction

b) spot desmosome

c) plasmodesma

d) hemidesmosome

________ are members of an integral membrane glycoprotein family that bind to specific sugar arrangements in oligosaccharides that project from the surfaces of other cells.

a) Selectins

b) Integrins

c) Immunoglobulin super family proteins

d) Cadherins

You are studying an animal and inject fluorescein, a fluorescent dye, into a single cell on the surface epithelium of the animal.  After a brief period of time, the dye spreads to cells neighboring the injected cell.  What do you conclude?

a) The cells are connected by zonulae adherens.

b) The cells are connected by tight junctions.

c) The cells are connected by gap junctions.

d) The cells are connected by plasmodesmata.

What forms the barrier of the tight junctions that seals off the space between adjacent cells?

a) paired rows of aligned integral membrane proteins

b) paired rows of aligned phospholipids

c) paired rows of carbohydrates

d) interdigitating integral membrane proteins