TLS Online TPP Program

#Question id: 7154


Cancer is believed to often arise from stem cells, rather than fully differentiated cells. Which of the following are consistent with this view?

#Unit 5. Developmental Biology
  1. Stem cells are actively dividing and express few differentiated functions, so they may have fewer changes to undergo than do fully differentiated cells in becoming cancer cells.
  2. DNA replication is necessary for mutations to occur, and stem cells are replicating their DNA whereas differentiated cells are for the most part not replicating their DNA.
  3. Teratocarcinomas are tumors that arise from germ cells or embryonic stem (ES) cells, under certain circumstances, demonstrating that tumors can arise from stem cells without further mutation.
  4. All of the above are reasons that cancer cells may more readily arise from stem cells than from fully differentiated cells.
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TLS Online TPP Program

#Question id: 2524

#Unit 2. Cellular Organization

Which cytoplasmic fibrils are most like the nuclear lamins?

TLS Online TPP Program

#Question id: 2525

#Unit 2. Cellular Organization

What kind of molecules must pass between the nucleus and the cytoplasm?

TLS Online TPP Program

#Question id: 2526

#Unit 2. Cellular Organization

cell walls essential and are important features of plant cells that perform a number of essential functions. Which of the following is not the characteristics of cell wall?

TLS Online TPP Program

#Question id: 2527

#Unit 2. Cellular Organization

Transpirational water flow in the xylem requires a mechanically strong wall that resists from,

TLS Online TPP Program

#Question id: 2528

#Unit 2. Cellular Organization

Cell walls of prokaryotes, fungi, algae, and plants differ from each other in chemical composition and molecular structure, yet they all serve three common functions:

a) regulating cell volume

b) determining cell shape

c) mechanically protecting the delicate protoplast against biochemical and physical assaults

d) used to make synthetic fibers

Which of the following common functions is correct?

TLS Online TPP Program

#Question id: 2529

#Unit 2. Cellular Organization

Cell walls commonly are classified into two major types. This classification is based not on structural or biochemical differences;

A) primary walls and

B) secondary walls

i) walls formed during cell growth

ii) walls that are formed after cell enlargement stops

iii) multilayered walls that are strengthened and waterproofed by lignin

iv) Usually they are thin and simple, but some times may be thick and multilayered, such as those found in collenchyma or in the epidermis

v) highly specialized in structure and composition, reflecting the differentiated state of the cell

Which of the following is the correctly represents features of primary and secondary walls?