lecture four

Question 1

what is the shoot apical meristem?

Answer 1

small mass (dome) of undifferentiated cells capable of rapid cell division to produce new cells for the primary growth of the stem

Question 2

what is the root apical meristem?

Answer 2

small mass (upside down dome) of undifferentiated cells capable of rapid cell division to produce new cells for the primary growth of the root

Question 3

what is plant growth dependent on?

Answer 3

the presence of embryonic meristematic tissue

Question 4

what do meristems house a collection of?

Answer 4

initials: actively dividing cells that maintain the meristem as a continuing source of new cells
derivatives: undifferentiated cells of the meristem that arise from division of initials

Question 5

what is the tunica?

Answer 5

the outermost layer(s) of SAM; undergoes surface growth by anticlinal cell divisions (in planes perpendicular to the meristem surface)

Question 6

what is the corpus?

Answer 6

the interior layers of SAM, beneath the tunica; undergoes volume growth by cell division in all planes

Question 7

what is the defining difference between initials and derivatives?

Answer 7

initials stay meristematic while derivatives leave to enter differentiation

Question 8

what are the SAM zones?

Answer 8

central zone: contains pluripotent, undifferentiated cells that divide infrequently
peripheral zone: surrounds the central zone and is mitotically active
primordia: buds/outgrowths from the SAM that form new organs

Question 9

what are the functions of the root cap?

Answer 9

• protects RAM
• sheds and secretes mucilage to lubricate root movement
• senses gravity

Question 10

what is the quiescent centre?

Answer 10

a rarely dividing pool of stem cells within the RAM. maintains the initials

Question 11

intercalary meristem

Answer 11

• located at base of internodes and is unique to monocots
• enables rapid growth in height of bamboo (internode elongation)
• enables regrowth of grass removed by grazing or mowing