plant form and plasticity

Question 1

what are the three main groups of angiosperm (flowering plants)?

Answer 1

1. archaedicotyledenous plants
2. eudicotyledenous plants
3. monocotyledonous plants

Question 2

difference between monocots and eudicots. (3)

Answer 2

1. monocots have one seed leaf and eudicots have two.
2. monocots have parallel leaf veins and eudicots have vein networks.
3. monocot floral organs are in threes and eudicot floral organs are in multiples of 4 and 5.

Question 3

difference between plants and animals (4)

Answer 3

1. animals are mobile, plants are sessile.
2. animals have determinate development, plants have indeterminate.
3. little developmental plasticity in animals, but lots in plants
4. animals aren’t as regenerative as plants

Question 4

what are the three phases of plant development?

Answer 4

1. embryogenic
2. vegetative
3. reproductive

Question 5

what is a meristem?

Answer 5

population of stem cells that renews itself while producing new cells. cells differentiate via asymmetric cell division.

Question 6

what are the 2 primary kinds of meristem?

Answer 6

1. root apical
2. shoot apical

Question 7

2 lateral meristem types.

Answer 7

1. vascular cambium
2. cork cambium

Question 8

what is phyllotaxis and what are 4 examples?

Answer 8

arrangement of leaves around the stem.

1. alternate
2. spiral
3. opposite
4. whorled

Question 9

what is auxin?

where is it produced?

Answer 9

determines new cell/organ fate or growth rate.

produced in shoot apical meristem.

Question 10

what do meristem zones do? three main zones.

Answer 10

CZ - stem cells
PZ - produces organs (leaves and flowers)
RZ - produces vasculature and stems

Question 11

function of layers in meristem

Answer 11

L1 - anticlinal division to produce epidermis
L2 - produces internal tissues
L3 - produces internal tissues and vasculature

Question 12

anticlinal division of meristem.

Answer 12

division is at a right angle to surface.

Question 13

periclinal division of meristem.

Answer 13

division is parallel to surface of meristem.

Question 14

three types of plant tissue

Answer 14

1. epidermis
2. ground tissue
3. vasculature

Question 15

epidermis

Answer 15

outermost cell layer (skin).

Question 16

vasculature (vascular tissue)

Answer 16

xylem and phloem tissue.

structural support and transport of water.

called the vascular bundle when these two are packed together.

Question 17

what is secondary growth and what meristems does it involve?

Answer 17

plants grow older and generate additional cells.

vascular cambium produces more vascular tissue for structural support and transport.

cork cambium provides new protective layers.

Question 18

lenticel

Answer 18

scores on tree bark enabling better gas exchange with outside air.

Question 19

how does vascular cambium generate xylem and phloem?

Answer 19

vascular cambium in vascular bundles is activated and spreads to other bundles.

cylinder of cambium layer gives rise to numerous numbers of xylem and phloem.

Question 20

secondary growth stages of cork cambium

Answer 20

1. cork cambium divides periclinally (parallel to surface)
2. phelloderm cells are produces on the inside of cork cambium and phellem to the outside.
3. epidermis must divide anticlinally to make room for this secondary growth.

Question 21

what is the function of cork cells (phellem)?

Answer 21

impregnated with Suberin (waxy hydrophobic compound) which helps it protect stems and roots from water loss and pathogens.

Question 22

dicot root apical meristem: closed or open?

Answer 22

closed

Question 23

monocot root apical meristem: closed or open?

Answer 23

open

Question 24

layers of root apical meristem starting from the outside.

Answer 24

cortex
–
endodermis
–
pericycle
–
stele

Question 25

root hairs and their function

Answer 25

part of epidermal cell. elongation through tip growth

increases surface area for efficient uptake of water and nutrients.

Question 26

process of root branching.

Answer 26

1. auxin travels to focal point in pericycle.
2. auxin accumulates to an extent that bulging occurs.
3. ground tissue cells die to give way for this.

Question 27

what happens to root production in areas of high nutrients?

Answer 27

more lateral roots are produced. costly process.

Question 28

what promotes production of lateral roots?

Answer 28

• high nutrient content in soil.
• availability of water
• root bending

Question 29

response of deciduous trees to leaning.

Answer 29

tension on outside of lean promotes increase in cellulose.

Question 30

response of conifers to leaning.

Answer 30

compression on inside of lean promotes increase in lignin.

Question 31

photomorphogenesis

Answer 31

light-induced developmental programme.

seedlings growing in the dark do not produce cotyledons.

Question 32

apical dominance

and why it is important

Answer 32

auxin is produced in the shoot apical meristem and inhibits growth of buds. there will be more auxin towards the top to ensure growing slows at top and tree becomes bottom heavy.

heavier branches at bottom make it more steady.

Question 33

importance of plant propagation and tissue culture.

Answer 33

propagation - can make clones of an individual with desired traits.

meristem cultures - allow exclusion of viruses.

Question 34

importance of plant grafting

Answer 34

can create plants with parts of multiple different species. this means desirable traits can be sent form shoot to root via long distance signalling.

Question 35

function of sieve and companion cells

Answer 35

sieve cells don’t have a nuclei so are helped to function by companion cells which do have nuclei, in the phloem.

Question 36

xylem: dead or alive

phloem: dead or alive

Answer 36

xylem: dead

phloem: alive