Plant structure and growth

Question 1

secondary growth in woody plants

Answer 1

occurs in stems and roots but rarely in leaves

Secondary plant body consists of tissues produced by the vascular cambium and cork cambium

Question 2

Secondary growth characteristic of

Answer 2

gymnosperms and many eudicots, not monocots

Question 3

Process of secondary growth in woody stem

Answer 3

primary growth from apical meristem nears completion, vascular cambium forms.
Secondary xylem and phloem thicken stem, vascular rays form. Cells external to the cambium can’t divide, so rupture, incl the epidermis. Cork cambium develops from the parenchyma cells

Question 4

vascular rays

Answer 4

radial files of parenchyma connecting secondary xylem & phloem for nutrient & water movement & repair

Question 5

developmental plasticity describes

Answer 5

effect of environment on development (influences expression of genes eg in different parts of the plant)

Question 6

growth

Answer 6

irreversible incr in size

Question 7

morphogenesis

Answer 7

development of body form and organisation

Question 8

what accounts for the incr in plant size during growth

Answer 8

cell expansion not cell division (only incr cell number and potential for growth)

Question 9

New CWs form in what plane

Answer 9

plane perpendicular to main axis of cell expansion

Question 10

When is the plane in which a cell divides determined

Answer 10

late interphase

Question 11

What predicts future plane of cell division

Answer 11

mcrotubules become conc into a ring called preprophase band- predicts future plane

Question 12

leaf growth consists of what 2 types of cell division

Answer 12

tranverse and longitudinal

Question 13

Plane of cell division determines what

Answer 13

leaf form, but leaf shape does not depend solely on precise spatial control of cell division

Question 14

what determine cell fate

Answer 14

symmetry of cell division

distribution of cytoplasm between daughter cells

Question 15

Formation of guard cells

Answer 15

involves asymmetric cell division- key event in development

and change in plane of cell division

Question 16

what do asymmetric cell divisions play a role in establishing

Answer 16

polarity- critical step in plant morphogenesis

Question 17

Polarity

Answer 17

having structural or chemical differences at opposite ends of an organism

Question 18

First division of a plant zygote

Answer 18

asymmetrical and initiates polarisation into the shoot and root

Question 19

how is expansion of plant cells different from animal cells

Answer 19

animal cells mainly grow by synthesising protein rich cytoplasm- metabolically expensive
Plant cells grow rapidly and at lower energy cost by intake and storage of water in vacuoles
Only 10% of plant cell expansion is in cytoplasm
Plant cells expand primarily along the plant’s main axis - shoot and root

Question 20

What causes restricting direction (along main axis) of cell elongation in plants

Answer 20

orientation of cellulose microfibrilis

don’t stretch so cell expands perpendicular to their orientation

Question 21

role of enzymes in cell expansion

Answer 21

weaken cw cross links allowing expansion

Question 22

What is made to maintain expanding CW

Answer 22

more wall microfibrils

Question 23

lineage based hypothesis to explain fate of plant cells

Answer 23

cell fate determined early in development and passed on to progeny cells

Question 24

position based hypothesis

Answer 24

cell fate determined by final position in an emerging organ

Question 25

which is correct

Answer 25

experiments suggest plant cell fate is established late in development and depends on signalling from neighbouring cell

Question 26

cell fate in animals

Answer 26

lineage dependent mostly

Question 27

How can positional info be conveyed

Answer 27

cell to cell communication eg arabidopsis root epidermis forms root hairs or hairless cells depending on number of cortical cells it is touching

Question 28

phase changes

Answer 28

developmental phases plants pass through going from juvenile phase to adult vegetative phase to adult reproductive, phase,

Question 29

phase changes in animals

Answer 29

affect morphology of organism

Question 30

phase changes in plants

Answer 30

occur only in shoot apical meristem

most obvious morphological changes are in leaf size and shape

Question 31

flower formation

Answer 31

involves phase change from vegetative to reproductive growth

Question 32

flowering triggered by combo of

Answer 32

environmental cues eg day length and internal signals eg hormones

Question 33

transition from vegetative growth to flowering associated with

Answer 33

switching on of floral meristem identity genes

Question 34

difference between vegetative and floral growth

Answer 34

floral growth determinate

Question 35

MADS box genes

Answer 35

organ identity genes that regulate development of floral pattern

Question 36

abnormal floral development

Answer 36

mutation in plant organ identity gene

Question 37

3 classes of floral organ identity genes encoding MADS box transcription factors

Answer 37

A, B and C genes

regulate expression of other genes responsible for development of se, pe, sta, ca

Question 38

sepals

Answer 38

A

Question 39

Pe

Answer 39

A and B

Question 40

STa

Answer 40

B and C

Question 41

CA

Answer 41

C