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CHAPTER 4 :
REPRODUCTION & GROWTH
4.6 Growth In MulticellularOrganisms
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LEARNING OUTCOMES
To explain briefy the necessityor growth in organisms;
To explain what growth is.
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The Necessity For Groth i!Or"#!is$s
To increase in size & change inshape.
To become more specific in form& structure to play vital rolesof life (respiration,photosynthesis)
To interact with externalenvironmental factors
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WHAT IS GROWTH%
GROWTH= an irreversible processwhich involves an increase in thenumber of cells size, complexity &organ functionsin the organisms
bo!y.
"uantitative changes bo!y size,mass & number of cells.
"ualitative changes shape, function& complexity#specializations.
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GROWTH STAGES
a) The stage o cell division The number o cells must rst increase
by mitosis.
Cells increase in geometric progression
!"#$!%&"%#!"$'''.
(ll daughter cells ormed are small identical to the parent cell*+ygote)
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b) The stage o cell elongation ,enlargement
-ust grow in si+e
ccurs by assimilation o ood into the cells.
/ynthesi+ing protoplasm
0acuolation absorption o water.
c) The stage o cell specialisation ,di1erentiation
-aximum si+e di1erentiate.
2eers to gradual changes in the structure o ageneral cell to turn it into a specialised cell orcarrying out a specic unction.
/pecic morphological physiological
changes.
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Cells tissue organ organ system complex organism
-ay occur throughout the lie cycle o atcertain times only.
(ll parts or certain parts only.
3n plants4 limited to the apical meristems cambium*lateral meristems).
5rowth development o the shoot alsoincludes growth o leaves leapromordia*small outgrowth)
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