Structure Growth & Development

Question 1

Definition of growth?

Answer 1

• Growth:
– no. & size of cells increases (text)
– increase in dry weight & irreversible
increase in size (Peng Dict Pl Sci)
• development: single-celled reproductive structure → adult
• development is by: – growth
– cell specialisation/differentiation
• Growth:
– new cells – from meristems
• cell division doesn‟t occur all over a plant • occurs in specialised areas - meristems

Question 2

What are the organ systems of plants?

Answer 2

• Organ systems
– eg flowers, buds, fruits, seeds
• Organs
– eg stem, root, leaf
• Tissues
– eg parenchyma, collenchyma
• Cells
– eg parenchyma, tracheids, etc

Question 3

What are the two type of Meristems called?

Answer 3

Primary Apical and Secondary apical meristems

Question 4

What is the definition of a Meristem?

Answer 4

• Meristematic
– actively dividing
• (think of a shoot apex in winter – is a meristem but is not meristematic)
• appearance: – small cells
– thin cell wall
– large nucleus
– dense cytoplasm

Question 5

What do Primary apical meristems do?

Answer 5

• Primary apical meristems
• produce primary growth
• found in shoot (apical and axillary) and
root tips
• responsible for increase in length/height
• they produce 3 tissue systems:
– protoderm → epidermis
– procambium → vascular/conducting – ground meristem → ground tissues

Question 6

What do shoot apical meristems produce?

Answer 6

• Shoot apical meristems produce:
– New stem tissue – nodes & internodes
• great variation in internodal distances
• influences appearance and function – New leaves
– Axillary buds (NOT auxiliary)
• active – produce branches
• dormant – allow for recovery after fire, cyclones, etc

Question 7

What do secondary apical meristems produce?

Answer 7

• Secondary/lateral meristems
• produce secondary growth
• found in trees, shrubs, woody vines –
„woody‟ plants with bark
• increase girth/diameter
• vascular cambium
– secondary xylem and phloem – support & conduction
• cork cambium (phellogen) – the true bark - protection

Question 8

What do tissues in the plant compose of?

Answer 8

• Tissues:
– Simple – one or two cell types
• parenchyma
• collenchyma • sclerenchyma
– Complex – several cell types • xylem
• phloem

Question 9

What is Parenchyma?

Answer 9

• Parenchyma
– ground tissue
– thin-walled, isodiametric, non-lignified – large vacuoles
– starch storage, coloured vacuoles
– able to divide – grafting, wound healing – if large air spaces – aerenchyma
– if many chloroplasts - chlorenchyma