Stem and Leaves

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Stem and Leaves

• Assignment answers

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Plant Stems.

• 1. What is the difference between woody stems
  and herbaceous stems?
• Woody stems are thick and tough (wood) and live
  for more than 2 years.
• Herbaceous stems are soft green and juicy and
  live 1 -2 years.

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• Diagram of the stem.

Terminal bud
Lateral bud
Bud scale scar
Lenticels
Leaf scar
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• 2. Budsthe main function of the bud occurs
  during growing season and involves cell division
  to grow new leaves and stems.
• Leaf scar the attachment points of leaves that
  fell off the previous growing season. A layer of
  tissue is produced to protect the internal
  tissues of the stem.
• lenticels holes that pass through the cork and
  allow the exchange of oxygen and carbon dioxide.

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• How could you tell how much the plant grew?
• You can tell how much the plant has grown by
  measuring between the bud scale scar and the new
  bud. This represents 1 years growth.

1 years growth
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• 3. In a dicot tree trunk, what causes the wood
  rings to occur?
• The xylem causes the wood rings in a tree trunk.
  The production of new xylem every year causes a
  new ring to form in the trunk. The phloem is
  also produced in layers however it is sloughed
  off and not allowed to accumulate on the outside
  of the cambium.

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• 4. Leaf diagram.

Leaf blade
Stem
vein
petiole
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• 5. Cross section of Leaf

cuticle
epidermis
mesophyll
chloroplast
xylem
phloem
Guard cell
stomata
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• 6. What is the purpose of the following
  structures?
• A) cuticle waxy and protects the leaf from
  infection and loss of moisture
• b) epidermis one cell thick and tightly packed.
  Protects the leaf form infection. Cells contain
  no pigment to allow light to pass through to the
  mesophylls.
• c) mesophyll photosynthetic tissue for food
  production and food storage
• d) stomata small openings in the epidermis that
  allow for the exchange of O2 and CO2.

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• e) guard cell control the opening of and the
  closing of the stomates.

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• 7. Label the guard cells and the stomata on the
  following picture.

Guard cell
stomata