RHS Level 2 Certificate
Year 1 Week 5: Stems
and Leaves
Quiz answers
1. Cytoplasm - Jelly like substance that contains and supports
the organelles
Mitochondria – Organelle that i...
Quiz answers
4. The DNA of the cell and the location of the cell in the plant.
5. (a) tissue that transports water and dis...
Learning objectives
1. Stems – structure and purpose
1.1 Describe how the stem develops.
1.2 Describe different types of b...
Stems – Structure and Purpose
o What are stems for?
o support for leaves and flowers – competition for
light and access fo...
Stems – vascular system
 Vascular system in a number of bundles – in a
dicot root there is a single vascular bundle, in a...
Young Dicot stem
Stem Adaptations
 Water storage – e.g. Opuntia sp.
 Thorns for protection - Crataegeus
monogyna (Common Hawthorn)
 Dorm...
Buds – different types
 Apical bud – at the tip of the shoot.
 Axillary buds – at the joint between leaf and
stem (at th...
Fruit or wood?
Leaves –function and structure (1)
 Function of leaves –
photosynthesis
 External structure
– Petiole
– Lamina
– Midrib
...
Leaves –function and structure (2)
Cuticle –waxy layer on
surface that slows water
loss
Epidermis – cells that form
‘skin’...
Leaf – internal structure
Stomata
 Pairs of specialised guard cells on either side
of small openings in the underside of leaves
and in soft stems.
...
Electron-micrograph of lettuce
stomata
Leaf Adaptations
 Tendrils or suckers – for climbing e.g. Lathyrus
odoratus
 Leaf Hairs – for protection from the sun e....
Leaf adaptations (2)
 Leaf fall for deciduous
trees – recovery of
chemical components of
chlorophyll; formation of
abscis...
Leaf form and leaf arrangement
(phyllotaxy)
 Various different leaf forms – known by
different descriptive names to enabl...
Learning outcomes
1. Stems – structure and purpose
1.1 Describe how the stem develops.
1.2 Describe different types of bud...
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Rhs level 2 certificate year 1 week 5 2013

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Transcript of "Rhs level 2 certificate year 1 week 5 2013"

  1. 1. RHS Level 2 Certificate Year 1 Week 5: Stems and Leaves
  2. 2. Quiz answers 1. Cytoplasm - Jelly like substance that contains and supports the organelles Mitochondria – Organelle that is the site of respiration. Nucleus - Contains the DNA and RNA of the cell Vacuole - Contains water, some nutrients and cell waste products - helps the cell maintain its shape. Chloroplast - The site of photosynthesis within the cell Middle lamina -Membrane that physically connects cells together into plant tissues. 2. The release of stored energy from carbohydrate in the mitochondria for use by the plant. 3. At the meristems (apical and lateral)
  3. 3. Quiz answers 4. The DNA of the cell and the location of the cell in the plant. 5. (a) tissue that transports water and dissolved mineral nutrients from roots (b) tissue that transports sugars/carbohydrate made during photosynthesis from the leaves 6. All except (a) 7. (a) and (c) 8. (a) 9. (c) 10. ? What did you chose?
  4. 4. Learning objectives 1. Stems – structure and purpose 1.1 Describe how the stem develops. 1.2 Describe different types of buds and state where they occur in the plant. 1.3 Identify the two elements of the vascular system and name their purposes 1.4 Describe transverse sections of the young dicotyledon stem, should include the location of the following: epidermis, cortex, xylem, phloem, pith, cambium, vascular bundles, endodermis. 1.5 Describe how the stem is adapted in order to perform specific functions. 2. Leaves – structure and purpose 2.1 Describe the structure of the leaf. 2.2 Describe how leaf shape, size, form and colour can vary. 2.3 Describe how leaves are adapted in order to perform certain functions 2.4 Describe transverse sections of the young dicotyledon leaf; this should include the location of the following: epidermis, xylem, phloem, vascular bundles, palisade & spongy mesophyll, cuticle, stomata.
  5. 5. Stems – Structure and Purpose o What are stems for? o support for leaves and flowers – competition for light and access for pollinators o transport of water and nutrients around the plant o What is the internal structure of the stem? o Stem vascular system o Differences between stem and roots? o Differences between monocot and dicot stems?
  6. 6. Stems – vascular system  Vascular system in a number of bundles – in a dicot root there is a single vascular bundle, in a monocot there is a regular circular arrrangment.  Monocots in the stem – scattered irregularly  Dicots in the stem – arranged regularly around the circumference  Xylem (in both)– located on the ‘inside’ of the bundle  Phloem (in both) – on the ‘outside’  Vascular cambium – meristematic tissue that generates new xylem and phloem.
  7. 7. Young Dicot stem
  8. 8. Stem Adaptations  Water storage – e.g. Opuntia sp.  Thorns for protection - Crataegeus monogyna (Common Hawthorn)  Dormancy – storing food to allow avoidance of hostile conditions over winter or during summer drought e.g. Zingiber officinale (Ginger ) has a rhizome, Solanum tuberosum ssp. Tuberosum (potato) has stem tubers  Climbing – stems twine to aid the plant in climbing e.g. Wisteria sinensis.
  9. 9. Buds – different types  Apical bud – at the tip of the shoot.  Axillary buds – at the joint between leaf and stem (at the node). Usually dormant or leaf producing.  Fruit buds – produce flowers, usually a distinct shape and form, differing from…  Wood buds – produce new stems, sometimes only if the apical bud is removed.
  10. 10. Fruit or wood?
  11. 11. Leaves –function and structure (1)  Function of leaves – photosynthesis  External structure – Petiole – Lamina – Midrib – Veins
  12. 12. Leaves –function and structure (2) Cuticle –waxy layer on surface that slows water loss Epidermis – cells that form ‘skin’ of leaf Palisade cells – arranged like picket fence, contain chloroplasts Chloroplasts – site of photosynthesis Spongy mesophyll – packing cells, allow water vapour and other gasses through Stomata – active control of entry and exit of gasses and water vapour. Phloem – dissolved sugars Xylem – water and mineral nutrients
  13. 13. Leaf – internal structure
  14. 14. Stomata  Pairs of specialised guard cells on either side of small openings in the underside of leaves and in soft stems.  Guard cells swell when the plant has enough water – pulling apart to open the stomata and allowing water vapour and waste gasses out and oxygen and CO2 in.  When water levels fall the guard cells empty and the stomata close to conserve water.
  15. 15. Electron-micrograph of lettuce stomata
  16. 16. Leaf Adaptations  Tendrils or suckers – for climbing e.g. Lathyrus odoratus  Leaf Hairs – for protection from the sun e.g. Stachys byzantina  Spines – for protection from grazing animals e.g. Ilex aquifolia  Food storage – for over-wintering, e.g. Narcissus spp.  Attracting pollinators – modified, highly coloured leaves known as bracts surround insignificant flowers e.g. Euphorbia pulcherima.
  17. 17. Leaf adaptations (2)  Leaf fall for deciduous trees – recovery of chemical components of chlorophyll; formation of abscission layer, a layer of weak cells; vascular bundles plugged; leaf fall.  Juvenile trees retain dead leaves, protects buds
  18. 18. Leaf form and leaf arrangement (phyllotaxy)  Various different leaf forms – known by different descriptive names to enable clear identification  Phyllotaxy is the name for the arrangement of leaves on a plant. Prevents the leaves from shading each other.
  19. 19. Learning outcomes 1. Stems – structure and purpose 1.1 Describe how the stem develops. 1.2 Describe different types of buds and state where they occur in the plant. 1.3 Identify the two elements of the vascular system and name their purposes 1.4 Describe transverse sections of the young dicotyledon stem, should include the location of the following: epidermis, cortex, xylem, phloem, pith, cambium, vascular bundles, endodermis. 1.5 Describe how the stem is adapted in order to perform specific functions. 2. Leaves – structure and purpose 2.1 Describe the structure of the leaf. 2.2 Describe how leaf shape, size, form and colour can vary. 2.3 Describe how leaves are adapted in order to perform certain functions 2.4 Describe transverse sections of the young dicotyledon leaf; this should include the location of the following: epidermis, xylem, phloem, vascular bundles, palisade & spongy mesophyll, cuticle, stomata.
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