Plant Tissues and Organs

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Plant Tissues and Organs
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Plant Tissues

• All plants are made up roots, stems, leaves and
  flowers. These structures are made up of cells
• These cells are not always the same in structure.
  They differ depending on what function they
  perform
• Some groups of cells have a supportive function.
  Others may be involved in photosynthesis.
• Cells which have a similar function, are similar
  in structure and form tissues.

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Examples of some Plant Tissues

• Epidermal tissue a single layer of cells found
  covering the surface of the plant
• Some epidermal cells are specialised for perform
  a certain function. Examples
• Guard cells in leaves
• Roots hairs in roots

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Vascular Tissue Two types-

• Xylem transports water from the roots via the
  stems to the leaves. The cells are elongated and
  hollow with thickened, lignified cell walls. They
  are arranged end-to-end. They also have a
  supportive function.

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Vascular Tissue

• Phloem transports food made in the leaves to
  the rest of the plant. Cells are also elongated
  and arranged end-to-end.

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Supportive Tissues
Supportive tissues collenchyma and sclerenchyma
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Other Plant Tissues

• Photosynthetic Tissue found in the leaves the
  cells contain many chloroplasts.
• Storage and packing tissues called parenchyma.
  This tissue is the most common plant tissue found
  in plants.

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Plant Organs

• Tissues are grouped together to form a structure
  with a special function. This structure is called
  an organ. Examples of plant organs are
• Roots
• Stems
• Leaves
• Flowers

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Function of the Root

• To anchor the plant in the soil
• To absorb water and nutrients from the soil for
  photosynthesis in the leaves
• Some roots store extra food e.g. carrot

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Function of the Stem

• Support the plant
• Conduct water and nutrients from the roots to the
  leaves
• Conduct food (glucose) manufactured in the leaves
  to rest of plant

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Structure and Functions of a Plant Leaf
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Function of the Leaf

• Photosynthesis
• Gaseous exchange
• take in O2 and release CO2 during respiration
• take in CO2 and release O2 during photosynthesis
• Water Vapour can be lost from the surface of the
  leaf in a process known as Transpiration.

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Photosynthesis
Glucose (Stored as starch)
Energy (Sun)
O2 (Released into air)
CO2 (from air)
H20 (from roots)
In chloroplast (chlorophyll)
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Structure of the Leaf
Transverse section of a leaf
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phloem
xylem
Water-carrying cell
Opening for CO2 and O2 and water vapour
Leaf vein
Transverse section of a leaf at cellular level
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Stomata Functions

• The stomata are responsible for the interchange
  of gases for respiration and photosynthesis.
• The stomata allow for the loss of excess water in
  the form of water vapour, which also allows for
  cooling.

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Quiz Label the parts of the leaf
Palisade mesophyll
Spongy mesophyll
Stoma
Upper epidermis
cuticle
Air spaces
A
B
C
D
E
F
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Brainstorm

• How are leaves adapted to their functions of
  photosynthesis and gaseous exchange? - Try to
  think of 7 adaptations

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How is the Leaf adapted to its function?

• Broad, flat-shape large surface area for
  absorption of sunlight and carbon dioxide
• Thin gases have a short distance to travel
  (Epidermis 1 cell layer thick)
• Large air spaces between the cells of the spongy
  mesophyll allow for easy passage of carbon
  dioxide and oxygen
• Waxy Cuticle (reduces water loss)
• Many stomata in the lower surface allow for the
  exchange of carbon dioxide and oxygen with the
  air outside (open during day, close at night)
• More chloroplasts in upper palisade than spongy
  mesophyll cells where they receive the most
  sunlight
• Branching network of veins which provide a good
  water supply to the cells for photosynthesis.