Link from the Lab to Today: - PowerPoint Presentation

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Link from the Lab to Today:Slide2
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Leaf Structure and Function

and AC Leaf Hunter Activity!! (on Monday)Slide5

Copy this into your notebooks.

Leaf Structure

Fig. 1:

Cross-Section of a LeafSlide6
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Term Definitions:

Epidermis – Outer layer of

leaf tissues

(cuticle and leaf hairs)

Cuticle

 –

Waxy protective outer layer of epidermis that prevents water loss on leaves, green stems, and fruits.  It’s made of wax and cutin (a lipid)

; the

amount of

hydrophobic

cutin

increases

with light intensity

.Slide8

1) Upper layer: The most

photosynthetically

active portion of the leaf:

Palisade

mesophyll

– 

A tightly packed layer of parenchyma tissues filled with chloroplasts for PS.Chloroplasts – Sub-cellular, photosynthetic structures in leaves and other

green

tissues.  Slide9

1) Upper layers: The most

photosynthetically

active portion of the leaf:

Chlorophyll --

a green plant pigment that

captures the energy in light and begins the transformation of that energy into sugars.Slide10

Significance of leaf structure

… Why is there more air space on the bottom? Why are the chloroplasts more dense on top?Slide11

2) Lower Layer: Gas exchange and nutrient transport

Vascular

bundle (leaf veins)

 –

Xylem (top -- water conduction)

and phloem tissues (bottom – sugar and nutrient transport).Spongy mesophyll – Layer of parenchyma tissues loosely arranged to facilitate movement of oxygen, carbon dioxide, and water vapor.  It also may contain some chloroplasts. Slide12

2) Lower Layer: Gas exchange and nutrient transport

Spongy

mesophyll 

– Layer of parenchyma tissues loosely arranged to facilitate movement of oxygen, carbon dioxide, and water vapor.  It also may contain some chloroplasts. Slide13

Gas exchange in the leaf.Slide14

2) Lower Layer: Gas exchange and nutrient transport

Stomata

 –

Openings

in leaves and

non-woody stems that allow for gas exchange (water vapor, carbon dioxide, and oxygen).Guard

cells – Specialized kidney-shaped cells that open and close the stomata (based on water levels.)Slide15

External Features of the leaf:

Leaf blade 

– Flattened part of the leaf

Petiole 

– Leaf stalk

Stipules – 

Leaf-like appendages at the base of the leafSlide16

Copy this into your notebooks.

Fig. 2:

Leaf External StructureSlide17

Make a heading in your notebooks entitled ‘’AC Leaf Hunter”

We

will be going outside to document and draw different types of leaves; take a picture of the leaves you find to add further details to your drawing once we return to the classroom.

Find 6 different types of leaves

. Label whether each one is a monocot or a dicot. Describe the texture of the leaf; does it have a waxy coating? Are the leaf veins parallel or branched? Does the top surface have a waxy feel or appearance? Describe the size, structure, shape and distribution of the leaves…

e.x

. jagged vs. smooth edges, single vs. clustered leaves, branched vs. un-branched petioles, thickness of the blade, petiole and veins, etc…Slide18

Monocot vs. dicot (parallel vs. branched veins)Slide19

Leaf arrangement on the petiole:Slide20

Leaf structure and qualities

Describe the texture of the leaf; does it have a waxy coating? Are the leaf veins parallel or branched? Does the top surface have a waxy feel or appearance? Describe the size, structure, shape and distribution of the leaves…

e.x

. jagged vs. smooth edges, single vs. clustered leaves, branched vs. un-branched petioles, thickness of the blade, petiole and veins, etc…Slide21

Take a picture of the leaf and the plant after making your sketch…

We can add more details later and determine more specifics about the type of leaf,

e.x

.

Whether the leaf is simple or complex (and palmate or pinnate)Slide22

Simple vs. Compound leavesSlide23

Specific Leaf Shape (advanced)Slide24
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Making Biological Drawings

(final draft version: 10 marks.)

Write the

species

of the leaf on top of the page (as your title)

Don’t ‘shade’ a line that’s solid.Use pencil; when completed, draw over the pencil with dark blue or black ink.

Use a ruler to make all straight lines;Drawing on the left side of the page.

Writing on the

right

.Slide26

Making biological drawings…

Dicot Leaves

Start a new page, after the rough drawings we made outside.

Take your best leaf drawing; compare it with the picture you took.

Make sure you know what species of leaf it is

!Label all structures of the leaf; use the leaf guide to describe the exact leaf shape, arrangement on the stem, etc…Slide27

SC30243 Leaf Hunter Assignment

Drawing of a _____________ leaf.

Description of leaf size, shape

and arrangement on the stem

Scale:

____ = x cmSlide28

SC30243 Leaf Hunter Assignment

Drawing of a

Carica

papaya

Leaf