Biology

Chapter 2 The Structure and Function of Leaves

Three basic leaf shapes.

Broad and Flat Long and Narrow

Needlelike or Scalelike

In what other ways do leaves vary from plant

to plant?Leaves also vary in texture or thickness

Leaf Arrangements

Rosette leaf arrangementshas a cluster of leaves growing at its base

Opposite Leaf Arrangementshave 2 leaves attached to each node: leaves re arranged at

right angles to the leaves

Alternate Leaf Arrangementshave only one leaf growing from each node: leaves are

arranged in an alternating pattern

Whorled Leaf Arrangementshave 3 or more leaves growing from each node

How leaves orient themselves so that each blade is at about a 90 degree angle

to the source of light

the petiole is able to twist and turn in order to

maintain the proper angle with the light source

(phototropism)

What is the function of xylem and phloem?

xylem tissue transports water and dissolved minerals

upward to the leaves: phloem tissue transports food

manufactured in the leaves downward to the rest of the plant

What kind of tissue forms the majority of a leaf?

Parenchyma (food-making) tissue

Describe parallel, pinnate, and palmate venation.

Parallel venation: veins are usually parallel to each other along the length of

the leaf

Pinnate Venationwings are in a branching pattern, characterized by

one major twin (the midrib) with smaller veins extending outward from it

Palmate Venationtwo or more major veins extend outward from

one point

What are the 3 main parts of every cell?

cell membrane, nucleus and cytoplasm

Purpose of cell membranes and cell walls

to separate from environment and regulate what enters and leaves the cell and to provide the cell

with support and protection, allowing the stems and leaves of plants to stand erect.

What form is glucose usually

transported throughout a

plant?

sucrose

In what forms do plants store excess sugars?

starch

The process of photosynthesis

What are the factors which affect the rate of photosynthesis?

the primary factors are the amount of water available, the amount of carbon dioxide available, transportation and the

intensity of the sunlight

Light is the MOST IMPORTANT factor

List the names and colors of three common leaf pigments normally hidden

by chlorophyll.

xanthophyll (yellow) carotene (yellowish-orange)

anthocyanin (bright red, blue or purple)

What are the 5 factors that can affect the rate of transpiration?

* humidity of the air * temperature intensity of

the sunlight * wind speed

* amount of carbon dioxide in the air

* amount of soil water available

How are a leaf’s stomata open and closed?

when the guard cells are turgid (swollen with water), the stomata are opened; when the guard cells lose water, the

stomata close