Assignment #Transpiration

(Transport in Plants)

BiologyMrs. McCarthy

Thursday, April 20, 2023

I. Plant tissues

A. Plants are made of tissues that form organs

B. Plant organs are:1. Roots2. Stems3. Leaves4. Reproductive structures –

flowers, fruits, seeds

I. Plant tissues

C. Plants have vascular tissues that transport materials

1. Xylem carries water and minerals

a. Xylem only carries one way – from roots to leaves

b. Roots absorb the water by osmosis needed by the

plant

2.Phloem carries food and

other dissolved materialsa. phloem can carry food to

and from the leaves – both waysb. food is made in the leaves

during photosynthesis

c. Plant carbohydrates are stored as:

1. Starch (can be digested)2. Fiber or cellulose

(cannot be digested)d. Extra food is stored in the

roots

e.In the spring, when plants need energy to make

leaves, the sap moves up the phloem

f. Sap is made of dissolved raw materials

(carbohydrates)

II. Transpiration – evaporation of

water from plant surfaces

A. All plants need water to survive, but much of the water is lost to the atmosphere by evaporation

B. Cuticle is the thin, waxy outer layer of a leaf that helps to prevent water loss and protects the plant from infections

C. Transpiration takes place through stomates

D. Stomates are pores in the epidermis of a leaf1. Pores – tiny holes or

openings2. Epidermis – outer covering

of the leaf

3. Stomata (stomates) are used for the exchange of

oxygen and carbon dioxide during photosynthesis

E. The rate of transpiration is controlled by the size of the opening of each stomate

1. Guard cells control the opening and closing of

each stomate

2. The stomata open and close as the guard cells

gain or lose water by osmosis

a. When guard cells become swollen with water (called

turgid), the uneven thickness of their

walls cause them to bend outward. This makes the stomate OPEN.

b. When the guard cells lose water, they shrink and

the cells come close together. The stomate CLOSES.

3. The stomata of most plants are open during the day for photosynthesis to occur, and they close at night.a. However, the stomata will

close when:1. The plant does not have

enough water2. The temperatures is low3. There is little or no light

Journal Entry #April 20, 2023

A. How would a plant change if placed in colored water for 24 hours? Explain using these words:

Xylem, stomates, transpiration

Label the Leaf Cross Section Diagram