1. What are the main parts of this tree?

2. What is the function of each part?

REVIEW

How do plants obtain energy?

In the food chain, they are the producer….

PLANT STRUCTURE AND FUNCTIONRoots:Anchors the plant

Collects water and nutrients for plant

Cannot carry out photo.

ROOTS

Stem: Above ground

Transports nutrients

If green, can photosynthesizeSTEM

Leaves:

LEAVES

Major Photosynthesis

Transpiration

Remember Capillary Action and Adhesion

ROOTSRoots can be short or long

Roots can be thick and massive or thin and thread-like.

Most roots grow in the soil, some do not….

Rhizome

TYPES OF ROOTS

1. TAPROOTS: like carrots and beets

single thick structures with smaller branching roots

accumulate and store food

TYPES OF ROOTS

2. Fibrous Roots: have many small branching roots from a central point

example: grass

TYPES OF ROOTS

3. PROP ROOTS: originate above ground to help support the plant

example: corn

Plant HormonesPlant Hormones

• Plants, like animals, have hormones that regulate growth, help them respond to the environment, and send chemical messengers.

• A hormone is a chemical that is produced in one part of an organism and transported to another part, where it causes a physiological change.

• The plant’s hormones are produced in the ROOTS.

STEMSStems transport water, dissolved minerals, and

sugar to and from roots and leaves.

1. Herbaceous Stems 2. Woody stems

Fleshy, green stems, Can also carry out photosynthesis.

Grow year after year Have cork tissue for protection

• These annual growth rings can be used to estimate the age of the plant.

Annual growth rings

Xylem

Vascular cambium

PhloemCork

Woody stems are composed primarily of dead xylem cells.

A tree trunk is one example of a woody stem.

Besides age, the thickness of a tree can show how much water was available at the time.

A thin tree ring indicates a year of drought.

LEAVES

Cuticle

Upper epidermis

Palisade Layer

(where most chloroplasts are found)

• The primary function of the leaves is photosynthesis.

• Sunlight passes through the transparent cuticle into the photosynthetic tissues just beneath the leaf surface.

LEAVES

Size, Shape, and type of leaves vary enormously.

Opposite Arrangement

• Gases can also move in and out of a leaf through the stomata, which are located in the upper and/or lower epidermis.

LEAVES

Stomata

• Guard cells are tiny cells that surround and control the size of a stoma.

LEAVES

• The loss of water through the stomata is called transpiration.

TranspirationTranspiration

• When water enters the guard cells, the pressure causes them to bow out, opening the stoma.

Stoma

Guard cell

Water

LEAVES

TranspirationTranspiration• As water leaves the

guard cells, the pressure is released and the cells come together, closing the stoma.

Water

LEAVES

One way to distinguish among different groups of plants is to examine the pattern of veins in their leaves.

LEAVES

PARALLEL VEINS

(Monocot)

NET-LIKE VEINS

(Dicot)

• Although a plant lacks a nervous system and usually cannot make quick responses to stimuli, it does have mechanisms that enable it to respond to its environment.

• Plants can respond to:

Gravity

Light

Temperature

PLANT RESPONSES

• Tropism is a plant’s response to an external stimulus.

• The tropism is called negative if the plant grows away from the stimulus.

• The tropism is called positive if the plant grows toward the stimulus.

PLANT RESPONSES

WE WILL LOOK AT THREE TYPES OF TROPISM

• As these cells lengthen, the stem bends toward the light.

The growth of a plant toward light is called phototropism.

TROPISM

Gravitropism is plant growth in response to gravity.

Roots that grow down into the soil are able to anchor the plant and can take in water and dissolved minerals.

TROPISM

Stems usually exhibit a negative gravitropism.

How do growing seeds exhibit both phototropism and gravitropism?

Some plants exhibit another tropism called thigmotropism, which is a growth response to touch.

• Because tropisms involve growth, they are not reversible.

• The position of a stem that has grown several inches in a particular direction cannot be changed.

TROPISM

Ivy is a good example of a plant that exhibits all three types of tropism.

• A responsive movement of a plant that is not dependent on the direction of the stimulus is called a nastic movement.

• An example of a nastic response is the sudden closing of the hinged leaf of a Venus’s-flytrap.

PLANT RESPONSES

• Naustic movements do not involve growth.

• The relative lengths of daylight and darkness each day have a significant effect on the rate of growth and the

timing of flower production in many species of flowering plants.

• The response of flowering plants to daily daylight-darkness conditions is called photoperiodism.

Question 1 Most plants produce their own food in the form of

_______.

D. chlorophyll C. glucose B. proteins A. cellulose

The answer is C.

Question 2 Which of the following is NOT a function of most

plant roots?

D. anchoring the plant C. store starch B. conducting photosynthesis A. absorbing water and nutrients

The answer is B.

Most roots that humans eat are _____ roots.

Question 3

D. aerial rootsC. prop rootsB. fibrous roots

A. taproots

The answer is A, taproots.

Question 4

If a plant becomes too dry, are the stomata in the leaves more likely to be open or closed?

Answer

The stomata are more likely to be closed to prevent any more water loss from the plant.

Question 5What is the main difference between tropisms and nastic responses?

AnswerThe main difference between the two is that tropisms are not reversible and nastic responses are reversible. Also, nastic responses do not depend on the direction of the stimulus, tropisms do.

As you walk through a room, you notice that a plant sitting on a table 2 m from a window is leaning toward the window. What type of response is the plant exhibiting?

Question 6

phototropism.Answer

Question 7Name the two stages of a plant’s life cycle, and describe which each entails.

AnswerGametophyte: Haploid stage

Sporophyte: Diploid stage