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 FUNCTION Roots: Anchors the plant Collects water and nutrients for plant ROOTS Stem: Above ground Transports nutrients STEM Leaves: LEAVES Photosynthesis Transpiration

ROOTS Roots 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….

TYPES OF ROOTS 1. TAPROOTS: like carrots and beets sing 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

STEMS Stems 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

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

Section 23.2 Summary – pages 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

Section 23.2 Summary – pages 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.

Section 23.2 Summary – pages Transpiration When water enters the guard cells, the pressure causes them to bow out, opening the stoma. Stoma Guard cell Water LEAVES

Section 23.2 Summary – pages Transpiration As water leaves the guard cells, the pressure is released and the cells come together, closing the stoma. Water LEAVES

Section 23.2 Summary – pages 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)

Section 23.3 Summary – pages 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

Section 23.3 Summary – pages 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

Section 23.3 Summary – pages As these cells lengthen, the stem bends toward the light. The growth of a plant toward light is called phototropism. TROPISM

Section 23.3 Summary – pages 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.

Section 23.3 Summary – pages 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

Section 23.3 Summary – pages 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 Nastic movements do not involve growth.

Section 1 Check Question 1 Most plants produce their own food in the form of _______. D. chlorophyll C. glucose B. proteins A. cellulose The answer is C.

Section 1 Check 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.

Section 2 Check Most roots that humans eat are _____ roots. Question 3 D. aerial roots C. prop roots B. fibrous roots A. taproots The answer is A, taproots.

Chapter Assessment 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.

Chapter Assessment Question 5 What is the main difference between tropisms and nastic responses? Answer The 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