Structure and Function in Living Systems Chapter 8: Systems in Organisms 8.1: Systems help organisms meet their needs 8.2: Plants have several levels of organization 8.3 Animals have several levels of organization 8.4 Human health depends on a balance among systems

Plants have several levels of organization 1. Living organisms need only water and air to survive. 1. Living organisms need only water and air to survive. Living organisms need energy, materials, water, and air to survive. Living organisms need energy, materials, water, and air to survive. 2. Plants and animals are multicellular organisms. 2. Plants and animals are multicellular organisms. true true 3. If the muscles in the heart stop working, blood will continue moving through the blood vessels and circulatory system. 3. If the muscles in the heart stop working, blood will continue moving through the blood vessels and circulatory system. If the heart muscles stop working, the whole circulatory system will fail to function correctly. If the heart muscles stop working, the whole circulatory system will fail to function correctly.

Plants are a diverse group of organisms Earth = amazing variety of plant life Earth = amazing variety of plant life Each is suited to its own environment Each is suited to its own environment **All have in common… **All have in common… multicellular organisms, their cells have cell walls, and they capture energy from sunlight in the process of photosynthesis multicellular organisms, their cells have cell walls, and they capture energy from sunlight in the process of photosynthesis Examples: cold and harsh tundra: birch trees - shrubs that can be only a few centimeters tall warm and rich central California: giant sequoias grow 90 meters (about 300 ft) tall dry climates: plants tend to have thick leaves and stems that conserve moisture dense tropical rain forests: tall trees prevent sunlight from reaching the forest floor - orchids grow on the trunks of trees

Plants have three main types of tissue Some plants, like mosses, are nonvascular Some plants, like mosses, are nonvascular *We are most familiar with vascular plants *We are most familiar with vascular plants Specialized plant cells form three basic tissues in vascular plants Specialized plant cells form three basic tissues in vascular plants dermal tissue for protection and exchange dermal tissue for protection and exchange vascular tissue for support and transport vascular tissue for support and transport ground tissue for photosynthesis, storage, and support ground tissue for photosynthesis, storage, and support

Dermal Tissue Covers a plant - like skin Covers a plant - like skin Protects the underlying tissue from injury or drying out Protects the underlying tissue from injury or drying out Can be: Can be: thin and flexible - a blade of grass, or thin and flexible - a blade of grass, or rigid and tough - the bark of trees rigid and tough - the bark of trees At the root ends, dermal tissue is only one cell thick At the root ends, dermal tissue is only one cell thick allows the roots to absorb water and nutrients from the soil. allows the roots to absorb water and nutrients from the soil. Dermal tissue is thicker in the stems and leaves Dermal tissue is thicker in the stems and leaves

Dermal Tissue Photosynthesis: Photosynthesis: Through stomata – allow enough CO2 without drying plant out…to prevent this: Through stomata – allow enough CO2 without drying plant out…to prevent this: outermost layer of dermal cells on the leaves and stems may secrete a waxy coating outermost layer of dermal cells on the leaves and stems may secrete a waxy coating protects against water loss and repels bacteria and fungi protects against water loss and repels bacteria and fungi Stomata closing in dry weather Stomata closing in dry weather water vapor, oxygen, carbon dioxide water vapor, oxygen, carbon dioxide Salty environment: may have salt glands to get rid of excess salt Salty environment: may have salt glands to get rid of excess salt

Vascular Tissue Provide support and transport Provide support and transport specialized cells move water, nutrients, and the products of photosynthesis throughout the plant specialized cells move water, nutrients, and the products of photosynthesis throughout the plant Usually two types of long, tubelike cells: Usually two types of long, tubelike cells: xylem: transports water and dissolved nutrients from the roots up a stem to the leaves xylem: transports water and dissolved nutrients from the roots up a stem to the leaves like straws bundled together like straws bundled together Phloem: carries the energy-rich sugars and carbohydrates down a stem and to the roots Phloem: carries the energy-rich sugars and carbohydrates down a stem and to the roots

Ground Tissue makes up the bulk of a plant makes up the bulk of a plant Found between vascular bundles and dermal tissue in all parts of the plant Found between vascular bundles and dermal tissue in all parts of the plant three main functions: three main functions: contain most of the chloroplasts  most of the photosynthesis contain most of the chloroplasts  most of the photosynthesis Some cells are specialized for storing sugars and starches Some cells are specialized for storing sugars and starches found in stems, roots, fruits, and seeds found in stems, roots, fruits, and seeds provides support for the plant provides support for the plant

Plant tissues work together in systems Most plants have three main organs—roots, stems, and leaves Most plants have three main organs—roots, stems, and leaves make up two organ systems, the make up two organ systems, the root system and shoot system root system and shoot system Both are subsystems of the vascular system Both are subsystems of the vascular system Also have reproductive organs and a reproductive system Also have reproductive organs and a reproductive system

The Root System Anchors plant Anchors plant Exchange of materials with soil Exchange of materials with soil Stores excess sugar (as starch) Stores excess sugar (as starch) Examples: Examples: Beets, turnips, and carrots Beets, turnips, and carrots

The Shoot System Stems and leaves Stems and leaves Structures for photosynthesis, support, storage, and the exchange of materials with the atmosphere Structures for photosynthesis, support, storage, and the exchange of materials with the atmosphere Stems: Stems: provide support for plants above ground provide support for plants above ground Pathways of the vascular system Pathways of the vascular system Some plants modify this for food storage Some plants modify this for food storage Potatoes, taro, yams, garlic, and onions Potatoes, taro, yams, garlic, and onions Leaves: the organs of photosynthesis Leaves: the organs of photosynthesis Most chloroplasts are found here (produce sugar) Most chloroplasts are found here (produce sugar)

System Failure Trees: damage by Trees: damage by Natural: strong winds, lightning, ice storms, and heavy snow can break limbs…deer can strip bark Natural: strong winds, lightning, ice storms, and heavy snow can break limbs…deer can strip bark Construction Construction injure a tree’s trunk or roots injure a tree’s trunk or roots Healthy trees can repair small wounds Healthy trees can repair small wounds Weakened trees cannot Weakened trees cannot wound becomes an entry place for viruses, fungi, and insects wound becomes an entry place for viruses, fungi, and insects Houseplants: Houseplants: Roots can outgrow their space Roots can outgrow their space grow around and around into a tangled ball grow around and around into a tangled ball can no longer absorb enough water for the plant, and the plant weakens can no longer absorb enough water for the plant, and the plant weakens

Plants have adapted to their environments – modified stems Adaptations by species to their environments Adaptations by species to their environments Modified Stems Modified Stems Ex: Desert plants, cactus: Ex: Desert plants, cactus: Thick, leathery dermal tissue covering their stems – protective Thick, leathery dermal tissue covering their stems – protective resist the drying effects of sunlight and wind resist the drying effects of sunlight and wind stems are swollen with water stems are swollen with water Roots vs stems: Roots vs stems: stem has joints along its length, called nodes stem has joints along its length, called nodes shoots and buds can grow from these shoots and buds can grow from these root does not have these nodes root does not have these nodes

Plants have adapted to their environments – modified stems Some stems are soft, and some are hard Some stems are soft, and some are hard Some plants (ex: trees and shrubs), have tough, thick stems that do not die each year Some plants (ex: trees and shrubs), have tough, thick stems that do not die each year stems keep growing taller and thicker stems keep growing taller and thicker develop a type of tough xylem tissue that is not found in soft stems develop a type of tough xylem tissue that is not found in soft stems This tough tissue is called wood This tough tissue is called wood Underground Stems: Potatoes have nodes, called eyes, from which new plants can grow Iris: underground stem called rhizomes horizontal stems just below the surface of the ground Onion bulbs - underground stem the short, central part of the bulb is the stem the layers of flesh around the stem are modified leaves

Plants have adapted to their environments – modified leaves Some plants develop long, thin organs – tendrils Some plants develop long, thin organs – tendrils Usually modified leaves Usually modified leaves Ex: peas, morning glories, tropical vines, grape vines, Ex: peas, morning glories, tropical vines, grape vines, grows out from the plant – when it touches a source of support, the tendril winds itself around it grows out from the plant – when it touches a source of support, the tendril winds itself around it helps the plant grow upward = more sunlight helps the plant grow upward = more sunlight The leaves of the cactus have become modified into spines, and the chloroplasts are in the stem The leaves of the cactus have become modified into spines, and the chloroplasts are in the stem Spines do not dry out Spines do not dry out protection protection

Plants have adapted to their environments – modified roots Shallow, broad root system allows the plant to capture as much water as possible from a quick rain Shallow, broad root system allows the plant to capture as much water as possible from a quick rain Ex: Cactus Ex: Cactus Some plants have roots that never reach the ground Some plants have roots that never reach the ground adapted to being exposed to air - aerial roots adapted to being exposed to air - aerial roots Ex: orchids grow on the trunks of the very tall trees in rain forests Ex: orchids grow on the trunks of the very tall trees in rain forests High enough for photosynthesis High enough for photosynthesis Tree trunk is support Tree trunk is support Do not harm tree (commensalism) Do not harm tree (commensalism) Ex: mistletoe Ex: mistletoe roots that grow into the vascular tissue of tree branches to obtain water and nutrients roots that grow into the vascular tissue of tree branches to obtain water and nutrients take nutrition from the trees - can harm their hosts (parasitic) take nutrition from the trees - can harm their hosts (parasitic)

PLANTS HAVE SEVERAL LEVELS OF ORGANIZATION PLANTS HAVE SEVERAL LEVELS OF ORGANIZATION Comparing Structures During photosynthesis, plants capture energy from sunlight and convert it to chemical energy in the form of sugars. Plants often store extra sugars as starches. When the plant needs energy, the starches are broken down into sugars and energy is released. Many plant stems or roots, such as the examples shown below, are adaptations for storing sugar or starch. Comparing Structures During photosynthesis, plants capture energy from sunlight and convert it to chemical energy in the form of sugars. Plants often store extra sugars as starches. When the plant needs energy, the starches are broken down into sugars and energy is released. Many plant stems or roots, such as the examples shown below, are adaptations for storing sugar or starch.

1. Sugar cane is a commercially valuable crop plant that stores large amounts of sugar in its stems. Where does the sugar come from? 2. A sugar beet is a biennial plant. A biennial plant is a plant that takes two growing seasons to produce seeds. The flowers and seeds of biennial plants do not form until the second growing season. Explain an advantage that the storage root offers to sugar beets. 3. A potato forms sprouts that can become new plants. What is the energy source for the sprouts? 4. Plants living in extreme environments sometimes have unusual adaptations. For example, the desert cactus has a fleshy, green stem covered with spines instead of leaves. Suggest two purposes of the unusual cactus stem.

1. The sugar is produced during photosynthesis. 2. The plant will use the stored sugars in the root as an energy source for producing flowers and seeds during the second growing season. 3. The starch stored in the potato will provide energy for the growing sprouts. 4. The cactus stem captures sunlight and performs photosynthesis. The cactus stem also stores a large amount of water. 1. Sugar cane is a commercially valuable crop plant that stores large amounts of sugar in its stems. Where does the sugar come from? 2. A sugar beet is a biennial plant. A biennial plant is a plant that takes two growing seasons to produce seeds. The flowers and seeds of biennial plants do not form until the second growing season. Explain an advantage that the storage root offers to sugar beets. 3. A potato forms sprouts that can become new plants. What is the energy source for the sprouts? 4. Plants living in extreme environments sometimes have unusual adaptations. For example, the desert cactus has a fleshy, green stem covered with spines instead of leaves. Suggest two purposes of the unusual cactus stem.