2 ㅡ Summary investigating structures at the level of the cell and organelle relating structure of cells and cell specialisation to function Comparison of Unicellular, Colonial & Multicellular Unicellular Examples Bacteria & Cyanobacteria Colonial Multicellular Bluebottle, Sponges, Corals and Cyanobacteria Plants, Animals and Fungi Number of Cells Single-cell Many cells Many cells Prokaryote Eukaryote ALL prokaryotes (some eukaryotes) Eukaryotes Eukaryotes One cell carries out all functions to sustain life Individual organisms (zooids) work together to perform functions to sustain the colony Cells are specialised to perform specific functions required by the organism Functions are carried out within the cell Functions are carried out by individuals with specific roles in the colony Functions are carried out at cellular, tissue, organ and system level Microscopic size SA: V limits size Usually macroscopic Macroscopic Cell Role Functions Size 3 ㅡ Investigate Structure & Function: Tissues, Organs & Systems investigate the structure and function of tissues, organs and systems and relate those functions to: cell differentiation and specialisation (ACSBL055) ACSBL055: The specialised structure and function of tissues, organs and systems can be related to cell differentiation and cell specialisation Cell Differentiation & Cell Specialisation Cell Differentiation: This is the process by which a less specialized cell changes to become a specialised type of cell. For example, the process of a blood stem cell differentiation into a red blood cell. Cell Specialisation: Speciation refers to the poifect function which a cell has that is determined by their physiology (gene expression) and cellular structures. For example, red blood cells are specialised with haremoglic molecules to carry oxygen around our body. Stem cells are undifferentiated cells. When an organism begins as emrys all our cells are embryonic cells. When division ours these cells begin to differentiate. The changing of a stem cell into a type of cell is differentiation and the final form they take its specialization. Structure & Function of Tissues, Organs & Systems Structure + Function Example In Plant & Animal Tissues Tissues are collections of specialized cells, which work cohesively to perform a set function. Animal: Muscle tissue make up muscles and are composed of mycotpes which are elongated cells containing specialised cytoskeleton. The structures help the cells contract, adding the function of movement. Plant: Xylem tissue is made of tracheid which are elongated and have a thick cell wall, this epcilastion allows for water flow. Organs Organs are groups of tissues arranged in order to perform large-scale function. An organ's structure is influenced by the function it is required to perform. Animal: The heart which contains cardiac muscle tissue, connective tissues and nervous tissues. Plant: The stem is made of epidermis, vascular and ground tissues. It transports water and nutrients between the roots and the leaves. Organ Systems A structure which is composed of a number of tissues which work together to perform a shared function. CIRCULATORY SYSTEM PURPOSE: Pass blood to all cells in the body. HOW?: Some organs deliver the blood and some pump the blood. COMPONENTS: Heart and blood vessels (arteries, veins and capillaries). VASCULAR SYSTEM PURPOSE: Transport nutrients/water around the plant. HOW?: The xylem transports water and the phloem transports food. COMPONENTS: Xylem and Phloem. 4 ㅡ Hierarchy of Living Things justify the hierarchical structural organisation of organelles, cells, tissues, organs, systems and organisms (ACSBL054) Organelles → Cells → Tissues → Organs → Systems → Organisms Of Course Tiny Owls Sleep Outside Definitions 1. An organelle is a membrane-bound compartment or structure in a cell that performs a special function. 2. The cell is the basic unit of life, cells are specialized to carry out particular tasks. 3. A tissue is a group of cells with similar structure and functions. 4. An organ is a group of tissues together to make a structure with a special function. 5. A system is a group of organs whose function is closely related. ACSBL035: Select, construct and use appropriate representations, including diagrams of structures and processes; and images from different imaging techniques, to communicate conceptual understanding, solve problems and make predictions. ACSBL032: Conduct investigations, including microscopy techniques, real or virtual dissections and chemical analysis, safely, competently and methodically for the collection of valid and reliable data. Autotrophs The majority of autotrophic organisms are plants. Most plants are described as vascular plants because they possess a transport system to move substances from one part of the plant to another. A small number of plants are nonvascular plants because they do not possess this transport system (mosses). M ost plants are vascular plants and possess a transport system to move substances around the plant and provide support. ● Vascular plants contain a number of ‘body’ systems – the root, shoot and vascular system. ● Each system has specialised organs to carry out specific functions. ● These organs allow the plant to obtain the required nutrients and gases and to carry out all functions efficiently and effectively. ● The two types of vascular tissue are xylem and phloem. Nutrient & Gas Requirements Inquiry question: What is the difference in nutrient and gas requirements between autotrophs and heterotrophs? investigate the structure of autotrophs through the examination of a variety of materials, for example: (ACSBL035) dissected plant materials (ACSBL032) microscopic structures using a range of imaging technologies to determine plant structure 5 ㅡ Xylem Tissue ㅡ Phloem Tissue Xylem Tissue ● The absorption of water and mineral ions occurs at the root hairs. The water and mineral then move up the stem to the leaves via the xylem. The xylem tissue is a specialised plant tissue. ● Xylem tissue consists of dead cells that lie and to end. ○ Xylem tissue first started as living cells which over time elongates, loses its cytoplasm and then dies. ○ The end walls of the dead cells disintegrate and produce a continuous, hollow, fluid filled tube for water and mineral ion transfer. ● The moment of water and mineral ions in the xylem is unidirectional- from roots to shoots. Phloem Tissue ● Phloem tissue is a series of living connected calls that run from leaves to roots. ● The phloem is made up of: ○ Sive tubes: Series of cells joined end to end with perforated cross walls between cells (sieve plates) that transport the sugars throughout the plant. ○ Companion Cells: Specialised cells with a nucleus that always accompanies the sieve tube elements and serves to regulate metabolic activity of the sieve tube elements. ● Specialized tissue that transports sugars from the leaves to the rest of the plant. ○ The movement of sugars is bidirectional hence can move wherever needed. 6 ㅡ Function of Structures in a Plant investigate the function of structures in a plant, including but not limited to: ㅡ Leaves Plant Transport Systems Throughout the root and shoot system of plans run nutrient, water and gas exchange systems, These systems allow the plant to: 1) Supply leaves, stems and roots with glasses required for photosystems/respiration. 2) Transport mineral ions and water thought the plant 3) Transport products synthesized during photosynthesis throughout the plant. Cuticle Structure & Function of Leafs Epidermis Stomata Mesophyll Part of Leaf Vascular Bundles Structure Function Cuticle Thin, Waxy, Waterproof The cuticle reflects heat and reduces water loss from the leaf. Also assists to maintain the shape of the leaf and provides protection. Epidermis Upper & Lower Tightly packed layer of cells located beneath the cuticle. Reduce water loss and has stoma for gas exchange. Stomata Pre found on the underside of the lead. Air spaced feigned by two guard cells. Regulates gas exchange and water loss. Mesophyll Palisade & Spongy Palisade: Cells are enlarged in shape and contain abundant chloroplasts. Sponegy: Loosely packed, rounded cells with fewer chloroplasts. Palisade Function: PHOTOSYNTHESIS Spongy: Allows oxygen and carbon dioxide to easily diffuse through the leaf internally. Vascular Bundles (Xylem, Phloem & Cambium) Tubular vessels Transport materials around the plant. 7 ㅡ The Root System The Root System The Root System Roots absorb water and nutrients which are necessary for plant growth and function. Roots can also store food. Roots also anchor the plant into the soil. Often plants have different types of root systems, but generally they can be categorised into two groups: 1. A tap root consists of one main root with only small secondary roots branching of it, these types of roots allow for deeper access into the soil for water. They also achor plants deep into the soil which is advantageous in harsh conditions. 2. A fibrous root consists of many smaller roots that are all equally spaced. These root systems are much thicker and have more surface to maximize water absorption. They are also good at anchoring plants. ㅡ Root Hairs Root hairs are short lived (1-2 days) and are regularly replaced by new hairs. Root Hairs Root hairs are fine, hairlike structures found on the surface of roots. Root hairs are a server to increase the surface area of a root that is 8 ㅡ Root Nodules Symbiotic relationships benefit both parts. ㅡ Root Tip ㅡ Root Cap ㅡ incontact with the soil, this allows for more gas exchange. Root Nodules Root nodules are found on many legumes (beans). They provide a home for symbiotic nitrogen-fixing bacteria called rhizobia. - They are connany found in soil that is low in nitrogen. The bacteria convert nitrogen gas from the atmosphere into ammonia which is then used in the formation of amino acids and nucleotides. - Their ability to fix gaseous nitrogen makes legumes an ideal agricultural organism as their requirement for ringtone fertilizer is reduced. When the plant dies the fixed nitrogen is released, making is available to other plants. Root Tip The root tip is the growing region of the pant. Its made up of the; 1. Meristematic Region Located behind the root cap. In this region the cells are very active and divide rapidly to form new cells which later differentiate to form specialized tissues. 2. Elongation Region This is where cells undergo a process of rapid enlargement causing the entire root tea grown in length. Root Cap The tip of the root is covered by a cap. The root cap protects and covers the delicate growing region from damage and injury as it pushes its way through the soil. Function Related to Structure ● The main functions of the root system are to anchor the plant in the soil and absorb water and mineral ions. ● A large surface area is required for efficient absorption of water and mineral ions. ● This large surface area is achieved with flattened epidermal cells that possess fine extensions called root hairs. ● Branching root systems increase the surface area for absorption. ● Water moves from the soil into the root by osmosis. ● Mineral ions usually move into the root by diffusion, but if the concentration gradient is too low they are moved in by facilitated diffusion or active transport. ● Root cells do not contain chloroplasts and do not photosynthesise but, as with all living cells, they carry out aerobic cellular respiration. ● Oxygen gas diffuses into the root cells and carbon dioxide gas diffuses out. Stems Stems Stem functions can be easily summarized through: ● Support for leaves, flowers and fruits. ● Transport for fluids between the roots and leave visa xylem and phloem ● Storage of nutrients. ● Production of new living tissues since stems have meristems that contruoghly grow to generate new tissue. The stem contains dermal tissue, vascular tissue and ground tissue: ● The dermal tissue makes up the outer layer of the stem and provides waterproofing as well as protection and control of gas exchange. ● The vascular tissue is composed of xylem and phloem tissues that are arranged in the 9 stem in structures called vascular bundles and reach from the roots to the leaves. These provide structural support and enable transport of materials. The water and mineral ions that are absorbed by the roots and have moved into the xylem continue their journey to the leaves through the stem. The products of photosynthesis move from the leaves to all parts of the plant through the phloem tissue in the stem. The arrangement of vascular tissues varies between different plant species. ● Ground tissue in the stem fills in around the vascular tissue. The three types of tissue carry out functions such as storage, photosynthesis and extra support for the plant. ㅡ Microscopic Structures microscopic structures using a range of imaging technologies to determine plant structure 10 ㅡ Imaging Technologies used to Determine Plant Structure Imaging Technologies Name ㅡ Movement of Photosynthesis Products tracing the development and movement of the products of photosynthesis (ACSBL059, ACSBL060) Description of technology works to identify plant structures. MRI( Magnetic resonance Imaging) Magnetic resonance imaging (MRI) is a scan used for an imaging procedure. It uses a magnetic field and radio waves to study cell water balance, phloem and xylem transport in large potted plants. PET(Positron Emission Tomography) Positron-emission tomography is a nuclear medicine functional imaging technique that is used to observe metabolic processes in the uptake, distribution, retention and clearance of positron-emitting compounds administered to living organisms. Neutron tomography (NT) Neutron tomography is a unique non-invasive 3D tool used to visualize plant root systems together with the soil water distribution. X-ray computed microtomography ( micro- CT) X-ray microtomography, uses x-rays to create cross-sections of a physical object that can be used to recreate a virtual model without destroying the original object. In plants, this method is used to observe the architecture of the root system of plants. Movement of Photosynthesis Products ● Radioisotopes are forms of an element that emit radiation, which can be detected by a number of means. They act as tracers and are used to follow the pathways of molecules involved in photosynthesis. ● Radioisotopes were used to determine that oxygen produced in photosynthesis came from the water molecule and not the molecule of carbon dioxide. ● Carbon-14 added to the carbon dioxide supply traced the movement of the glucose produced through the plant. ● New technologies can be used to produce 3D images of the structures and pathways involved in the movement of products of photosynthesis. ● Smael Rubin also used an isotope of oxygen, Oxygen-18 to trace the movement of water, he did this by giving plants “heavy water” (labeled water) and discovered that oxygen gas released from photolysis comes solely from water taken in by plants not from carbon dioxide. 11 ㅡ Gas Exchange: Plants investigate the gas exchange structures in animals and plants (ACSBL032, ACSBL056) through the collection of primary and secondary data and information, for example: – microscopic structures: alveoli in mammals and leaf structure in plants ㅡ Stomata Gas Exchange in Plants Unlike animals plants don't have a specialised gas exchange system. Instead various structures allow higher order plants to obtain gasses from the internal environment such as stoma, lenticels and roots. Simple Plants: ● Simple plants such as algae can rely on simple diffusion of glasses over their surfaces. ○ Due to their small size and flat shape they have larger surface area to volume ratio. ○ They are found in water or damp environments and have no waxy cuticle to prevent glasses entering. Stomata ● Stomata are microscopic openings or pore on leaves which help regla;te the exchange of glasses. ● They are more abundant on the siderside of the wave compared to the top.. ● However, since stomata are pores in leaves, the plant will constantly lose water if they are always open. Hence the plant must regulate when to open or close. ● Guard cells regulate the opening and closing: ○ The size of the stomatal pore is depending upon the turgor (internal water pressure) of the two guard cells that are sounding it. ■ When the guard cells are turgid (high internal pressure due to influx of water molecules and ions) the stomatal pore increases. ■ When the guard cells are flaccid (water ions leave the cells) the stomatal pore decreases.
