Transcript Chapter 5
Types of Nutrition and Photosynthesis Nutrition The activities by which an organism obtains, processes, and uses food to carry on their life functions Two Types of Nutrition 1. Heterotrophic 2. Autotrophic Nutrition Nutrition (I) Autotrophic Nutrition A type of nutrition in which an organism can make its own food Ex: green plants algae some bacteria Autotroph An organism capable of making their own food Photosynthesis The most common type of autotrophic nutrition In this process, organisms use energy from sunlight, carbon dioxide, and water to make its own food Chloroplast Contains a green pigment called chlorophyll It is in the chloroplast that light energy is trapped by chlorophyll and glucose is formed as the product (food) Structure of Chloroplast Formula for Photosynthesis Reactants: 1.) CO2 2.) Water 3.) Light Energy Products: 1.) Glucose 2.) Oxygen 3.) Water ROY G BIV The maximum amount of photosynthesis will occur when exposed to red and blue light because it is these two colors that are easily absorbed in great quantity by the chlorophyll For green leaves, green light is reflected and therefore has the least affect on photosynthesis Photosynthesis occurs in two stages: 1. Light Reaction 2. Dark Reaction Light Reaction Dark Reaction 1. Light Reaction 1. 2. 3. 4. 5. 6. Occurs in the grana of the chloroplast First stage of photosynthesis Begins with the absorption of light energy by chlorophyll Photolysis occurs- a reaction in which H2O molecules split into oxygen and hydrogen All oxygen given off during photosynthesis comes from the photolysis of water ATP (Adenosine triphosphate), which is a form of energy, is produced 1- Light Reaction "PHOTOLYSIS" Light Reaction 2. Dark Reaction Occurs in the stroma of the chloroplast The second stage of photosynthesis It is here that CO2 is converted to carbohydrates (glucose) by a process called carbon fixation Light is not required CO2 + H atoms + ATP are combined during the first part of dark reaction to form PGAL + water PGAL = phosphoglycerolaldehyde The PGAL molecules are then synthesized to form a glucose molecule. Dark Reaction http://www.brainpop.com/science/plantsandanimals/photosynthesis/index.weml Factors Affecting the Rate of Photosynthesis Light Intensity 2. Water 3. Carbon dioxide level 4. Temperature 1. 1.) Increasing the level of CO2 tends to increase the rate of photosynthesis. 2.) Limiting the amount of water to the extent of creating drought conditions will limit the amount of photosynthesis. 3.) Increasing temperature from 0ºC to 35ºC tends to increase the rate of photosynthesis. 4.) Increasing temperatures over 35ºC will decrease the rate of photosynthesis. 5.) Increasing light intensity will increase the rate of photosynthesis until a certain light intensity is reached, after this intensity is reached, increasing the light intensity will have no effect on the photosynthesis rate. Adaptations for Photosynthesis A. Unicellular Organisms 1. Almost all chlorophyll-containing unicellular organisms are aquatic (live in water) 2. The raw materials for photosynthesis are absorbed directly from the water and into the cell Ex: algae B. Terrestrial Plants (land-dwelling) 1. Occurs in leaves that provide the maximum surface area for the absorption of light Cross section of Leaf 1. Outer most layer is the epidermis which is covered by a waxy coat called the cuticle – which prevents excess water loss 2. Stomates- allows the exchange of O2 and CO2 between the leaf and the external environment 3. Guard cells- control the opening and closing of the stomates 3. Palisade Layeris where most of photosynthesis takes place 3. Vein- contain xylem and phloem (known as vascular tissue) WHY DO LEAVES CHANGE COLOR IN THE FALL? http://photoscience.la.asu.edu/photosyn/education/colorchange.html (II) Heterotrophic Nutrition These are organisms that can not make their own food Therefore they have to obtain premade organic food from the environment IngestionDigestion Egestion Ingestion The taking in of food into the body Digestion The process by which large molecules are broken down into smaller molecules that can be used by the cells. Types of digestion: 1. 2. Intracellular digestion- takes place inside the cell (no digestive tract) Ex: simple, unicellular organisms and plants Extracellular digestion- takes place outside of the cell and usually in a digestive tract Ex: animals Mechanical digestion- the increase in surface area of food by physically grinding and cutting food into smaller pieces Ex: chewing food with teeth 4. Chemical digestion- Large food molecules are broken down into smaller ones by the use of enzymes (Hydrolysis) 3. What type of digestion would this be? Adaptations for Heterotrophic Nutrition Fungi Live in or on their food source (substrate). Have specialized structures called rhizoids that grow into the food. Protozoa In the Ameba, food is ingested by the process of phagocytosis (engulfing of food). Phagocytosis is accomplished by using an extension of the cell called the pseudopod. Figure 28.26 Use of pseudopodia for feeding In the Paramecium, food is brought into the cell by the beating action of the cilia. The cilia directs food particles into the oral groove (“mouth”). In both the ameba and the paramecium, digestion is intracellular and takes place within the food vacuole. Food is ingested through the mouth with the aid of tentacles. Extracellular digestion takes place in the cavity with the aid of enzymes secreted by the cell layers of the hydra. Undigested food is egested through the mouth of the hydra. The hydra has a two-way digestive tract. (think of a two-way street; food goes in one way, it is digested, and wastes make a “U-E” and back out of the mouth). Hydra Earthworm Food is ingested through the mouth. Food is temporarily stored in the crop. Gizzard- breaks down the food mechanically by grinding. Intestine- where chemical digestion occurs and nutrients are absorbed. Anus- undigested materials are egested (eliminated) out. The earthworm has a one-way digestive tract (think one-way street, food in one way and out one way). Grasshopper Basically the same as the earthworm. Mouth contains specialized mouthparts for chewing. Chemical digestion is aided by salivary glands and the gastric caeca, which secretes enzymes into the digestive tract. The grasshopper also has a one-way digestive tract (mouth anus). Chemosynthesis A type of autotrophic nutrition Does not require light as an energy source Energy is obtained from inorganic molecules that seep out of the deep ocean crust. Bacteria use these molecules to form organic molecules. Found in deep ocean thermal vents Tube worms