Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chapter 5: Obtaining energy and nutrients for life • • • • • Heterotrophs and autotrophs Autotrophs and photosynthesis Heterotrophs and food The digestive system Digestion in animals Today’s lesson • Heterotrophs and autotrophs • Autotrophs and photosynthesis Autotrophs • Plants • Algae Autotrophs • Soak up sunlight to gain energy they need for living (photosynthesis) • Build their organic matter from simple inorganic matter taken up from their surroundings • Terrestrial autotrophs (air and soil) • Aquatic autotrophs (water) Heterotrophs • All animals • All fungi • Some bacteria Heterotrophs • Obtain energy for living and material for building and repairing their structure from organic matter in their surroundings • Organic matter used by heterotroph is its food Autotrophs and photosynthesis Autotrophs and photosynthesis • Plants algae and some protists (phytoplankton) can make organic molecules (sugar) by photosynthesis • Energy is obtained from sunlight • Organisms that can do this are autotrophic • Photosynthesis occurs in the chloroplasts, found in the cytosol of some cells. Ins and outs of photosynthesis • • Sunlight is converted to chemical energy in sugars 2 sets of reactions 1. First set of reactions depends on the availability of light and presence of chlorophyll 2. Second set of reactions does not depend on light but depends on products from the first set of reactions First set of reactions Sunlight oxygen + hydrogen ions Water + ADP Chlorophyll ADP = Adenosine diphosphate ATP = Adenosin triphosphate + ATP Second set of reactions Carbon dioxide + hydrogen ions + ATP Glucose + ADP ADP = Adenosine diphosphate ATP = Adenosin triphosphate Where does Carbon dioxide come from? Combining the two • ATP and ADP are used during the reactions (chemical energy) End result: Sunlight Carbon dioxide + water Glucose + oxygen Chlorophyll Sunlight 6CO2 + 6H20 C6H12O6 + 6O2 What makes it all happen? • Sunlight provides the energy required to drive the first reaction • The ATP produced from the first reaction is a high-energy compound that provides energy that drives the second set of reactions • This leads to the production of glucose from the carbon dioxide and hydrogen ions Plant structures in relation to photosynthesis • Certain characteristics exist in plants which enable photosynthesis to occur • Leaves, trunk and roots Leaves • Flat shape- provides large surface area exposed to sunlight • Chloroplasts- enables it to trap energy from sunlight • Stomata (pores) on leaf surface provide access into leaf for carbon dioxide • Thinnes- diffusion of carbon dioxide to photosynthetic cells in the leaf tissue • Vascular tissue and xylem vesselstransport water and other compounds Stems • Xylem vessels and fibres give rigidity to a stem and assist upright stance • Branching of stems allows layers of leaves, increasing total surface area • Xylem vessels transport water and minerals from roots to all aerial parts of plant • Phloem transports products of photosynthesis Roots • Extensive root systems taps a significant volume of soil for water and mineral salts • Root hairs- increases area available for absorption of water and mineral salts • Oxygen from air in soil diffuses through root hairs into plants • All the characteristics of leaves, stems and roots ensure that these structures combine to provide the sunlight energy, carbon dioxide and water that a plant requires for photosynthesis • In other words, it enables the plant to get what it needs for the reactions to take place efficiently Summary • Heterotrophs- all animals, fungi, bacteria • Autotrophs- all plants, algae, some bacteria • Autotrophs make their own organic material from inorganic substances (using sunlight) • Heterotrophs rely on food, organic matter • Photosynthesis- converting energy of sunlight to chemical energy in sugars • Raw materials of photosynthesis are carbon dioxide and water, products are sugar and O2 • Structures of various parts of plants maximise plant’s ability to obtain raw materials necessary for photosynthesis