DOCSLIB.ORG

YEAR 9 BIOLOGY TIME: 2 Hours

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
YEAR 9 BIOLOGY TIME: 2 Hours DEPARTMENT FOR CURRICULUM, LIFELONG LEARNING AND EMPLOYABILITY Directorate for Learning and Assessment Programmes Track 2 Educational Assessment Unit Annual Examinations for Secondary Schools 2019 YEAR 9 BIOLOGY TIME: 2 hours Name: _____________________________________ Class: _________________________ Section A Section B Question No. 1 2 3 4 5 6 7 1 2 3 4 5 Max 6 9 8 11 8 7 6 15 15 15 15 15 mark TOTAL Actual MARK mark 85% Theory Paper 15% Practical 100% Final Score Biology – Year 9 – Track 2 – 2019 Page 1 of 12 Section A: This section carries 55 marks. Answer all questions in this section. 1. Figure 1 shows an animal cell and an enlarged diagram of one organelle labelled ‘organelle A’. organelle A Figure 1 a. Identify ‘organelle A’. ___________________________________________________________ (1) b. Describe the function of ‘organelle A’. ___________________________________________________________ (1) c. Name one plant cell that would benefit from having a very large number of these organelles. Provide a reason for your answer. ___________________________________________________________ ___________________________________________________________ (2) d. Explain why observing this organelle with a light microscope is limited. ___________________________________________________________ ___________________________________________________________ (2) [Total: 6 marks] Page 2 of 12 Biology – Year 9 – Track 2 – 2019 2. While Buskett is known for its diversity of plants, various fungi such as different species of mushrooms also grow in this habitat. a. An important biological difference between plants and fungi is in the cell wall. State the difference between the cell walls of fungi and plant cells. ___________________________________________________________ ___________________________________________________________ (2) b. Figure 2 includes five photos of different species of mushrooms that grow at Buskett. One of them, Suillus collinitus, is a mushroom that uses the ground next to pine trees as its substrate and has a mutualistic relationship with this tree. It has a short swollen stem. Its top part (fruiting body) is chunky and rather flat or slightly rounded as opposed to other mushrooms that have a pointy (umbrella-like) fruiting body. i. Using the information above, identify the photo that is showing the mushroom Suillus collinitus. ___________________________________________________________ (1) A B C D E Figure 2 ii. Define the term ‘mutualistic relationship’. ___________________________________________________________ (1) Biology – Year 9 – Track 2 – 2019 Page 3 of 12 iii. Pine trees are gymnosperms. Describe their reproductive structures. ___________________________________________________________ ___________________________________________________________ (2) c. Oranges that fall from trees at Buskett are often attacked by moulds which are filamentous forms of fungi. Describe the typical structure of a filamentous fungus and explain how it feeds. ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ (3) [Total: 9 marks] 3. A newly discovered organism (Figure 3), found in a cave in China, has an elongated head with no eyes. It has one pair of thin and very long antennae attached. Its thorax is also elongated and has six long and slender legs. a. Name the phylum and the class into which this organism should be classified. _____________________________________ _____________________________________ (2) b. Give one reason for your answer. _____________________________________ _____________________________________ (1) c. This organism consists of three segments. Name another segment of this organism apart from the head and the thorax. _____________________________________ (1) d. Provide a possible biological reason why this source:https://www.ncbi.nlm.nih.gov/pmc/ organism has evolved a head with no eyes. articles/PMC5769675/figure/F1/?report=obje ctonly Figure 3 ___________________________________________________________ ___________________________________________________________ (2) e. This organism undergoes ‘complete metamorphosis’. Describe the life cycle of an organism that undergoes complete metamorphosis. ___________________________________________________________ ___________________________________________________________ (2) [Total: 8 marks] Page 4 of 12 Biology – Year 9 – Track 2 – 2019 4. a. Oily skin results when sebaceous glands produce an excess amount of sebum. This flows from inside the epidermis to the surface of the skin through pores and hair follicles. i. Figure 4 is a diagram showing the cross-section of the human skin. On this diagram label the epidermis, the sebaceous gland and the hair follicle. (3) Figure 4 ii. Explain the function of sebum in human skin. ___________________________________________________________ (1) b. Figure 5 is a skin care product that treats oily skin by entering pores to remove extra sebum and dead skin cells. i. Explain the importance of the skin having a first layer of dead skin cells. ______________________________________________ ______________________________________________ (2) ii. Being acidic, these products can cause a burning sensation. Name the skin structures that sense this stimulus. Figure 5 ______________________________________________ (1) c. The skin has a thermoregulatory function. Explain, giving full biological details, the role of the skin in maintaining a constant body temperature. ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ (4) [Total: 11 marks] Biology – Year 9 – Track 2 – 2019 Page 5 of 12 5. Figure 6 shows a plant growing in a room with no other sources of light except for one window. window source: https://www.thoughtco.com Figure 6 a. i. Describe the growth pattern shown by the plant. ___________________________________________________________ (1) ii. Name the biological process that produces this growth pattern in the shoot. ___________________________________________________________ (1) b. Explain how this biological process brings about the growth pattern described. ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ (4) c. Explain how this biological function is beneficial to plants. ___________________________________________________________ ___________________________________________________________ (2) [Total: 8 marks] Page 6 of 12 Biology – Year 9 – Track 2 – 2019 6. Euglena, which is a fresh water protist, and an adult frog are inhabiting the same pond. a. Name the process by which the Euglena’s cell membrane and the frog’s skin exchange gases with the surrounding environment. ___________________________________________________________ (1) b. Explain why the frog has lungs to assist with oxygen uptake whenever the skin cannot cope, while the Euglena can rely completely on its cell membrane. ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ (3) c. i. Specialised cells in some frogs’ skin can release poisons that deter predators. Explain the term ‘specialised cells.’ ___________________________________________________________ (1) ii. Give one example of a specialised cell in animals. ___________________________________________________________ (1) d. Being plant-like, Euglena can feed autotrophically. Name an organelle which is only present when an organism feeds autotrophically. ___________________________________________________________ (1) [Total: 7 marks] Biology – Year 9 – Track 2 – 2019 Page 7 of 12 7. Figure 7 shows two plants: a bryophyte and a pteridophyte. A pteridophyte, growing vertically from the ground. A bryophyte, spreading horizontally over the ground. source: https://www.coolgalapagos.com/biology/classification_plants.php Figure 7 a. i. Explain why the pteridophyte can afford to grow taller than the bryophyte. ___________________________________________________________ ___________________________________________________________ (2) ii. Give one advantage that the pteridophyte has over the bryophyte by growing taller. ___________________________________________________________ (1) b. i. Pteridophytes can limit water loss, while bryophytes cannot. Mention one feature of pteridophytes that allows them to control water loss. ___________________________________________________________ (1) ii. Give one advantage that pteridophytes have over bryophytes by being able to control water loss. ___________________________________________________________ ___________________________________________________________ (2) [Total: 6 marks] Page 8 of 12 Biology – Year 9 – Track 2 – 2019 Section B: This section carries 45 marks. Answer any three questions in this section. Write your answers on the separate A4 sheet provided. 1. The sources of plant disease may be abiotic or biotic. Examples of abiotic plant diseases include damage caused by growth in poor light, moisture or temperature conditions. Many biotic diseases are caused by bacteria that are microscopic, single-celled prokaryotic organisms and which are able
Load more

Recommended publications
  • General Botany Lab Review Fungi, Algae, Bryophytes, Ferns & Fern Allies
    General Botany Lab Review Fungi, Algae, Bryophytes, Ferns & Fern Allies You have looked at a lot of stuff – both live and via prepared slides. You’ve also labeled at least one Life Cycle Diagram for each of the groups. Know what your benchmarks are for a general life cycle diagram and be able to label them. I will not ask you to identify anything to species or genus; be able to identify things to “group” (i.e., ascomycete, bryophyta, etc.) Be able to identify growth form (e.g., unicell, filamentous, etc.). Recognize the differences between sexual and asexual reroductive structures. All questions will be multiple choice. Material looked at: UNIT 1: FUNGI EXERCISE 1: CHYTRIDS/ CHYTRIDOMYCOTA: Allmyces arbusculus – life and prepared slides EXERCISE 2: ZYGOMYCETES/ ZYGOMYCOTA: Rhizopus stolonifer – live and prepared slides EXERCISE 2: MYCORRHIZA and the GLOMEROMYCETES/ GLOMEROMYCOTA – prepared slides only EXERCISE 3: ASCOMYCETES/ ASCOMYCOTA Aspergillus sp., Penicillium sp., Saccharomyces cerevisiae, Peziza sp., Sordaria fimicola, and Morchella sp. – a mixture of live and prepared materials EXERCISE 4: BASIDIOMYCETES/BASIDIOMYCETES Agaricus, Coprinus, Cronartium (a rust), Ustilago (a smut) – slides, fresh, and dried EXERCISE 5: SLIME MOLDS – live and prepared Physarum EXERCISE 6: LICHENS – live and prepared slides be able to identify the various growth forms UNIT 2: ALGAE EXERCISE 1: CYANOBACTERIA Anabaena sp., Nostoc, and Oscillaroria – live and prepared material EXERCISE 2: SUPERGROUP EXCAVATA (Phylum Euglenophyta) – live and prepared material
    [Show full text]
  • XI MOBILE NO:9340839715 CHAPTER-3 Plant Kingd
    NAME OF THE TEACHER: SR. RENCY GEORGE SUBJECT: BIOLOGY TOPIC: CHAPTER -1 CLASS: XI MOBILE NO:9340839715 CHAPTER-3 Plant Kingdom Objectives :- Observe plants closely to notice features and characteristics of growth and development. Observe and identify differences in plants and animals. Observe similarities among plants (seeds, roots, stems, leaves, flowers, fruit) Learning Strategies:- • Explain Different systems of Classification. • Differentiate between Artificial and Natural System of Classification. • Explain Algae and its significance. • Differentiate between various classes of Algae. • Explain various modes of reproduction in Algae. RESOURCES: i.Text books ii.Learning Materials iii.Lab manual iv.E-Resources,video ,L.C.D etc… CLICK HERE TO PLAY CONTENT RELATED VIDEO ON YOU TUBE. https://youtu.be/SWlVX1gDd98 https://youtu.be/P_MyyxIQzm4 https://youtu.be/KmbFGIiwP4k https://youtu.be/mepU8gStVpg https://youtu.be/fnE01M0YlTc https://youtu.be/xir7xvLi8XE Contents Introduction Plant kingdom includes algae, bryophytes, pteridophytes, gymnosperms and angiosperms. ... Depending on the type of pigment possessed and the type of stored food, algae are classified into three classes, namely Chlorophyceae, Phaeophyceae and Rhodophyceae. Eukaryotic, multicellular, chlorophyll containing and having cell wall, are grouped under the kingdom Plantae. It is popularly known as plant kingdom. • Phylogenetic system of classification based on evolutionary relationship is presently used for classifying plants. • Numerical Taxonomy use computer by assigning code for each character and analyzing the features. • Cytotaxonomy is based on cytological information like chromosome number, structure and behaviour. • Chemotaxonomy uses chemical constituents of plants to resolve the confusion. Algae: These include the simplest plants which possess undifferentiated or thallus like forms, reproductive organs single celled called gametangia.
    [Show full text]
  • Introduction to the Cell Cell History Cell Structures and Functions
    Introduction to the cell cell history cell structures and functions CK-12 Foundation December 16, 2009 CK-12 Foundation is a non-profit organization with a mission to reduce the cost of textbook materials for the K-12 market both in the U.S. and worldwide. Using an open-content, web-based collaborative model termed the “FlexBook,” CK-12 intends to pioneer the generation and distribution of high quality educational content that will serve both as core text as well as provide an adaptive environment for learning. Copyright ©2009 CK-12 Foundation This work is licensed under the Creative Commons Attribution-Share Alike 3.0 United States License. To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/us/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA. Contents 1 Cell structure and function dec 16 5 1.1 Lesson 3.1: Introduction to Cells .................................. 5 3 www.ck12.org www.ck12.org 4 Chapter 1 Cell structure and function dec 16 1.1 Lesson 3.1: Introduction to Cells Lesson Objectives • Identify the scientists that first observed cells. • Outline the importance of microscopes in the discovery of cells. • Summarize what the cell theory proposes. • Identify the limitations on cell size. • Identify the four parts common to all cells. • Compare prokaryotic and eukaryotic cells. Introduction Knowing the make up of cells and how cells work is necessary to all of the biological sciences. Learning about the similarities and differences between cell types is particularly important to the fields of cell biology and molecular biology.
    [Show full text]
  • The Associations Between Pteridophytes and Arthropods
    FERN GAZ. 12(1) 1979 29 THE ASSOCIATIONS BETWEEN PTERIDOPHYTES AND ARTHROPODS URI GERSON The Hebrew University of Jerusalem, Faculty of Agriculture, Rehovot, Israel. ABSTRACT Insects belonging to 12 orders, as well as mites, millipedes, woodlice and tardigrades have been collected from Pterldophyta. Primitive and modern, as well as general and specialist arthropods feed on pteridophytes. Insects and mites may cause slight to severe damage, all plant parts being susceptible. Several arthropods are pests of commercial Pteridophyta, their control being difficult due to the plants' sensitivity to pesticides. Efforts are currently underway to employ insects for the biological control of bracken and water ferns. Although Pteridophyta are believed to be relatively resistant to arthropods, the evidence is inconclusive; pteridophyte phytoecdysones do not appear to inhibit insect feeders. Other secondary compounds of preridophytes, like prunasine, may have a more important role in protecting bracken from herbivores. Several chemicals capable of adversely affecting insects have been extracted from Pteridophyta. The litter of pteridophytes provides a humid habitat for various parasitic arthropods, like the sheep tick. Ants often abound on pteridophytes (especially in the tropics) and may help in protecting these plants while nesting therein. These and other associations are discussed . lt is tenatively suggested that there might be a difference in the spectrum of arthropods attacking ancient as compared to modern Pteridophyta. The Osmundales, which, in contrast to other ancient pteridophytes, contain large amounts of ·phytoecdysones, are more similar to modern Pteridophyta in regard to their arthropod associates. The need for further comparative studies is advocated, with special emphasis on the tropics.
    [Show full text]
  • Pteridophyte Fungal Associations: Current Knowledge and Future Perspectives
    This is a repository copy of Pteridophyte fungal associations: Current knowledge and future perspectives. White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/109975/ Version: Accepted Version Article: Pressel, S, Bidartondo, MI, Field, KJ orcid.org/0000-0002-5196-2360 et al. (2 more authors) (2016) Pteridophyte fungal associations: Current knowledge and future perspectives. Journal of Systematics and Evolution, 54 (6). pp. 666-678. ISSN 1674-4918 https://doi.org/10.1111/jse.12227 © 2016 Institute of Botany, Chinese Academy of Sciences. This is the peer reviewed version of the following article: Pressel, S., Bidartondo, M. I., Field, K. J., Rimington, W. R. and Duckett, J. G. (2016), Pteridophyte fungal associations: Current knowledge and future perspectives. Jnl of Sytematics Evolution, 54: 666–678., which has been published in final form at https://doi.org/10.1111/jse.12227. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version - refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher’s website.
    [Show full text]
  • Curitiba, Southern Brazil
    data Data Descriptor Herbarium of the Pontifical Catholic University of Paraná (HUCP), Curitiba, Southern Brazil Rodrigo A. Kersten 1,*, João A. M. Salesbram 2 and Luiz A. Acra 3 1 Pontifical Catholic University of Paraná, School of Life Sciences, Curitiba 80.215-901, Brazil 2 REFLORA Project, Curitiba, Brazil; [email protected] 3 Pontifical Catholic University of Paraná, School of Life Sciences, Curitiba 80.215-901, Brazil; [email protected] * Correspondence: [email protected]; Tel.: +55-41-3721-2392 Academic Editor: Martin M. Gossner Received: 22 November 2016; Accepted: 5 February 2017; Published: 10 February 2017 Abstract: The main objective of this paper is to present the herbarium of the Pontifical Catholic University of Parana’s and its collection. The history of the HUCP had its beginning in the middle of the 1970s with the foundation of the Biology Museum that gathered both botanical and zoological specimens. In April 1979 collections were separated and the HUCP was founded with preserved specimens of algae (green, red, and brown), fungi, and embryophytes. As of October 2016, the collection encompasses nearly 25,000 specimens from 4934 species, 1609 genera, and 297 families. Most of the specimens comes from the state of Paraná but there were also specimens from many Brazilian states and other countries, mainly from South America (Chile, Argentina, Uruguay, Paraguay, and Colombia) but also from other parts of the world (Cuba, USA, Spain, Germany, China, and Australia). Our collection includes 42 fungi, 258 gymnosperms, 299 bryophytes, 2809 pteridophytes, 3158 algae, 17,832 angiosperms, and only one type of Mimosa (Mimosa tucumensis Barneby ex Ribas, M.
    [Show full text]
  • The Structure, Function, and Biosynthesis of Plant Cell Wall Pectic Polysaccharides
    Carbohydrate Research 344 (2009) 1879–1900 Contents lists available at ScienceDirect Carbohydrate Research journal homepage: www.elsevier.com/locate/carres The structure, function, and biosynthesis of plant cell wall pectic polysaccharides Kerry Hosmer Caffall a, Debra Mohnen a,b,* a University of Georgia, Department of Biochemistry and Molecular Biology and Complex Carbohydrate Research Center, 315 Riverbend Road Athens, GA 30602, United States b DOE BioEnergy Science Center (BESC), 315 Riverbend Road Athens, GA 30602, United States article info abstract Article history: Plant cell walls consist of carbohydrate, protein, and aromatic compounds and are essential to the proper Received 18 November 2008 growth and development of plants. The carbohydrate components make up 90% of the primary wall, Received in revised form 4 May 2009 and are critical to wall function. There is a diversity of polysaccharides that make up the wall and that Accepted 6 May 2009 are classified as one of three types: cellulose, hemicellulose, or pectin. The pectins, which are most abun- Available online 2 June 2009 dant in the plant primary cell walls and the middle lamellae, are a class of molecules defined by the pres- ence of galacturonic acid. The pectic polysaccharides include the galacturonans (homogalacturonan, Keywords: substituted galacturonans, and RG-II) and rhamnogalacturonan-I. Galacturonans have a backbone that Cell wall polysaccharides consists of -1,4-linked galacturonic acid. The identification of glycosyltransferases involved in pectin Galacturonan a Glycosyltransferases synthesis is essential to the study of cell wall function in plant growth and development and for maxi- Homogalacturonan mizing the value and use of plant polysaccharides in industry and human health.
    [Show full text]
  • An Illustrated Guide to the WETLAND FERNS and FERN ALLIES of FLORIDA John David Tobe, Ph.D
    INDEX TO FAMILIES OF FLORIDA WETLAND FERN AND FERN ALLIES ASPLENIACEAE 15 ATHYRIACEAE 22 AZOLLACEAE 25 BLECHNACEAE 26 DENNSTAEDITACEAE 30 DRYOPTERIDACEAE 32 EQUISETACEAE 36 GLEICHENIACEAE 37 HYMENOPHYLLACEAE 38 ISOËTACEAE 40 LYCOPODIACEAE 41 LYGODIACEAE 43 MARSILEACEAE 45 NEPHROLEPIDACEAE 47 OPHIOGLOSSACEAE 49 OSMUNDACEAE 53 PARKERIACEAE 55 POLYPODIACEAE 56 PSILOTACEAE 58 PTERIDACEAE 59 SALVINIACEAE 65 SCHIZAEACEAE 66 SELAGINELLACEAE 67 TECTARIACEAE 69 THELYPTERIACEAE 71 An Illustrated Guide to the WETLAND FERNS and FERN ALLIES of FLORIDA John David Tobe, Ph.D. First Edition Illustrated and Written by John David Tobe Copyright © 2019 John David Tobe All rights reserved under International and Pan-American Copyright Conventions. No part of this book may be reproduced in any form or by any means without permission in writing from John David Tobe. CONTENTS INTRODUCTION ............................................................................... 1 The Natural History of Ferns and Fern Allies ...................................... 3 Fern Life Cycle ..................................................................................... 4 Pteridophyte Structural Terminology ................................................... 5 Fern Leaf Types .................................................................................... 7 Illustrated Key to the Pteridophytes of Florida .................................... 8 DESCRIPTIVE PTERIDOPHYTE FLORA Illustrated Ferns and Fern Allies ..................................................... 9-78 INDEX
    [Show full text]
  • Plant:Animal Cell Comparison
    Comparing Plant And Animal Cells http://khanacademy.org/video?v=Hmwvj9X4GNY Plant Cells shape - most plant cells are squarish or rectangular in shape. amyloplast (starch storage organelle)- an organelle in some plant cells that stores starch. Amyloplasts are found in starchy plants like tubers and fruits. cell membrane - the thin layer of protein and fat that surrounds the cell, but is inside the cell wall. The cell membrane is semipermeable, allowing some substances to pass into the cell and blocking others. cell wall - a thick, rigid membrane that surrounds a plant cell. This layer of cellulose fiber gives the cell most of its support and structure. The cell wall also bonds with other cell walls to form the structure of the plant. chloroplast - an elongated or disc-shaped organelle containing chlorophyll. Photosynthesis (in which energy from sunlight is converted into chemical energy - food) takes place in the chloroplasts. chlorophyll - chlorophyll is a molecule that can use light energy from sunlight to turn water and carbon dioxide gas into glucose and oxygen (i.e. photosynthesis). Chlorophyll is green. cytoplasm - the jellylike material outside the cell nucleus in which the organelles are located. Golgi body - (or the golgi apparatus or golgi complex) a flattened, layered, sac-like organelle that looks like a stack of pancakes and is located near the nucleus. The golgi body modifies, processes and packages proteins, lipids and carbohydrates into membrane-bound vesicles for "export" from the cell. lysosome - vesicles containing digestive enzymes. Where the digestion of cell nutrients takes place. mitochondrion - spherical to rod-shaped organelles with a double membrane.
    [Show full text]
  • Chloroplasts Are the Food Producers of the Cell. the Organelles Are Only Found in Plant Cells and Some Protists Such As Algae
    Name: ___________________________ Cell #2 H.W. due September 22nd, 2016 Period: _________ Chloroplasts are the food producers of the cell. The organelles are only found in plant cells and some protists such as algae. Animal cells do not have chloroplasts. Chloroplasts work to convert light energy of the Sun into sugars that can be used by cells. It is like a solar panel that changes sunlight energy into electric energy. The entire process is called photosynthesis and it all depends on the little green chlorophyll molecules in each chloroplast. In the process of photosynthesis, plants create sugars and release oxygen (O2). The oxygen released by the chloroplasts is the same oxygen you breathe every day. Chloroplasts are found in plant cells, but not in animal cells. The purpose of the chloroplast is to make sugars that feed the cell’s machinery. Photosynthesis is the process of a plant taking energy from the Sun and creating sugars. When the energy from the Sun hits a chloroplast and the chlorophyll molecules, light energy is converted into the chemical energy. Plants use water, carbon dioxide, and sunlight to make sugar and oxygen. During photosynthesis radiant energy or solar energy or light energy is transferred into chemical energy in the form of sugar (glucose). You already know that during photosynthesis plants make their own food. The food that the plant makes is in the form of sugar that is used to provide energy for the plant. The extra sugar that the plant does not use is stored as starch for later use. Mitochondria are known as the powerhouses of the cell.
    [Show full text]
  • Plastid in Human Parasites
    SCIENTIFIC CORRESPONDENCE being otherwise homo­ Plastid in human geneous. The 35-kb genome-containing organ­ parasites elle identified here did not escape the attention of early Sm - The discovery in malarial and toxo­ electron microscopists who plasmodial parasites of genes normally - not expecting the pres­ occurring in the photosynthetic organelle ence of a plastid in a proto­ of plants and algae has prompted specula­ zoan parasite like tion that these protozoans might harbour Toxoplasma - ascribed to it a vestigial plastid1• The plastid-like para­ various names, including site genes occur on an extrachromosomal, 'Hohlzylinder' (hollow cylin­ maternally inherited2, 35-kilobase DNA der), 'Golgi adjunct' and circle with an architecture reminiscent of 'grof3e Tilkuole mit kriiftiger that of plastid genomes3•4• Although the Wandung' (large vacuole 35-kb genome is distinct from the 6-7-kb with stout surrounds) ( see linear mitochondrial genome3-6, it is not refs cited in ref. 9). Our pre­ known where in the parasite cells the plas­ liminary experiments with tid-like genome resides. Plasmodium falciparum, the To determine whether a plastid is pre­ causative agent of the most sent, we used high-resolution in situ lethal form of malaria, hybridization7 to localize transcripts of a identify an organelle (not plastid-like 16S ribosomal RNA gene shown) which appears sim­ from Toxoplasma gondii8, the causative ilar to the T. gondii plastid. agent of toxoplasmosis. Transcripts accu­ The number of surrounding mulate in a small, ovoid organelle located membranes in the P. anterior to the nucleus in the mid-region falciparum plastid, and its of the cell (a, b in the figure).
    [Show full text]
  • Lesson 1: Plant Cells
    LESSON 1: PLANT CELLS LEVEL 1 What is a plant? A quick answer might be “something that is green and has leaves.” But are all plants green? There’s a type of maple tree that has purplish-red leaves. Obviously it is a plant because it is a tree. So being green can’t be a requirement for being a plant, though most plants are indeed green. What about leaves? Do all plants have leaves? Think about a cactus. Do those sharp needles count as leaves? Or what about the “stone plant”? It looks like a rock. (No kidding--it really does!) What makes a plant a plant? The answer is... a plant is a plant because it can make its own food using a process called photosynthesis. Plants can use the energy from sunlight to turn water and carbon dioxide into sugar. (“Photo” means “light,” and “synthesis” means “make.”) Wouldn’t it be nice if you could make your own food from sunlight? No more going to the grocery store or planting a garden. You could just stand in the sunshine, take a deep breath, drink a glass of water, and make your own food. Sounds funny, but that’s exactly what plants do. They take water from the ground, carbon dioxide from the air, and energy from light and turn them into food. Photosynthesis is a very complicated chemical process. The exact details of how a plant takes apart the molecules of water and carbon dioxide and turns them into sugar is so complicated that you need a college degree in chemistry to really understand it.
    [Show full text]