Chapter 1. World Biology PDF

TCE-Anglais Module, is the scientific english taught for SNV L2, composed of several chapters from different disciplines World Biology Microbiology Genetics Biochemistry Immunolog...

TCE-Anglais Module, is the scientific english taught for SNV L2, composed of several chapters from different disciplines World Biology Microbiology Genetics Biochemistry Immunology and Ecology Email: [email protected] Website: http://www.usthb.dz/fbiol/ 1  Chapter I. World Biology Contents INTRODUCTION 1. Definitions 2. Living organisms 3. Classification 4. Organization, structure and functions 5. Different groups of living organisms 5.1. Plants 5.2. Fungi 5.3. Animals 2 INTRODUCTION Biology is the study of living things and their vital processes. The field deals with all the physicochemical aspects of life. The modern tendency toward cross-disciplinary research and the unification of scientific knowledge and investigation from different fields has resulted in significant overlap of the field of biology with other scientific disciplines. Modern principles of other fields for instance: *Chemistry (drugs), * medicine (molecules, functions...), *physics (energy) are included with those of biology in areas such as biochemistry, biomedicine, and biophysics. 1. Definitions 1.1. Biology is a branch of science that deals with living organisms and their vital processes. This branch encompasses several fields, including botany, zoology, ecology, genetics, marine biology, medicine, microbiology, molecular biology. Biology is subdivided into separate branches for convenience of study, though all the subdivisions are interrelated by basic principles. Thus, while it is custom to separate the study of plants (botany) from that of animals (zoology), and the study of the structure of organisms (morphology) from that of function (physiology), all living things share in common certain biological phenomena for example, various means of reproduction, cell division, and the transmission of genetic material. Biology is often approached on the basis of levels that deal with fundamental units of life. At the level of molecular biology, for example, life is regarded as a manifestation of chemical and energy transformations that occur among the many chemical constituents that compose an organism. 1.2. Cell biology is the study of cells, the fundamental units of structure and function in living organisms. Zacharias Janssen invented the microscope around 1590 and cells were first observed in the 17th century. 1.3. Population biology is interested to groups or populations of organisms that inhabit a given area or region. The organisms and populations may be further subdivided for study, giving rise to specializations such as morphology, taxonomy, biophysics, biochemistry, genetics, epigenetics and ecology. A field of biology may be especially concerned with the investigation of one kind of living organisms, for example the study of microorganisms in microbiology, the study of birds in ornithology, the study of fishes in ichthyology etc... 2. Living organisms Concern all organisms that display the key characteristics of life.These characteristics include the ability to grow, to reproduce, take in and use energy, excrete waste, respond to the environment, and possess an organized structure more complex than that of non-living things. 3 The body of all living organisms is made up of one or more cells, which carry out certain basic functions. Thus, cells are called “Basic structural and functional units of living organisms”. 3. Classification All living organisms are classified into groups based on very basic, shared characteristics. Organisms within each group are then further divided into smaller groups. The classification of living things includes 7 levels: kingdom phylum classes order families genus species Nowadays, 3 taxa exist based on RNA 16 S in all living things in the world (Woese et al., 1990): Procarya (or prokarya) with a primitive nucleus, called prokaryotic organisms as Bacteria Archaea, are also unicellular and prokaryotic organisms Eucarya (from Greek eu-, meaning true; carya: nucleus), called eukaryotic organisms. Eucarya is divided into 5 kingdoms (Cavalier-Smith, 1998) Kingdom of Plants Autotrophic with cell wall with cellulose Kingdom of Fungi Saprophytes, symbiotic or parasites, with cell wall with chitin Kingdom of Animalia, consumers with digestive nutritional mode, without cell wall. Kingdom of Chromista, brown line ex. brown algae Kingdom of Chromista, most protists Linnaeus Carl Von (1707-1778) has invented the system of biological taxonomy still used today in biology field. Each plant, animal, bacteria or fungus is identified by a genus and species name. This association of genus and species is named binomial nomenclature written in italic or underlined with Genus beginner by using capital letter (Upper case) and species with small letters (Lower case). 4 4. Organization, structure and functions Unicellular organisms only contain one cell, but multicellular organisms contain many cells that are specialized to perform different functions. Livings organisms include animals, fungi, plants and microorganisms (fig.1). Plants and animals are structured into cells, tissues, organs and organ systems. Cells are the basic structural and functional unit of all life. Examples include red blood cells and nerve cells. Tissues are groups of cells that share a common structure and function and work together. There are four types of human tissues: connective, which connects tissues; epithelial, which lines and protects organs; muscle, which contracts for movement and support and nerve, which responds and reacts to signals in the environment.  Organs are a group of tissues arranged in a specific manner to support a common physiological function. Examples include the brain, liver, and heart.  Organ systems are two or more organs that support a specific physiological function. Examples include the digestive system and central nervous system. There are eleven organ systems in the human body ex. Circulatory, digestive, immune with white blood cells, lymphatic tissue, marrow and others).  Organism is the complete living system capable of conducting all of life’s biological processes. Unicellular organisms Multicellular organisms Bacteria Animal cell Plant cell Figure 1. Cells of living organisms (see: shape and different organelles in each kind of cell) 5 5. Different groups of living organisms Living organisms can be grouped into five main groups called kingdoms: plants, animals, fungi, Protoctista and Monera. The last two are made up of micro- organisms, which are often called microbes, such as bacteria. 5.1. Plants represent the first kingdom of eukaryotic and autotrophic organisms. They are considered as a part of our lives since the beginning of time. From plants, we get vegetables and drugs, which are crucial and beneficial to our health. A plant is a natural autotrophic, multi cell organism with photosynthetic activity. 5.1.1. Plant structure (Fig. 2; Figs 3A and B) Each plant is generally composed of two parts; vegetative and reproductive structures: a/ The vegetative structures, are divided into two organ systems: Shoot system composed of stems and leaves. Root system composed of roots. Figure 2. The shoot and root systems of a plant b/ The reproductive structures, concern flowers, fruits and seeds. A theorical flower is composed from outside to inside of calyx + corolla + stamen + pistil Calyx, the collective name for sepals (∑ sepals) Corolla, is composed of petals (∑ petals) Stamen is consisting of anther and filament Pistil is consisting of stigma, style, and ovary. 6  A. Vegetative structures B. Reproductive structure (flower) Figure 3. Plant parts 5.1.2. Role of plants Most plants, algae and cyanobacteria perform photosynthesis to produce their food and to provide oxygen for all living beings.This process named photosynthesis is a used by plants and other organisms to convert light energy into chemical energy. Plants use energy from the sun to make their own food or energy (starch) and stored. Photosynthesis (fig. 4) is commonly written as: 6CO2 + 6H2O → C6H12O6 + 6O2. This means that the reactants, six carbon dioxide molecules (6CO2) and six water molecules(6H2O) are converted by light energy captured by chlorophyll (implied by the arrow) into a sugar molecule (C6H12O6) and six oxygen molecules(6O2). 6CO2 + 6H2O → C6H12O6 + 6O2 Figure 4. Photosynthesis process in plants 7 5.2. Fungi, is the second kingdom of eukaryotic organisms that include microorganisms such as yeasts, moulds and mushrooms. The organisms found in fungi kingdom contain a cell wall with chitin. They are classified as heterotrophs. Based on nutrition, kingdom fungi can be classified into 3 groups: 1. Saprophytic – The fungi obtain their nutrition by feeding on dead organic substances. Examples: Rhizopus, Penicillium (fig.5) and Aspergillus. Figure 5. Morphological aspect of saprophytic, and microscopic fungus Ex. Penicillium on PDA (Potato Dextrose Agar) medium 2. Parasitic – The fungi obtain their nutrition by living on other living organisms (plants or animals) and absorb nutrients from their hosts. Examples: Taphrina and Puccinia in plants and pathogenic fungi in humans (fig. 6). Figure 6. External morphology of parasitic fungus in humans 3. Symbiotic – These fungi live by having an interdependent relationship association with other species in which both are mutually benefited. Examples: Lichens (fig. 7) and mycorrhiza. Lichens are the symbiotic association between algae and fungi. In this association fungi provide shelter for algae and conversely, algae synthesize carbohydrates for fungi. Figure 7. External morphology of lichen. Ex. Xanthoria parietina (algae+fungi) 8 Fungi (fig. 8) are divided into two parts (cap with gills, stalk or stem with or without ring and hyphae). The mushrooms we eat are generally composed of a stipe (stem), a pileus (cap), and lamellae (gills). Figure 8. Parts of a fungus 5.3. Animalia, is the third kingdom of multicellular eukaryotes. The semi-rigid cell walls found in plants and fungi, which constrain the shape and hence the diversity of possible cell types, are absent in animals. If they were present, mobility would not be possible. Thus, animals are found almost anywhere on Earth where there is life. a/ Classification: In one way or another, we can classify the animals according to the chosen criteria: Number of cells forming the body. Based on this criterion, we can identify (table 1) 2 Sub-Kingdoms: Table 1. Differences between Protozoa and Metazoa Sub-Kingdoms Protozoa Metazoa  Protozoans are unicellular animals.  Metazoans are multicellular animals.  Generally microscopic  Generally seen in naked eyes.  Single cell can perform all sorts of  Body of Metazoa is differentiated into functions like a complete cells which may transform into multicellular organism. tissues, organs and systems in most cases. 9 Presence/ absence of the spine Based on presence/ absence of a backbone (vertebral column or spine), we can identify 2 main groups: - Invertebrates (animals without a backbone).Ex: butterflies, ants, bees. - Vertebrates (animals with a backbone). Ex: fish, amphibians, reptiles, birds and mammals. b/ vertebral column structure and roles The spinal column, is made up of 33 vertebrae, which are grouped into 5 regions (fig.9). Figure 9. Side view of a vertebral column The main functions of the vertebral column are: -Protection of the spinal cord and nerve roots which transfer messages up and down the body. -Enable flexibility and mobility. -Provide structural support and balance to maintain an upright posture. 10  Exercises Exercise 1. Cells are units of life? Exercise 2. Give the scientific names of Wheat semolina and a domestic cat Exercise 3. Calculate the magnification of the microscope Magnification= X. Ocular lens (eye piece). Objective X: Size of sample Weak magnification: X 10. 10 (less power) Strong magnification: X 10. 40 (high power) Strong magnification: X 10. 100 is used for observing very small particles as bacteria … Put the preparation to watch between glass slide and lamella then, calculate the magnification. Exercise 4. According to the pictures above, complete the table with the correct word. Eukaryotic cells Animal cell Plant cell Cell wall Centrioles Chloroplasts Vacuoles 11 Exercise 5. Complete the matching relating each cell structure and organelle with its function in cells cell wall Organelle in which photosynthesis occurs chloroplast Extracellular structure that protects and supports Central Storage of water and other materials in plant cells vacuole Exercise 6. Draw cell including whatever organelles you can see in examining plant cells Exercise 7. Fill in the gaps with a correct word The organisms made up of a single cell, are called………………….………organisms. Ex: Protozoa as Amoeba, Paramecium etc... However, animals made up of more than one cell, are called……………….organisms. Exercise 8. Give a title to the paragraph below What is the main idea of this study? Bring out key words of the text. All living organisms are made of individual and identifiable cells, whose number, together with their size and type, ultimately defines the structure and functions of an organism. Knowing the total cell number of the human body as well as of individual organs is important from a cultural, biological, medical and comparative modeling point of view. Exercise 9. Give a title to the paragraph below What is the main idea of this study? Bring out key words of the text. Common types of cells that many animals have include nerve cells, bone cells, skin cells, stomach cells, liver cells, blood cells and hair cells. However, not all animals have all of the various cell types, as reptiles, for instance, do not have hair cells. However, cells that make blood, nerves and bones are nearly ubiquitous. Animals also produce sex cells, called gametes. 12