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cells. Instead the Aseptate hypha Septate hypha protoplasm is either continuous or is interrupted Nuclei Septum at intervals by cross walls (Coenocytic) Fig : 1.11. Coenocytic hypha and septate hypha called septa which divide the hyphae into compartments similar to cells. Thus hyphae may be aseptate(hyphae without cross walls) or septate (hyphae with cross walls).When aseptate they are coenocytic containing many nuclei. Each hypha has a thin rigid wall, whose chief component is chitin, a nitrogen containing polysaccharide also found in the exoskeleton of arthropods. Within the cytoplasm the usual eukaryotic organelles are found such as mitochondria, golgi-apparatus, endoplasmic reticulum, ribosomes and vacuoles. In the older parts, vacuoles are large and cytoplasm is confined to a thin peripheral layer. Nutrition Fungi are heterotrophic in their mode of nutrition that is they require an organic source of carbon. In addition they require a source of nitrogen, usually organic substances such as amino acids. The nutrition of fungi can be described as absorptive because they absorb nutrients directly from outside their bodies. This is in contrast to animals which normally ingest food and then digest it within their bodies before absorption takes place. With fungi, digestion is external using extracellular enzymes. Fungi obtain their nutrients as saprotrophs,parasites or symbionts. Saprotrophs A saprotroph is an organism that obtains its food from dead and decaying matter. It secretes enzymes on to the organic matter so that digestion is outside the organism. Soluble products of digestion are absorbed and assimilated within the body of the saprotroph. Saprotrophic fungi and bacteria constitute the decomposers and are essential in bringing about decay and recycling of nutrients. They produce humus from animal and plant remains. Humus, a part of soil, is a layer of decayed organic matter containing many nutrients. Some important fungi are the few species that secrete the enzyme cellulase which breaks down cellulose. Cellulose being an important structural component of plant cell walls, rotting of wood and other plant remains is achieved by these decomposers secreting cellulases. Parasites A parasite is an organism that lives in or on another organism, the host from which it obtains its food and shelter. The host usually belongs to a different 32
species and suffers harm from the parasite. Parasites which cause diseases are called pathogens. Some parasites can survive and grow only in living cells and are called biotrophs or Obligate Parasites. Others can infect their host and bring about it’s death and then live saprotrophically on the remains, they are called necrotrophs or facultative parasites. Fungal parasites may be facultative or obligate and more commonly attack plants than animals. The hyphae penetrate through stomata, or enter directly through the cuticle or epidermis or through wounds of plants. Inside the plant hosts, the hyphae branch profusely between cells, sometimes producing pectinases(enzymes) which digest the middle lamellae of the cell walls. Subsequently the cells may be killed with the aid of toxins and cellulases which digest the cell walls. Cell constituents may be absorbed directly or digested by the secretion of further fungal enzymes. Obligate parasites often possess specialized penetration and absorption devices called haustoria. Each haustorium is a modified hyphal outgrowth with a large surface area which pushes into living cells without breaking their plasma membrane and without killing them. Haustoria are rarely produced by facultative parasites. Symbiosis : Two important types of symbiotic union are made by fungi. 1. Lichens and 2. Mycorrhizae. Lichens They are symbiotic association found between algae and fungi. The alga is usually a green alga or blue green alga. The fungus is an ascomycete or basidiomycete. It is believed that the alga contributes organic food from photosynthesis and the fungus is able to absorb water and mineral salts. The fungus can also conserve water and this enables some lichens to grow in extreme dry conditions where no other plants can exist. Mycorrhizae These are symbiotic associations between a fungus partner and roots of <strong>higher</strong> plants. Most land plants enter into this kind of relationship with soil fungi. The fungus may form a sheath around the center of the root (an ectotrophic mycorrhiza) or may penetrate the host tissue (an endotrophic mycorrhiza). The former type is found in many forest trees such as conifers,beech and oak and involve the fungi of the division basidiomycetes. The fungus receives carbohydrates and vitamins from the tree and in return breaks down proteins of the soil humus to amino acids which can be absorbed and utilized by the plant. In addition the fungus provides a greater surface area for absorption of ions such as phosphates. Classification of Fungi 33
Page 1 and 2: BOTANY HIGHER SECONDARY - FIRST YEA
Page 3 and 4: PREFACE We are passing through an "
Page 5 and 6: Unit 5 : Plant Physiology (30 hours
Page 7 and 8: 5. Physiology Experiments 5..1 Tran
Page 9 and 10: III. PLANT MORPHOLOGY .............
Page 11 and 12: Diversity in living organisms I. BI
Page 13 and 14: the fossil records which form the b
Page 15 and 16: Other colorless forms ingest small
Page 17 and 18: 2. Their mode of nutrition is heter
Page 19 and 20: Difficulties in classification Sinc
Page 21 and 22: Introduction 2. Salient Features of
Page 23 and 24: Structure of a virus A virus is com
Page 25 and 26: 4. Bacteriophages Virus that infect
Page 27 and 28: the Diptheria bacillus which is det
Page 29 and 30: It has created panic among the peop
Page 31 and 32: Two Marks 1. Justify: Viruses are b
Page 33 and 34: C. Tetracocci: Cells divide in two
Page 35 and 36: Acetobacteria and Lactobacillus are
Page 37 and 38: 2. Transduction : Donor DNA is carr
Page 39 and 40: 2. Vinegar Vinegar (Acetic acid) is
Page 41: 2.3 Fungi Conventionally Fungi have
Page 45 and 46: Mucor Rhizopus Sporangium Spores Sp
Page 47 and 48: organisms play an important role in
Page 49 and 50: 2.3.1 Mucor Division : Eumycota Sub
Page 51 and 52: As a consequence, the sporangium bu
Page 53 and 54: Fig.1.20 Life-Cycle of Mucor SELF E
Page 55 and 56: 2.4 Algae Salient Features Algae ar
Page 57 and 58: The yellow, orange or red coloured
Page 59 and 60: 1. Pigmentation 2. Reserve food 3.
Page 61 and 62: It is used in sound and fire proof
Page 63 and 64: 2.4.1 Spirogyra Class : Chlorophyce
Page 65 and 66: (c) By aplanospores During unfavour
Page 67 and 68: Fig.1.28 Schematic representation o
Page 69 and 70: 2.5 Bryophytes There are fossil rec
Page 71 and 72: the dominant generation in the top
Page 73 and 74: 2.5.1 Riccia Class : Hepaticae Orde
Page 75 and 76: Chlorophyllous tissue The dorsal re
Page 77 and 78: Structure of mature archegonium Mat
Page 79 and 80: to form a diploid zygote which grow
Page 81 and 82: 2.6. Pteridophytes This division in
Page 83 and 84: Ferns represent a more specialized
Page 85 and 86: 2.6.1 Nephrolepsis Division : Trach
Page 87 and 88: The vascular cylinder is diarch and
Page 89 and 90: Each mature archegonium is differen
Page 91 and 92: 2.7 Spermatophytes (Gymnosperms) Th
Page 93 and 94:
5. The sporophyte bears two types o
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SELF EVALUATION One Mark Fill in th
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Normal roots: The long-lived primar
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lignified and pitted cell walls. Th
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The vascular bundles are arranged i
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Reproduction : Cycas reproduces by
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(anemophyllous). Further developmen
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Fertilization : The fusion of male
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II. CELL BIOLOGY 1. The Cell - Basi
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Table 2.1 Differences between plant
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2. Cell Theory In the year (1839) S
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3. Prokaryotic and Eukaryotic Cell
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Surrounding the DNA in the darker r
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and size of the chromosomes are the
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air and that is the reason why the
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5.Cell Wall The cells of all plants
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wall is very strongly anisotropic a
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SELF EVALUATION One Mark Choose the
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Lipids The lipid molecules form a c
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The rate of diffusion is directly p
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itself to the other binding site of
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Five Marks 1. List the functions of
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Smooth ER This type of ER does not
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It is formed by a stack of flattene
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Mitochondria A Mitochondrion is als
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Stroma, a semi fluid, colourless, c
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Self Evaluation One Mark Choose the
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In plants, active mitotic cell divi
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Cytokinesis The division of the cyt
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3. Anaphase I 4. Telophase I Propha
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Consequently at each pole only half
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III. PLANT MORPHOLOGY 1. Root, Stem
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4. Zone of cell differentiation : (
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2. Respiratory or breathing roots I
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Vanda Tinospora Leaf Photosynthetic
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Phylloclade: These are green, flatt
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Scale leaf Ginger Bud Potato Eye sp
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VENATION Reticulate Parallel Pinnat
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1.Unipinnate: In Digitate - Bombax
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5. Pitcher In the pitcher plant (Ne
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2. Inflorescence The reproductive o
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Simple Raceme This is a very simple
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is called involucre of bracts from
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Simple Cyme The stem or the axil of
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IV. Special Type of Inflorescence T
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3. Flowers, Fruits and Seeds Struct
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Parts of a flower A typical flower
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coloured and highly developed, whic
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II. Filmbriate: Petals fringed with
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Valvate Twisted Descendingly Imbric
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iii. Gynandrous: Stamens adhere to
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1. Axile Placentation This type of
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iii. Asymmetric: A flower which can
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In these fruits either the entire p
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2. Cremocarp: Fruit is produced fro
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the flowers are sterile and seeds a
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maize grain is yellow in colour and
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Fill in the blanks 1. A special lea
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IV. GENETICS 1. Concept of Heredity
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this concept the progeny of a black
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2. Mendel's Laws of Inheritance Int
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1. It is a naturally self-fertilizi
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Monohybrid Cross (Experiments with
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Dihybrid Cross (Cross involving two
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characters that appear in the F 1 h
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Fill in the blanks 1. The pairs of
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contained as a sequence of nucleoti
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Physical and Chemical Basis of Here
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other and not the alleles. In Mirab
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Epistasis can be of the following t
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White Green P WWYY X wwyy Gametes W
Page 235 and 236:
SELF EVALUATION One Mark Choose the
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