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22: Gymnosperms - Biology

22: Gymnosperms - Biology


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Learning Objectives

Content Objectives

  • Understand the changing conditions on Earth during the period in which gymnosperms evolved and how those conditions selected for features found in this group.
  • Learn the characteristics that distinguish gymnosperms from SVPs
  • Connect what you have learned about secondary growth and xerophytic leaf anatomy to gymnosperm structure
  • Learn the life cycle of pines

Skill Objectives

  • Correlate features of gymnosperm morphology and life history traits with adaptation to the changing environment
  • Identify structures involved in the gymnosperm life cycle and describe their functions
  • Distinguish between different groups of gymnosperms
  • Distinguish between gymnosperms and SVPs, particularly ferns and cycads

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26.2 Gymnosperms

By the end of this section, you will be able to do the following:

  • Discuss the type of seeds produced by gymnosperms, as well as other characteristics of gymnosperms
  • Identify the geological era dominated by the gymnosperms and describe the conditions to which they were adapted
  • List the four groups of modern-day gymnosperms and provide examples of each
  • Describe the life cycle of a typical gymnosperm

Gymnosperms , meaning “naked seeds,” are a diverse group of seed plants. According to the "anthophyte" hypothesis, the angiosperms are a sister group of one group of gymnosperms (the Gnetales), which makes the gymnosperms a paraphyletic group. Paraphyletic groups are those in which not all descendants of a single common ancestor are included in the group. However , the "netifer" hypothesis suggests that the gnetophytes are sister to the conifers, making the gymnosperms monophyletic and sister to the angiosperms. Further molecular and anatomical studies may clarify these relationships. Characteristics of the gymnosperms include naked seeds, separate female and male gamtophytes, pollen cones and ovulate cones, pollination by wind and insects, and tracheids (which transport water and solutes in the vascular system).

Gymnosperm seeds are not enclosed in an ovary rather, they are only partially sheltered by modified leaves called sporophylls . You may recall the term strobilus (plural = strobili) describes a tight arrangement of sporophylls around a central stalk, as seen in pine cones. Some seeds are enveloped by sporophyte tissues upon maturation. The layer of sporophyte tissue that surrounds the megasporangium, and later, the embryo, is called the integument .

Gymnosperms were the dominant phylum in the Mesozoic era. They are adapted to live where fresh water is scarce during part of the year, or in the nitrogen-poor soil of a bog. Therefore, they are still the prominent phylum in the coniferous biome or taiga, where the evergreen conifers have a selective advantage in cold and dry weather. Evergreen conifers continue low levels of photosynthesis during the cold months, and are ready to take advantage of the first sunny days of spring. One disadvantage is that conifers are more susceptible than deciduous trees to leaf infestations because most conifers do not lose their leaves all at once. They cannot, therefore, shed parasites and restart with a fresh supply of leaves in spring.

The life cycle of a gymnosperm involves alternation of generations, with a dominant sporophyte in which reduced male and female gametophytes reside. All gymnosperms are heterosporous. The male and female reproductive organs can form in cones or strobili. Male and female sporangia are produced either on the same plant, described as monoecious (“one home” or bisexual), or on separate plants, referred to as dioecious (“two homes” or unisexual) plants. The life cycle of a conifer will serve as our example of reproduction in gymnosperms.

Life Cycle of a Conifer

Pine trees are conifers (coniferous = cone bearing) and carry both male and female sporophylls on the same mature sporophyte. Therefore, they are monoecious plants. Like all gymnosperms, pines are heterosporous and generate two different types of spores (male microspores and female megaspores). Male and female spores develop in different strobili, with small male cones and larger female cones. In the male cones, or staminate cones, the microsporocytes undergo meiosis and the resultant haploid microspores give rise to male gametophytes or “pollen grains” by mitosis. Each pollen grain consists of just a few haploid cells enclosed in a tough wall reinforced with sporopollenin. In the spring, large amounts of yellow pollen are released and carried by the wind. Some gametophytes will land on a female cone. Pollination is defined as the initiation of pollen tube growth. The pollen tube develops slowly, and the generative cell in the pollen grain produces two haploid sperm or generative nuclei by mitosis. At fertilization, one of the haploid sperm nuclei will unite with the haploid nucleus of an egg cell.

Female cones, or ovulate cones , contain two ovules per scale. Each ovule has a narrow passage that opens near the base of the sporophyll. This passage is the micropyle, through which a pollen tube will later grow. One megaspore mother cell, or megasporocyte , undergoes meiosis in each ovule. Three of the four cells break down only a single surviving cell will develop into a female multicellular gametophyte, which encloses archegonia (an archegonium is a reproductive organ that contains a single large egg). As the female gametophyte begins to develop, a sticky pollination drop traps windblown pollen grains near the opening of the micropyle. A pollen tube is formed and grows toward the developing gametophyte. One of the generative or sperm nuclei from the pollen tube will enter the egg and fuse with the egg nucleus as the egg matures. Upon fertilization, the diploid egg will give rise to the embryo, which is enclosed in a seed coat of tissue from the parent plant. Although several eggs may be formed and even fertilized, there is usually a single surviving embryo in each ovule. Fertilization and seed development is a long process in pine trees: it may take up to two years after pollination. The seed that is formed contains three generations of tissues: the seed coat that originates from the sporophyte tissue, the gametophyte tissue that will provide nutrients, and the embryo itself.

Figure 26.8 illustrates the life cycle of a conifer. The sporophyte (2n) phase is the longest phase in the life of a gymnosperm. The gametophytes (1n)—produced by microspores and megaspores—are reduced in size. It may take more than a year between pollination and fertilization while the pollen tube grows towards the growing female gametophyte (1n), which develops from a single megaspore. The slow growth of the pollen tube allows the female gametophyte time to produce eggs (1n).


Gymnosperm Life Cycle

The gymnosperms are classified into four separate divisions, viz. the Coniferophyta, Gnetophyta, Cycadophyta and Ginkgophyta. Of these, the Coniferophyta represents the largest group. Similar to other evolved plants, alternation of generations are present in the life cycle of gymnosperms. Two different forms that alternate each other are the spore bearing plant (sporophyte) and gamete bearing structure (gametophyte). The former is the dominant one and lasts for a longer period than the gametophyte phase in the gymnosperm life cycle. For simple understanding, you can study the life cycle of spruce or pine.

Sporophyte: Spore-bearing Phase

The sporophyte phase represents the adult, photosynthetic, diploid gymnosperm plant that produces the male cones (or pollen cones) and the female cones (ovulate cones). The former is usually smaller than the latter one. They develop in the same plant (monoecious) or different plants (dioecious). When present in the same plant, the female cones or strobili are produced in the upper part of branches, while the pollen cones are found in the lower portion. The sporophylls of the male strobili bear microspores, while that of the female cones form megaspores.

Gametophyte: Gamete-producing Phase

The microspores give rise to microgametophytes (haploid male gametophytes) or pollen grains after undergoing meiosis. Similarly, the megaspores borne on the ovulate strobili develop into megagametophytes (haploid female gametophytes). Both these gametophytes are short-lived, and end with production of sperm cells by male gametophyte and egg cells by the female gametophyte. Thus, male cones produce pollen grains and the female cones bear eggs. While they depend on the sporophyte plant for nutrition, the female gametophyte remains attached to it until fertilization takes place and seeds disperse.

The production of sperm cells and egg cells is followed by pollination process. Pollination of gymnosperms takes place by means of winds and natural agents. Over here, the pollen grains containing the sperm cells are carried to the female gametophyte of the ovulate cones by wind or insects. Once pollens are carried to the ovules, closure of the female cone takes place for an extended period (say till the next year). In the mean time, pollen grains germinate to form pollen tubes, which take about a year and make their way to the female gametophyte for fertilization.

The pollen tube delivers sperm cells to fertilize the egg, which in turn results into a sporophyte. Thus, the time period between pollination and fertilization in gymnosperms is quite long, about a year. This newly formed sporophyte is enclosed in a seed in the form of an embryo. When favorable conditions arrive, the scale bearing the seeds separate and the seeds are dispersed by means of wind and rain. They are disseminated to various places, where sporophytes germinate and develop into new photosynthetic, diploid plants. This way, the life cycle of gymnosperms begins with the spore producing mother plant, which alternates with the short gametophyte generation.

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Biology of Organisms

SEED plants………
Gymnosperms & the Angiosperms
xxxxx
Seed = A ready to go ‘baby plant!’ along with a food supply,
w/protective coat, (multicellular and more complex) seed can travel further and withstand harsher conditions (than non-seed spore).
Allowed for their ‘domestication’
Gametophytes we can not easily see…..
xxxxxx
Advantage tiny gametophyte?
Sporophyte –dominant generation, with a much reduced, dependent, (mostly MICROSCOPIC) gametophyte………..
Advantage is to have the female gametophyte be protected (living off the sporophyte) – instead of off on its own.
xxxxxx
Other seed plant traits:
Unlike the seedless plants that produce only one type of spore which creates both male and female gametophytes (homospory) …..
SEED PLANTS are HETEROSPOROUS – two diff types of spores, from diff places: microspores>>male g’phyte (pollen grain) AND megaspores>>>female g’phyte
Female’s ‘OVULE’ = megaspore + megasporangium + integument
xxxxxx
POLLINATION… transfer of pollen to female
Seed created after fertilization (pollen grain delivers sperm via tube to egg produced by female gametophyte)
xxxxxx
The Gymnosperms
Naked seeds – [b/c they’re unlike Angiosperm seeds which are covered by fruit / ovary]
Seeds on modified leaves(woody parts of cone)
xxxxx
Include 4 phyla : Coniferophyta, Cycadophyta, Ginkgophyta, Gnetophyta
xxxxx
Coniferophyta - CONIFERS
Pines, firs, & redwoods, cypress (LARGE!)
Most ‘evergreens’ ….Juniper w/blueberries?
Shhhh !! Oldest living tree secret :4,600yrs –bristlecone pine in White Mountains, CA
XXXXXXX
Life cycle ….Sporophyte w/ Ovulate & Pollen cone, Megasporangium>megasporocytes & Microsporangium>microsporocytes MEIOSIS , pollen grains, Pollination, MEIOSIS, megaspore, fertilization = SEED(time, conditions, germinate) >>SEEDLING…..Sporophyte (FIG 30.6)
XXXXXXX note- you should have rec'd an email of a diagram of clarification of
what this info, above means.

Cycadophyta - CYCADS
LARGE cones
Palm-like leaves
xxxxxx
Ginkgophyta
Ginkgo Biloba aka Maidenhair Tree is the ONLY SPECIES of this phyla
Ornamental usage / deciduous leaves
Plant only male trees, b/c female seeds terrible smell (

stinkgophyta!!)
xxxxxx
Gnetophyta
Ex: Ephedra (desert shrub) "Mormon tea" produces EPHEDRINE decongest. Also for stimulant, concentration, weight loss………………….. ADDICTIONS??
xxxxxxx
(NO COPY):Try to get sudafed lately? (not responsible for info on this act of 2005!!)
The House passed the Combat Methamphetamine Epidemic Act of 2005 as an amendment to the renewal of the USA PATRIOT Act. Signed into law by president George W. Bush on March 6, 2006, the act amended the US Code (21 USC 830) concerning the sale of ephedrine-containing products. The federal statute included the following requirements for merchants who sell these products:
A retrievable record of all purchases identifying the name and address of each party to be kept for two years.
Required verification of proof of identity of all purchasers
Required protection and disclosure methods in the collection of personal information
Reports to the Attorney General of any suspicious payments or disappearances of the regulated products
Non-liquid dose form of regulated product may only be sold in unit dose blister packs
Regulated products are to be sold behind the counter or in a locked cabinet in such a way as to restrict access
Daily sales of regulated products not to exceed 3.6 grams without regard to the number of transactions
Monthly sales not to exceed 9 grams of pseudoephedrine base in regulated products
The law gives similar regulations to mail-order purchases, except the monthly sales limit is only 7.5 grams.


Gymnosperms: Free Online Study Materials & Tutorials, Lecture Notes, PPTs, MCQs

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133 Gymnosperms

By the end of this section, you will be able to do the following:

  • Discuss the type of seeds produced by gymnosperms, as well as other characteristics of gymnosperms
  • Identify the geological era dominated by the gymnosperms and describe the conditions to which they were adapted
  • List the four groups of modern-day gymnosperms and provide examples of each
  • Describe the life cycle of a typical gymnosperm

Gymnosperms , meaning “naked seeds,” are a diverse group of seed plants. According to the “anthophyte” hypothesis, the angiosperms are a sister group of one group of gymnosperms (the Gnetales), which makes the gymnosperms a paraphyletic group. Paraphyletic groups are those in which not all descendants of a single common ancestor are included in the group. However , the “netifer” hypothesis suggests that the gnetophytes are sister to the conifers, making the gymnosperms monophyletic and sister to the angiosperms. Further molecular and anatomical studies may clarify these relationships. Characteristics of the gymnosperms include naked seeds, separate female and male gametes, pollination by wind, and tracheids (which transport water and solutes in the vascular system).

Gymnosperm seeds are not enclosed in an ovary rather, they are only partially sheltered by modified leaves called sporophylls . You may recall the term strobilus (plural = strobili) describes a tight arrangement of sporophylls around a central stalk, as seen in pine cones. Some seeds are enveloped by sporophyte tissues upon maturation. The layer of sporophyte tissue that surrounds the megasporangium, and later, the embryo, is called the integument .

Gymnosperms were the dominant phylum in the Mesozoic era. They are adapted to live where fresh water is scarce during part of the year, or in the nitrogen-poor soil of a bog. Therefore, they are still the prominent phylum in the coniferous biome or taiga, where the evergreen conifers have a selective advantage in cold and dry weather. Evergreen conifers continue low levels of photosynthesis during the cold months, and are ready to take advantage of the first sunny days of spring. One disadvantage is that conifers are more susceptible than deciduous trees to leaf infestations because most conifers do not lose their leaves all at once. They cannot, therefore, shed parasites and restart with a fresh supply of leaves in spring.

The life cycle of a gymnosperm involves alternation of generations, with a dominant sporophyte in which reduced male and female gametophytes reside. All gymnosperms are heterosporous. The male and female reproductive organs can form in cones or strobili. Male and female sporangia are produced either on the same plant, described as monoecious (“one home” or bisexual), or on separate plants, referred to as dioecious (“two homes” or unisexual) plants. The life cycle of a conifer will serve as our example of reproduction in gymnosperms.

Life Cycle of a Conifer

Pine trees are conifers (coniferous = cone bearing) and carry both male and female sporophylls on the same mature sporophyte. Therefore, they are monoecious plants. Like all gymnosperms, pines are heterosporous and generate two different types of spores (male microspores and female megaspores). Male and female spores develop in different strobili, with small male cones and larger female cones. In the male cones, or staminate cones, the microsporocytes undergo meiosis and the resultant haploid microspores give rise to male gametophytes or “pollen grains” by mitosis. Each pollen grain consists of just a few haploid cells enclosed in a tough wall reinforced with sporopollenin. In the spring, large amounts of yellow pollen are released and carried by the wind. Some gametophytes will land on a female cone. Pollination is defined as the initiation of pollen tube growth. The pollen tube develops slowly, and the generative cell in the pollen grain produces two haploid sperm or generative nuclei by mitosis. At fertilization, one of the haploid sperm nuclei will unite with the haploid nucleus of an egg cell.

Female cones, or ovulate cones , contain two ovules per scale. Each ovule has a narrow passage that opens near the base of the sporophyll. This passage is the micropyle, through which a pollen tube will later grow. One megaspore mother cell, or megasporocyte , undergoes meiosis in each ovule. Three of the four cells break down only a single surviving cell will develop into a female multicellular gametophyte, which encloses archegonia (an archegonium is a reproductive organ that contains a single large egg). As the female gametophyte begins to develop, a sticky pollination drop traps windblown pollen grains near the opening of the micropyle. A pollen tube is formed and grows toward the developing gametophyte. One of the generative or sperm nuclei from the pollen tube will enter the egg and fuse with the egg nucleus as the egg matures. Upon fertilization, the diploid egg will give rise to the embryo, which is enclosed in a seed coat of tissue from the parent plant. Although several eggs may be formed and even fertilized, there is usually a single surviving embryo in each ovule. Fertilization and seed development is a long process in pine trees: it may take up to two years after pollination. The seed that is formed contains three generations of tissues: the seed coat that originates from the sporophyte tissue, the gametophyte tissue that will provide nutrients, and the embryo itself.

(Figure) illustrates the life cycle of a conifer. The sporophyte (2n) phase is the longest phase in the life of a gymnosperm. The gametophytes (1n)—produced by microspores and megaspores—are reduced in size. It may take more than a year between pollination and fertilization while the pollen tube grows towards the growing female gametophyte (1n), which develops from a single megaspore. The slow growth of the pollen tube allows the female gametophyte time to produce eggs (1n).


SHORT QUESTIONS OF GYMNOSPERMS

Ans: Gymnosperms are naked seeded plants. Gymnosperms are a group of ancient plants. They become dominant in the Jurassic period. Most of the gymnosperms are evergreen trees. Some shrubby plants are also found in this group. They have worldwide distribution. They are most abundant in the temperate region. The fossils of gymnosperms are found near coal and oil deposits.

2. How do fertilization and seed formation occur in gym nos perms?

Ans: Pollen tube carries male gametes to egg (oosphere). Fertilization occurs and diploid oospore is formed. Oospore is the beginning of gametophyte generation. The oospore gives rise to the embryo. Prothalial tissues provide nourishment to developing embryo. Integument is transformed into the seed coat The unutilized prothalial cell becomes endosperm.

3. What is meant by Ferns with seeds?

Ans: The primitive gymnosperms like Cycas are much identical with Pteridophytes (ferns). They were taken as Pteridophytes for long time. They were called Ferns with seeds.

4. Give two resemblances between gymnosperms and pteridophytes.

Ans: Both have regular alternation sporophytic and the gametophytic generations. Their sporophyte is dominant and forms the main plant body. Gametophyte is reduced to prothellus. Both are heterosporous

5. Give two differences between gymnosperms and pteridophytes.

Ans: There is no seed formation in the Pteridophytes. But present in gymnosperms. The male cells or sperms are carried by pollen-tube to the archegonia in the gymnosperms. But pollen tube is absent in Pteridophytes.

6. Give two similarities between gymnosperms and angiosperms.

Ans: They are similar in their external morphology, i.e., the
differentiation into root stem and leaves. Both have identical internal anatomy. Cambium is present in gymnosperm and dicot angiosperms.

7. Give two differences between gymnosperms and angiosperms.
Ans: The reproductive structures of angiosperms are flowers, those of gymnosperms are cones. In angiosperms, the seeds are enclosed by true carpels and at maturity, a carpel forms a fruit. It is absent in gymnosperms.
8. Name of order of gymnosperms.
Ans: Cycadofilicales, Bennettitales, Cycadales, Cordaitales, Ginokoales and Gnetales.

9. Which plant is called living fossil? Why?

Ans: Cycas is called a living fossil. It has several characters
common with the Ptcridophytes.

10. What are coralloid roots? Give their advantage to plant.

Ans: Cycas produces coralloid roots. Coralloid roots are short tufts and dichotomously branched roots. These roots contain an endophytic alga in the inner part of their cortex. Sometimes, bacteria are also present in the cortex. Bacteria fix nitrogen.

11. What are transfusion tissues? Give their function.

Ans: Transfusion tissues are present around mid ribs. They cause lateral conduction in the leaf.
12. How is microspore germinate in Cycas?

Ans: The microspore cut off lateral prothalial cell towards one side of the spore. The larger cell then cuts off a small generative cell adjacent to the plothalial cell. It itself becomes tube cell. The microspore is liberated at this stage. Spores are dispersed by wind.

13. How does fertilization occur in Cycas?

Ans: Pollen grain reaches the archegonial chamber by pollination.
The wall of the pollen grain protrudes towards the archegonial chamber. The pollen grain bursts and release antherozoids into the archegonial chamber. Antherozoid enters the oosphere. Male nucleus unites with the oosphere nucleus. Fertilized oosphere secretes a thick wall and becomes the oospore. Oospore develops embryo.

14. Give occurrence and common species of pinus.

Ans: The genus Pinus has about 90 species. It has world wide in distribution. They are mostly present in the temperate regions. Four species of pinus are found in Pakistan: Pinus wallichiana Pinus halepensis Pinus roxburghii Pinus gerardiana.


22: Gymnosperms - Biology

Mechel Golenberke: My First Website

Biology II &ndash Chapter 22 Plan: Introduction to Plants

22.1 What is a Plant & 22.2 Seedless Plants

Describe what plants need to survive

Describe how the first plants evolve

Explain the process of alternation of generation

Identify the characteristics of green algae

Describe the adaptations of bryophytes

Explain the importance of vascular tissue

answer questions on video &ndash move to lab table for answers

Labs: Comparing Algae & Plants Bryophytes & Ferns

Distinguish among unicellular, filamentous, and colonial forms of organization.

Locate and identify chloroplasts, holdfasts, and pyrenoids of various species of algae.

Examine an example of nonvascular plants: liverworts

Identify and study the structure and function of liverwort parts

Examine an example of nonvascular plants: mosses

Identify and study the structure and function of liverwort parts

Observe reproductive structures in a moss

Trace the life cycle of a moss

Demonstrate the absorptive ability of sphagnum moss

Examine an example of vascular plants: ferns

Identify and study the structure and function of fern parts

Explain the reproductive pattern of ferns

22.3 Seed Plants &ndash Gymnosperms

1. Biology Junction Gymnosperms & Angiosperms (NO QUESTION GUIDE) (124 slides) (1-41 Gymnosperms only)

answer questions on video &ndash move to lab table for answers

Describe the reproductive adaptations of seed plants

Identify the reproductive structures of gymnosperms

Gymnosperm Reproduction Lab

1. Reproductive Structures of Gymnosperms Lab

To describe the general features of gymnosperms

To understand the life cycles of gymnosperms

To identify the significant features of the life cycles for various gymnosperms and state the particular evolutionary importance

To be able to differentiate between representative organisms in each group: pine, cycad, ginkgo, Ephedra and Welwitschia.

22.4 Flowering Plants & Reproductive Structures of Angiosperms

1. Biology Junction Gymnosperms & Angiosperms (NO QUESTION GUIDE) (124 slides) (42-124 Angiosperms only)


CBSE Class 11 Biology Syllabus 2021-22 (New): CBSE Academic Session 2021-22

Check CBSE Class 11 Biology Syllabus 2021-22 (New). It is applicable for CBSE Academic Session 2021-22.

Check CBSE Class 11 Biology Syllabus 2021-22 (New). This CBSE Syllabus 2021-22 for Class 11 Biology is applicable for CBSE Academic Session 2021-22. The link to download this CBSE Class 11 Biology Syllabus is given at the end of this article.

CBSE Class 11 Biology Syllabus 2021-22

Theory: Time: 03 Hours, Max. Marks: 70

Diversity of Living Organisms

Structural Organization in Plants and Animals

Cell: Structure and Functions

Unit-I Diversity of Living Organisms

Chapter-1: The Living World

What is living? Biodiversity Need for classification taxonomy and systematics concept of species and taxonomic hierarchy binomial nomenclature tools for study of taxonomy- museums, zoological parks, herbaria, botanical gardens, keys for identification.

Chapter-2: Biological Classification

Five kingdom classification Salient features and classification of Monera, Protista and Fungi into major groups Lichens, Viruses and Viroids.

Salient features and classification of plants into major groups - Algae, Bryophyta, Pteridophyta, Gymnosperms and Angiosperms (salient and distinguishing features and a few examples of each category): Angiosperms - classification up to class, characteristic features and examples. Plant life cycles and alternation of generation

Basis of Classification Salient features and classification of animals, non-chordates up to phyla level and chordates up to class level (salient features and distinguishing features of a few examples of each category).

(No live animals or specimens should be displayed in school.)

Unit-II Structural Organization in Plants and Animals

Chapter-5: Morphology of Flowering Plants

Morphology and modifications: Morphology of different parts of flowering plants: root, stem, leaf, inflorescence, flower, fruit and seed. Description of families: Fabaceae, Solanaceae and Liliaceae (to be dealt along with the relevant experiments of the Practical Syllabus).

Chapter-6: Anatomy of Flowering Plants

Anatomy and functions of different tissues and tissue systems in dicots and monocots. Secondary growth.

Chapter-7: Structural Organisation in Animals

Animal tissues Morphology, Anatomy and functions of different systems (digestive,

circulatory, respiratory, nervous and reproductive) of an insect-cockroach (a brief account only).

Unit-III Cell: Structure and Functions

Chapter-8: Cell-The Unit of Life

Cell theory and cell as the basic unit of life, structure of prokaryotic and eukaryotic cells Plant cell and animal cell cell envelope cell membrane, cell wall cell organelles - structure and function endomembrane system- endoplasmic reticulum, ribosomes, golgi bodies, lysosomes, vacuoles mitochondria, plastids, microbodies cytoskeleton, cilia, flagella, centrioles (ultrastructure and function) nucleus.

Chemical constituents of living cells: biomolecules, structure and function of proteins, carbohydrates, lipids, nucleic acids concept of metabolism Enzymes - properties, enzyme action, factors, classification, Co-factors.

Chapter-10: Cell Cycle and Cell Division

Cell cycle, mitosis, meiosis and their significance

Chapter-11: Transport in Plants

Movement of water, gases and nutrients cell to cell transport - diffusion, facilitated diffusion, active transport plant-water relations, imbibition, water potential, osmosis, plasmolysis long distance transport of water - Absorption, apoplast, symplast, transpiration pull, root pressure and guttation transpiration, opening and closing of stomata Uptake and translocation of mineral nutrients - Transport of food, phloem transport, mass flow hypothesis.

Chapter-12: Mineral Nutrition

Elementary idea of hydroponics as a method to study mineral nutrition essential minerals, macro- and micronutrients and their role deficiency symptoms mineral toxicity nitrogen metabolism, nitrogen cycle, biological nitrogen fixation.

Chapter-13: Photosynthesis in Higher Plants

Photosynthesis as a means of autotrophic nutrition early experiments, site of photosynthesis, pigments involved in photosynthesis (elementary idea) photochemical and biosynthetic phases of photosynthesis cyclic and non-cyclic photophosphorylation chemiosmotic hypothesis photorespiration C3 and C4 pathways factors affecting photosynthesis.

Chapter-14: Cellular Respiration

Exchange of gases do plants breathe cellular respiration - glycolysis, fermentation (anaerobic), TCA cycle and electron transport system (aerobic) energy relations - number of ATP molecules generated amphibolic pathways respiratory quotient.

Chapter-15: Plant - Growth and Development

Seed germination characteristics, measurements and phases of plant growth, growth rate conditions for growth differentiation, dedifferentiation and redifferentiation sequence of developmental processes in a plant cell growth regulators - auxin, gibberellin, cytokinin, ethylene, ABA seed dormancy vernalisation photoperiodism.

Chapter-16: Digestion and Absorption

Alimentary canal and digestive glands, role of digestive enzymes and gastrointestinal hormones Peristalsis, digestion, absorption and assimilation of proteins, carbohydrates and fats egestion nutritional and digestive disorders - indigestion, constipation, vomiting, jaundice, diarrhoea.

Chapter-17: Breathing and Exchange of Gases

Introduction to respiratory organs in animals Respiratory system in humans mechanism of breathing and its regulation in humans - exchange of gases, transport of gases and regulation of respiration, respiratory volumes disorders related to respiration - asthma, emphysema, occupational respiratory disorders.

Chapter-18: Body Fluids and Circulation

Composition of blood, blood groups, coagulation of blood composition of lymph and its function circulatory pathways human circulatory system - Structure of human heart and blood vessels cardiac cycle, cardiac output, ECG double circulation regulation of cardiac activity disorders of circulatory system - hypertension, coronary artery disease, angina pectoris, heart failure.

Chapter-19: Excretory Products and their Elimination

Modes of excretion - ammonotelism, ureotelism, uricotelism human excretory system – structure and function urine formation, osmoregulation regulation of kidney function - renin - angiotensin, atrial natriuretic factor, ADH, diabetes insipidus micturition role of other organs in excretion disorders - uremia, renal failure, renal calculi, nephritis dialysis and artificial kidney, kidney transplant.

Chapter-20: Locomotion and Movement

Types of movement – amoeboid, ciliary, flagellar, muscular types of muscles skeletal muscle, contractile proteins and muscle contraction skeletal system and its functions joints disorders of muscular and skeletal systems - myasthenia gravis, tetany, muscular dystrophy, arthritis, osteoporosis, gout.

Chapter-21: Neural Control and Coordination

Neuron and nerves Nervous system in humans - central nervous system and peripheral nervous system generation, conduction and transmission of nerve impulse reflex action sensory perception sense organs elementary structure and functions of eye and ear.

Chapter-22: Chemical Coordination and Integration

Endocrine glands and hormones human endocrine system - hypothalamus, pituitary, pineal, thyroid, parathyroid, thymus, adrenal, pancreas, gonads hormones of heart, kidney and gastrointestinal tract mechanism of hormone action (elementary idea) role of hormones as messengers and regulators, hypo - and hyperactivity and related disorders dwarfism, acromegaly, cretinism, goiter, exophthalmic goiter, diabetes, Addison's disease.

Note: Diseases related to all the human physiological systems to be taught in brief.


Materials and Methods

A list of all gymnosperm species was obtained from the Royal Botanic Gardens, Kew online resource “World Checklist of Selected Plant Families” 17 . Available DNA sequence data for gymnosperms for the plastid regions rbcL, matK, rpoC, rps4, and trnL, as well as the nuclear marker PHYP, were obtained from GenBank and downloaded using the data-mining tool SUMAC 54 (data accessed on 3 rd March 2016). Forty-one taxa of angiosperms and fifteen ferns and their allies were also included in our analyses as outgroup taxa. Regions were selected based on the level of coverage they achieved either across gymnosperms as a whole or with a focus on particular lineages. Details of species sampled for each region (including GenBank accession numbers) are listed in Supplementary Table S1.

To increase taxonomic coverage, we obtained sequence data for the plastid rbcL exon (ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit) for 129 species, of which 35 were for species otherwise not represented in the data set. DNA was isolated using a modified version of the 2× CTAB method 55 and subsequently purified on a caesium chloride/ethidium bromide gradient (1.55 g/ml density) to yield material suitable for long-term storage in the DNA & Tissue Collections at the Royal Botanic Gardens, Kew (http://apps.kew.org/dnabank/homepage.html). PCR amplifications were performed using primer combinations from Olmstead and colleagues 56 . PCR reactions were made with the ReddyMix PCR Master Mix from ABgene (2.5 mM MgCl2 Epsom, Surrey, UK) with the addition of 1 μl of bovine serum albumin 0.4% and 50 ng of each primer, in a final volume of 25 μl. The amplification cycle started with 2 min initial denaturation at 94 °C, followed by 32 cycles of 1 min denaturation at 94 °C, 1 min annealing at 48 °C, 1.5 min extension at 72 °C, and a final extension of 3 min at 72 °C. After purification with the Nucleospin Extract II kit (Machery-Nagel, Duren, Germany), cycle sequencing reactions were performed in 10 μl reactions using 1 μl of BigDye® Terminator cycle sequencing chemistry (v3.1 ABI Warrington, Cheshire, UK) and run on ABI 3730 automated sequencer. Geneious 57 (version 7.1.2) was used to assemble complementary strands and verify base-calling.

Sequences of each region were compiled in Geneious 57 (version 7.1.2) and aligned using the MUSCLE 58 algorithm. All partitions were concatenated using an R script (S. Buerki, pers. comm.) and all subsequent analyses were performed on the resulting supermatrix. A phylogenetic tree was reconstructed using the maximum likelihood (ML) criterion as implemented in the software RAxML (v. 8.2.8 59 ) on the CIPRES portal (www.phylo.org) with 1,000 rapid bootstrap replicates followed by the search of the best ML tree. The GTRCAT model was used and all the other parameters were set as default settings. All fifteen ferns and allies were designated as outgroup taxa (e.g. 20,22 ).

Several attempts to obtain an ultrametric tree using the Bayesian approach implemented in the package BEAST 60 were unsuccessful. Constraining the topology to the ML tree obtained from the software RAxML, thus allowing only the optimisation of branch lengths alone, was also unsatisfactory. In all cases, the analyses failed to converge on a single solution and the majority of effective sample size values were consistently below the threshold of 200. We thus opted to transform the ML phylogenetic tree of gymnosperms into an ultrametric tree using the programme treePL 61 , which implements the penalized likelihood method 62 . The default cross validation procedure was performed and identified 0.1 as the most appropriate smoothing value. A set of 15 calibration points based on fossils used by previous studies and molecular estimates from a recent study of cycads were applied (see Supplementary Table S2). Outgroup taxa were pruned from the tree prior to the calculation of ED scores.

Despite having a reasonably good species coverage in our phylogenetic analysis (i.e. ca 85%), incomplete sampling could potentially biased EDGE rankings, thus we used the following approach to add to our ultrametric tree the 167 species for which no suitable sequence data was available for the markers used here. We used the function add.species.to.genus from the R 63 package phytools 64 and the option “random”, which add randomly the missing species to their respective genera, while retaining the ultrametricity of the tree. We performed this step 100 times to assess how the random position assigned to each species within its genus affects the ED and EDGE values, and the resulting EDGE ranks.

ED scores for all species of gymnosperms were obtained using the 100 ultrametric trees and were inferred using the function evol.distinct from the R 63 package picante 65 . The median value of all 100 resulting ED values for each species was compiled and used to produce the EDGE scores. Probability of extinction assessments were obtained from the IUCN Red List (www.iucnredlist.org, version 2015.4 accessed on 29 th April 2016). These assessments were converted into probabilities of species extinction using two probability of extinction transformations, the original logarithmic transformation of Isaac and colleagues 10 , and the IUCN50 probability transformation proposed by Mooers and colleagues 30 . EDGE scores were subsequently calculated using the median ED value by implementing the EDGE equations in an R 63 script. Species that were Data Deficient (DD) or Not Evaluated (NE) were scored as Critically Endangered. Threatened species (i.e. those assigned CR, EN, VU, as well as DD and NE) were ranked by decreasing ED scores to provide a classification conservation priority species less dependent on the transformation of probability of extinction.

The gymnosperm species with the top 100 EDGE values obtained with the ISAAC transformation together with their ED scores were compared to those of amphibians, mammals and bird (obtained from www.edgeofexistence.org) using boxplots produced in R 63 . We compared the effect of probability of extinction transformations (IUCN50 vs. ISAAC) on the overall EDGE species ranking by plotting the difference in species rankings using the IUCN50 transformation as reference negative values indicate that the IUCN50 transformation prioritize a given species over the ISAAC transformation, whereas positive values denote the opposite. Differences in EDGE species rankings were plotted using R 63 and each species was coloured according to its IUCN Red List category. To assess the effect of ED on EDGE species ranking, boxplots of ED values for the species prioritized by each transformation were also produced in R 63 . A difference of ranking between plus or minus 10 was considered equivalent for the boxplot (following 30 ). A figure displaying the gymnosperm dated tree together with EDGE values (inferred using the IUCN50 transformation) and IUCN Red List assessments was produced in R 63,64 . The GSA geological time scale was used to set boundaries between geological periods 66,67 .

To map gymnosperm diversity, data from the World Checklist of Selected Plant families 17 (accessed 30 August 2016) were matched to the Taxonomic Databases Working Group (TDWG) geographical scheme level 3 geography 68 . Data was displayed and processed in ArcGIS 10.1 69 , using the Winkel I projection orientated around the date line (180 degrees) and to give an interpretable and reproducible map, colours were derived from Color Brewer 70 . To evaluate if the mapped ranking follows what is expected by chance, we used Exact Binomial Test performed in R 63 against the top 100 EDGE species using the IUCN50 transformation, assuming that the number of top 100 species in each TDWG level 3 region is expected to be proportional to the observed total number (species richness). We repeated the same analysis with the top 100 ED threatened species. The overall result (all TDWG regions) was not significant, but was highly significant for some of the individual TDWG regions, with either more or fewer species than expected by chance (see Fig. 3A).


Watch the video: GYMNOSPERM PLANTS Characteristics, Examples, Reproduction and more! (June 2022).


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