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DO NOW Exam 2006. The recovery of the black robin from near extinction is an internationally renowned conservation success story
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DO NOW Exam 2006 • The recovery of the black robin from near extinction is an internationally renowned conservation success story • In 1980 there were only 5 black robins in NZ, with just a single breeding pair left. Today the population is over 250. This has caused changes in the black robin gene pool. • Define the term gene pool • Discuss how this near-extinction affected the gene pool of the black robin and why it is still classified as endangered
Homework • Explain how enzymes function as catalysts • Enzyme activity may be affected by • Temperature • pH • Co-factor/co-enzymes • Inhibitors Discuss how enzyme activity is affected by these factors
DO NOW Exam 2004 • Describe the structure of the cell membrane. You may use labelled diagrams in your answer • Discuss the importance of the cell membrane in maintaining a constant internal environment for the cell
Do NOW • Name two organelles that plants have that animals do not and their function • Define founder effect
Plant Diversity MAH – Year 12 Biology
What you need to know... • How three taxonomic groups of plants reproduce • Compare and contrast the three types • Describe how the plants are adapted for their environment in relation to reproduction
Plant reproduction • Vegetative reproduction (asexual) • Low metabolic cost to the plant • Allows efficient exploitation of the resources in the environment • Does not promote genetic diversity • Environmental change and pathogens present risks • Sexual reproduction: • Promotes genetic diversity in a population • Involves the alternation of generations • High metabolic cost to the plant • Allows species survival in changing environment
REPRODUCTION …is the biological process by which new individual organisms are produced. Genes are passed on to the next generation, which ensures continuation of the species
Alternation of Generations • Variation in plants exists from sexual reproduction • INVOLVES AN ALTERNATION OF GENERATIONS • Involves a haploid stage (n) called gametophyte(gamete producing plant) • Involves a diploid stage (2n) called a sporophyte (spore-producing plant)
Alternation of generations • Sexual reproduction occurs in all types of plants • Involves the “alternation of generations” • Definitions: • Sporophyte = diploid or 2n stage, produces spores by meiosis • Gametophyte= haploid or n stage, produces gametes by mitosis • Spore= haploid structure that develops directly into an organism (the gametophyte) • Gamete = haploid structure that fuses through fertilisation to produce a diploid zygote (the sporophyte)
fuses through fertilisation to produce a diploid zygote that develop directly into an organism (the gametophyte)
Alternation of generations • To do: Stick in the handout and fill in the words • Explain in your own words what is happening
A Spore – some definitions… • A minute, typically one-celled, reproductive unit capable of giving rise to a new individual without sexual fusion, characteristic of lower plants, fungi, and protozoans • (in a plant exhibiting alternation of generations) A haploid reproductive cell that gives rise to a gametophyte
Kingdom Plantae • 1. Bryophytes • Mosses, liverworts and hornworts. liverwort moss hornwort moss
Bryophytes • Lack water gathering roots and specialised vascular tissues for transport • Usually less than 15cm in height but may sprawl over a considerable area • Absorb moisture and minerals through above ground structures via diffusion and therefore grow in moist environments • They do not have roots as such however they are anchored to the substrate they grow in by rhizoids • They have small leaf like structures however they lack the specialised tissues of the true leaf and are only one to a few cells thick. • The body of the plant is designed for storage and support
Bryophyte reproduction • The gametophyte phase dominates • Gametes are produced by mitosis in structures called the antheridium (male) and archegonium (female) • Bi-flagellate sperm are released by the antheridium that swim to the archegonium in the process of fertilisation[No water = No reproduction] • The zygote develops into a sporophyte phase that is often totally dependent on the gametophyte for nutrition • The sporophyte consists of a foot, stalk and single sporangium that produces and spreads spores by meiosis
DO NOW • What is the name of the structure that produces sperm on the male gametophyte of mosses? • Describe two ways in which bryophytes are dependent on liquid water • If you looked at the chromosome numbers of what looked like a complete small moss plant, which part would be diploid and which part haploid?
TO DO • In groups of 3 • Use the play dough to ‘model’ the bryophyte life cycle • You will need to be able to explain it to another group • Include the structures etc..
DO NOW • What is a bryophyte? • Define gametophyte and sporophyte? • What is the cytoplasm?
Plant Group 2 – the Ferns • Ferns are vascular plants that can grow much larger than bryophytes • Presence of vascular system allows internal transport of water and food • Leaves (fronds) are made up of leaflets (pinnae), efficiently capturing light, ferns are often found in lower levels of a forest • Leaves are composed of a variety of different cell types
Reproduction • Spores give rise to bisexual gametophytes. • The spores develop into a flat membranous type structure with rhizoids. The antheridia and archegonia grow on the underside. • The gametophyte contains both the male and female parts (The male part = the antheridia and the female part = archegonia). (ie male and female parts on the same gametophyte) • The antheridia and archegonia mature at different times ensuring cross fertilisation. • Flagellated sperm are produced by the antheridia and therefore requiring water for fertilisation • Fertilisation occurs in the archegonia and development of the sporophyte also occurs here. • Initially the sporophyte receives nutrients form the gametophyte however, it soon becomes photosynthetically independent. • Once the sporophyte is independent, the gametophyte disintegrates
Copy diagram from Board • Diagram also pg. 298 (Bayley) • Once finished you will need to collect a rearrange sentences sheet from Mrs H • Then draw a table that outlines similarities and differences between the reproduction of moss and ferns
Dioecious refers to a plant population having separate male and female plants. • Monoecious, an individual that has both male and female reproductive units on the same plant;
Angiosperms • What are they? • Flower Structure • Male and Female Gametes • Reproductive cycle
Plant group 3 – The Angiosperms • Angiosperms (flowering plants) are the most abundant and successful plant group • 300,000 different species counted so far • Vascular plants with a wide range of sizes, adaptations and habitats
Angiosperms • Angiosperms are the final improvement on plant reproduction; • They grow their seeds inside an ovary; • The ovary is embedded inside a flower; • After fertilisation the flower falls away and the ovary swells to become a fruit.
Flowers • Angiosperm sporophytes produce unique reproductive structures called flowers • Flowers consist of four types of highly modified leaves • Sepals • Petals • Stamen • Pistil (or carpel) • Their site of attachment to the stem is the receptacle Reproduction and Development
Flower Structure Reproduction and Development
Wind Pollinated Flowers • Copy diagram on the board and reasons for the changes
Flower Anatomy • Sepals and petals are nonreproductive organs • Sepals – protect the other three, the floral bud • Petals – attract pollinators and act as “landing pads” Reproduction and Development
Flower Anatomy • Anthers and carpels are male and female reproductive organs, respectively • Anther – consists of filament (long, thin) and anther (pollen) • Carpel – consists of stigma (sticky opening), style (long tube connecting stigma to ovary), ovary (houses ovules; becomes fruit), and ovules (develops female gametes; become seeds) • COPY DIAGRAMS ON BOARD Reproduction and Development
Flower Anatomy • Complete flowers – have all four floral organs • Ex: Trillium • Incomplete flowers – missing one or more of the four floral organs Reproduction and Development
Flower Anatomy • Bisexual flower (perfect flower) is equipped with both stamens and carpals • All complete and many incomplete flowers are bisexual • A unisexual flower is missing either stamens (carpellate flower) or carpels (staminate flower) Reproduction and Development
Unisexual Flowers • Monoecious plants: staminate and carpellate flowers at separate locations on the same individual plant • Ex: corn ears derived from clusters of carpellate flowers; tassels consist of staminate flowers Reproduction and Development
Unisexual Flowers • Dioecious plants: staminate and carpellate flowers on separate plants • Ex: Date palms and Sagittaria (below) have carpellate individuals that produce dates and staminate individuals that produce pollen Reproduction and Development
