3.1 From Algae to Terrestrial Plants Algae are both unicellular and multicellular photosynthetic, aquatic protists -multicellular algae are referred to as seaweed -green alga is considered to be t he evolutionary link between protists and plants -classified into three phyla based on colour: brown ( phaeophyta), red (rhodophyta) and green (chlorophyta) Brown Algae (Phylum Phaeophyta) -large, complex and diverse -kelp can grow up to 60m in height and provides food and shelter to numerous marine organisms -do not have true roots or leaves, instead, they have specialized tissues -a holdfast anchors the algae (similar to roots) -a stipe extends from the holdfast (similar to a stem) -from the stipe, blades grow and are used to collect light, t ake in carbon dioxide and give off oxygen (similar to leaves) Red Algae (Phylum Rhodophyta) -includes 6000 species -one of them appears to be the t he first multicellular species on earth -live on the warm coastal waters at shallow and deep depths -has green chlorophyll -all contain red pigment called phycoerythrin -this pigment allows them to thrive at ocean depths of up to 100m or more -valuable ecologically and economically as food (seaweed) and food additives Green Algae (Phylum Chlorophyta) -live in diverse habitats such as freshwater, saltwater, sea ice, tree surfaces, etc. -are the most plant-like of all the algae -structurally diverse; has both unicellular and multicellular organisms -contain the same type of chlorophyll and colour of most land plants -similar to plants, their cell walls are compromised of cellulose, and also store food re serves in the form of starch The Shift to Land Evidence suggests that green algae and land plants are closely related: -both have chlorophylls a and b in their cells -both have cellulose-based cell walls -both store food as starch -they have shown genetic similarities -green algae use a number of reproductive strategies, such as sexual sporic reproduction (plants use as well) -first terrestrial plants were small, limited by the speed of diffusion to transfer water and dissolved substances throughout the plant -many changes over a long period of time occurred in the evolution of plants -in time, early plants evolved to reproduce with embryos Vascular Tissue, Leaves and Roots -early land plants lacked tissues that transports materials over long distances -eventually, tissues evolved and vascular plants emerged -the phloem tissue transports sugars -the xylem tissue transports water and minerals -xylem is made up of dead tube shaped cells that allows water and minerals to be t ransported throughout the plant called lignin -vascular tissue allowed the evolution of roots, thus providing strong anchoring ability and specialized cells such as the xylem and the phloem Alternation of Generations -plants and green algae use sporic reproduction reproduction meaning there are two multicellular stages in the life cycle -they alternate between the gamete gamet e (haploid) making and the spore (diploid) making cycle -a gamete is a male or female reproductive cell (egg or sperm) -a haploid is a cell or organism that contains half the number of chromosomes (egg/sperm) -a diploid is a cell or organism that contains two sets of chromosomes (fertilized egg)
-the haploid version of the organism is referred to as the gametophyte and produces gametes by mitosis -the diploid version of the organism is referred to as the sporophyte and this happens when the gametes fuse together and form a diploid cell
3.2 The Plant Kingdom -plants can be arranged into a few major groups on a basis of several fundamental characteristics such as the presence or absence of vascular tissues and seeds Non-Vasular Plants: Bryophytes -bryophytes are small, non vascular plants -includes three phyla of plants; mosses, liverworts and hornworts -are dependent on diffusion and osmosis to transport nutrients -grow in mats of low, tangled ve getation that can hold water like a sponge -this allows them to survive in both cold and dry periods -do not have any roots; has root-like str uctures called rhizoids Bryophyte Description Importance Mosses (Phylum Bryophyta)
Liverworts (Phylum Hepatophyta)
Hornworts (Phylum Anthocerophyta)
-short, vertical stems with leaf like structures that are usually only one cell thick -thrive in a variety of ecosystems -second most diverse group of plants (twice as many species of mosses than mammals) -appear as leafy stems or as small, sm all, flattened blades, but like the mosses, they are typically one cell thick -more horizontal growth -grow in moist, shady places on rocks, trees, rotten wood and soil -one chloroplast per cell, similar to algae -sporophyte grows out of the gametophyte as a long horn-like extension -on tree trunks, riverbanks and other damp locations
-the sphagnum moss is sometimes the most abundant biomass in the bogs, the peat accumulated is used in gardens and for burning fuel -Aboriginal peoples used the sphagnum moss to make diapers, mark trails and to clean -one of the first organisms to colonize disturbed areas -help reduce soil erosion and serve as food for animals -are the land plants that are most similar to green algae -play a role in the nutrient cycle within ecosystems -modern hornwort diversity is small; approx 100 species -has pharmaceutical potential
Bryophyte Life Cycle -the haploid gametophyte is the larger, longer-lasting dominant form ONE. -the gametophyte produces sporophytes that grow up on tall stalks above the gametophyte TWO. -inside the end capsule of the sporophyte, the spores produced by meiosis are released -the spores are dispersed with the wind and germinate on the ground -develops into a male or female g ametophyte THREE. -female gametophyte develops an archegonium , a structure that produces eggs -male gametophyte develops an antheridium , the structure that produces sperm FOUR. -the antheridium releases sperm, which swims to the archegonium, where fertilization takes place FIVE. -a zygote (diploid cell formed by the fusion of two gametes) is produced -it undergoes mitosis and forms a new sporophyte
Seedless Vascular Plants -includes whisk ferns, club mosses, horsetails and the ferns -different from non-vascular plants in several ways -developed vascular tissue that allowed them to grow tall -the sporophyte generation is the dominant stage in their life cycle Seedless Vascular Plants Key Features -grows in moist, tropical environments Whisk Ferns -does not have leaves or roots (Phylum Psilotophyta) -photosynthesis in the stem -produces spores which are dispersed by the wind
Club Mosses (Phylum Lycophyta)
-common in moist, woodland environments -have small, needle-like leaves -produce wind-dispersed spores that form in compact clusters of leaves at the end of the stem
Horsetails (Phylum Sphenophyta)
-common in moist tropical and temperate environments -have hollow stems with scale-like leaves that grow from nodes (joints) along the stem -ends of stems produces spores
Ferns (Phylum Pteridophyta)
-common in warm, moist environments but also inhabit cooler, drier habitats -have roots, stems and leaves; leaves are prominent -in most species, leaves first appear in a curled form— a fiddlehead
Additional Facts -only three known species -no fossil record -one species, Psilotum nudum, is cultivated as a greenhouse plant and known for its unusual growth form -classification is controversial -approximately 1000 species worldwide -oldest living group of vascular plants -have been used as holiday decoration -approximately 50 species -commonly called scouring rushes because the tough, rigid stems are abrasive, making them useful for scrubbing pots and polishing wood -approximately 10, 000 species -specimens vary in size, from 5cm to 10m in height -used by florists and gardeners as an ornamental plant
The Fern Life Cycle -the sporophyte is the large, longer-lived stag e of the organism, and the gametophyte is much smaller ONE. -a sporangium produces haploid spores that germinate to form a gametophyte called a prothallus TWO. -the prothallus produces male organs (antheridia) and female organs (archegonia) THREE. -sperm from the antheridia swim via droplets of wate r to an egg produced by the archegonium FOUR. -the fertilized egg begins to g row into a sporophyte FIVE. -sporophyte matures -roots and fronds develop out of the growing rhizome (horizontal stem) SIX. -sori (gamete producing body) develop on the pinnae (leaves) -spores are formed in the sori by meiosis Seed-Producing Vascular Plants: Gymnosperms and Angiosperms -gymnosperms are vascular plants with non-enclosed seeds -angiosperms are vascular plants with seeds enclosed in a protective tissue
-seeds allow plants to reproduce sexually without needing water and provide protection against harsh environmental conditions—seeds can survive without water for many years Gymnosperm Diversity -gymnosperms have seeds that are exposed on the surface of cone scales -word gymnosperm means naked seed in latin -includes cone-bearing trees (conifers) such: pines, firs, yew, spruce, cedars, redwood and more Reproduction in Gymnosperms: Cones and Pollens -the reproductive structures of conifers are called cones -male cones are soft and short-lived—female cones are hard and longer-lasting -sexual reproduction in seed plants requires the transport of sperm from the male cone to the unfertilized eggs in the female cones -for this to happen, pollen grains (gametophytes) are produced in large quantities and rele ased in the wind -a few land on female cones, releasing the sperm nuclei, which then fertilizes the eggs Angiosperm Diversity -commonly known as flowering plants and are also vascular seed plants -reproduce using flowers, their seeds contained in a fruit -flowering plants are diverse—can range from roses and trilliums to non-coniferous trees such as oaks and maples -90% of all plants are angiosperms Angiosperm Characteristics -the flower is a collection of structures in angiosperms used for sexual reproduction -many angiosperms have small or non-colourful flowers -others, have flowers that are large and colourful, which attract animals who then become transporters of pollen and they move from plant to plant Fruits -a fruit is a mature ovary of a flower that protects and disperses dormant seeds -different types of fruit represent adaptations to disperse see ds successfully -for example, sweet fruits are eaten by animals, which excrete the seeds later, in a different location Angiosperm Classification -are divided into two main groups based on a structure called a seed leaf or cotyledon— t hat cotyledon—a structure in the embryo that helps to nourish the plant as it first starts to grow -monocots are angiosperms whose embryos only have one cotyledon -angiosperms whose embryos have two cotyledons are called dicots -common dicots include dandelions, crab apples and maple tre es -some monocots include corn, orchids and onions -monocots tend to have flowers and fruits divided into three or multiples of three -dicots usually have flowers and fruit divided into four or five parts and have netted leaf veins -angiosperms have separate male and female plants but can be both male and female
3.3 The Fungus Kingdom -fungi are a stationary, heterotrophic eukaryotic organism whose cell walls contain chitin Structure of Fungi -the basic structural units that make up the body of a multicellular fungus are called hyphae—a thread-like filament -the hyphae are densely packed in a tight mass -the bulk of the organism is called the mycelium—similar to the root of a plant -the fruiting body is the spore-producing reproductive structure in fungi -DNA suggests that fungi are more closely related to animals than plants Fungal Nutrition -they feed by releasing digestive enzymes into their surroundings, and then absorbing the digested nutrients into their cells -one way of classifying fungi is through the four different ways they obtain their nutrients
Type of Nutrition Parasitic
Description -absorb nutrients from the living cells of a host organism -fungi lives inside the host organism
Predatory
-mycelia have specialized structures for trapping prey -are soil fungi
Mutualistic
-have partnerships with other organisms -the mycelia covers the roots of t he plants, allowing the plant to absorb more nutrients -the fungus receives sugars from the plant -type of relationship is called mycorrhiza
Saprobial
-feeds on dead organisms/organic waste -are decomposers -absorb nutrients from dead/decaying organisms -play an important role in recycling nutrients in ecosystems
Fungal Reproduction -have both sexual and asexual methods of reproduction -asexual reproduction in fungi would include spore production -some unicellular yeasts use budding— budding—involves a smaller cell that develops while attached to the parent cell -the smaller cell is eventually pinched off the parent cell to pro duce a new individual -another asexual method of reproduction is fragmentation fragmentation— —where a piece of mycelium breaks and forms a new individual -both sexual and sexual cycles of fungi include the production of trillions of single-celled spores from the fruiting bodies -these spores are surrounded by a protective cell wall and most will never form new individuals -spores can be carried by wind or water to a new area with life-supporting conditions Fungal Classification -are classified into five groups -fungi are classified on the basis on whether the re production is sexual or asexual (or both) and on the structure of the fruiting body Fungi Imperfecti (Phylum Deuteromycota) -reproduce asexually -group is very diverse since there are no sexual structures to compare -examples include Penicillium, a greenish mould commonly found on moldy fruit -some imperfecti fungi are very important to humans -for example, the drug Cyclosporine is given to patients after transplant surgery—helps keeps patients from rejecting the transplanted organs Chytrids (Phylum Chytridomycota) -mostly unicellular -most are aquatic species and their spores have flagella; can be found in mar ine and freshwater ecosystems -can be parasites or live on decaying plants or insects Zygospore Fungi (Phylum Zygomycota) -are multicellular and mostly terrestrial -reproduce asexually, sometimes sexual -during sexual reproduction, the fungi produce zygospores—a diploid structure that develop after two haploid hyphae of opposite types combine and fuse their nuclei together -the zygospore remains dormant until conditions are favourable for growth —then, it absorbs water and the nuclei undergo meiosis Sac Fungi (Phylum Ascomycota) -fungi in this phylum develop small finger-like sacs called asci (sing. ascus) during sexual reproduction -they obtain nutrients by breaking down materials in wood and bone -includes single-celled yeasts (reproduce asexually by budding)
Club Fungi (Phylum Basidiomycota) -includes the mushrooms that are found on lawns -all short-lived fruiting bodies; they release spores called basidiospores from a club shaped hyphae called basidia Reproductive Cycle of a Club Fungus: A. the fruiting body consists of a stipe that supports a cap B. the gills extend out from the stalk on the underside of the mushroom cap—club-shaped basida line the gill surfaces C. when basidiospores lands in a suitable environment, it germinates and produces hyphae that form a haploid mycelium D. mycelia have two different mating types—when mycelia from two different types come together, the hyphae fuse and a new mycelium forms; each cell contains one haploid nucleus from each of the mating types E. compact masses of hyphae form under the soil’s surface F. the masses (also called buttons) develop into a mushroom. inside each hyphae, the haploid nuclei join to form a diploid cell —meiosis occurs, producing four haploid nuclei, each one becoming a basidiospores G. as the basidiospores mature, they detach from the basidia and are dispersed by the wind Lichens -are an organism that results from a mutualistic relationship between a fungus and a photosynthetic plant -are called composite organisms due to the relationship that the fungi forms with the ot her organism -some can survive in environments that are harsh, such as those with ex treme temperatures or that are ar e nutrient poor -are an important food source to many animals -can be used by humans as a source of natural dyes
3.4 The Animal Kingdom What is an Animal? -all animals share the following characteristics: •they are eukaryotic, multicellular organisms, their cells do not have cell walls •are heterotrophs that usually ingest and then digest their food o f their lives •are usually mobile, or have the ability to move, in at least one stage of •they reproduce sexually and produce an embryo that undergoes stages o f development Characteristics Used to Classify Animals -invertebrates are animal that does not have a backbone -vertebrates are animals with an internal skeleton and a backbone -other characteristics used to help classify animals include: Levels of Organization -classified on the basis of differences in their structure, tissues and organ systems -all cells in animals are organized into tissues— tissues—a group of similar cells that is specialized to perform specific tasks -tissues are then organized into organs and organ systems, each with particular functions Number of Body Layers -all animals (except for sponges) have three layers of cells -the three layers are: the t he ectoderm (outer), the mesoderm (middle) and the endoderm (inner) -the development of these layers helps sort out cells into an arrangement that produces specialized tissues and organs -the ectoderm produces the skin, nerve tissue and some sense organs -the mesoderm produces muscles, blood, kidneys, and the reproductive organs -the endoderm produces the lungs, liver, pancreas, bladder and stomach lining Symmetry and Body Plans -different groups of animals have different arrangements of cells, tissues and organs -some have an asymmetrical body plan, meaning their body shape is irregular -some have radial symmetry , meaning they can be divided along any plane through a central axis -others have bilateral symmetry meaning they can be divided into two mirror halves only along one plane Body Cavity -some animals have their organs suspended in a fluid-filled cavity called the coelom (provides space for development and suspension of organs) -animals with a coelom are called coelomates
-animals without a coelom are called acoelomates -is important since it allows for the development of more complex o rgan systems -for example, the digestive tract can grow longer than the body to accommodate with ingested mate rials and produced waste Segmentation -segmentation is the division of multicellular bodies into a series of repetitive parts -an advantage of segmentation is that a single segment can be damaged, but the other functions can continue to function properly -also, mobility is more effective because segments move independently, allowing for complex patterns of movement Movement -the evolution of nerve and muscle tissue in animals allowed the development of both complex and fast movement -some animals on the other side, are sessile, or stationary as adults Reproduction -most animals reproduce sexually using gametic reproduction -zygotes are produced by either exter nal or internal fertilization -external fertilization occurs when gametes combine outside the body -internal fertilization occurs when the egg and sperm combine inside the female body -some animals can reproduce asexually (e.g. aphids) Invertebrate Animals -they occupy almost all terrestrial and aquatic ecosystems on Earth Sponges and Cnidarians -sponges are found in both marine and freshwater environments -only consists of two layers of cells and have no tissues -are sessile as adults and traps food particles in wate r as they water passes through the internal channels of their bodies -cnidarians are one of the oldest animal groups -they include a variety of classes, including: freshwater hydras, jellyfish, sea anemones and corals -they also only have two layers of cells but unlike sponges, they have tissues -this allows them to swim and capture prey -food is then digested in the gastrovascular gastrovascular cavity -they have two basic body forms: a polyp—the tube-shaped sessile body form, and medusa—the umbrella shaped, freeswimming body form Worms -they are acoelomates have three layers of cells -also have a simple nervous system with a brain-like cluster of cells -they have a segmented body, they have long tube-like bodies that are divided into a se ries of ringed segments Molluscs -are the second most diverse animal phylum, with about 100 000 species -have bilateral symmetry , three layers of cells, a coelom, and two body openings -they have a soft body, protected by a hard shell -clams, mussels, oysters and scallops are marine species that are protected by a hinged shell (class Bivalvia) -shelled snails and non-shelled slugs are found in terrestrial, freshwater and marine ecosystems (class Gastropoda) -octopuses and squids are marine organisms with tentacles, which are used for locomotion and gathering food (class Cephalopoda) -all molluscs have a similar body plan despite the diversity -they have a mantle—a membrane that surrounds a molluscs’ internal organs -body contains all organ systems except for skeletal Echinoderms -include sea stars, sea urchins, sea cucumbers and sand dollars -are marine animals with radial symmetry, spiny endoskeletons and tube feet -an endoskeleton is an internal skeleton that protects organs and provides support for muscle attachment -tube feet are small, muscular, fluid-filled tubes that end in str uctures similar to suction cups -they have a water-vascular system, which is a system of closed tubes that are used to move -they would force water into the tube feet, making them extend, therefore moving the organism
Arthropods -largest animal phylum -include spiders, scorpions, crustaceans and insects -term arthropod means jointed foot —arthropods are characterized by having legs made up of moveable sections connected by joints -they have a body divided into segments and have a hard exoskeleton —an external skeleton that protects organs, provides points of attachment for the muscles that move the leg s Arthropod Group Distinguishing Distinguish ing Characteristics Chelicerates: -two body segments—a cephalothorax and abdomen Spiders, mites and scorpions -six pairs of jointed appendages -no antennae -special appendages for feeding -some are poisonous
Myriapods: Millipedes and centipedes
-each segment has one or two legs -have a single pair of antennae and sometimes sim ple eyes -live in moist habitats -centipedes are poisonous, millipedes are not
Crustaceans: Crabs, lobsters, shrimp and barnacles
-five pairs of jointed appendages -two pairs of antennae -have fewer body segments, with a tendency for segments in the head and thorax regions to fuse and become specialized
Insects: Beetles, bees, butterflies, moths, ants and flies
-three body segments—head, thorax and abdomen -three pairs of legs -one or two pairs of wings, or no wings -mouthparts specialized for siphoning, piercing, sucking and chewing
Vertebrate Animals -roughly 50 000 species in this phylum, and is divided into five classes: fish, amphibians, reptiles, birds and mammals -one significant feature is notochord , a flexible rod-shaped structure that extends t he length of the body, used for the attachment of movement muscles (replaced by the spine) -another important feature is the dorsal nerve cord , a tube-shaped cord that extends along the back of the body Fish -almost half of all vertebrates are fish -occupy the freshwater and saltwater habitats -they have gills to obtain dissolved oxygen from water -two groups of fish: sharks and rays (class Chondrishthyes), and bony fish (class Osteichthyes) -the first group, have a skeleton m ade up of cartilage , a flexible, non-bony tough material, rather than bone -the second group, have a skeleton made of bone -also, most bony fish have an air sac called a swim bladder , which is used by fish to rise and sink in water by filling it up or emptying it with oxygen Amphibians -fossil records show that over time, fins of some bony fish have changed into limbs -these organisms are known as tetrapods —vertebrates with two pairs of limbs -the first tetrapods were amphibians -most amphibians are one of two orders: the frogs and toads (Order Anura) and the salamanders (Order Urodela) -most species use their moist skin to assist in gas exchange -they reproduce using external fertilization Reptiles -three orders of reptiles: lizards and snakes (Order Squamata), turtles (Order Testudines), and crocodilians (Order Crocodilia) -they have body scales that create a water proof barrier that helps prevent dehydration in dry air -having shelled eggs provide another advantage for reptiles since they have survive in both dry and wet environments
-fertilization in reptiles occurs internally -after the egg and sperm join inside the female, several layers of membranes develop around the egg prior to the secretion of the shell—this type of egg is called an amniotic egg -female reptiles then deposit eggs in places that provide environmental heat for incubation—temperature of incubation determines the sex of the t he offspring Birds -Class Aves -birds are related to at least one group of dinosaurs, and are very similar to reptiles -proven by looking at skeletal similarities, fossil evidence and the presence of scales on the legs of birds -reptiles are ectothermic —they rely on the environmental heat for determining internal body temperature, and have a three-chambered heart -birds are endothermic —they use metabolic heat to maintain a high, constant body temperature and have a four chambered heart -they have a unique respiratory system which promotes one-way movement of air through the use of air sacs that connect to the lungs -most birds can fly and have skeletal adaptations which help them to fly (hollow bones) Mammals -most distinctive feature of mammals is the mammary glands, a gland that produces and secretes milk for nourishing the developing young, of females -are also distinguished by having hair which has multiple functions, including insulation, camouflage, waterproofing and communication -mammals are also endothermic, have four-chambered hearts and highly developed brains Mammal Group Distinguishing Distinguis hing Characteristics Monotremes -egg laying mammals -platypus -only found in Australia and New Guniea Marsupials -pouched mammals -short gestation period (amount of time offspring develops in the uter us) -mostly found in Australia Placental Mammals
-have a placenta , an organ in the pregnant uterus that exchanges nutrients and oxygen between the mother and developing offspring -great diversity in species and structure
3.5 The Biodiversity Crisis -one of the problems associated with human overpopulation and development is a higher rate of extinction -mass extinction is a large-scale dying out of a large percentage of all living organisms within an area over a short time -the biodiversity crisis is the current decline in genetic, species and ecosystem diversity that may represent a mass extinction The Threat of Climate Change to Biodiversity -some threats that species can experience are: habitat destruction, competition from invasive species, illegal trade and pollution -climate change is another major threat to the survival of species -scientists use the method of modelling, where an idea about a mechanism is formulated and real-life data are then used to see if the data fit the model Climate Change and Food Sources -a 2009 study reported that caribou and reindeer population have decreased by 60 percent over t he last three decades -they hypothesized that climate change has several impacts on caribou -caribou dig through the snow to find lichen since it’s their primary food source in the winter -warmer summers favor the growth of plants over the growth of lichen -climate change would reduce the caribou’s access to the lichen
Climate Change and Habitat -as altitude increases, plant communities change in a way that is similar to t he way they change with the increase in latitude -this is due to the temperature decrease with the increasing altitude -plant communities that thrive in warmer temperatures are found at low elevations and cold-tolerant plant communities are found farther up -in mountainous regions that are experiencing long-term warming, the average temperature is increasing omg I hate this, this is so stupid its just common sense, I’m kind of losing my mind sssssssso yeah just read the chapter yourself. it’s only 3 pages.
