What is Biology?

What is Science?

Science is a way of gaining knowledge and understanding about our natural world.

Whenever we ask why or how something happens we are dealing with science.

What is Biology?

Biology is the study of living things.

There are six major categories (Kingdoms) that living things have been divided into: Animals Plants Fungi Protista Bacteria Archaea

There are many branches or divisions of biology, each specializing in the study of a specific group of living things.

Division Area of Specialty

What is a living thing?

In order for something to be considered alive it must show certain characteristics. Living things…

are composed of cells require energy (for movement, repair etc…) grow respond to the environment have a limited life span produce waste (heat, carbon dioxide, urine etc…) produce offspring like themselves evolve or change over time

Living things will show all of these characteristics but there are some exceptions. For example, a horse + a donkey = a mule.

Non-living things may show one or a few of these characteristics but not all.

Development of the Cell TheoryThroughout history people have wondered what causes life and how life is maintained. It was not until the invention of the microscope and improvements on the microscope that we were able to look at living tissues and make detailed observations.

With these observations scientists came up with a formal cell theory that is used to explain observations of living things.

1. All living things are composed of one or more cells.

2. The cell is the basic organizational unit of life.

3. All cells come from previously existing cells.

Types of Microscopes

Simple Light Microscope – single hand-held lens (earliest type of microscope)

Compound Light Microscope - contains 2 lenses, an eyepiece (ocular lens) and objective lenses.

Transmission Electron Microscope – uses an invisible beam of electrons to pass through an object. Specimen must be dead and sliced very thin. Is capable of magnifying up to 5 000 000 x.

Scanning Electron Microscope – reflects electrons from the surface of a specimen, allowing thicker specimens to be viewed. Is capable of magnifying up to 300 000 x.

Historical Look at the CellAristotle - Classified all known organisms into two kingdoms: plant and animal. (334 BC)

Robert Hooke - Observed tree bark lining with a compound microscope; described the magnification as “empty room-like compartments or cells” (1665)

Anton Van Leeuwenhoek - Reports living “beasties” as small as 0.002 mm observed with a simple single lens microscope (1674)

Matthias Jacob Schleiden - “All plants are made of cells” (1838)

Theodor Shwann - “All animals are made of cells” (1839)

Carl Heinrich Braun - “The cell is the basic unit of life” (1845)

Rudolph Virchow -“Cells are the last link in a great chain [that forms] tissues, organs, systems and individuals… Where a cell exists, there must have been a pre-existing cell…Throughout the whole series of living forms… there rules an eternal law of continuous development” (1858)

Loiuse Pasteur - Demonstrates that living organisms cannot arise spontaneously from non-living matter (1860)

Classification of OrganismsTaxonomy - the science of organizing and classifying living things according to

several criteria.

The purpose of classification is to provide a clear and practical way to organize and communicate information about organisms. Classification reduces confusion, provides clues about organisms’ structures and indicates lines of decent (lineage).

A History of Classification

1. Aristotle

Greek philosopher (322 B.C.) Divided organisms into 2 groups - plants and animals Divided animals into 3 groups according to how they move - walking, flying, or

swimming System was used into the 1600’s

2. Carolus Linnaeus

Classified plants and animals according to similarities in form - the more features organisms have in common, the closer the relationship His classification system is still used today

Designed a system in which each organism is given a 2-part scientific name (latin) He called this binomial nomenclature

1. “Genus” is always capitalized 2. “species” remains uncapitalized

The scientific way of writing binomial nomenclature would be in italics or underlined.

Examples:Salmo salar Atlantic salmon Canis familiaris DogFelis domesticus Cat Canis lupus Wolf

Levels of Classification

Rank - categories used to classify organisms.

There are 8 ranks to distinguish between different degrees of similarity, organisms are classified according to six Kingdoms within three Domains. Each kingdom is subdivided into progressively smaller groups. The named group for each organism is referred to as its taxon. As you proceed down the ranks, the numbers of members of each taxon becomes fewer.

Rank Human Taxa ______TaxaDomain EukaryaKingdom AnimaliaPhylum ChordataClass MammaliaOrder PrimateFamily HominidaeGenus Homo

Species sapiens

The most widely used definition of a species is the biological species concept. This idea focuses on organisms that interbreed freely in nature and produce viable, fertile offspring. There are also the morphological species concept (similarities in appearance) and the phylogenetic species concept (evolutionary relationships).

3. Charles Darwin

Ushered in a new era of taxonomy with the publication, The Origin of Species (1859)

Identified natural selection as a driving force behind evolution Focus on groups that had descended from a common ancestor Attempts were made to find, “missing links” between higher taxa, such as the fossil

Archaeopteryx between reptile and birds

4. Modern Taxonomy

Advances in molecular biology have had a huge impact on the field of taxonomy Biologists can now clone and sequence the DNA (deoxyribonucleic acid) of many

different organisms and compare these DNA sequences to estimate relationships and construct classification systems

Dichotomous KeysA dichotomous key is a tools used to aid in the identification of organisms. In this type of key, 2 questions are asked about the organism. Based on your response you are directed to another question in the key.

Example:

_________

Determining Relatedness in SpeciesOne goal of taxonomy is to determine the evolutionary history of groups of organisms. To do this, scientists compare species living today with species that existed in the past. To study evolutionary relationships, scientists can use several different forms of evidence:

1. Evidence from Anatomy

By studying the anatomy of living organisms or fossil remains, scientists are able to determine the evolutionary history of different organisms. Biological features that have a common evolutionary origin are said to be homologous. For example: the bones in a human arm, a cat’s leg, a bat's wing and a whale's flipper.

Homologous structures differ from analogous structure; these are ones that perform the same or similar functions by a similar mechanism but evolved separately. For example, the wing of a bird and an insect.

2. Evidence from Development

Scientists compare the early stages of development of an organism to reveal relationships that are not always obvious from comparison of adult organisms alone.

3. Evidence from biochemistry

Scientists are now able to compare the molecules from which organisms are made. Comparison of macromolecules like proteins among organisms can indicate genetic similarities and differences.

4. Evidence from DNA

The study of DNA can determine the percentage of genes in common for different organisms. The DNA from humans and chimpanzees are 98% identical.

DNA analysis can also determine how long ago two species began to diverge from a common ancestor. Divergence can be predicted by studying mitochondrial DNA (which differs from chromosomal DNA) as it is passed directly from a mother to her offspring and mutates at a predictable rate.

Phylogeny

When scientists classify species into various taxa, they are presenting a hypothesis about the evolutionary history, or phylogeny of the organisms. This information is often organized in a phylogenetic tree.

The base of the tree represents the oldest ancestral species, the upper branches represent the present-day descendant species and forks are where a species split into two new species. New features evolved from a primitive ancestor are called derived characteristics.

Prokaryotes EukaryotesKingdoms Bacteria

Archaea Protista Fungi Plantae Animalia

SBI 3UIProkaryotes and Eukaryotes

Arrangement of DNA Plasmid DNA (circular) Single chromosomal

DNA Not bounded by a

membrane - Nucleoid

Chromosomal DNA In nucleus bounded by a membrane

Cell Division Binary fission Conjugation

Mitosis Meiosis

Reproduction Usually asexual Usually sexual

Cell Structures no membrane bound organelles

no mitochondria

many membrane bound organelles

Size small (1-10 μm) large (100-1000 μm)

Oxygen Requirements anaerobic (no O2) aerobic (O2)

Examples Escherichia coli Bacillus subtilis

Paramecium Nerve cell Etc…

Kingdom ArchaeaThe Kingdom Archaea contains one of the oldest groups of organisms on Earth. These micro-organisms are all single celled (unicellular) prokaryotes and tend to live in very extreme environments (extremophiles). Some environments where they thrive are:

Extremely cold or hot water and land masses(-4oC, 95oC) Highly Acidic and/or basic waters (ph 2, ph 12) Extremely salty waters (25%)

Archaea have evolved diverse ways to obtain their energy. Some are anaerobic and obtain their energy from inorganic molecules (chemotrophs), while others are aerobic and obtain their energy from organic molecules (heterotrophs). Others use light (phototrophs) as their energy source.

Although members of Kingdom Archaea and Bacteria look similar in appearance to each other, biochemically and genetically they are more different than plants and animals. The genes (DNA) of the two kingdoms differ, as well as the composition of their RNA. In addition, the cell membranes of organisms within Kingdom Archaea contain unusual lipids that allow them to survive in extreme environments that would normally kill most cells.

Archaea’s ability to flourish in such extreme conditions is unique and not completely understood. But the fact that these micro-organisms can tolerate

such environments have allowed scientists to use some of their components (enzymes) when conducting experiments that require harsh processing i.e. PCR – polymerase chain reaction

Kingdom Archaea can be divided into two major phyla :

1. Euarchaeota – which contains three main groups of archaea:

a) Methanogens (methane producing) Live in oxygen free environments and produce methane as a waste product Utilize inorganic molecules such as carbon dioxide, nitrogen gas or hydrogen

sulfide as a source of energy Found below the surfaces of swamps, and marshes, as well as sewage disposal

plants

Example: Methanococcus jannischii. This organism was isolated from a "white smoker" hydrothermal vent some 2600m deep on the bottom of the Pacific Ocean...at a place called the East Pacific Rise.

b) Halophiles (salt loving) Live in extremely saline environments – concentrations may reach up to 25%

(seawater is 3.5% salt) Found in the Dead Sea, as well as other hypersaline water bodies including the

interior lakes of San Salvador Island in the Bahamas

Example: Halobacterium salinarium carries out aerobic respiration but in water up to 5M (25%!) NaCl (salt). It can be found in the Great Salt Lake in Utah and the Red Sea in Asia Minor.

c) Thermophiles (heat loving) Live in extremely hot water or land masses Can be found in piles of hot coals or in rocks deep below Earth’s surface

2. Crenarcheaota – most of the organisms in this phylum are:

a) Thermoacidophiles (heat and acid loving)

Live in very acidic hot water environments (corrosive conditions) Grow best at temperatures above 80oC Some use carbon dioxide (autotrophic) while others use sulfur from hot sulfur

springs as their energy source Found in hot springs, volcanoes, and deep sea vents

While many archaea live in harsh environments, they have since been found in a broad range of habitats, such as soils, oceans, and marshlands. Archaea are particularly numerous in the oceans, and the archaea in plankton may be one of the most abundant groups of organisms on the planet. Archaea are now recognized as a major part of life of Earth and may play an important role in both the carbon cycle and nitrogen cycle. No clear examples of archaea pathogens are known.

Kingdom BacteriaAll are prokaryotes and the majority live as single cells (unicellular) but some occur in colonies. They reproduce mainly asexually by binary fission but can have a sexual reproductive stage (conjugation). Most bacteria are heterotrophs, but some bacteria can perform photosynthesis (cyanobacteria)

Biological Importance of Bacteria

Advantages

1) Industry Used in the production of cheese, vinegar, yogurt etc…

2) Agriculture Used as natural pesticides or added to soils to enrich nitrogen content (nitrogen fixation)

3) DecomposersRecycle organic material from dead organisms. Some bacteria are found in our intestines and aid in the digestion process.

4) Genetic EngineeringScientists have used bacteria to study cell metabolism and molecular biology.Engineered bacteria are used to produce useful substances like: insulin, antibiotics, hormones and anti-cancer drugs.

5) Fighting DiseaseSome bacteria naturally produce substances, which inhibit the growth of harmful organisms (examples: streptomycin, erythromycin)

6) BioremediationThe process of using bacteria to destroy, transform or immobilized environmental contaminants.

For example, the bacterium Pseudomonas is used in the treatment of wastewater and sewage; a toxic wood preservative can be removed from soil by a bacterium from the genus Flavobacterium.

A relationship between two organisms (such as a bacteria and a human or plant or animal) is called a symbiotic relationship. In cases in which both partners benefit from the interaction it is referred to as mutualism.

Disadvantages

1) Spoilage of Food The action of bacterial decomposers can cause food to spoil and become harmful to

eat. Example: Clostridium botulinum (Botulism)

2) Disease Many bacteria are pathogens. These bacteria can also be termed parasites,

meaning that one organism (the parasite) benefits at the expense of another organism (the host), which is often harmed but usually not killed.

These pathogenic (disease causing) micro-organisms typically produce deadly substances called toxins. A toxin is a poison produced in the body of a living organism. It is not harmful to the organism itself but only to other organisms.

There are two types of toxins that bacteria produce, endotoxins and exotoxins.

Endotoxins ExotoxinsReleased when certain bacteria

splitReleased by living, multiplying

bacteria that travel throughout the host’s body

Seldom fatal Often fatal, highly toxicCause fever, vomiting, diarrhea Does not produce fever

Example: Salmonella Example: Botulism

Just one gram of the exotoxin that causes botulism could kill a million people!!!

Classification of Bacteria

Bacteria can be classified using many different criteria. Some of these include:

1) Shape (three types): cocci (round) bacillus (rod) spirillium (spiral)

These shapes can be arranged in patterns or groupings: singles (mono) doubles (diplo) chains (strepto) clusters (staphylo)

2) Metabolic Needs

Classification based on: Whether they are heterotrophs or autotrophs Do they need oxygen? (aerobic or anaerobic) Special food sources – carbon, nitrogen etc…

Examples:

Term DescriptionAerobic Needs oxygenObligate anaerobe Die when exposed to oxygenFacultative anaerobe Can grow with or without oxygenPhototrophs Use light as an energy sourceChemotrophs Use chemical compounds as an

energy sourceSaprotrophs Feed on dead organisms or organic

wasteThermophiles Grow in temperatures above 50oCPhsychrophiles Grow best in temperatures below

15oC

The Shapes of Bacteria

Thousands of different types of bacteria are known and have been observed. Scientists can tell these organisms apart by the shape of the bacteria or by the way they join together. Write the meaning of the following terms.

1. bacillus ___________________________ 4. diplo _________________________

2. coccus ___________________________ 5. strepto _______________________

3. spirillum __________________________ 6. staphylo ______________________

Use the terms you defined above to name the bacteria in each diagram below. Write the name on the line below each diagram. Note: Some names will combine two of the terms. For instance, a chain (strepto) of round (coccus) bacteria is called a streptococcus.

__________________ ________________ __________________

__________________ ________________ __________________

__________________ ________________ ___________________

3) Colony Morphology

Describes the appearance of a colony in a Petri dish. Such as: Elevation Form Colour Margin

4) Reaction with Gram Stain

Gram + retain crystal violet stain (purple) - contain a thick protein layer in their cell wall

Gram - do not retain crystal violet stain (pink) – contain a thin protein layer in their cell wall

5) Presence/Absence of:

Flagellum - used for movementCapsule - usually a carbohydrate layer surrounding the cell used for protection

6) Spore Formation

Dormant form of many bacteria that is highly resistant to environmental conditions

Diagram of a Bacterium

Reproduction in BacteriaThe majority of time, prokaryotes reproduce asexually by a process known as binary fission. Sexual reproduction is not very common in prokaryotes, but does occur in some, such as Escherichia coli, by a process known as conjugation.

Asexual Reproduction (Binary Fission)

Asexual reproduction is the formation of a new individual from a single organism. It results in a genetically identical offspring. In favourable conditions, a bacterium can grow and divide through binary fission in as little as 20 minutes.

Binary fission is prokaryotes can be broken down into stages:

1. DNA replicate (chromosomal and plasmid), resulting in identical copies of genetic material

2. The two strands of DNA will then separate

3. A new plasma membrane and cell wall will develop through the midsection of the prokaryote

4. The cells will eventually become two identical prokaryotes, which may separate or remain attached

Sexual Reproduction (Conjugation)

Sexual reproduction is a process involving two organisms and results in offspring that are genetically different from both parents.

Conjugation in prokaryotes can be broken down into stages:

1. Two bacteria join together by forming a specialized structure called a sex pilus.

2. Genetic information (plasmid DNA) is exchanged through the pilus, resulting in an altered set of characteristics.

3. Following the transfer, the two bacteria separate and can then undergo binary fission.

The result of the uptake of a new piece of DNA by conjugation can have many effects including:

1) Add a new property to the bacterium that was not present before.

2) The replacement of a bacterial gene that has been damaged by a mutation.

In both cases, if the piece of DNA is inserted into the chromosome, then the process is called recombination.

This produces a permanent change in the DNA of the cell, which is passed on to the offspring of that cell.

During unfavourable conditions, some prokaryotes survive by forming dormant or resting cells, called endospores, which can withstand harsh environments such as heat and acidity. When suitable conditions return, the prokaryote will re-emerge and begin replicating.

Bacterial Growth

Bacterial growth curves take on a particular pattern, which shows the rate at which bacteria will reproduce when conditions are optimal. A typical growth curve consists of 4 different phases:

Lag phase – bacteria are adjusting to their new surroundings

Exponential growth phase – bacterial population grows rapidly

Stationary phase – bacteria begin to run out of nutrients; waste starts to accumulate. The death rate is equal to the birth rate

Death phase – the number of bacteria dying becomes greater than the number being created

Bacterial Growth Curve

The maximum number of organisms a particular environment can support is termed the carrying capacity.

Growth rate is the time it takes for a population of bacteria to double in number.

Like all organisms, bacteria thrive under optimal conditions.

The primary reason that our planet isn’t buried under a thick layer of bacteria can be attributed to the fact that conditions are rarely optimal for the bacteria to grow. Scientists who study bacteria try to create the optimal environment in the lab: culture medium with the necessary energy source, nutrients, pH, and temperature, in which bacteria grow predictably.

Generation times for some common bacteria under optimal conditions of growth

Bacterium Medium Growth Rate (minutes)

Escherichia coli Glucose-salts 17Bacillus  megaterium Sucrose-salts 25Streptococcus lactis Milk 26Streptococcus lactis Lactose broth 48Staphylococcus aureus Heat infusion broth 27-30Lactobacillus acidophilus Milk 66-87Rhizobium japonicum Mannitol-salts-yeast

extract 344-461Mycobacterium tuberculosis Synthetic 792-932Treponema pallidum Rabbit testes 1980

VirusesA virus is an extremely small (nanometers), lifeless particle that carries out no metabolic functions and cannot reproduce on its own. On this basis, viruses occupy a position between living and non-living matter.

A virus consists of genetic material (DNA or RNA) wrapped in a protein coat (capsid), but lack all other cell structures.

All viruses are host specific, reproducing by infecting a specific cell and using the host’s machinery to replicate itself. For this reason they are known as intracellular parasites.

Temperate viruses are those that reproduce without killing their host cell. Typically viruses will reproduce in two ways: through the lytic cycle and the lysogenic cycle.

Viral Reproduction

The Lytic Cycle (T4 Example)

Phage finds the right bacterium,attaches to the cell with its tail fibres to a specific receptor site and uses an enzyme to bore a hole through the cell wall.

Bacteriophage injects its genetic material into the bacterium.

The bacteriophage genome makes many copies of itself byusing host machinery (ribosomes).

The bacteriophage components and proteins continue to be produced.

The components of the bacteriophage are assembled.

Bacteriophage enzyme breaks down the bacterial cell wall causes the bacterium to split open (lyses)

The Lysogenic Cycle

In the lysogenic cycle, the phage's DNA recombines with the bacterial chromosome. Once it has inserted itself, it is known as a prophage. The bacteria and the prophage can coexist normally. Sudden changes in the environment may activate the phage nucleic acid and cause a production of viral particles.

Classification of Viruses

Viruses cannot be classified in the same way as bacteria. Viruses are clustered according to:

i. The type of genetic material (DNA or RNA)ii. Structure/shape (Rod, Polyhedral, Helical)iii. The type of host cell they infect (plant, animal, bacteria)iv. The type of disease they cause

Viral shape is an important characteristic because it…

i. Allows for protection of the nucleic acidii. Allows the virus to remain relatively undetected by the host’s immune systemiii. Confers resistance to harsh conditionsiv. Determines the cell receptors to which the virus can attach

Structure of a Virus

How Do Viruses Spread?

Viruses are usually spread by vectors. Vectors are anything that assists the spread of an infection.

Ex. Animals, humans, water…

How Do Animals Spread Viruses?

Viruses are contained within the infected animal. During a bite, the virus located in the bodily fluids (saliva or blood) can come into contact with another animal’s blood causing transmission of the virus infection.

How Do Humans Spread Viruses?

Viruses can be spread by contact of an infected individual’s bodily secretions with a non-infected individual’s secretions.

Ex. Mouth contact, touching hands, drinking from the same glass, sexual activity…

How Do Viruses Spread by Water?

Many viruses replicated within the host are excreted and carried away with the sewage. Some viruses can survive water treatment and are released into lakes and streams.

How do Viruses cause problems in humans?

Typically the symptoms displayed from a viral infection are NOT a result of cells being destroyed, but rather the body’s own response and attempts to fight off the virus (ex. Fever)

Differences Between the Common Cold (Rhinovirus) and the Flu (Influenza)Symptoms Cold FluFever Rare Characteristic, high

(100-102°F); lasts three to four days

Headache Rare Prominent

General Aches, Pains Slight Usual; often severe

Fatigue, Weakness Quite mild Can last up to two to three weeks

Extreme Exhaustion Never Early and prominent

Stuffy Nose Common Sometimes

Sneezing Usual Sometimes

Sore Throat Common Sometimes

Chest Discomfort,Cough

Mild to moderate;hacking cough

Common; can become severe

ComplicationsSinus congestionor earache

Bronchitis, pneumonia;can be life-threatening,Vomiting and diarrhea

PreventionNone Annual vaccination*; Symmetrel, Flumadine,

orTamiflu (antiviral drugs)

TreatmentOnlytemporaryrelief of symptoms

Symmetrel, Flumadine, Relenza,or Tamiflu within 24-48 hoursafter onset of symptoms

Incubation Period 1-4 days 1-4 days

Nucleic Acid RNA RNA

Structure

Vaccination – the administration of an antigenic agent that stimulates the body to develop resistance to a pathogen.

A vaccination against the small pox virus was the first created (1976) and administered on a global scale, such that it is the only pathogen to be eradicated from the planet (1977).

Kingdom ProtistaAll Protists share the following features:

Most are unicellular; multicelluar forms do not form tissue Cells are Eukaryotic

Cells reproduce asexually, but some can reproduce with complex sexual reproductive cycles

Always found in moist environments (fresh water, salt water, animal fluids…)

The Kingdom Protista can be separated into three distinct groups based on their nutrition:

Plant-like Protists Animal-like Protists (Protozoa) Fungi-like Protists (Slime moulds and Water moulds)

Classifying protista can be difficult because the members of this Kingdom are grouped together mainly because they do not fit into the other Kingdoms, rather than because they are similar or closely related to one another.

Plant-like Protists (Algae)

These organisms are autotrophs that contain chlorophyll, the pigment that begins the process of photosynthesis. During periods of darkness, some cells will engulf solid food.

Algae are type of plantlike protist and are responsible for about 80% of the global supply of oxygen. These can range in size from single cells to giant seaweeds 60 m in length. Algae are classified into six phyla, based partly on the type of chloroplasts and pigments they contain.

Human waste and industrial contaminants can reduce algal populations. Excessive algae (algal bloom) can block sunlight from penetrating the water

Algae can be consumed as food, used as fertilizer or in the production of cosmetics.

Animal-like Protists (Protozoa)

Protazoa are heterotrophs that move around to obtain food, using cilia, flagella or pseudopods. Some will engulf their food; others will absorb nutrients directly through their cell membranes.

Some protozoa are unable to move; they are exclusively parasitic and form reproductive cells called spores.

Protozoa are classified mainly by their mode of locomotion.

Fungi-like Protists (Slime moulds and Water moulds)

These organisms are referred to as slime moulds (2 groups) or water moulds (1 group). They prefer cool, shady, moist places usually under fallen leaves or rotting logs. These organisms are heterotrophs.

Helpful and Harmful Protista

In addition to providing food and oxygen, protists also live in our digestive tracts to aid in the digestion process.

Some of the world’s most serious diseases are caused by protists:

Plasmodium vivax (malaria)Giardia intestinalis (found in untreated drinking water)Trypanosoma (African sleeping sickness)

Life Cycle of the Plasmodium vivax

Most widespread human parasite

Causes malaria in humans

Can be treated with drugs

Kingdom Fungi

Fungi DO NOT photosynthesize. Fungi are heterotrophs (saprotrophs) that feed by releasing digesting enzymes into their surroundings, then absorbing the nutrients into their cells; this is called external digestion.

Fungi are composed of eukaryotic cells that may be unicellular (yeasts), but the majority are multicellular (moulds and mushrooms). Fungal cells have cell walls composed of chitin. Fungi can reproduce sexually and asexually but will always produce spores. Spores are typically haploid (contain half the amount of genetic information) and in multicellular fungi are produced in sporangia. If a spore germinates, it produces hyphae, which are a network of fine filaments. Hyphae are the main part of fungi and are found under the ground; a group of hyphae are referred to as a mycelium.

Fungi can be harmful and cause disease in humans (athlete’s foot), plants and animals. Fungi are also very important to ecosystems because of their role as decomposers. Fungi form many symbiotic relationships:

a) Plant Roots (form myccorhizae) The fungal hyphae help the plant absorb nutrients – increase the surface area The plant shares its carbohydrates and amino acids

b) Cyanobacteria or Green Algae (form lichens) Fungal mycelia provide structural support and carbon dioxide and water to the

autotrophic partner The autotrophic partner shares carbohydrates

Fungi Reproduction

Fungi reproduce asexually. When a piece of hyphae is broken off it will grow into a new mycelia. This is referred to as fragmentation.

Spores are the main means for reproduction employed by fungi. The spores that are produced by fungi may be asexual (produced by mitosis) or sexual (produced by meiosis). Spores have a protective outer coating that prevents them from drying out. Fungi will produces spores in the trillions, which like seeds can spread by wind, water or on the bodies of animals. If a spore finds a suitable environment it can grow into a new organism.

Classifying Fungi

1. Zygospore Fungi (Zygomycotes)

This group includes bread moulds. During sexual reproduction they form zygospores after the mating of two opposite strains of hyphae (mating strains + and -). Some of these fungi produce two kinds of hyphae, stolons (horizontal) and rhizoids (downward) that anchor and secrete digestive enzymes.

During asexual reproduction sporangiophores project above the mycelium to release spores from sporangium.

2. Club Fungi (Basidiomycotes)

This group includes the mushrooms that grow on lawns. These have short lived reproductive structures called basidiocarps (fruiting bodies) that form basidiospores on a structure called basidia. The largest part of the club fungus is a vast, sprawling network of hyphae that spread underground.

3. Sac Fungi (Ascomycotes)

This is the largest group of fungi and includes mildew and single-celled yeasts. Sac fungi form small finger-like sacs called asci during sexual reproduction. Spores are produced directly at the tip of modified hyphae.

4. Imperfect Fungi (Deuteromycotes)

Do not appear to have a sexual phase. They develop asexually from spores called conidia.Many of these fungi produce antibiotics (penicillin and cyclosporin) or are used in the production of foods (soy sauce and cheese).

Kingdom PlantaePlants are multicellular, eukaryotic organisms. Plants are autotrophs, meaning that they produce their own food through the process of photosynthesis.

Plants have a life cycle in which they alternate between two forms (called alternation of generations):

i) Haploid form Called a gametophyte (produces gametes)

ii) Diploid formCalled a sporophyte (result of the union of two gametes)

Major Divisions

Vascular and Non-vascular Plants

Most plants consist of roots, stems and leaves:- Roots penetrate the soil to anchor the plant and to reach sources of water- Leaves provide a greater surface area to carry out photosynthesis- Stems supply rigid tissues that raise and support the leaves

In order for roots, leaves and stems to grow they need a regular supply of water, and nutrients

These tasks are carried out by vascular tissue - vascular tissue are made up of cells that conduct solutions throughout the plant (similar to a circulatory system)

There are two main types of vascular tissue:

Xylem - conducts water and dissolved minerals

Phloem - conducts sugars produced by the leaves

Evolution of vascular tissue has allowed plants to increase in size

Non-vascular Plants (Mosses and their Relatives)

There are three divisions of Mosses:

1. Mosses (Bryophytes) - Lack vascular tissue and do not have well-developed roots- Thrive in diverse

habitats such as bogs, tundra, exposed rocks and deep shade

2. Liverworts (Hepatophytes)

- Grow flat and close to the ground

- Rarely more than 30 cells thick

3. Hornworts (Anthocerophytes)

- Gametophytes are broad flat and usually less than 2 cm in diameter

- Have a blue-green colour

Seedless Vascular Plants (Ferns and their Relatives)

Developed vascular tissue that allowed them to grow tall

Sporophyte generation is the dominant stage Gametophyte generation are tiny, short-lived and depended

on moisture to carry out sexual reproduction (prothallus)

Vascular Plants (disperse by seeds) Seeds allow a plant to reproduce sexually without needing water Seeds also provide protection against harsh environmental

conditions

There are two groups of seeds:

1. Gymnosperms "naked seeds"

These are cone-bearing plants with most possessing needles. There are both male and female cones.

Generalized life cycle of a gymnosperm:

In male cones, microspore mother cells undergo meiosis to produce haploid pollen grains, the male gametophytes.

Female cones have ovules in which a megaspore mother cell undergoes meiosis to produces only one megaspore, or female gametophyte.

Pollen gets trapped on sticky sap secreted by the female cone. After fertilization, the diploid zygote develops into an embryo, which remains in the

ripened ovule, now called a seed. Mature "naked" seeds fall out of the female cones. It may be several years before the seedling grows into a mature plant to produce its

own cones.

2. Angiosperms

Flowering plants that protect their seeds within a fruit. Monocots have one cotyledon (seed leaf) and dicots have two cotyledons.

Generalized life cycle of an angiosperm:

Within the anther chambers, microspore mother cells undergo meiosis to produce haploid pollen grains, or male gametophyte.

Within the ovule, a megaspore mother cell undergoes meiosis to produce only one megaspore, or female gametophyte.

Pollination is aided by wind, insects, birds, and bats. Pollen gets trapped by the sticky substance on the stigma. Self-pollination involves one plant only; cross-pollination involves two separate plants. After fertilization, the diploid zygote grows into an embryo, which remains in the

ripened ovule, now called a seed. As the seeds develop, the ovary and other parts develop into the fruit enclosing the

seeds.

The Life Cycle of a Flowering Plant

Kingdom Animalia

Animals are eukaryotic, multicellular heterotrophs that reproduce sexually and are usually capable of movement at some stage of their lives.

This complex kingdom is divided into two broad groups:

1. Invertebrates (majority of animals)Do not have a backbone. Examples: leeches, clams,insects

2. Vertebrates Have a notochord (a rod shape structure that extends the length of the body; often replace by the spine) Examples: fish, amphibians, birds, reptiles and mammals

The following are major characteristics used to classify animals:

1. Body organization Organized of tissues into organs, organ systems etc…

2. Body Layers Three different types:i) Ectoderm (outer e.g. skin, nervous system)ii) Endoderm (inner e.g. lining of body cavity)iii) Mesoderm (middle layer e.g. circulatory system)

3.Body Symmetry i) Assymetricalii) Radialiii) Bilateral

4. Digestive tract or guti) One opening – Example: Hydraii) Two openings - Example: Earthworm

5. Coelom Fluid filled body cavity Allows for the development of

more complex organ systems

A Quick look at Animals

The First Animals

Sponges (Porifera) Live permanently attached to one surface Cells are organized in a simple fashion Single opening No tissue no organs and only two layers of

cells

Jellyfish, Corals and Anemones (Cnidaria) Two cell layers and a single opening Simple nervous system and muscle tissue Allows then to swim and capture prey Use digestive enzymes for external

digestion No special excretory or respiratory systems

Flatworms (Platyhelminthes) Parasitic tapeworms and flukes as well as free living

planarians Digestive system is a closed pouch with one opening Lack circulatory system but have a simple excretory

system Simple nervous system and a brain like concentration of

nerve cells at the head No coelom

Segmented Worms (Annelida)

Earthworms and leeches Body is divided into ringed segments that contain similar sets of organs for excretion,

circulation and nerve control Other specialized organ systems including digestive, and reproductive Open digestive system; two openings Contain a coelom

Squid, Clams, Snails (Mollusca) Soft Body, hard shell (for many of the

organisms) Three cell layers Open digestive system; two openings Contain a coelom 3 different classes include the Bivalves, Gastropods and Cephalopods Second most diverse group but all have a similar body plan including a mantle

which surrounds internal organs and secretes calcium carbonate for the shell as well as a muscular foot for movement

Contain specialized organ systems including digestive, circulatory, respiratory, excretory, reproductive and nervous

Starfish (Echinodermata) All are marine Include starfish, sea urchins, sea cucumbers and sand dollars Adults are radially symmetrical, larvae are bilateral Contain a coelom Open digestive system; two openings Contain specialized organ systems including water vascular, digestive, respiratory,

circulatory, nervous, reproductive etc..

Joint-Legged Animals (Arthropoda) Arthropods resemble annelids in basic structure Annelids are very similar to larval stages of insects Open digestive system; two openings Contain a coelom

As arthropods evolved they developed several distinct differences from annelids. Such as:

Fewer body segments Hard external cuticle which acts as an exoskeleton Legs divided into moveable segments connected by joints Have separate muscles organized into groups related to specific movements

of body parts Strongly developed jaws Better developed nervous systems and sense organs Other specialized organ systems including digestive, respiratory, circulatory

and reproductive

Chordates (Chordata)At some stage in their life history all chordates have: A dorsal nerve cord from which other nerves branch A notochord, or rod of cartilage, which runs along the dorsal length of the body A notochord occurs only in the embryo A backbone of cartilage or bone replaces the notochord Gill slits in the pharynx, or throat (in terrestrial vertebrates the gill slits only appear in

the embryo) Contain a coelom Open digestive system; two openings Contain specialized organ systems including digestive, respiratory, circulatory,

nervous, reproductive etc..