Topic 1: Cells and Organisation - Cell Structure and Function of Each Cell Part - Chloroplasts vs Mitochondria - Plant Cell vs Animal Cell - Division of Labour - Parts of a Microscope - Biological Drawings Cell Structure and Function of Each Cell Part Protoplasm: Nucleus, cytoplasm and cell membrane Organelle Structure Function Nucleus (Plant and Animal Cell) Spherical, usually the largest organelle Controls cell activities like cell repair and reproduction – controls protein synthesis and makes ribosomal ribonucleic acid (rRNA). Is needed for cell’s survival and contains chromosomes Chromosome (Plant and Animal Cell) Long thread- like structures and made up of proteins and deoxyribonucle ic acid (DNA) Has genes which contain hereditary material which are passed down from parents to their offspring. Cytoplasm (Plant and Animal Cell) Jelly-like substance Contains chemicals and other tiny structures that carry out special functions and is the site of many chemical reactions in the cell.
Transcript
Topic 1: Cells and Organisation
- Cell Structure and Function of Each Cell Part- Chloroplasts vs Mitochondria- Plant Cell vs Animal Cell- Division of Labour- Parts of a Microscope- Biological Drawings
Cell Structure and Function of Each Cell Part
Protoplasm: Nucleus, cytoplasm and cell membrane
Organelle Structure FunctionNucleus (Plant and Animal Cell)
Spherical, usually the largest organelle
Controls cell activities like cell repair and reproduction – controls protein synthesis and makes ribosomal ribonucleic acid (rRNA). Is needed for cell’s survival and contains chromosomes
Chromosome(Plant and Animal Cell)
Long thread-like structures and made up of proteins and deoxyribonucleic acid (DNA)
Has genes which contain hereditary material which are passed down from parents to their offspring.
Cytoplasm(Plant and Animal Cell)
Jelly-like substance Contains chemicals and other tiny structures that carry out special functions and is the site of many chemical reactions in the cell.
Vacuoles (Animal Cell)
Fluid-filled spaces within cytoplasm, surrounded by membranes. Many tiny vacuoles.
Stores water and nutrients required for organism to survive and is filled with food being digested and waste materials on the way out of cell.
Cell Membrane(Plant and Animal Cell)
Thin membrane surrounding the cell.
Partially permeable (only allows certain substances to pass through), serves as a boundary between cell and external environment and controls substances entering or
leaving cell.Mitochondrion(Plant and Animal Cell)
Oblong shape and has double membrane
Site of aerobic respiration and breaks down glucose to release forms of energy used by organism.
Ribosomes (Plant and Animal Cell)
Made up of rRNA and proteins
Free ribosomes in cytoplasm attach to endoplasmic reticulum (ER) and plays an important part in protein synthesis
Cell Wall (Plant Cell)
Thick layer surrounding the cell membrane and is made up of cellulose
Supports cell and gives it regular shape and bonds with other cells to form plant structure
Chloroplast (Plant Cell)
Oblong shape and has double membrane
Contains chlorophyll which is needed to absorb energy from the sun and convert it to chemical energy to be stored as glucose (photosynthesis)
Vacuole (Plant Cell)
A single large space surrounded by membrane
Contains cell sap (water and dissolved materials like sugars and mineral salts) and maintains turgidity (shape of cell)
Chloroplasts vs Mitochondria
- In plants, chloroplasts make glucose and the mitochondria use that glucose to make energy
- Animals eat food containing glucose to obtain the glucose for their mitochondria to use.
- Both organelles have their own DNA and can reproduce independently within the cell
- Chloroplast is bigger than mitochondria
Plant Cell vs Animal Cell
Plant cell Animal cellHas cell walls and chloroplast Do not have cell walls and chloroplastsHas large singular vacuole Have tiny multiple vacuolesMake food via photosynthesis Obtain food through energy
consumed by the organismRegular shape Irregular shape
Multicellular vs UnicellularCells of multicellular organism have specialized structures to carry out basic functions within a cell like respiration. A unicellular organism requires more than those basic functions to survive as it is self-dependent, like the removal of wastes and responding to the environment.
Division of Labour
Division of labour is the breakdown of workload into smaller and more specific tasks for maximum efficiency.
Within each cell, there are many special structures or organelles. Each organelle is specially designed to carry out a specific job.Multicellular organisms are made up of different types of cells performing different functions. The cells have different shapes, sizes and structures, designed to perform specific tasks. Cells of the same kind that perform the same job are grouped together to form a tissue. Some tissues have more than one type of cell. These are called complex tissues.An organ is formed by several tissues working together to perform a specialised function.Organs with related roles coordinate to function efficiently. They work together for a specialised purpose to form an organ system.The different organ systems work together to make up the entire body of an organism.
Examples:Plant Animal
Cell Guard cell (Controls gaseous exchange)
Heart muscle cell (contracts rhythmically)
Tissue Epidermal tissue (Made of cells including guard cell. Reduces water loss, enables gaseous exchange and absorption of water and nutrients)
Heart muscle tissue (made up of heart muscle cells, contracts and relaxes at a steady rate)
Organ Leaf (Outer layer formed by epidermal tissue and is site of
Heart (formed by muscle, nerve and connective tissues, as well
production of food substances) as blood vessels. Pumps blood around the body)
Organ System
Shoot system (includes, leaves, stems, buds and flowers)
Cardiovascular system (formed by heart, arteries and veins. Transports blood to all parts of the body.)
Refer to page 8 of Notes for more examplesParts of a MicroscopeRefer to page 6 of Notes
Biological Drawings
Drawings and tables1. Must be done using sharp 2B pencil2. Must have suitable titles3. Must occupy more than ¾ of the space given, allowing space for labelling
Drawings1. Must have clear outlines (no sketching, shading or colouring)2. Must be in proportion3. Must state magnification of drawing4. Must resemble shape
Labels1. Must be ruled with pencil2. Must point to structures accurately3. Must not cross each other4. Must be printed or in pencil
Tables1. Must be ruled with suitable headings and include units where
appropriate2. Contents may be written in ink3. Recording of whole experiment must be in ink
Important Questions
Is blood a tissue? A tissue is made up of the same type of cells grouped together to
perform a specialized function. Blood consists of different types of cells such as red blood cells and white blood cells, that perform the function of transporting digested food, oxygen, enzymes, hormones and antibodies around the body. As such, it is a complex tissue.
Is the stomach an organ? The stomach is an organ because it comprises of several tissues like
connective tissue, nerve tissue, and blood tissue that work together to perform a specialized function like digesting food.
Is skin an organ or a tissue? It is an organ as it is made up of tissues including epithelial tissue, blood
tissue, nerve tissue and connective tissue, working together to perform specialized functions such as acting as a protective covering over the body surface, and to regulate our body temperature.
Topic 2: DNA
What is DNA?DNA (deoxyribonucleic acid) are blueprints in the form of genetic material which contains instructions to create new cells and is mostly found in the nucleus, mitochondria and chloroplasts of cells.
What is the structure of DNA? Double helix Sugar-phosphate backbone Nitrogenous base Hydrogen bonds
Backbone + nitrogenous base = nucleotideBase pairings: A (adenine) T (thymine) [two hydrogen bonds] G (Guanine) C (Cytosine) [three hydrogen bonds]Adenine and Guanine are doubly-ringed structures, purines, while Thymine and Cytosine are singly-ringed structures, pyrimidines.
For visual representation, go to pg 13 of Notes
How does DNA become chromosomes?
DNA Winds up to form a double helix Is packaged around histones (a type of protein) to form
Chromatin Is more condensed Which winds upon itself to form
Chromosome Two Chromatids form a Chromosome
In a human cell, there are 23 pairs of chromosomes or 46 chromatids and is inherited from parents
How does DNA from proteins?DNA
TranscriptionRNA
Translation through ribosomes in the cytoplasm Ribosomes decode RNA to use amino acids to make
Proteins
Transcription is a process of copying a short section of DNA into mRNATranslation is a process of decoding the specific sequence of mRNA into a polypeptide [a type of protein made up of amino acids]mRNA is like DNA but only has one nucleotide and the letter T is replaced by U
Practical: Extraction of DNA from TissuesAim: To extract DNA from plant and animal cells
Materials: 50g chicken liver (blended) 100g onion (blended)3g salt (NaCI) 10ml detergent1ml 2% tenderiser 3ml ice cold ethanol100ml distilled water
Method:1. Pour 10ml of detergent into two 250ml beaker each with 100ml of
water.2. Add 3g of salt into each beaker.3. Add 50g of chopped liver to one beaker and 100g of chopped onions into
the next and mix well. Blend the mixtures for 5 seconds.4. Place the beakers in a water bath at 60oC for 15 minutes then cool it in
an ice bath for 5 minutes and stir frequently.5. Place a coffee filter paper into a funnel and moisten with water. Pour the
mixture from the beaker into the funnel and collect the filtrate in a conical flask. Throw away the filer paper with the remains of the pulp.
6. Pipette 3ml of the chicken liver filtrate and 3 ml of onion filtrate into separate test tubes.
7. Pipette 1.5ml of tenderiser to each test tube, mix well with the stirring rod and leave it to stand for 10 minutes. Clean the glass rod with soap and water then put back on side bench after mixing.
8. Carefully pipette 3ml of ice cold ethanol down the side of each tube so that the alcohol remains in a layer above the juice. With a lower density, the alcohol will ‘float’ on top of the mixture. Be very careful not to mix the contents of the test tube.
9. Let the mixture sit for 5 minutes. You can watch DNA precipitate out in the layer between the mixture and the ethanol.
Detergent – break down fat molecules present in cell and nuclear membranes.
Salt – Neutralises the negative changes of phosphate groups, allowing DNA strands to clump together. Otherwise DNA would be hard to extract
Ethanol/Alcohol – DNA will precipitate out of the mixture as DNA is insoluble in ethanol.
Tenderiser – The enzymes in the tenderiser breaks down soluble proteins to release up more DNA for extraction.
60oC water bath – to remove enzymes that would denature the DNA and less DNA will be broken down.
Chop liver/ onion – To break down the tissues and increase the surface area to volume ratio for the action of the detergent and salt on the cells.
Ice Bath – To slow down the breakdown of DNA Filtration – To get filtrate which contains DNA & soluble proteins
Topic 3: Variables
What are the different kinds of variables and what are their purposes?
Independent variable is a variable that is manipulated and tested to see its effect. In graphs, it occupies the X-axis.
Dependent variable is a variable that might be affected by the independent variable. It is observed, measured and collected as data of the investigation. In graphs, it occupies the y-axis.
Controlled variable is a variable that is unchanged over the course of the experiment to allow for a fair test.
Topic 4: Tables and Graphs
What is a table? An arrangement of data in columns and rows Headings list independent and dependent variables with units in
brackets If there is no data available for a certain box, NA should be used Ditto marks and etc should not be used Should have a title above the table
What is a graph? A drawing that shows a relationship and is used to analyse data of an
experiment Independent variable should be on x-axis and dependent variable of y-
axis The place where the two axis meet is the origin and both axis should be
calibrated to the units of variables represented
For visual representation of graphs, go to page 17 of notes
Topic 5: Photosynthesis, Respiration and Bioreactors
What is photosynthesis?Photosynthesis is the process by which green plants, in the presence of chlorophyll and light energy, manufacture glucose from carbon dioxide and water, releasing oxygen in the process. (through palisade mesophyll cells)
Chemical formula:Carbon Dioxide + Water (using Light Energy and Chlorophyll) Glucose + Oxygen
Carbon dioxide is taken in through stomata on leaves while water is taken through the roots and reaches the leaf through the xylem.
During the day, the plant releases excess oxygen while taking in carbon dioxide. During the night, the plant releases carbon dioxide while taking in oxygen.
Photosynthesis is important as it provides the plant with energy which is consumed by other organisms which in turn supports the food chain.
Factors: Light is needed to provide energy for photosynthesis to occur to be
converted into If the temperature is too high, enzymes required for photosynthesis will
be denatured. If temperature is too low, there will be insufficient energy to activate enzymes.
What is respiration?
Respiration is the process by which food molecules are broken down to release energy.
It is needed by the human body to get energy to synthesize new protoplasm for growth & repair, transmit nerve impulses and absorb food substances in the small intestine using active transport.
There are two types; aerobic respiration and anaerobic respiration.
Aerobic respiration is the process by which food molecules are broken down, in the presence of oxygen, to release carbon dioxide, water and a large amount of energy.
It occurs in the mitochondria and oxygen-breathing living things.
Glucose + Oxygen Carbon Dioxide + Water + Energy
Anaerobic respiration is the process by which sugar is broken down to release small amount of energy in the absence of oxygen.
Fermentation is a type of anaerobic respiration and there are two types:
Ethanol Fermentation occurs in yeast when there is no oxygen
Glucose Carbon Dioxide + Ethanol + Energy
Ethanol fermentation can be used to make alcoholic drinks and makes bread rise. Ethanol can be used as a biofuel to generate electricity or run cars.
Lactic Acid Fermentation occurs in humans when there is no oxygen and some bacteria
Glucose Lactic Acid + Energy
Lactic acid fermentation results in muscle fatigue in humans and provides an alternative source of energy when oxygen is absent. Lactic acid can be used to make products like kimchi and yoghurt and helps to preserve food by preventing growth of harmful organisms.
What are bioreactors and what types of bioreactors are there?Bioreactor is an apparatus that is used to carry out bio-processes.
Yeast is a common microorganism used in bioreactors to make beers (from barley), wines (from grapes), vodka (from potatoes) or just plain ethanol and can survive without oxygen by using ethanol fermentation.
There are three kinds of batch reactor:
Important Questions
* In starch test, iodine solution turns dark blue in positive result and stays brown in negative result** In variegated leaves, white parts do not have chlorophyll no starch present*** Burning removes oxygen for tests on anaerobic respiration
What is the purpose of the various steps in starch test? Exposing leaf to strong sunlight for 1 week: Time would be long enough
for glucose to be produced and excess to be stored as starch, otherwise we may not have a positive result for starch test with iodine solution
Destarching plant: There may already be starch in the leaves even before they are placed in sunlight for this experiment. This ensures a fair experiment as the parts not exposed to light would be destarched.
Boil leaf in ethanol placed in a hot water bath: Green colour (chlorophyll) is removed as much as possible as colour change will not be evident with iodine solution if the leaf is not decolourised.
Brittle leaf to be placed in hot water: If leaf is not soft enough, we would not be able to spread the leaf on the while tile for the iodine solution to completely cover the leaf.
Cover leaf completely with iodine solution so that colour change would be evident.
What are some factors in production of alcohols? Type of yeast: Commercial yeast gives a uniform product while wild
yeast can vary the product Type of glucose/carbohydrate used: The amount of glucose in the
carbohydrate causes sweetness to differ (eg. apples have more sugar than blackberries)
Container: Wood can be used to impart flavour while steel retains original flavour
What are the effects of lactic acid fermentation on milk? Lower pH and sour smell: The bacteria in the yoghurt carried out lactic
acid fermentation and produced lactic acid. The acid lowers the pH and has a sour smell.
Semi-solid: Lactic acid causes the protein in the milk to clump together resulting in the curdling of the milk.
How do horticulturists increase the amount of carbon dioxide in a greenhouse to increase the rate of growth of plants?
Burn carbon-based fuels such as kerosene in specialized carbon dioxide generators
Release carbon dioxide directly from tanks of pure carbon dioxide.
Topic 6: Diversity of Life and Classification
What is biodiversity and its function?Biodiversity is the existence of a wide range of different types of organisms in a given place in a given time (or the world as a whole)
Different species of plants, animals, fungi & microorganisms provide us with food, medicines, fuel, building materials, fiber for clothing & industrial products.
Makes life possible on Earth, like plants providing oxygen for us to breathe.
How is biodiversity classified?Terminology:
Taxonomy--the branch of science that classifies and names living things. Nomenclature--a system for naming things In biology, there is a two-word system that is used to name organisms. It
is called Binomial Nomenclature (a two named--naming system). Carl Linnaeus devised this in the 1800's using these two subgroups for
the nameGENUS & SPECIES
(more general) (more specific)
Carl Linnaeus also created a hierarchal system of classification. It is as follows, with the most inclusive category being at the top and the least at the bottom:
Kingdom Phylum Class Order Family Genus Species
Thomas Whittaker created another classification system, with five kingdoms:
Eukaryotes: Well-defined nucleus and other membrane-bound organellesProkaryotes: Genetic material freely found in the cytoplasm and is not enclosed by the nuclear membrane. Lack membrane-bound organelles like mitochondria and endoplasmic reticulum.
Topic 7: Diversity of Animals
What are vertebrates and invertebrates?
Vertebrates Animals with spinal columns. Include fishes, amphibians, reptiles, mammals and birds. Built along the basic chordate body plan – a stiff rod running through the
length of the animal (vertebral column) and a hollow tube of nervous tissue (spinal cord)
Make up less than 10% of animals no earth
Invertebrates Animals that do not develop vertebral columns Include insects, worms, clams, crabs, octopus, snails, starfish
(arthropods, molluscs, worms, echinoderms, sponges) Make up over 90% of animals on Earth
What are the 5 classes of vertebrates and what are their features?
General FeaturesMammalia Reptilia Amphibia Pisces Aves
Outer Covering
Hair Dry scales, waterpro-ofed by keratin
Moist skin Wet scales
Feathers
Respiratory Organ
Lungs Lungs Moist skin and lungs
Gills Lungs
Movement Limbs Limbs Limbs Fins and tail
Wings
Reproduction Give Birth to live young – mammary glands produce milk
Lay eggs Lay eggs – usually return to standing water
Lay eggs Lay eggs
Blood Type Warm-blooded – can regulate
Cold-blooded – cannot
Cold-blooded – cannot
Cold-blooded – cannot
Warm-blooded – can
body temp. regulate bodytemp.
regulate body temp.
regulate bodytemp.
regulate body temp.
Other features:
Animalia Monotremes are egg-laying mammals. Include the duck-billed platypus
& echidnas or spiny anteaters Marsupials have a brief gestation and give birth to tiny, embryonic
offspring that complete development while attached to the mother’s nipples
Eutherians are mammals that bear fully developed live young. They are commonly called placental mammals because their placentas are more complex than those of marsupials
Mammals have to eat a lot to maintain high body temperature Have larger, well-developed brains compared to other animals.
Examples are dolphins, chimpanzees and humans Mammals give young more protection and training compared to other
animals
Aves Have adapted to flight
- Forelimbs evolved into feather-covered wings called airfoils- Large flight muscles anchored to a central ridge along the
breastbone provide power- Present-day birds lack teeth, the tail is supported by only a few
small vertebrae, feathers have hollow shafts and their bones have a honeycombed structure that makes them strong but light. All these are to reduce weight for flight
- Flightless birds have vestigial or adapted wings for swimming Flight is costly and birds have a high metabolism rate Only animals that are endothermic – use metabolism to maintain high
body temperature Have a beak, a projection forming their mouth Have two legs (bipedal) to perch, walk, hop or run
Amphibia Skin is smooth and moist, making it quite permeable to gas and water –
can undergo gaseous exchange Can absorb oxygen directly into bloodstream through skin and expel
carbon dioxide back into the air External fertilization Offspring mostly develop through metamorphosis
Pisces Jawed vertebrates Three lineages of jawed fishes with gills and paired fins:
- Chondrichthyans — sharks and rays- Ray-finned fishes — tuna, trout, and goldfish- Lobe-finned fishes — coelacanths and lungfishes
Mostly undergo external fertilisation
Topic 8: General Ecology
Definitions:
Ecology is the scientific study of the interactions among living organisms and their environment. These interactions determine distribution of organisms and their abundance.
Habitat is the physical location in which an organism lives.
Niche is an organism’s role in a community in the physical space it occupies, its interaction with other organisms and its effects on the environment.
Species are organisms that interbreed by sexual reproduction to produce fertile offspring.
Population is a group of organisms, of the same species, living together in a particular habitat at a given time
Community is the different populations of organisms interacting in a given area.
Ecosystem is made up of different species of a community, together with their abiotic environment and a complex set of relationships among the living resources, habitats, and residents of an area
What are abiotic and biotic factors?
An ecosystem uses both energy and materials (inorganic nutrients). Energy from the sun enters it and flows through it in a non-cyclic manner
as energy is lost as heat. Energy needs to be constantly supplied Materials flow in a cyclic manner and need not be constantly supplied In a balanced ecosystem, materials are never lost and are continually
recycled e.g. carbon cycle.
Common Abiotic factors (the physical or chemical environment, non-living)
Factors EffectLight Physical All green plants need light energy from the Sun to undergo
photosynthesis and make food and are called photoautotrophs. All other life-forms depend on plants indirectly or directly for energy and are thus also dependent on light
Mineral salts and salinityChemical
For healthy growth, plants and animals need minerals. Plants are able to obtain minerals from the soil while animals obtain it from their diet or water
Water Physical
Water is essential for life and is present in the environment of every organism. However, due to the imbalance of water distribution, animals adapt to survive in different environments.
Temperature Physical
Most organisms are active at temperatures between 0 and 40 degrees Celsius as any temperature beyond that range generally impairs vital life processes. However, other organisms have adapted to live in extreme temperatures outside this zone
pH (alkalinity/acidity) Chemical
Neutral or alkaline soils are generally conducive for plants. Freshwater organisms live in water at about 7 while marine organisms live in an environment of 8. Some plants prefer acidic soil.
Air Physical Most organisms need oxygen for respiration. Land organisms take in oxygen from the air while aquatic organisms take in dissolved oxygen in water.
Biotic factors refer to all the living organisms in the habitat. Some common factors include:
Prey Predators Parasites Competitors
Other abiotic factors include: Soil Topographical location Climate
All these contribute to the habitat. As habitats are different, abiotic and biotic factors also differ, depending on the location.
What are some examples of ecosystems and their organisms?
Ecosystem Features OrganismsDesert Very little water
Very high temperature and light
Camel:- can drink a lot of water at one time- body fats can break down to
provide them with energy and metabolic water
Cactus:- spines to reduce water loss- thick stem to store water
Tropical Rainforest
High temperature High rainfall Competition for light & nutrients
Monkey ladder vine:- twine up trees to reach sunlight
Orchid mantis- Mimics an orchid to stay safe from
predatorsLianas and epiphytes
- Grows in the canopy to get lightMangroveSwamps
Tidal environmentHigh salinityWater-logged soil
Avicennia:- Pneumatophores (erect side
branches of the horizontal roots) help to take in oxygen
Aegiceras corniculatum:- salt glands in leaves to get rid of
Photoautotrophs - Make glucose from carbon dioxide and water with light energy (Use Light energy)
Plants, algae and certain bacteria
Chemoautotrophs - Make use of energy from chemical reactions (Use Chemical energy)
Certain bacteria
Consumers - Heterotrophs Heterotrophic nutrition
- Feed on organic substances produced by autotrophs
- Ingest living or recently killed organic matter
- Obtain energy from other organisms
- AnimalsHerbivores - Feed only on plants Horse, DeerCarnivores - Feed only on other animals Lion, TigerOmnivores - Feed on both plans and other
animalsPig, Bear
Scavengers - Feed on dead organic matter Vulture, HyenaDetritivores - Heterotrophs
Heterotrophic nutrition- Organisms that feed
Earthworms, dung beetles
on/ingest partially broken down or decaying remains of animals or plants/ non-living organic matter (detritus)
- Detritus may have been partially or fully decomposed
- Recycle detritus, returning it to food chain
- Are animalsDecomposers - Saprotrophs Saprotrophic
nutrition- Cannot make food for
themselves a type of Heterotroph
- An organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion
- Fundamental to the recycling of nutrients within an ecosystem – break down organic matter into simple inorganic substances which are available for producers
- Are not animals
Most fungi, many bacteria and protozoa
What are some relationships between these organisms?
These relationships are symbiotic relationships or symbiosis, which is the act of living together
Description & Effect ExamplesPredation - In which one species, the
predator, kills and eats the other, the prey
- Predators have acute senses to locate and identify prey and have adaptations like claws, stingers, fangs, poison to
Lion eating gazelle
catch and subdue prey- Prey have adaptations to
combat this like mimicry (appearing like another organism to deter predator) and camouflage
- Effect: Predator benefits and prey is harmed
Parasitism - In which one species, the parasite, lives in or on another organism, the host, gaining food and shelter from the host and harming the host
- While parasites generally do not kill host, high numbers will
- Adaptations (e.g. specialised mouthparts and lack of a digestive tract) enable them to spend their life inside the intestines of other vertebrate hosts.
- \Effects: One organism (parasite) benefits at the expense of another (host).
Ectoparasites: parasites that feed on the external surface of a host such as dogs.
Ticks, mites, lice, bed bugs and fleas live attached to the outside of the host, where they suck body fluids, cause irritation and act as vectors for pathogens.
Endoparasites: parasites that live within the body of their host.A primary host (in which the parasite becomes sexually
Tapeworms and malarial parasites (pork tapeworm, Taenia solium are highly specialised to exploit the resource of the host – pig)
mature) and one or more intermediate host (houses larval stages) are required to complete the lifecycle
Malaria caused by protozoan parasite, Plasmodium, which is transmitted by Anopheles mosquito.- Mild flu-like symptoms
- Severe (confusion, coma, neurologic focal signs, severe anaemia, respiratory difficulties)
- Tests to confirm anaemia and renal failure.
- Antimalarial drugs to get rid of parasite.
Mutualism - Relationship in which both species benefit (none suffers)
- Nitrogen-fixing bacteria, Rhozobium, live inside root nodules in leguminous plants
- Lichen Usnea subfloridana is a symbiosis of a fungus and an algae
- Cleaner wrasse will continually attempt to clean parasites and groom other fish. Through this symbiotic relationship, the cleaners get a meal by eating the parasites off the fish and the reef fish get a shower
Commensalism - One party (the commensal) benefits while the host is unaffected.
- Epiphytes (perching plants) gain access to a better position in the forest canopy, with more light for photosynthesis but do no harm to the
host tree.- Commensal anemone
shrimps live within the tentacles of host sea anamones. The shrimp gains protection from predators but the anemone is neither harmed nor benefitted.
Ammensalism - The situation where the presence of one species has a harmful effect on the other but is not itself affected by the association.
- It is opposite to the relationship between a commensal and its host.
Grazing mammals trample and destroy vegetation around waterholes, creating bare zones. The mammals are unaffected by the loss as they go there primarily to drink and not feed.
Antibiosis - Describes the chemical inhibition of one party by another
- Effect: One party is harmed; the other is unaffected or may even benefit
- In allelopathy, one plant releases toxic compounds (e.g. phenols or alkaloids) which inhibit the growth of nearby plants. Allelopathic plants include black walnut, swamp chestnut oak and eucalyptus and neem trees.
- In autoxicity, a parent plant produces chemicals to inhibit the growth of its own seedlings.
- Fungi produce antibiotics
to inhibit the growth of bacteria.
Competition - Contest between organisms for niche, resources and mates.
- Occurs naturally between living organisms which co-exist in the same environment
- Intraspecific competition: competition within a species
- Interspecific competition: competition between species
- Animals compete over water supplies, food, mates and other biological resources
Important Questions
What are the consequences of releasing pets into an external environment? Both the biotic and abiotic components of the new environment would
be different from the initial enpoyhgvironment and his fishes might die. This release might also create an unbalance in the new ecosystem as the pets might compete with native organisms for food and resources.
How is dead matter recycled? Give named examples where possible. Decomposers live on or in dead organic matter, secrete digestive
enzymes into it and absorb the products of digestion through saprotrophic nutrition, causing decomposition.
Examples of decomposers include bacteria & fungi. Detritivores feed on the decomposing organic material through
heterotrophic nutrition. Examples of detritivores include earthworms & dung beetles. The dead
organic matter are broken down into simple inorganic substances which are available for the producers.
As such, nutrients are recycled within the ecosystem.
Topic 10: Energy flow & conserving the environment
*A trophic level is the position that an organism occupies in a food chain and determine what it eats and what eats it
A combination of food chains that integrate to form a network is called a food web
The more complex a food web, the more stable it is a shift in the population of one organism would not adversely affect the other organisms in the ecosystem to a great extent compared to a simple food web
The factors that affect the ecosystem (abiotic and biotic factors) also affect food webs. Here are some examples:
o Disease outbreakso Introduction of new animals/plants/specieso Human activities (Eg. deforestation, over-fishing)
Decomposers break down dead plants and animals and the waste of other organisms, returning them to the soil as essential nutrients for producers Without them, plants would not get essential nutrients and dead matter and waste would pile up
What is the transfer of energy between trophic levels and ecological pyramids?
Energy is continuously being lost from one organism to the next, mainly in the form of heat (other ways include sound, movement, wasteful digestion, respiration etc) energy must be added to keep it going otherwise the energy will be lost population of lower trophic levels must be significantly higher than that of higher trophic levels
Only 10% of energy is captured and used by the organisms in the next trophic level transfer of energy not 100% efficient non-cyclic
An ecological pyramid shows the relative sizes of different components of the trophic levels in a food chain
There are three types:o Pyramid of numberso Pyramid of biomasso Pyramid of energy
What is ecological balance?
A condition of dynamic balance within an ecosystem in which the species and diversity remain in a stable state
This ensures the continued survival of organisms
How do humans impact the ecological balance?
Humans can both benefit and harm the environment Important as humans require healthy ecosystems to survive
ecosystems provide use with food, water, air and others We harm it through pollution and global warming We benefit it through conservation
These are the main ways humans affect the environment:Definition Causes Effects
Water Pollution
Water pollution is the contamination of water bodies with organic (insecticides), inorganic (heavy metals) or macroscopic pollutants (trash)
Industries, agricultural runoff, household wastes
Death of marine & human life (lack of clean water)
Air Pollution The introduction into the atmosphere of chemicals, particulates, or biological materials that cause discomfort, disease, or death to
Coal industry, Volcanoes, Vehicles
Pneumonia, Smog, Acid rain (dissolves nutrients in soil & washes them away before
humans and other living organisms such as food crops.- Examples of
pollutants: Sulphur Oxides, Nitrogen Oxide
plants can use them), threatening plant & animal life (endangered Northern spotted owl)
Land Pollution
The degradation of Earth's land surfaces, often caused by human activities and their mis-use of land resources.
Urbanization & Industrialization,haphazard disposal of urban and industrial wastes, exploitation of minerals, improper use of soil by inadequate agricultural practices
Human comfort, Changes to the arctic/ wildlife/ rainfall/ agricultural/ patterns, Rising sea levels
Conservation The preservation, protection and careful management of natural resources
Alternative energy sources (eg. wind turbines), recycling etc
Makes sure that natural resources are sustained for continued use by humans, preserving the ozone layer,
reducing the amount of UV radiation that reaches the earth’s surface
Topic 11: Introduction to microorganisms & viruses
There are three kingdoms that consist of microorganisms – Monera, Protista and Fungi
They can be split into prokaryotes and eukaryotesGo to Page 11 for more
Prokaryote EukaryoteKingdom Monera Fungi, ProtistaSize Very small in size Fairly large in sizeNucleus Has nuclear region (nucleoid)
Not surrounded by nuclear membrane Nucleus not well defined No true nucleusNucleolus absent
Nuclear material surrounded by a nuclear membrane Well defined nucleus True nucleusNucleolus present
Cell Wall Cell wall composition differs from kingdom to kingdomWhat are Viruses?
Microscopic, non-cellular and infectious particles Lack protoplasm, organelles or locomotion Range from 450nm to 20nm Cannot survive without a living host Made of genetic material (DNA or RNA), surrounded by a protein coat Eg. Herpes Virus, HIV
What is Practical Microbiology?
We are looking at 3 aspects of Practical Microbiology: Culture Media Basic Microbiological Techniques Methods for Culturing Bacteria
Culture Media: Liquid media
o State: Water-based solution that do not solidify at room temperature above freezing
o Tend to flow freely when container is tiltedo Components: Nutrient broth, a common laboratory medium
contains beef extract and peptone
Solid mediao Firm surfaceo Function: Allows cells to form discrete colonieso Isolating and subculturing bacteria and fungio Nutrient agar/Blood-based agar
Semisolid mediao Clot-like consistency at room temperatureo Determines motility of bacteriao Contains certain amount of solidifying agent (agar or gelatin) that
thickens the media but does not produce a firm substrate Agar
o Agar is a complex sugaro Solid at room temperature, liquefies at boiling temperature of
watero Once liquefied, only solidifies until cools to 42 degrees Celsius
Needs to be over 42 degrees to be poured and seto Agar can be inoculated and poured in liquid form at 45 to 50
degrees Celsius will not harm microbes or handlero Flexible and moldableo Provides basic framework to hold moisture and nutrientso Is not a digestible nutrient for most microorganisms
Basic Microbiological Techniques Used by microbiologists to manipulate, grow, examine and characterize
microorganisms in the laboratory These techniques are: Inoculation, Incubation, Isolation, Inspection and
Identification
Inoculation: To culture microorganisms Introducing a tiny sample of the microorganism into a container of
nutrient medium This provides an environment which they multiply
Incubation:
To encourage multiplication Placing the inoculated medium in a temperature-controlled chamber
(incubator) between 20 to 40 degrees Celsius
Isolation: The result of inoculation and incubation Isolation of the microorganism in the form of colonies on solid media or
turbidity in liquid media
Inspection:
Observing the culture for obvious growth characteristics like colour, texture or size which are useful in analysing the specimen
Identification: To pinpoint an isolate down to the level of species Performing specialized tests and accumulating data to develop the
profile of the microorganism and identify it
Methods of Culturing BacteriaLoop Dilution or Pour Plate Method
Sample inoculated serially into a series of cooled but still agar tubes To dilute cells in each successive tube in series Inoculated tubes poured into nutrient agar plates and are allowed to
solidify
Spread Plate Method Pouring a small volume of diluted sample is pipetted onto surface of
medium Spread around evenly by a sterile spreading tool Cells are pushed to different areas of surface to form individual colonies
Streak Plate Method Small droplet of sample spread over surface of medium according to a
pattern that gradually thins out sample Spatially separates the cells over several sections of the surface of the
agar
Topic 12: Diversity of organisms – Monera, Fungi, Protista
We are looking at the three kingdoms, Monera, Fungi and Protista and their cell structure, modes of nutrition, locomotion, reproduction and beneficial and harmful aspects
Monera Fungi Protista
Cell Structure - Genetic material found freely in cell and no membrane-bound organelles prokaryotic
- Causes death of organisms, leading to surface scum and odour
Paralytic Shellfish PoisoningProtozoa- Parasitic
diseases like Giardiasis (Giardia) and Malaria (Plasmodium)
Topic 13: Antibiotics
Contents:- Discovery- Definition- Mode of Action of Antibiotics- Resistance Mechanisms in Bacteria
- Methods of Acquiring or Spreading Antibiotic Resistance- Super Bugs- Practicals
Discovery- Discovered by Sir Alexander Fleming - Was culturing Staphylococci bacteria- Plate was contaminated by a fungus, with a zone of inhibition around it- This fungus was Penicillium notatum, with the antibiotic Penicillin
Definition- Substances produced by the natural processes of some microorganisms
that can kill or inhibit the growth of other microorganisms- Mostly produced by bacteria (eg. Bacillus species) or fungi (eg.
Penicillium species)
Mode of Action of Antibiotics- Antibiotics can act in a variety of ways – affecting the bacterial cell wall,
affecting the production of nuclear material, affecting the production of proteins and disrupting cell membrane function
Mode of Action
Process
Affecting the Bacterial Cell Wall
Prevents formation of peptidoglycan in the cell wall, interrupting completion of the cell wall, causing the cell to rupture due to water lysis (water entering cell)Eg. Penicillin
Affecting Production of Nuclear Material
Prevents synthesis of hereditary material, affecting the reproduction of the cellEg. Rifampin
Affecting the production of proteins
Disrupts construction of essential proteins required for normal functioning of the cell, also affecting its growthEg. Tetracycline
Disrupting cell membrane function
Damages the cell membrane, disrupting its partially permeability and allowing harmful substances to enter and useful substances to leave the cell, potentially causing the cell to burstEg. Polymyxin
Resistance Mechanisms in Bacteria- Bacteria can also evolve to gain resistance against antibiotics in two
ways – activation of drug pumps and drug inactivation mechanisms
Mode of Action ProcessActivation of drug pumps
Specialised membrane proteins are activated and continually pump the drug out of the cell so that the antibiotic cannot affect the cell
Drug inactivation mechanisms
Enzymes are produced to permanently alter the structure of or break down the antibiotic, rendering the antibiotic ineffective
Methods of Acquiring or Spreading Antibiotic Resistance- Bacteria can pass their resistance on to other cells through conjugation,
transformation, transduction and spontaneous mutation
Mode of Action ProcessSpontaneous mutation
The primary resistance and is very rare. Caused by errors taking place during replication of DNA, and can be passed on quickly due to rapid rate of reproduction of bacteria, spreading resistance to the whole population.
Transduction DNA containing resistance gene is transferred through bacteria-specific viruses called bacteriophages
Transformation Parts of DNA are taken up by bacteria from external environment due to death of resistant bacterium
Conjugation Direct cell-cell contact via pilus allowing transfer of small pieces of DNA containing antibiotic resistance genes called plasmids
Super Bugs- Bacteria which are resistant to a wide range of antibiotics- If cycle of antibiotics is not completed, resistant bacteria multiply and
become more common- Eventually, the entire infection becomes a resistant strain
- This may lead to the emergence of super bugs
Practicals - Ethanol is used in disk diffusion test to act as an organic solvent and
dissolve antimicrobial compounds within the substance tested- If the substance has antimicrobial compounds, the zone of inhibition
would be greater than that of the negative control- Negative controls are to act as a comparison to find out whether the
substance tested contains antimicrobial compounds- Positive controls are to show that the experiment is functional- The plates are inverted to prevent water condensed at the top from
falling onto the culture medium and affect the experiment.
Biotechnology- Refers to the practical application of microbiology in the manufacture of
food, industrial chemicals, drugs and other products
- Use mass controlled microbial fermentations and bioengineered microorganisms
Food Production]- Bacteria can impart a desirable aroma, flavour or texture to foods - Lactobacillus sp. is main bacteria used and is used to produced rye bread
and curd
Medicines:- Two types: antibiotics and vaccines
- Most antibiotics produced by Bacillus sp.- Eg. Polymyxin and Bacitracin
- Bacterial vaccines contain killed or attenuated bacteria that activate the immune system
- This allows antibodies to be built against that particular bacteria and prevents future bacterial infection
- Eg. Bordetella pertussis causes whooping cough and is used in DPT (Diptheria, Pertussis and Tetanus) vaccine. Mycobacterium tuberculosis causes tuberculosis and is used in tuberculosis BCG (Bacille, Calmette and Guerin) vaccine
Waste Management- Bacteria play an important role to play in waste management in three
applications – environmental waste management, treatment of sewage water and bioremediation
Application ProcessEnvironmental Waste Management
Bacteria like soil bacteria play an important role in ecosystems, degrading plant and animal matter and wastes, also reducing organic compounds to inorganic compounds like carbon dioxide and minerals Eg. Psuedomonas fluorescens
Treatment of Sewage Water
In the aeration tanks, bacteria rapidly decompose biodegradable constituents of the wastewater when oxygen is added
Solid particles settle to the floor in the clarifier as sludge and purified water can be returned to the environment
Non-biodegradable components are removed before part of the bacteria is returned to aeration tank and the remainder are pumped into the bioreactor
Anaerobic bacteria consume aerobic bacteria which had died due to lack of oxygen and are pumped back into the aeration tank, where they themselves die but aerobic bacteria thrive
Through this process, 90-95% of sludge has been converted to carbon dioxide and water due to bacteria
Bioremediation The use of biological agents to break down hazardous substances, removing dangerous chemicals from the environment. Bacteria can metabolize hydrocarbons and other contaminants and convert them to less toxic products.
This can happen naturally or by humans. Humans inject specific bacteria into groundwater, sometimes with nutrients for the bacteria to remove hydrocarbons in groundwater
Natural bioremediation occurs when naturally occurring bacteria living in the aquifer (groundwater) degrade toxic contaminants into less toxic compounds
Practicals- Bacitracin is not consumed orally as they pass through the alimentary
canal (digestive tract) and get absorbed into the bloodstream, which may be too long to take effect
- Polymyxin is not consumed orally as it is not absorbed from the alimentary canal and it would be more effective for localized application
- Similarities between treatment of sewage and bioremediation:o Both use microorganisms like bacteria
o Both result in harmless products like carbon dioxide being formed- Differences between treatment of sewage and bioremediation:
o Organic waste is broken down in sewage treatment but hazardous contaminants are broken down in bioremediation
