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Grade 7 Science

Interactions within Ecosystems

Types of Ecosystems

Ecosystems

PWe are surrounded by biotic (living) andabiotic (non-living) things. All animals, plantsand microorganisms are living things andbiology is the study of these living things.

PAny living thing is referred to as an organism.

Types of Ecosystems

Ecosystems

POrganisms are found in just about every placeon Earth that you can imagine. From thecoldest regions of Antarctica to the hottestundersea volcanoes.

PEach organism has adaptations that allows itto survive in its chosen environment.

PAdaptations are inherited characteristics thathelp an organism survive in its environment.

Types of Ecosystems

Biotic and Abiotic

PBiotic factors of an environment include allliving things in that environment. From thelargest elephant to the tiniest bacterium.

PAbiotic factors include all the non-livingthings in the environment such as air, water,rocks & minerals and sunlight.

Types of EcosystemsWhat is an Ecosystem?

PAn ecosystem is all the biotic and abiotcfactors of a particular environment.

PEach organism is suited to survive in theirparticular ecosystem.

PEcosystems can be as large as an ocean or assmall as a rotting log in the forest.

PWithin one large ecosystem there may bemany smaller ones.< Ex. A forest ecosystem may have a smaller river

ecosystem or a bog ecosystem.

Reading Check

Page 9

PAnswer questions 1 - 4

Types of Ecosystems

Ecosystems of Atlantic Canada

PCoastlines and Oceans< Long stretches of rocky coastline, sometimes

covered in saltwater and other times exposed to airas the tide moves out.

< Organisms found on the coastline (seaweed,barnacles, mussels) are able to attach to the rocks tokeep from being washed away by the waves.

< Organisms found in the ocean must be able to adaptto cold temperatures, moving currents and watersalinity (saltiness).

Types of Ecosystems


PCoastlines and Oceans< Many organisms have the capability of swimming

(cod, seals and whales) while others just drift withthe moving currents (jellyfish and plankton).

< Sunlight can only penetrate to about 100m to200m. Even though plants cannot survive belowthese depths, there are many organisms such asbacteria and certain animals that are adapted to livehere.

Types of Ecosystems


PFreshwater Ecosystems< This includes rivers, lakes and ponds< They get their supply of freshwater from rain and snow< Whether an area is dry or muddy after a rainfall depends

on the type of soil and rock found in the ground< Some plants like a very wet soil, such as tamarack and

willow trees< In this type of ecosystem, there are many habitats for

animals such as trout, beavers, ducks, loons, frogs, insectsand various water dwelling plants.

Types of Ecosystems


PArctic< This ecosystem has very low temperatures and very little

precipitation... it is basically a cold desert.< During winter the nights are long and days are short... the

opposite happens in the summer.< About one metre below the surface is permafrost...

permanently frozen ground.< There is not enough moisture to support the growth of trees,

only low shrubs, mosses, lichens and small flowering plants.< Animals found in the Arctic include caribou, wolves,

lemmings, polar bears< Birds fly north in summer to mate and south in the winter

since it is too cold for them to survive.

Arctic Animals

Types of Ecosystems


PForests< There are many types of forest ecosystems< The island of Newfoundland is Boreal forest and much of

Labrador is called Taiga< The type of forest is named based on the type of vegetation

that grows there< The type of vegetation is determined by the abiotic factors

of the region ex. Soil type, rainfall, amount of sunlightand temperatures

< Poorly drained areas sometimes become bogs or marshes. Dead plant material decays very slowly here and the build-up of dead plant material can sometimes produce peat.

Abiotic Parts of Ecosystems

P Organisms require certain conditions in order tosurvive in a particular ecosystem.

P Too much light can cause leaves on a plant to burn,not enough and the leaves turn brown.

P Too much water and roots will rot, too little andleaves droop and the plant will die

P Some plants like soil acidic while others do not.


Range of Tolerance

PEvery population of organism lives best in anecosystem that has an acceptable range ofabiotic factors.

P If this range goes too high or low, you willfind less and less numbers of these organisms.

PThe range of abiotic factors that is best fororganism survival is called their Range ofTolerance.


Abiotic Influences - Light and Light Intensity

PAll green plants and algae depend onlight from the sun to carry outphotosynthesis.

PThe amount and intensity of light in anarea will determine the type of plantsthat will grow there

PSeaweed and fresh water plants cangrow at or near the surface of thewater. However, below 200 meters,there is no light and, therefore, outsidethe range of tolerance for plants.



PUnlike plants, many animals live in low lightor no light conditions< Example - caves, deep ocean, in the soil

PSome of these animals sleep during the dayand only come out at night.

PThese animals have special adaptations tomake them more functional in conditions oflow light.< Sense of hearing, touch or smell are better than

normal



Grotto Salamander Texas Blind Salamander Vampire Bat

Giant Isopod Corolla Angler Fish


Abiotic Influences-Temperature

PAnimals that cannot regulate their internal bodytemperature are referred to as cold-blooded.

PTheir internal body temperature becomes whatever theoutside air or water temperature happens to be.

PAs a result, the activity level and even where they liveis determined by temperature

PEven the growth rate of micro-organisms, such asbacteria, is determined by temperature.

PPlants, such as strawberries, will only produce fruitwhen the temperature is warm enough.

Abiotic Parts of EcosystemsAbiotic Influences - Soil

P Soil consists of biotic and abiotic components.< Biotic parts are decomposing dead plants and

animals as well as waste products they excrete< Abiotic parts rock materials, air, water, acidity

P The type of soil will affect the type of animal and plant life that can live in it

P Insects and worms burrow through the soil, looseningit by creating air pockets. This, in turn , allows forbetter water absorption and it also makes it easier forplant roots to grow.

P The soil also provides an anchor point for plant roots.


Abiotic Influences - Air & Wind

P Animals use oxygen from air for respiration

P Plants use carbon dioxide for photosynthesis

P Many animals, such as birds, insects and bats, fly throughthe air.

P Wind is important for plants that distribute their seeds inthis way ex. Dandelion seeds

P Along coastlines, wind can be strong and frequent. Thiswill dry out the soil and often send a salty spray over theland. Plants that live here must be adapted to dry soil andhigher than normal salt content.

P Lichens have a high tolerance for salt and are often foundgrowing on rocks along the coastline.


Abiotic Influences - Water

PEvery living thing requires water to survive.

PSome organisms live in water, while other organismshunt for their food in water. However, all organismsMUST consume water.

PThere are some organisms that have a wider range oftolerance for water than others and can therefore livein very dry conditions for a long time ex. Cactus

PLarge bodies of water help to regulate airtemperatures on land

PPolar bears depend on ice to hunt seals in the spring.

Biotic Parts of Ecosystems

PEcosystems include many different species oforganisms.

PA species is a group of organisms that canreproduce among themselves to produceoffspring of the same type that can alsoreproduce successfully.

PA dog can mate with another dog but not acat... because they are two different species.


Levels of Organization

PA single member of a species is called an individual.

PAn entire group of individuals that live in the sameecosystem at the same time are called a population.

P In any ecosystem there are many different populationsof animals and plants.

PThe interaction of these different populations is calleda community.

PThe interaction of all the biotic and abiotic factors ofan area is called an ecosystem.


PWithin any community, each species interacts with thebiotic and abiotic factors differently.

PFor example, ducks eat waterweeds and mosquitolarvae while the kingfisher eats fish.

PSome plants grow at the surface of the pond while otherare rooted at the bottom.

PThe role a species has, including where it lives, how itobtains its food, and how it affects its environment iscalled its niche.

P If two species have the same niche, they are incompetition and one of the species will die off.

Types of Interactions in Ecosystems

PThe biotic and abiotic parts of the environmentinteract together in many different ways.

PAs you breathe you are interacting with an abioticpart of your environment... the air.

PPlants are affected by temperature, rainfall, soil typeand amount of sunlight... all interactions with theabiotic part of their ecosystem.

PAn animal eating a plant is one biotic part interactingwith another biotic part of the ecosystem.

PEven two abiotic parts can interact - the sun dryingout a mud puddle is an example.

Types of Interactions in Ecosystems

Symbiosis

PSymbiosis is the relationship between two differentspecies in an ecosystem. Sometimes thisrelationship is good while other times it’s not.

Types of Interactions in EcosystemsSymbiosis

PThere are THREE types of symbiosis.

PParasitism is a type of symbiosis where one speciesgets a benefit while the other species is harmed insome way. In extreme cases the host may die.

PThe parasite obtains its food from the other organismwhich is called the host.

PParasites can be external or internal

Scabies mite

Examples of Parasites

Tomato Hornworm covered in Braconid Wasp pupae

Human Tapeworm

Fungal parasite onMaple tree Cordyseps Fungus

on Carpenter Ant

Raflesia parasitzes a grape plant

Types of Interactions in EcosystemsSymbiosis

P Mutualism is a type of symbiosis whereboth species in the relationship get abenefit.

P Termites cannot digest wood, so a typeof single-celled organism that can digestwood lives in their digestive system. The termites are providing the micro-organism with a place to live and a foodsource and in turn, the micro-organismbreaks down the wood into simplesugars that the termite can use for a foodsource.

Examples of Mutualism

Bees get nectar, flowers get pollinated Crocodile and Egyptian Plover

Lichens - mutualism between fungus & algae

Ants and aphids

Types of Interactions in EcosystemsCommensalism

PCommensalism is when there is a relationshipbetween two organisms where only one of themgains a benefit. The other does not get any benefit,but it is not harmed either.

Clown fish and sea anemone Woodpecker living in a tree Barnacles on a whale

Types of Interactions in EcosystemsFood and Populations

PThe relationship between predator and prey is alsosymbiotic.

PThe predator keeps the prey animal populationunder control by hunting it.

P If the population of the prey animal goes down, itbecomes harder for the predator to get food. As aresult, the population of the predator goes downtoo.

P In this way, there is always a balance in theecosystem.

Roles of Organisms in Ecosystems

PAll living things must have a food source.

PWe can classify organisms based on what they eat.

PHerbivores are organisms that consume only plantmaterial.

PCarnivores are organisms that eat only otheranimals.

POmnivores are organisms that eat both plant andanimals.


PWe can also classify organisms onhow they get food

POrganisms that must consume otherorganisms, whether they are animalsor plants are called consumers.

POrganisms that can produce theirown food, such as green plants, arecalled producers.


POrganisms that feed off dead organisms or thewaste of other organisms are called scavengers.


POrganisms that break down dead organisms or thewaste of organisms into their basic chemical partsare called decomposers.

Decomposers in our Food

PThere are two basic ways to prevent decomposers,such as mold and bacteria, from growing on ourfood.< Keep them off the food in the first place, by making sure

our hands are clean before handling food, using cleanutensils to prepare food and by keeping food well coveredand sealed.

< Slow down or prevent the growth of decomposers byusing methods like refrigeration, canning, vacuumpacking, freezing, freeze-drying or radiation.


P Drying removes moisture which all organisms require tosurvive.

Freezing removes warmth thus slowing or stoppingreproduction

P Radiation kills bacteria.

P Canning and vacuum packing removes air. Withoutoxygen most organisms cannot survive.

P Salting food prevented growth of bacteria ex salt cod orpickling food in brine

P Pickling food prevents harmful bacteria from growing,since bacteria have a hard time surviving in vinegar.


P Sometimes the growth of these decomposers are helpful to us

P For example, we use a friendly form of bacteria to produceyogourt and sour cream. This type of bacteria will not makeus sick, in fact, it helps keep us healthy by preventingharmful bacteria from growing in our intestines.

P There is a type of yeast (a form of fungus), that will turnsugars into alcohol and produce carbon dioxide bubbles. Weuse this yeast to make bread, cheese, beer and wine.

P The main reason for using yeast in making bread is to get thedough to rise so that when baked it is light and fluffy. Theyeast does this with the carbon dioxide bubbles. The alcoholproduced is evaporated when baked.

Food Chains, Food Webs & Energy Transfer

Food Chains

PGreen plants and algae require energy from the sunto make food.

PThe plants and algae use some of this energy fortheir own life processes. When a herbivore eatsthem, some of the trapped energy is passed on to theanimal.

PA carnivore eats the herbivore and some of theenergy the herbivore consumed is passed on to thecarnivore.

Food Chains, Food Webs & Energy Transfer

Food Chains

PThe transfer of energy from organism to organism isreferred to as a Food Chain.

Roles of Organisms in Food Chains

PEach type of organism has a role in the food chain.

PEvery food chain must have a producer at thebottom.

PProducers trap the energy from sunlight through aprocess called photosynthesis. It is this energy thatis passed up the food chain.

PThe next level of a food chain are organisms calledherbivores. They eat plants only and are calledprimary consumers because they are the first in theline of consumers in any food chain.

Roles of Organisms in Food Chains

PThe next level of consumers are those that eat otherconsumers. We often call them carnivores, but in afood chain they are called secondary consumers.

PFood chains usually have up to four links, but itcan’t be too much longer since energy begins to runout as the food chain gets longer.

Roles of Organisms in Food ChainsFood Webs

PEvery organism is a member of a food chain. However, it is rare that an organism is a member ofonly one.

P In fact, most organisms are members of several foodchains. When several food chains cross over oneanother in the same ecosystem like this we call it afood web.

POf course, the last stage of any food web are thedecomposers. Anything that dies in the food webwill be broken down by decomposers.

Food Web

Energy Transfer in Food Chains

P When an organisms eats, it is consuming food for energy. Most of this energy is being used for life processes suchas respiration, growth and movement.

P Another large portion of the energy is passed out of theanimal in the form of waste products such as gases, solidwaste or urine.

P Only about 10% of all the energy that an organismconsumes is actually stored in the animals living tissues.

P That means the second organism that eats this firstorganism is only getting about 10% of all the energy thatit consumed.

Energy Pyramid

Cycles of Matter in Ecosystems

Nutrients

PFood provides more than just energy to organisms.

PNutrients such as carbon and nitrogen are alsocontained in food.

PNutrients are used for growth and repair of theorganisms body.

PProducers get their nutrients from the soil, water andair.

PConsumers get their nutrients from the foods that theyeat.

Cycles of Matter in Ecosystems

Nutrients

PThere is only a limited supply of nutrients on theplanet. Therefore, nutrients must be used over andover again.

PWhen the nutrients are in the soil, air or water they areabiotic but when these nutrients are used in thegrowth and repair of an organism they are biotic.

PThe process that moves nutrients from organisms tothe soil and from soil to organisms is called thenutrient cycle.

Nutrient Cycle

Cycles of Matter in EcosystemsSteps in the Nutrient Cycle

P 1) Plants absorb nutrients from the soil, water or air.

P 2) Primary consumers eat plants and Secondary consumerseat other animals. In both cases, nutrients are passed tothem.

P 3) The consumers release some of these nutrients bybreathing out or excreting waste products (urine or feces).

P 4) The rest of the nutrients are held in their body structureuntil they die.

P 5) Decomposers take the dead organisms apart and place thenutrients back into the environment to be used again byplants.

Natural Disturbances & Succession

PEcosystems are constantly changing.

PSometimes these changes are gradual and other timesthey are sudden and destructive.

PNatural, sudden changes include things likehurricanes, tornados, floods, volcanoes, earthquakes,forest fires or landslides.

POther sudden changes can be man-made, such asclearing large areas of forest for factories or shoppingmalls, paving over huge areas of land for roads orparking lots.


Succession

P These sudden changes can leave an area bare of any life.

P If left long enough, these areas will become re-populated byorganisms.

P The first organisms to re-populate these types of areas arethose that are adapted to dry and very exposed areas.

P By doing this, they change the environment and make it moresuitable for other organisms.

P Eventually (thousands of years), the environment willrecover and be re-populated by plants and animals.

P The process of a biological community changing over time iscalled succession.


Primary Succession

PEcosystems do not start off with lots of vegetation.

PThe early stages of ecosystem growth starts with ahabitat that is without soil or shelter. These habitatsare very hostile to life and only special types oforganisms can survive there.

PSpecies that can begin life in areas without soil orshelter are known as pioneer species.

PExamples of pioneer species include bacteria, mossand lichens.


Primary Succession

PLichens are a species that can begin life on bare rockas long as there is plenty of water and light.

PPioneer species begin a chain of events that allowmore complex organisms to grow in an area. This iscalled primary succession.

P If this process of succession is left to continue to itsfinal stages, we end up with a climax community.

PA climax community is a mature, stable ecosystemthat can remain unchanged for centuries.

Primary Succession

Natural Disturbances & SuccessionSecondary Succession

PSuccession in an ecosystem does not always startfrom bare rock.

PSometimes an ecosystem that already exists isdisturbed in a big way. For example, a landslide orforest fire could wipe out a large section of forest.

PSecondary succession is the process of change in anecosystem after it has been disturbed. Since part ofthe previous ecosystem still surrounds the damagedarea, the recovery of the ecosystem takes much lesstime than in primary succession.

Impact of People on Ecosystems

PPeople have such a large impact on ecosystems mainlydue to our powerful technologies and our large andever growing populations.

PExamples of impacts include< Destruction of habitats< Introduction of non-native species< Stripping of natural resources< Pollution of air and water

PMuch of the impact we have on the earth is because ofour need to have natural resources.


PNatural Resources are things that are found in naturethat people require for their basic needs.

PExamples of this are water, oil, wood, metal and land(for building or farming).

Fish caught in the water near Fort Chipewyan. Water is polluted from the tar sands.

Impact of People on EcosystemsHabitat Loss

PMany human activities result in loss of habitat.

PThis can be a direct effect like the removal ofvegetation and soil which removes food and shelterfor many animals.

POr, it may be an indirect effect like digging largeholes in the earth that change the flow of rivers andstreams that will in turn affect the ecosystems in lakesand ponds that could be hundreds of kilometers away.


Endangered Species

P Some species of plants and animals are very adaptable tochange and can live in many types of ecosystems. Ex. Coyotes can adapt and survive in just about any habitat

P Other species cannot adapt at all to large scale changes intheir environment. When habitat gets destroyed, it placespressure on that species for finding food and shelter sinceit can’t adapt to any other ecosystem.

P A species becomes endangered when the population isso low it is in danger of becoming extinct. Extinctmeans that there is no more of that species anywhere onthe planet.


Introduced Species

PSpecies of plants and animals that live in an ecosystemthat are supposed to be there are called native species.

PSometimes humans introduce a species of plant oranimal to an ecosystem that is NOT native.

PThis can be done by accident like the Europeansbringing the Norway Rat and diseases like influenzaand smallpox to North America.

POr it can be deliberate like the introduction of mooseto the island of Newfoundland back in the 1800's.

Impact of People on EcosystemsIntroduced Species

PWhether it was deliberate or not, introducing a non-native species to an ecosystem can have destructiveresults.

PFor example, the purple loosestrife was brought toCanada from Europe because people like the way itmakes their gardens look. However, this species ofplant grows so well in wetlands that native speciescannot establish and the loosestrife removes so muchwater that it becomes an unsuitable habitat forwetland organisms.


Overharvesting

PRenewable resources are the living resources in theenvironment, like fish or trees, that can grow back ina short period of time.

PA resource is sustainable when it can replace itselfas quickly as it is harvested.

PA resource is unsustainable when it is harvestedfaster than it is being replaced.

PWhen a resource becomes unsustainable it is due tooverharvesting.


Causes of Unsustainability

P New Technology - new technologies allow theharvesting of natural resources, faster and in largerquantities.

P More Demand - increasing human population hascreated more demand for the resources.

P Lack of Conservation - governments do not followthe advice of scientists that warned aboutoverharvesting.

P Unsustainable Harvesting - governments setharvesting limits that are too high. The resourcescannot replace itself fast enough to keep up.

Impact of People on EcosystemsEffects of Pollution

PMonoculture is when farmers plant a single crop ina large open field. The obvious reason for this is togrow food for people, however, these crops are alsoa food source for insects.

PTo prevent the insects from eating all the crops, thefarmers use pesticides.

PTo make the crops grow faster and larger, thefarmers use fertilizer.


Effects of Pollution

PPollutants are anything that harms the air, water, soilor living things.

PThe fertilizer and pesticide that is put on farm cropsare examples of pollutants.

PPesticides eaten by insects are passed up the foodchain to higher consumers. This can harm a lot oforganisms in the ecosystem.

PFertilizers get washed into rivers and lakes and causewater plants to grow much faster than they should. Too many plants can cause problems in an ecosystem.


Effects of Pollution

PHumans introduce pollutants into the environment inmany ways< Exhaust from cars and trucks< Chemicals leaking into ground water from dumps< Oil spills from ships

PBurning fossil fuels creates waste gases like nitrogenand sulfur. When these chemicals combine withmoisture in the air, the result is acid rain.

PSince most organisms can only stand a certain acidlevel (called pH level), changing it with acid rain canhave a negative effect on an ecosystem.

Components of a Lab Report

P1) Purpose< Describe in a sentence, what question you are

hoping to answer by doing the experiment.

P2) Hypothesis< Based on your existing knowledge and research,

what result do you expect to have by doing theexperiment. Written as an “IF.....THEN...”statement.


P3) Materials< List ALL materials and resources used to carry

out the experiment

P4) Procedure< This is a step by step account of what you did to

perform the experiment. This should bewritten so that a stranger could duplicateexactly what you did. Best to be done in pointform.


P5) Results< Record all data collected during the experiment

and display your results in tables, charts orgraphs where appropriate.

P6) Conclusion< Here you discuss whether the results of the

experiment agree or disagree with yourhypothesis. Explain why you say what you do. Also, discuss any problems with the experimentand how they can be avoided in the future.

Scientific Method

PVocabulary for conducting experiments< Control - a standard that the results of an

experiment are compared to.< Manipulated Variable (Independant variable) -

the variable(s) that you can control in theexperiment.

< Responding Variable (Dependant variable) - theinformation you are measuring and recording inthe experiment.

Activity 1-5

PDo activity 1-5 on page 13

PThis will be group work and each memberwill have an assigned task to complete

PHand in a written lab report using the outlinegiven

PAnswer the five questions on page 13.

Other Growth Patterns

PMost animals give birth to young that looklike miniature copies of themselves

PSome species have young that look nothinglike the adult version

Examples:ButterfliesFrogs

Methods of Reproduction

Sexual vs Asexual

PSexual reproduction is when there has to bethe joining of two parent cells from a maleand female of the same species.

PAsexual reproduction is when an organismis capable of reproducing another like itselffrom a single parent cell using a method suchas cell division or budding.


Plants

PSince plants are not able to move from placeto place, they have many ways of spreading ordispersing their seeds.

PSeeds can be carried by < Wind< Water< Animals (in or on them)


Other methods of Plant Reproduction

PTubers or Bulbs - thickened undergroundstems that can grow into a new plant. Examples - potatoes, onions, tulip bulbs

PRunners - some plants can extend specialroots either on top of or under the ground. Ata point further away from the main plant anew plant will pop up. Example -strawberries


Asexual reproduction in animals

PPlanaria reproduces by splitting in two, this iscalled fragmentation. The top part grows anew tail and the bottom part grows a newhead.

PHydra reproduces by a process calledbudding. This is where a new hydra begins togrow out of the side of the parent hydra andthen eventually detaches itself.


Hydra Budding

Checkpoint

PDo questions 1 - 4 on page 26

Structural & BehaviouralAdaptations

Structural

PAll organisms have adaptations that help themsurvive and thrive.

PSome adaptations are structural. Structuraladaptations are physical features of anorganism like the bill on a bird or the fur on abear.

Structural and BehaviouralAdaptations

Behavioural

POther adaptations are behavioral.

PBehavioral adaptations are the thingsorganisms do to survive. For example, birdcalls and migration are behavioraladaptations.


Mutations

PAdaptations usually occur becausea gene mutates or changes byaccident!

PSome mutations can help an animalor plant survive better than others inthe species that don’t have themutation. Example is the pepperedmoth.


Structures for Getting Food

PAll living things need energy to grow,reproduce & move. They get this energy fromfood.

PDifferent organisms have different ways ofgetting this food.

P Insects have many things in common like allhaving six legs. However, they each havevery different mouthparts that allow them toget food from different sources.

Digestion

PDigestion - the process of breaking downfood into tiny usable particles.

Amoeba eating Paramecium

Movement

PThere are basically two types of movement< Internal movement - this sort of movement

happens inside the body. It includes things like theheart beating, the digestive system moving foodalong or the diaphragm contracting to make youbreathe.

< External movement - this is movement you cansee happening. Examples would be a plantmoving its leaves to follow the sun, or a dogscratching itself.

Movement

Internal movement

PMost internal movement is not under ourcontrol

PThings like heart beat, breathing or filteringthe blood of waste products happens withoutus having to think about it.

PMany of these are referred to as vital signs.

PVital signs include breathing, bodytemperature, pulse rate and blood pressure.

Movement

External movement

PMovement that happens outside the body.

PBlinking your eye, scratching your nose,waving to a friend are all examples of externalmovement.

PExternal movement such as swimming, flying,jumping, walking, running or crawling thatmoves an organism from one place to anotheris called locomotion.

Parts of a Microscope

Sensing & Responding

PA stimulus is anything that occurs in yourenvironment that causes one or more of yoursenses to respond.

PYou receive stimuli through your senseorgans (eyes, ears, nose, skin and tongue)

PWhen our body receives a stimulus it does sothrough special nerve cells called receptors.


PEach receptor is specially designed to receiveonly one kind of stimulus< The eye has receptors to detect light, the ear has

receptors to detect sound, etc.

PThere are internal receptors as well. Forexample there are receptors that detect theamount of carbon dioxide in the blood.

PWhen you exercise, the amount of carbondioxide builds up and stimulates your body tobreathe faster to get rid of the excess carbondioxide.


Negative & Positive Stimuli

PWhen an organism responds favorably to astimulus, it is called a positive response.< Example - A plant growing towards the light.

PWhen an organism responds unfavorably to astimulus it is called a negative response.< Example - An animal that only comes out at night

has a negative response to daylight.

The Animal Cell

The Plant Cell

Cell Parts & Functions

PCell Membrane < Found in all cells< Provides protection < Controls movement of materials in/out of cell

PCell Wall< Found in plants only< Provides support and protection instead of skeleton


PNucleus< Controls cell activity< Contains DNA

PCytoplasm< All the fluid and organelles inside the cell

PMitochondria< Breaks down food molecules to release energy< The cell’s power plant


PVacuole< Basically serves as storage for the cell

PChloroplast< Found in plant cells only< Site responsible for photosynthesis

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