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LIFE SCIENCE UNITS
Scientific Method (from sci book)
1. Ask a question
2. State your hypothesis
3. Identify and control variables
4. Test your hypothesis
5. Collect and record data
6. Interpret your data
7. State your conclusion
8. Go further
Science Tools
Balance- used to measure mass
Scale- used to measure weight
Spring Scale- used to measure force
Anemometer – measures wind speed
Barometer – measures air pressure
1
UNIT 1- CLASSIFICATION
Vocabulary words:
1. biosphere: part of the earth that supports life
- examples: deserts, oceans, fields, beaches, backyards,
forests and cities
2. adaptation: characteristics that help living things survive and reproduce
in their environment
example - cactus spines help keep water and protect it from
being eaten
3. species: a group of very similar organisms whose members can mate with
one another and produce offspring that are able to produce
offspring
- individuals in the same species don’t look exactly alike
- can be different size, color, shape etc
- examples: horses, humans, dogs, fish, birds etc
4. classification: the grouping of things according to their similarities
2
All living things share some common features:
1. made of cells
2. require a source of energy
3. reproduce
Adaptations- characteristics that help living things survive
Ex. cactus – spines are modified leaves
- shape helps keep water from leaving the plant
- spine protects it from being eaten
Species – 1. organisms must be able to mate with one another and produce
offspring that also produces offspring
-2. organisms of the same species can look very different from one
another (size, color, etc.)
-3. have similar body plans and structures
How Organisms are Grouped
Organisms with similar characteristics are grouped together.
Ex. music by your favorite artist is grouped by the artists’ name or by
the type of music
3
Scientists divide all living things on Earth into 6 kingdoms.
THE SIX KINGDOMS
Kingdom
1. Archaebacteria
Characteristics
Examples
- around for billions of years
- no nucleus
-found in hot springs (110˚c
water)
-water 10x saltier than sea
water
- single celled
- can live in extreme environments
2. Eubacteria
3. Protists
4. Fungi
- no nucleus
- single celled
- can cause disease
- can be helpful for vitamin
production in the body
- formed most of the gas and oil we
use today
- food for other organisms
- most are helpful, some are harmful
- used to make medicine
- grow off of compost (dead and
decaying matter)
- live in damp, dark places
- can not make their own food
5. Plants
- have roots, stems, leaves
- provide us with oxygen
- produce own food
6. Animals
- eat other organisms or their remains
4
- E. Coli
- found in yogurt
- Algae
- Amebas
- penicillin
- yeast
- mushrooms
- mold
- flowers (rose, tulips etc.)
- trees
- cactus, moss
- dog, snake, tiger
Kingdoms are then divided into sub-groups to identify specific organisms.
Kingdom
Phylum
Class
Order
Family
Genus
Species
King Phillip came over for great spaghetti
Ex.
Mall = Kingdom
Music store = Phylum
Genre (type) = Class
Pop = Order
Artist = Family
Album = Genus
Specific song = Species
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PLANT CLASSIFICATION:
All plants can be divided into two groups
1. vascular – have cells that form tubes or vessels to carry water and
nutrients throughout the plant
- two types of vascular plants
1. plants that make seeds
A. Angiosperms are seed plants that produce
flowers ex. roses
B. Gymnosperms are seed plants that do not
produce flowers. Ex. pine tree and fir trees
2. plants that do not make seeds
Ex. ferns and horsetails
2. nonvascular – material passes slowly from one cell to another
- this is why most nonvascular plants are small
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ANIMAL CLASSIFICATION:
-All animals can be divided into about 35 phyla
-All animals share certain characteristics:
1. multicellular organisms
2. get their food by eating other organisms
3. cells that contain a nucleus
4. cells do not contain a cell wall
-95% of all animal species are invertebrate which are animals without a
backbone
Examples: microscopic mites and the giant squid
- animals with backbones are called vertebrates
Examples: fish, amphibians, reptiles, birds and mammals
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UNIT 2 – CELLS
1. chromosome: a part of a cell that carries the instructions for building all of
the cell’s proteins
2. diffusion: the movement of a substance from an area of higher
concentration to an area of lower concentration
3. DNA: a material that stores information about how an organism will grow
and develop
4. endoplasmic reticulum: a set of folded membranes that work as a cell’s
transport system
5. mitrochondria: organelles that turn the chemical energy of food into a form
a cell can use
6. mitosis: the process in which the nucleus of a cell divides
7. organelle: a structure that performs specific functions in a cell
8. osmosis: the diffusion of water across a cell membrane
9. ribosome: the organelle that starts the process of making proteins
8
Unit 2 lesson 1
JOBS OF CELLS
- A cell is the smallest unit that can carry out the activities of life
- There 4 basic functions all single-cell organisms must perform to stay alive
1.
2.
3.
4.
get energy
remove wastes
grow
reproduce
-Larger organisms have many cells or multicellular
-In any one-celled organism, each part of its single cell performs a task
-In large organisms, different cells are specialized to do different tasks
Ex. muscle cells are specialized for movement, skin cells are for protection
CELL THEORY
Cells were not discovered until microscopes were invented.
-Robert Hooke was the first person to describe cells
Basis of cell theory
1. all living things are made of one or more cells
2. cells are the basic units of living things
3. all cells come from existing cells
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Unit 2 lesson 2
--(don’t have to do this lesson)
- Organelles --different structures inside the cell
--perform specific functions in a cell.
- Nucleus --control center of the cell.
- Chromosomes -- part of the cell that carries the instructions for building all
of the cells proteins.
- Endoplasmic Reticulum (ER) --a set of membranes that works as a cell’s
transport system and makes proteins the cell
needs
- Mitrochondria—organelles that turn the chemical energy of food into a form
a cell can use
- Mitosis -– the nucleus of the cell divides
- Osmosis -- water passes across the cell membrane
- Ribosome –starts the process of making proteins
10
- All living things are made of cells.
- Cells are the basic unit of life.
- The cell membrane acts as a boundary and allow certain things in and
out of the cell.
-Example of things allowed into the cell by the cell membrane
1) food particles which are used for fuel for energy
2) oxygen (burning fuel) goes into the cell.
-Wastes such as carbon dioxide passes out of the cell.
Diffusion- when substances move from higher concentration to lower
concentration
Osmosis-when water passes through the cell membrane
Nucleus --control center of the cell
Plant and Animal Cells—similarities and differences
Differences:
1. plant cells have a cell wall
animal cells do not
2. plant cells contain chloroplast which contain chlorophyll (plants make
food when sunlight hits chlorophyll)
3. plant cells have one large vacuole
animal cells have several little vacuoles
Similarities:
1. Some of the same parts—ex. vacuoles, nucleus, cell membrane, e.r.,
ribosomes
2. both perform life functions
11
Unit 2 lesson 3
Plant and Animal Cells—similarities and differences
Differences:
1. plant cells have a cell wall
animal cells do not
2. plant cells contain chloroplast which contain chlorophyll (plants make
food when sunlight hits chlorophyll)
3. plant cells have one large vacuole
animal cells have several little vacuoles
Similarities:
1. Some of the same parts—ex. vacuoles, nucleus, cell membrane, e.r.,
ribosomes
2. both perform life functions
Cell Division
Mitosis- the process in which the nucleus of a cell divides
DNA - is a material that stores information about how an organism will grow and
develop.
The cell’s nucleus contains DNA. (Deoxyribonucleic acid)
The cells need this information to make proteins which control chemical
reactions in the cell.
Chromosomes – carry the instructions to build all of the cell’s proteins
12
When mitosis begins, DNA coils tightly and forms rod-shaped bodies called
chromosomes.
Process of Mitosis:
1. The cell copies its DNA
2. Chromosomes become visible
3. Pairs of chromosomes line up in the middle of the cell
4. Each pair of chromosomes separates and moves to opposite ends of the
cell
5. A new membrane forms around each new nucleus
6. The cytoplasm divides
(Short version)
1. DNA copied
2. Chromosomes visible
3. Chromosomes pair up in middle of cell
4. Chromosomes pairs separate and move to opposite end
5. New membrane around nucleus
6. Cytoplasm divides
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UNIT 3 – REPRODUCTION
Voc. Words
asexual reproduction - when offspring come from one parent
egg cell - female sex cell
fertilization - when male and female sex cells join to form new cell
gene – a section of DNA that controls what substances the cell makes when it
makes them, determining traits of a living thing
heredity - the passing of traits from parents to offspring
meiosis – the process in which sex cells form when one cell divides into four
selective breeding – the process of selecting a few organisms with desired
traits to serve as parents of offspring
sexual reproduction - when offspring come from two parents
sperm cell – male sex cell
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UNIT 3 – REPRODUCTION
Lesson 1
Heredity – passing of traits from parent to offspring
- mother passes half of her genes and father passes half his
genes to their child
- how we get our hair color, eye color, height etc.
Asexual Reproduction
- one parent to create offspring
- by process called mitosis
- mitosis is when a cell’s nucleus copies and divides
- new offspring have exactly the same DNA as the parent
4 forms of Asexual Reproducion
1.
2.
3.
4.
Fission (mitosis) ex. Bacteria
forming spores ex. Mold
budding ex. yeast and a hydra
piece of parent ex. Sea star (if cut up-each piece will form a new sea
star)
- a fast form of mitosis is called fission
- some bacteria can create new cells in 20 minutes
- after 8 hrs – one cell of bacteria will have multiplied to almost 17 million new
bacteria
- In sexual reproduction, humans take approximately 9 months to produce one
offspring
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Lesson 2
Structure of DNA
James Watson and Francis Crick -- first scientists to describe “ladder” shape
of DNA -(twisted ladder)
-“ladder” contains 2 sides with a rung
- each rung is made up of 2 bases called base pairs
- bases are labeled as A,T,C, and G
DNA – stands for deoxyribonucleic acid
Different species have different number of chromosomes
- Humans have 46 chromosomes
- a gorilla has 48 chromosomes
Base Pairs - “A” is always with “T”
- “C” is always with “G”
Example- T, G, A, G, C, G, T, A
| | | | | | | |
A C T C G C A T
When a change occurs from the original DNA strand (something is added,
deleted or order changed) then a mutation occurs
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Lesson 3
SEXUAL REPRODUCTION
Living things that reproduce sexually have sex cells.
- Need a male and a female sex cell
- In the female they are called egg cells
- In the male they are called sperm cells
- Each sex cell will have only half the total number of chromosomes found in
that species.
Example- humans have 46 chromosomes
Egg cell has 23
Sperm cell has 23
Meiosis- one cell divides into four cells
Fertilization- a male and female cell join together to form a new cell
Zygote- first cell that is created when the male and female sex cells join
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FERTILIZATION IN FLOWERING PLANTS
Lesson 3 cont.
-flowers have both male and female parts
- female part is called the pistil and often has the shape of a bottle
- the pistil produces the egg
- male part of a flower is called the stamen
- the stamen produces pollen
- Pollen is a powder and contains the male sex cells
- Pollination is when pollen moves from the stamen to the pistil and an egg is
fertilized.
FERTILIZATION IN ANIMALS
- Fertilization can take place outside the female in some animals and is called
external fertilization.
- Many animals that live in or near water use this kind of fertilization.
Animals release egg and sperm cells into the water. The sperm cells swim to
the eggs and fertilize them.
Example- Staghorn coral
-for most land animals, fertilization takes place inside the female
-Some land animals lay eggs
- example- birds and turtles
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Asexual Reproduction
-
Sexual Reproduction
can happen quickly
requires less energy
needs just one parent cell
produces offspring with DNA
identical to parent
Lesson 4
- is a slow process
- requires more energy
- must have two parent cells
- produces offspring with unique
DNA
Dominant and Recessive Genes
Dominant gene – gene that masks another gene
Recessive gene – gene that is hidden
Punnett Square – shows all the possible offspring combination of genes
(copy Punnett square examples from book)
Selective Breeding
Selective Breeding – selecting living things with desired traits to serve as
parents
Example- one type of plant produces more than another plant. The
plant that produces more is used to produce more of those
plants.
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CHAPTER 5 PLANTS
Vocabulary
Vascular Plants - plants that have cells that form tubes or vessels to carry
water and nutrients throughout the plant
Epidermis – a thin outer layer of cells with root hairs that help roots take in
water
Xylem – moves water and minerals to other parts of the plant
Phloem – plant tissue moves glucose (sugar) through the plant
Stoma - small hole in the epidermis of the leaf of the plant
- moves water and gases in an out of the plant
Guard Cells – open and close the stoma
Transpiration – the loss of water in the leaf from gases in the air
Cellular Respiration – the process by which cells break down food with the
release of energy
Tropism – the movement of a plant in response to a stimulus
Glucose – a type sugar
20
PLANTS
There are 3 main parts of a plant — 1. roots
2. stems
3. leaves
ROOTS
-
Roots anchor a plant to the ground
some plants have one main root called a taproot example: carrot
other plants have a lot of smaller roots – example: sunflowers
take in water and minerals through the epidermis
Epidermis – thin outer layer of cells
Xylem – moves water and minerals to other parts of the plant
Phloem – moves glucose through the plant
Roots store glucose in the form of starch.
STEMS
-support the plant. They also have xylem and phloem.
- can be green and easy to bend – (herbaceous plants –ex. Clovers)
- can be thick and strong – (woody plants – ex. Trees, shrubs)
- stems that grow underground and store food are called tubers – ex
potato
LEAVES
-make the glucose which plants use for energy
- water and gases move in and out of the plant through a small hole in the
epidermis called a stoma
- two guard cells open and close the stoma
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- sunlight causes the guard cells to take in water which puts pressure on
the
walls of the guard cells and the stoma opens
- most stomata open in daytime and close at night
Transpiration – loss of water from a leave
- when the stoma opens, gases from the air enter the leave and
water leaves (exits) the leave
- when water exits a leave, more water is pulled up through the
xylem
- If a plant loses more water than it takes in, it may wilt
Photosynthesis- process in which plants make glucose
- plants use-- 1. carbon dioxide from the air
2. light energy from the sun and
3. water to form glucose and release oxygen
- energy is stored in glucose and the anything that eats the plants use the
glucose as a source of energy (ex humans, animals)
light energy
carbon dioxide + water -----------> glucose + oxygen
chlorophyll
Cellular Respiration – process by which cells break down food to release stored
energy
- glucose is broken down into simpler substances
22
- carbon dioxide and water are produced and energy is released
Lesson 3
Angiosperms - plant that produces seeds and flowers
- very common: 200,000-300,000 species
- example: peach trees, oak trees, grapes, tomatoes and orchids
- all are vascular plants-(specialized tissues for moving materials
around the plant ex. Xylem and phloem)
- most of the seeds develop into fruits
-fruits protect the seed until they are ready to grow
- we use them as food crops, medicine, lumber, rubber and fabric
Gymnosperms – a plant that produces seeds but do not grow flowers
- gymnosperms that produce seeds in cones are called conifers
- conifers can live for a long time ex. Redwoods live for
thousands of years
- conifers are woody plants with needles or scale like leaves
Ex. Pine tree
-conifers have 2 types of cones:
- 1. male- make pollen that contains sperm
- 2. female- have egg cells
- Wind then carries pollen from the male cones to the
female
cones and the sperm fertilizes the egg.
The seeds
grow
in the female cones until the seeds are mature.
-used for wood, paper products, paints, air fresheners and soaps
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These seeds are a source of food for animals.
Germination – when a plant starts to grow a seed
Seeds contain a small plant embryo.
-different plants need different conditions to grow (all seeds need
a certain temperature)
- some seeds become inactive if conditions are not right. These
seeds can then survive conditions that would normally kill a plant.
Ex. droughts, freezing temperatures and forest fires
Some plants grow from spores. Ex. mosses and ferns
-these plants usually require plenty of water
(copy chart from p13)
Tropism- movement of a plant in response to a stimulus (plants respond to their
environment by turning and bending)
- plant behavior caused by growth toward or away from something in
the environment
Phototropism- stems usually bend toward the light
Geotropism – roots grow downward because of gravity
Thigmotropism – plants grow toward the surface it touches ex. vines
24
CHAP 6
BIOMES –Lesson 1
Biosphere - the parts of the Earth in which living things are found
- different living things may live in different parts of the biosphere
but they all share Earth’s resources
example of Earth’s resources- water, air and light
- when something happens to one living thing, it often affects other
living things in the same biosphere
- human’s actions affect the biosphere
Ecology is the study of how living things interact with each other and their
environment.
All living things are called organisms.
An individual is a single organism that belongs to one species.
25
Organization of the Biosphere
Environment - anything that can affect an organism which includes both living
(ex. dogs, cats, insects etc) and nonliving things (ex. air, water,
sunlight)
- in any environment, many populations live together and interact
with each other
Population – group of individuals of the same species who live in the same area
- individuals within a population compete for food and water. If
these resources become limited, some individuals may die and the
population may get smaller.
Ex. zebras living in an area of the African plain
Community – a group of populations that interact
area
- Zebras, giraffes, and elephants are
on the African plain.
- your house may contain a community
- need the nonliving things (air, water
environment to live
with each other in a particular
all part of the same community
of humans, dogs and cats
and shelter) in their
Ecosystem – a community of organisms living together along with the nonliving
parts of the environment
- may be as small as a crack in the sidewalk or as large as a huge
forest or desert
Earth’s biosphere is made up of many ecosystems which interact with other
ecosystems.
26
Abiotic and Biotic Factors
Abiotic Factors – the nonliving parts of an ecosystem such as air, soil, water,
sunlight and temperature that organisms depend on to survive
examples of these abiotic factors:
Water: All living things (organisms) need water to survive. The amount of water
in an ecosystem can limit the number of organisms that live there.
Ex. desert gets very little water so organisms that require a lot
of water can not survive there.
Sunlight: Plants need sunlight to make their own food. Most organisms depend
on plants for food because they can not make there own food. Some
animals eat plants directly; others eat animals that eat plants.
Ex. The amount of sunlight an environment gets affects what
kinds of plants and animals that can live there.
Temperature: Each species can live only in a particular range of temperature.
Ex. Polar bears live where it is very cold
Air – Most organisms need oxygen to live. Plants need carbon dioxide to make
food. Both gases can be found in the air.
Biotic Factors – living organisms in an ecosystem
- some are too tiny to see without a microscope (ex. bacteria,
protists and mites)
27
Adaptations
Adaptation- characteristic that helps an organism live and reproduce in a
particular environment
ex. polar bears have thick fur that helps keep its body
warm. It has large paws and claws to help it move over
the ice and catch food.
ex. desert cactus grow slowly and have a waxy coating tht
keeps them from losing water
All organisms in an ecosystem have adaptations that help them survive
28
Biomes Lesson 2
Biome - a large group of ecosystems with similar climates and organisms.
Climate - the average temperature and precipitation of an area
- important in determining what organisms live in an ecosystem
Water, sunlight and temperatures in biomes can be different.
3 factors that determine which organisms live in a biome are
1. temperature
2. soil
3. adaptations
1. Temperature affects the growing season of plants and animals depend
on plants for food. When the plant populations get larger, then animal
populations get larger as well.
2. The type of soil an area has determines what plants can grow there.
- Some soils hold water near the surface so these areas have plants with
shallow roots. Plants with deep roots could not survive in this type of
soil.
3. Plants and animals have special adaptations that enable them to survive in
desert cactus grow slowly and have a waxy coating that keeps them from
losing water
29
The 6 Biomes
1. Tropical Rain Forest –
-
contain more species than any other biome
warm and rainy all year long
most nutrients are found in plants and not the soil
Trees grow very tall and their leafy tops form a dense
covering called the canopy.
- little sunlight shines through so few plants grow on the
forest floor
- most rain forest animals live in the treetops where
they eat leaves and fruit
2. Deciduous Forest – grow where summers are warm and winters are cold
- trees shed their leaves in autumn and grow new ones each
Spring
- soil is rich with nutrients because the leaves fall to the
ground and decay
- because it is cold during the winter, some animal species
hibernate while many birds move to warmer climates
3. Taiga – long, cold, dark winters
- most trees that grow are conifers
- animals such as squirrel and birds eat the seed and berries of
conifer trees
- large animals such as elk, deer, caribou and moose eat tree bark
and plant shoots
- Wolves, grizzly bears and hawks hunt and eat the small animals
4. Grasslands –
-
do not get enough rain for large trees to grow
soil is very rich in nutrients
many grasses have deep roots
soil is excellent for farming (wheat, corn, soybeans)
some of the largest animals live here- bison, rhinoceros,
giraffes
- smaller animals such as coyotes, rodents and grasshoppers are
also found here
30
5. Tundra – very cold and windy climate
- very few plants grow here – short shrubs, moss and some short
trees
- just beneath the surface, the soil is frozen solid all year long. This
frozen layer is called permafrost
- in the summer, the top layer of the permafrost thaws and the soil
turns soggy
- animals found here include foxes, hares, many birds and lemmings
6. Desert – very dry, some deserts get almost no rainfall
-usually hot during the day and cold at night
- many desert animals are active only at night when it is cooler
- desert birds, snakes, turtles, and other animals have adaptations
that enable them to live on little water
31
CHAP 7 ECOSYSTEMS
Lesson 1
Animals and plants have adaptations which enable them to survive in their
environment. They help them to find mates, reproduce, get energy or protects
them from dangers in their environment.
Fennec Fox lives in the desert and has adaptations that help keep it cool.
1. large ears help it stay cool by blood rushing to its ears when it
gets hot, body heat then moves from the fox’s blood into the air
2. pale fur reflects the sun’s rays to keep it cool
3. fur on the feet protects against burning desert sand
Arctic Fox lives in extreme cold and has adaptations that help keep it warm.
1. small ears help reduce heat loss
2. thick fur changes from white in winter to brown in summer to help
the fox blend in with its environment
3. thick fur on the feet reduces heat loss and helps keep the feet
warm
32
There are different types of adaptations
1. Structural Adaptations – develop over many generations
- a species changes as individuals are born with new
traits that give them a better chance to surviveindividuals that survive pass these traits to their
offspring. This process repeats over long periods of
time.
-
Ex. bright colors on a Mandrill’s face help
identify it to other Mandrills
2. Behavioral Adaptations – behavioral traits in animals are inherited over
generations
ex. the male Mandrill shows his large front
teeth to warn off other males
3. Body Processes – some animals hibernate in winter- body temperature falls,
heart rate and breathing slows down
33
Lesson 2 - How do organisms get energy?
Most living things on Earth depend on the Sun’s energy either directly or
indirectly.
Plants use this energy to make food (glucose) and use glucose as energy for life
functions. Plants are producers – organisms that can make their own food.
Animals cannot use sunlight to make their own food. They are consumers –
organisms that get energy by eating other organisms. (When a bear eats
berries, it gets energy stored in them)
Toadstools cannot make their own food or eat other organisms. They are not
producers or consumers, they are decomposers.
When organisms die and fall to the ground, their bodies decay. Decomposers
are organisms that get energy by breaking down the remains of dead organisms.
A food chain shows a path of energy through an ecosystem. The arrows on a
food chain always points toward the organism that is getting the energy. (p. 6
for picture)
Many different food chains exist in an ecosystem. A food web is made up of
several food chains that are interconnected. (p. 6 for picture)
Energy Pyramid – a model that shows how energy moves through an ecosystem
- the pyramid gets smaller as it nears the top
- there is more energy at lower levels because organisms must
use energy to grow, move, and reproduce so only part of the
energy can move to the next level
- only stored energy in the tissues of an organism can pass from
one level to the next
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Lesson 3 - How do organisms compete for resources?
Competition – is the struggle between organisms to survive when resources are
limited.
- When resources such as water and food are limited, then animals
compete for them to survive. Those who get them live.
Ex. Elephants and zebras compete for a small amount of water
to survive.
- competition only happens between organisms that have similar
needs
Predators- animals that feed on other animals
Ex. eagle (predator) eats a mouse (prey)
- have adaptations that help them hunt and kill which include
Ex. of structural adaptations
1. speed
2. strength
3. strong senses
4. eyes in the front of the head help them decide how far
away the prey is
- Behavioral adaptations –
Ex. pack animals such as wolves work as a group to separate
and attack individuals from a herd of prey
- Body Processes
Ex. Jelly fish have tentacles that release stinging cells that
stop the prey from moving
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Prey – the animal a predator eats
- have different adaptations that help protect it from predators
Ex. 1. eyes on the side of the head which allows it to see a wider
area and helps to avoid predators
2. release a poison when they are attacked
3. have bright colors to warn away predators
4. use camouflage to make themselves look like something else
- Behavioral adaptations
Ex. some prey curl up and pretend to be dead when a predator is
near
- Body Process adaptations
Ex. The dart frog has glands in its skin that protect the frog
by releasing poisonous chemicals
Symbiosis – close, long-term relationship between organism that benefits at
least one organism
- 3 kinds
1) Parasitism- one organism is helped and is called a parasite
and one organisms is hurt which is called the host
- the parasite depends on its host for food
- the parasite can live on or inside the host
Ex. athlete’s foot—fungus lives on the skin of
the foot and causes it to itch and makes
the foot look dry
2) Mutualism- when both organisms benefit
Ex. E. Coli bacteria live inside our bodies
3) Commensalism- one organism is helped but the other is neither
helped nor harmed
Ex. mites eat dead skin cells but this does not
help or harm us
36
Lesson 4 How do materials cycle through ecosystems?
(copy pictures from book p 16-19)
Nitrogen Cycle - Air is 78% “free” nitrogen
- Organisms need nitrogen that is “fixed” or combined with other
elements
- There are ways to “fix” nitrogen
1. bacteria that live in the soil –plants get it from the
Bacteria
2. Decomposers put fixed nitrogen into the soil by breaking
down dead organisms- animals get it from the plants
they eat
3. lightning fixes a small amount that is brought back to
the soil by rain
Caron Cycle — 18% of our body is carbon
- it is cycled through by
1. photosynthesis
2. cellular respiration
3. decomposers such as fungi and bacteria
Organisms that don’t decompose form fossil fuels such as coal, oil and natural
gas
These organisms had carbon in them when they live and it now gets released
into the air when the fuels are burned
Carbon is released as carbon dioxide when volcanoes erupt.
37
Water Cycle—
1. Evaporation is the process when the sun heats water on Earth (lakes,
oceans, paddle etc) as the water changes from a liquid to a gas.
2. When water evaporates, it forms a gas called water vapor
3. water vapors rise and then cools from hitting cold air
4. clouds form when the water vapors condense (comes together)
5. water returns to Earth as precipitation (rain, snow, sleet or hail)
Lesson 5 How do ecosystems change?
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