Download Cells

Objective 2
Living Systems &
Environment
Middle School Science
Science STAAR Need to Know
All living things are made up
of cells.
Unicellular (Single-celled)organisms that are made up
of only one cell.
Multicellular- organisms
made up of many cells.
(Some have billions &
trillions of cells!)
•All living organisms are composed of
cells. They may be unicellular or
multicellular.
•The cell is the basic unit of life.
•Cells arise from pre-existing cells.
Cells
Most basic part of a living system
“Cells are Building Blocks”
 Cells contain organelles
 Animal & Plant cells both contain:
 nucleus- command center of the cell
 cell membrane- protective outer layer
 cytoplasm- gelatin-like substance that fills inside of cell
(contains other organelles that are vital to the
processes of life)
 mitochondria- to provide power for cell activities
 vacuole – holds waste products or substances needed
by the cell
Only plant cells have cell walls for
support & chloroplasts to carry out
photosynthesis.
Eukaryotic – made
up of cells that have
a membrane
covered nucleus
Prokaryote – one-celled
organism that does not
have a nucleus – only
bacteria
Levels of Organization
Feedback
mechanism
A response of an organism to
a given change, such as
temperature or the amount of
light.
Example: Sweating
If the body temperature gets
too high, sweat glands open
up, causing a person to sweat.
The sweat then evaporates,
carrying heat energy away
from the body. This cools the
skin.
When the body temperature
returns to normal, another
nerve signal is sent out to
close the sweat glands.
Homeostasis
The body has ways of adjusting to different conditions.
Keeping conditions such as body temperature constant
is called equilibrium or homeostasis. Equilibrium
occurs when a system is balanced.
Adaptations
What if a change is too extreme & an organism can’t
maintain equilibrium? The organism may die!!
However, most organisms are adapted to the
environments where they live. Their body systems
& behaviors adjust or change to allow them to
survive in the new environment.
Genetic traits
Genes- a segment of DNA on a
chromosome that contains
information for specific genetic traits.
Genes are passed from parents to
offspring.
Genetic trait- a characteristic
passed on from a parent to offspring.
Genetic traits that help organisms to
survive in their environment are
called adaptations. Adaptations
can be either physical characteristics
or behaviors.
Process by which the characteristics
that help a species to survive are
passed on to the next generation.
the process of breeding plants
and animals for particular traits.
A dichotomous key is a method for determining
the identity of something (like the name of a
butterfly, a plant, a lichen, or a rock) by going
through a series of choices that leads the user
to the correct name of the item. Dichotomous
means "divided in two parts".
Ecosystem – includes the living & nonliving parts
of an environment.
Nonliving- water, soil, light, air
Living- plants, animals & other living organisms
(makes up the community)
Community – a group of different types
or populations or plants, animals, &
other organisms living & interacting with
one another in an environment.
Each population in a community lives in a
particular part of that environment called
a habitat.
As you move up the diagram,
each level is more complex.
A habitat is the specific place in which an
organism makes its home.
Each part of the community
has its own function, but
together they form the
entire pond ecosystem.
Organisms are connected by the energy that flows through the pond
community. Both plants & animals require energy.
This flow begins with the plants using energy from the sun and continues
through all the organisms in an ecosystem.
The variety of
organisms in a
specific
environment, or on
Earth as a whole.
Plants change radiant energy from the sun
into chemical energy.
Carbon dioxide and water are converted into
sugar and oxygen.
(Sugar is very important in an ecosystem- it’s food for plants & for other
organisms. When plants are eaten, the energy in the plant matter is
passed on to other organisms in the food chain.)
Chemical energy passes
from plants to animals
through a food chain
Producers- (plants) organisms that make
their own food
Primary consumers- animals that get their
energy from eating plants
Secondary (second-order) consumersanimals that eat primary consumer animals.
Animals can be both a
primary & secondary
consumer.
Types of
consumers
 Herbivores- animals that
eat only plants
 Carnivores- animals that
eat only other animals
 Omnivores- animals that
eat both plants & other
animals
An animal that kills and eats other animals
Organism that is killed
and eaten by another
organism
Organism, such as a tick, that
feeds on cells, tissues, or fluids of
another living organism (host)
Organism that supports a
parasite
Decomposers
Organisms that feed on dead
plants & animals. This
releases the chemical energy
and nutrients in the dead
plants and animals back into
the environment.
Decomposers play an
important role in recycling
nutrients & energy.
Biotic factors are all of the living things in the community
Abiotic factors are essentially non-living components that effect the living
organisms of a community.
Food Chain- shows the flow of energy from
one organism to another to yet another.
Food Web
Energy
passes in
many
different
directions
through all
the
organisms.
A complex system of energy flow
through overlapping food chains.
Succession
Rebuilding of populations in a
community or ecosystem that
has been changed.
Succession can happen in any
environment where change occurs.
Other examples: a plowed farm field, a
burned forest, or a grassland that
gradually receives less rainfall.
• Affected by run-off of fertilizers and pollution
• Artificial reefs used to create environments
for
different species
• Most valuable natural resource
-provides food about 200 billion pounds are caught each
year.
- used for transportation—both travel and shipping.
- provides a treasured source of recreation for humans.
- is mined for minerals (salt, sand, gravel, and some
manganese, copper, nickel, iron, and cobalt can be
found in the deep sea)
-drilled for crude oil.
-plays a critical role in removing carbon from the
atmosphere and providing oxygen.
-- regulates Earth's climate.
Systems in the Human Body
The human body includes systems such as:
Circulatory
Respiratory
Digestive
Excretory
Muscular
Skeletal
Nervous
Integumentary
Endocrine
Reproductive
Circulatory
system
 Arteries are tubes that
carry blood away from
the heart
 Veins are tubes that
return blood to the
heart
 Capillaries connect
arteries and veins.
They are tiny tubes
that exchange food,
oxygen and wastes
between blood and
body cells.
Respiratory
 BREATH IN -- your body gets oxygen from the air. Rib muscles
contract to pull ribs up and out. The DIAPHRAGM muscle
contracts to pull down the lungs. Tissue expands to suck in air.
 BREATH OUT -- you get rid of other gases that your body does
not need. Rib muscles relax. The Diaphragm muscle relaxes.
Tissue returns to resting position and forces air out.
Digestive
system
Breaks down and
absorbs food to
provide energy
for the body
Excretory
Gets rid of body wastes
and excess fluids
Muscles
 Muscle contracts to move bones and
body parts
 Muscles look either striated or smooth:
 Striated muscle has stripes or
striations in it.
 Smooth muscle does not.
Voluntary or Involuntary
Muscles
Voluntary muscles are muscles that
you can move whenever you want to.
Involuntary muscles contract and
relax automatically inside your body.
We can not control our involuntary
muscles
Did you know?????
 There are more than 600 muscles in
your body
 That nearly 35-40% of your body
mass is muscle
 The smallest bones are in your ear.
The largest bone, the femur, is found
in your thigh
Skeletal system
Function of bones
 protect internal organs
 support the body
 make blood cells
 store minerals
 provide for muscle
attachment
Joints
 A point where one bone attaches to
another bone.
 There are two different types of joints in the
body:
Movable joints (like ball-and-socket,
hinge, gliding and pivot joints)
Immovable joints (like the bones of the
skull and pelvis) which allow little or no
movement
Nervous system
collects, transfers and processes
information with brain, spinal cord,
peripheral nerves, and nerves
is the organ
system that protects
the body from
damage, comprising
the skin and its
appendages
(including hair, scales
, feathers, hoofs,
and nails).
is the system of
glands, each of
which secretes a
type of hormone
directly into the
bloodstream to
regulate the body
a system of organs
within an organism which
work together for the
purpose of reproduction.
Systems
 A group of parts that form a complex
whole- work together to achieve goals
that the parts could not reach alone.
 Parts can interact, be related to one another,
or depend on each other.
Example:
Circulatory and
Respiratory systems
work together
Type of reproduction by which
offspring arise from a single
parent, and inherit the genes of
that parent only
An organism, such as a plant, that makes its own food
An organism that obtains the energy it needs by feeding
on other organisms