7th Grade Science
http://www.bergoiata.org/fe/felins/10.htm
© Fall 2005, Pflugerville ISD, 7th Grade
http://www.jonathanpmiller.com/intercalation/B-DNA.jpg
Unit 2:
Life Science
Chapter 7: It’s Alive!! Or, Is It?
Section 1: Characteristics of Living Things
Section 2:The Simple Bare Necessities of Life
Chapter 8: The Cell In Action
Section 1: Exchange with the Environment
Section 2:Energy for the Cell
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapters 7,8,9,10,14
It’s Alive!! Or, Is It?
What Do You Think?
What characteristics do all living
things have in common?
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
There are Six Characteristics of
Living Things.
1. Living things have Cells.
2. Living things Sense and Respond to Change.
3. Living things have DNA.
4. Living things Reproduce.
5. Living things use Energy.
6. Living things Grow and Develop.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
• An object must
possess all 6 of the
characteristics in
order for it to be
considered a living
thing.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
1. Living Things Have Cells
•
•
•
•
Every living thing is made up of one or more
cells.
Cells are the simplest collection of matter
which has all the properties of life.
Some cells specialize to do specific jobs.
Examples are nerve cells, muscle cells,
etc…
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
2. Living Things Sense and Respond to
Change.
•
A stimulus is a change that causes the
activity of an organism to change.
• A stimulus can be internal (from inside).
– Examples are fever or vomiting when sick.
• A stimulus can be external (from outside).
– Example is squinting when the lights are
bright.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
2. Living Things Sense and Respond to
Change (cont…).
•
Homeostasis is the maintenance of a stable
internal environment.
- Our bodies are very good at controlling the
chemical reactions that keep us alive. These
reactions can only take place when conditions
are exactly right.
- Even though our outside conditions may
change, homeostasis keeps our internal
conditions the same.
- Example is body temperature.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
3. Living Things Have DNA.
•
•
•
DNA stands for deoxyribose nucleic acid.
DNA is the molecule that controls the
functions of a cell.
DNA is passed from parent to offspring.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
4. Living Things Reproduce.
•
•
•
Most living things reproduce by sexual
reproduction.
Sexual reproduction requires two parents that
produce offspring that share characteristics of
both parents.
Sexual reproduction produces more diverse
more diverse offspring.
Animals
http://www.jpbutler.com/thailand/images/elephant-and-baby.jpg
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
4. Living Things Reproduce (cont…).
•
•
•
Some things reproduce by asexual
reproduction.
Asexual reproduction occurs when a single
parent produces offspring that are exactly the
same as the parent.
This leads to more uniform offspring.
Hydra
http://universe-review.ca/I10-26-hydra.jpg
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
Click on the video below to see some differences
between sexual and asexual reproduction.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
5. Living Things Use Energy
•
•
Metabolism is the total of all of the chemical
activities that the organisms performs.
Metabolism includes:
- Making food.
- Breaking down food.
- Building cells.
- Moving materials in and out of cells.
http://www.faculty.ucr.edu/~insects/systems/metabolism/metabolism.gif
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
Click below to see how living things use energy.
www.unitedstreaming.com
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
6. Living Things Grow and Develop.
•
•
•
You grow as your body gets bigger.
Developing is the process of changing,
maturing, and going through different
stages.
Growing and developing depends on the
environment and the resources available.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
Visit the website below to
distinguish between Living
and Non-living things.
Ready?
Living and Non-living things
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
Let’s Review!
-1-
If the weather is cold outside,
how do you maintain your
body temperature?
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
Answer
• If it’s too cold, you will shiver to create heat.
Humans can add layers of clothes to keep
warm in the cold. Reptiles bask in the sun to
stay warm. Homeostasis allows us to do this.
http://www.utexas.edu/opa/news/02newsreleases/nr_200205/graphics/turtle2.jpg
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
Let’s Review
-2-
• What characteristics of living things does
a river have?
• Is a river alive?
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
Answer
• A river has energy (it moves) and can
grow larger (after rain), but it is not alive
because it is not made of cells, cannot
respond to stimuli, has no DNA, and
cannot reproduce.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
Websites to Visit
• Cells Alive
• Prokaryotes and Eukaryotes
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 1
It’s Alive!! Or, Is It?
What Do You Think?
What are several thing that are
necessary for living things to
survive?
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
It’s Alive!! Or, Is It?
• Food
• Water
• Air
• A place to live
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
It’s Alive!! Or, Is It?
Food
There are 2 ways to get food.
1. Make your own food
a. Producers make their own food through
photosynthesis.
- Plants are producers.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
It’s Alive!! Or, Is It?
Food continued…
2. Take food
a. Consumers must get (eat) their food from
other organisms to get energy.
- Example is an animal.
b. Decomposers break down nutrients in
dead organisms or in animal wastes.
- Example is an earthworm.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
It’s Alive!! Or, Is It?
Click the link below to see an Interactive Food Chain.
Food Chains
http://www.warwick.surrey.sch.uk/student%20zone/GCSE%20Science%20Website/03%20Environment%20Food%20Chains.htm
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
It’s Alive!! Or, Is It?
Water
• Our bodies are made of almost 70% water. In
order for chemical reactions that are involved
in the process of metabolism to occur, we
must have plenty of water in our body.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
It’s Alive!! Or, Is It?
• Click below to see examples of animals
needing water to survive.
www.unitedstreaming.com
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
It’s Alive!! Or, Is It?
Air
• Most living things need oxygen for the chemical
processes that release energy from food.
• Organisms that live on land get the oxygen from
the air.
• Organisms living in water either use dissolved
oxygen from the water, or come to the water’s
surface to get oxygen from the air.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
It’s Alive!! Or, Is It?
Air continued…
Click below to see how different
organisms get the oxygen they
need.
The Lung Association
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
It’s Alive!! Or, Is It?
A Place to Live
• All organisms must have a place to live.
• Some larger organisms, such as an elephant,
require a lot of space.
• Smaller organisms, such as bacteria, may spend
their whole lives on a single pore on the tip of
your nose.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
Let’s Review
-1Describe how producers, consumers, and
decomposers live together in an
environment.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
Answer
• Producers, consumers, and decomposers
make a food chain. Producers can make
their own food from the sunlight. They also
are food for the consumers and
decomposers. Decomposers break down
dead organisms into nutrients for the
producers to grow in. They all need each
other to survive.
http://www.explorelearning.com/index.cfm?method=cResource.dspView&ResourceID=381
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
It’s Alive!! Or, Is It?
How the Body Uses O2
Make Your Own Food Web!
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Section 2
It’s Alive!! Or, Is It?
Pre-AP Extensions for Chapter 7
There are 2 main types of cells.
1. Prokaryotic Cells
- have no nucleus
- found in the kingdom of Monera
- Examples are bacteria.
http://library.thinkquest.org/C004535/media/prokaryote.gif
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Pre-AP
It’s Alive!! Or, Is It?
Pre-AP Extensions for Chapter 7
There are 2 main types of cells
(cont…).
2. Eukaryotic cells
- have a true nucleus (that contains DNA)
- found in more complex kingdoms
(animal, plant, etc…)
http://www.ccnmtl.columbia.edu/projects/biology/lecture1/images/F04071s.jpg
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Pre-AP
It’s Alive!! Or, Is It?
Pre-AP Extensions for Chapter 7
Click below for an interactive tour of
prokaryotic (bacteria) and eukaryotic (plant
and animal) cells.
Prokaryotic and Eukaryotic Cells
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Pre-AP
It’s Alive!! Or, Is It?
Pre-AP Extensions for Chapter 7
Classification Websites to Visit
Taxonomy of Living Things
Classification and Taxonomy
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 7 : Pre-AP
The Cell in Action
What Do You Think?
How do food, water, and
wastes get into and out of a
cell?
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
Diffusion
• Materials must move
into and out of the
cell. This happens
through the cell
membrane.
• Molecules travel from
very crowded areas to
less crowded areas.
The Cell Membrane
http://library.thinkquest.org/C004535/media/cell_membrane.gif
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
Diffusion continued…
• The movement of particles from a high
(crowded) concentration area to a low (less
crowded) concentration area is called diffusion.
Simple Diffusion Animation
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
Diffusion goes from
an area of high
concentration to
low concentration
http://www.biologycorner.com/resources/diffusion-animated.gif
If perfume is sprayed in one corner of the room, it will
take a while before the back of the room can smell it. It
diffuses from a high concentration area to a low
concentration area.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
Diffusion of Water
• The diffusion of water across the cell membrane
is called osmosis.
• In osmosis, water molecules move from an area
of high concentration to an area of low
concentration.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
•Osmosis occurs when
water diffuses across the
cell membrane.
http://www.biologycorner.com/bio1/diffusion.html#
• Notice only the blue
water molecules are
traveling in and out of the
cell
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
Moving Things In and Out of the Cell
• Most things, like water and oxygen, can diffuse
directly through the lipid (fat) cell membrane
because they are so small.
• Some things are too large (sugars) to squeeze
through the cell membrane.
• The things that are too big to go through the
membrane use passive transport, active transport,
endocytosis, and exocytosis to get through the cell.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
Passive Transport
• This is the process of moving medium sized
particles across the cell membrane.
• This process happens when molecules diffuse
from an area of high concentration to an area of
low concentration.
• No energy is used- molecules just squeeze
through the proteins in the cell membrane.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
Moving Medium Sized Particles Across the Cell
Membrane
•Notice the red
molecules going from a
high to low
concentration area.
•NO energy was
used…the molecules
just squeezed through
the cell membrane.
Go.hrw.com
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
Active Transport
• This is the process of moving medium sized
particles across the membrane.
• This is the movement of substances through
proteins against the normal direction of diffusion.
• Molecules are moved from an area of low
concentration to a high concentration area.
• Energy IS required.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
Moving Medium Sized Particles Across the Cell
Membrane
•The red molecules are
moving from a low to
high concentration area.
•Energy is required!
Go.hrw.com
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
Moving larger particles across the
cell membrane
• Endocytosis is the process of bringing larger
particles into the cell.
http://www.biologycorner.com/bio1/active.html
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
Moving larger particles across the
cell membrane
• Exocytosis is the process of moving large
wastes products from inside the cell out of
the cell.
http://bio.winona.edu/berg/ANIMTNS/facdifan.gif
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
Let’s Review
-1How does a cell take in large particles?
How does a cell get rid of large particles?
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
Answer
• Large particles are
taken in by
endocytosis and
expelled by
exocytosis.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 1
The Cell in Action
What Do You Think?
How are photosynthesis and
cellular respiration similar?
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 2
The Cell in Action
Photosynthesis
• Takes place in the
chloroplasts of plant
cells
• Carbon dioxide and
water are used, in the
presence of sunlight,
to make glucose
(food) and oxygen.
© Fall 2005, Pflugerville ISD, 7th Grade
http://lhs.lps.org/staff/sputnam/Biology/U3Cell/chloroplast_1.png
Unit 2 : Chapter 8 : Section 2
The Cell in Action
Click below to learn more about
photosynthesis.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 2
The Cell in Action
Cellular Respiration • Cellular respiration is the
http://www.wappingersschools.org/RCK/staff/teacherhp/johnson/visualvocab/cellresp.jpg
© Fall 2005, Pflugerville ISD, 7th Grade
breakdown of food, like
glucose, using oxygen.
• Uses glucose and oxygen to
make carbon dioxide and
water.
• Often confused as
“breathing”. Not the same!
Breathing gives our cells the
oxygen needed for cellular
respiration.
Unit 2 : Chapter 8 : Section 2
The Cell in Action
Click below to learn more about cellular
respiration.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 2
The Cell in Action
Make a Venn diagram
comparing and contrasting
photosynthesis and cellular
respiration.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 2
Let’s Review!
-1Why are producers (who use
photosynthesis) important to
the survival of all other
organisms?
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 2
Answer
• Producers harness
energy in sunlight to
produce food
(glucose). This food
becomes an energy
source for producers
and for the organisms
that consume them.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Section 2
The Cell in Action
Websites to Visit
Good Diffusion Labs!
Transport In and Out of Cells
Photosynthesis
Cellular Respiration
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8
The Cell in Action
Pre-AP Extensions for Chapter 8
There are 2 types of endocytosis. Each
process bring particles into the cell.
1. Pinocytosis
2. Phagocytosis
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Pre-AP
The Cell in Action
Pre-AP Extensions for Chapter 8
1. Pinocytosis involves ingesting small molecules
and/or fluids surrounding the cell.
• The cell membrane surrounds and “pinches
off” small droplets and places them in a vesicle
inside the cell.
• Most of the molecules are already dissolved in
a solution during pinocytosis.
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Pre-AP
The Cell in Action
Pre-AP Extensions for Chapter 8
Pinocytosis
•The small
molecules are
ingested by the
cell membrane
and used inside
the cell.
http://www.cat.cc.md.us/courses/bio141/lecguide/unit2/eustruct/pinocyt.html
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Pre-AP
The Cell in Action
Pre-AP Extensions for Chapter 8
The second type of endocytosis is called
phagocytosis.
• Phagocytosis is the process of surrounding,
engulfing, and digesting larger, microscopically
visible particles.
• Phagocytosis is used by most protozoans to get
food.
http://www.oum.ox.ac.uk/children/animals/protists.gif
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Pre-AP
The Cell in Action
Pre-AP Extensions for Chapter 8
Phagocytosis
•In phagocytosis, the
food particle is too big
to “absorb” through
the cell membrane. It
must be surrounded
and engulfed.
http://academic.brooklyn.cuny.edu/biology/bio4fv/page/phago.htm
© Fall 2005, Pflugerville ISD, 7th Grade
Unit 2 : Chapter 8 : Pre-AP