© fall 2005, pflugerville isd, 7th grade 7th grade science

© Fall 2005, Pflugerville ISD, 7th Grade

7th Grade Science

http://www.bergoiata.org/fe/felins/10.htm

http://www.jonathanpmiller.com/intercalation/B-DNA.jpg

http://www.bergoiata.org/fe/felins/10.htm

Unit 2 : Chapters 7,8,9,10,14© Fall 2005, Pflugerville ISD, 7th Grade

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

Unit 2 : Chapter 7 : Section 1© Fall 2005, Pflugerville ISD, 7th Grade

It’s Alive!! Or, Is It?

What characteristics do all living things have in common?

What Do You Think?



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.



• An object must possess all 6 of the characteristics in order for it to be considered a living thing.



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…



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.



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.



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.



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



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



Click on the video below to see some differences between sexual and asexual reproduction.



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



Click below to see how living things use energy.

www.unitedstreaming.com



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.


It’s Alive!! Or, Is It?Tr

y Th

is! Visit the website below to distinguish between Living

and Non-living things.

Ready?

Living and Non-living things


Let’s Review!

- 1 -

If the weather is cold outside, how do you maintain your

body temperature?


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


Let’s Review

- 2 -

• What characteristics of living things does a river have?

• Is a river alive?


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.



Websites to Visit

• Cells Alive

• Prokaryotes and Eukaryotes

Unit 2 : Chapter 7 : Section 2 © Fall 2005, Pflugerville ISD, 7th Grade


What are several thing that are necessary for living things to

survive?

What Do You Think?



• Food

• Water

• Air

• A place to live



Food

There are 2 ways to get food.1. Make your own food

a. Producers make their own food through photosynthesis.

- Plants are producers.



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.



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



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.



• Click below to see examples of animals needing water to survive.

www.unitedstreaming.com



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.



Air continued…

Click below to see how different organisms get the oxygen they

need.

The Lung Association



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.


Let’s Review

- 1 -

Describe how producers, consumers, and decomposers live together in an

environment.


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



How the Body Uses O2

Make Your Own Food Web!

Unit 2 : Chapter 7 : Pre-AP© Fall 2005, Pflugerville ISD, 7th Grade


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




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




Click below for an interactive tour of prokaryotic (bacteria) and eukaryotic (plant

and animal) cells.

Prokaryotic and Eukaryotic Cells




Classification Websites to Visit

Taxonomy of Living Things

Classification and Taxonomy


The Cell in Action

How do food, water, and wastes get into and out of a

cell?

What Do You Think?


The Cell in Action

• 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.

Diffusion

The Cell Membrane

http://library.thinkquest.org/C004535/media/cell_membrane.gif


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


The Cell in Action

Diffusion goes from an area of high concentration to

low concentration

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.

http://www.biologycorner.com/resources/diffusion-animated.gif


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.


The Cell in Action

•Osmosis occurs when water diffuses across the cell membrane.

• Notice only the blue water molecules are traveling in and out of the cell

http://www.biologycorner.com/bio1/diffusion.html#


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.


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.


The Cell in Action

•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

Moving Medium Sized Particles Across the Cell Membrane


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.


The Cell in Action

Moving Medium Sized Particles Across the Cell Membrane

Go.hrw.com

•The red molecules are moving from a low to high concentration area.

•Energy is required!


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


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


Let’s Review

-1-

How does a cell take in large particles?

How does a cell get rid of large particles?


Answer

• Large particles are taken in by endocytosis and expelled by exocytosis.


The Cell in Action

How are photosynthesis and cellular respiration similar?

What Do You Think?


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.

http://lhs.lps.org/staff/sputnam/Biology/U3Cell/chloroplast_1.png


The Cell in Action

Click below to learn more about photosynthesis.


The Cell in Action

• Cellular respiration is the 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.

Cellular Respiration

http://www.wappingersschools.org/RCK/staff/teacherhp/johnson/visualvocab/cellresp.jpg


The Cell in Action

Click below to learn more about cellular respiration.


The Cell in Action

Make a Venn diagram comparing and contrasting photosynthesis and cellular respiration.

Activity


Let’s Review!

- 1 -

Why are producers (who use photosynthesis) important to

the survival of all other organisms?


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.

Unit 2 : Chapter 8 © Fall 2005, Pflugerville ISD, 7th Grade

The Cell in Action

Websites to Visit

Good Diffusion Labs!

Transport In and Out of Cells

Photosynthesis

Cellular Respiration


The Cell in Action


There are 2 types of endocytosis. Each process bring particles into the cell.

1. Pinocytosis

2. Phagocytosis


The Cell in Action


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.


The Cell in Action


Pinocytosis

http://www.cat.cc.md.us/courses/bio141/lecguide/unit2/eustruct/pinocyt.html

•The small molecules are ingested by the cell membrane and used inside the cell.


The Cell in Action


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


The Cell in Action


http://academic.brooklyn.cuny.edu/biology/bio4fv/page/phago.htm

Phagocytosis•In phagocytosis, the food particle is too big to “absorb” through the cell membrane. It must be surrounded and engulfed.

© fall 2005, pflugerville isd, 7th grade 7th grade science

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