Lecture on Life Science

Textbook- Life a Biological Science (Newton Edition) Harcourt, Brace, Jovanovich

Subject: Science

Grade: 7

Behavioral Objective-  The students will explore a variety of water environments from the tidal pools to the depths of the ocean.  The students will experiment and construct what a water environment consists of from their community and how it affects them in various ways.

Cognitive domain-  The students will experiment and observe the various environments around them to see how various adaptations may occur.  Students will learn about lakes, ponds, rivers and oceans with their similarities and differences.  They will also learn about the food chains that are presented.

Affective domain-  The students will learn some of the positive and negative effects of their environments on humans and all the other plants and animals.

Psychomotor domain-  The students will keep a journal of their observations of the environments around them.

Materials-  Chapter One    Freshwater Environments    Part One

The study of biology in short is the study of life.  Bio- meaning life and ology meaning study of. 

(The teacher could do this simple experiment to teach about water environments.  Take three jars or bags and fill them with water; one with a small snail, one with a plant, and one with the plant and snail and observe for changes.  The students will begin to learn how to make scientific observations.)

(A science notebook of organisms could be started with the following term.)

  Elodea- water plant (write on blackboard).

The teacher will then write these basic research questions on the blackboard:

• Will the organisms thrive best in which environments?
• What is your hypothesis?

Teacher will give a brief definition of the term ‘hypothesis’- an educated guess (on the blackboard).  The students will make their observations and record them in their notebooks.

Further questions are:  How many environments were created?  How are they different and similar?  By doing this experiment we are gaining new knowledge in gathering, verifying, and organizing what we are observing.

Life in a Pond

‘Producers’ in a pond

According to the picture on 5 of Life A Biological Science ‘What is the green stuff on the pond?’  Teacher will write on the blackboard the term ‘algae’ and define it as a small green plant that manufactures food. 

Other areas where small microscopic plants may be (write on blackboard) ponds, gently running streams, outdoor fish ponds, and damp/hot places.

Also here is a list of terms that the teacher can write on the blackboard and have students put these terms in their notebooks.  The heading is Microscopic Plants

• Pondscum- Spirogyra- a bright, green, slippery long strings in water floating masses that cover over ponds- a spiral band within cell-cylinder shape.
• Stonewort- Chara- branched and needle-like branches arranged in whorls along the main stem.  Stiff, slimy only in ponds with large amount of dissolved limestone in water.
• Waternet- Hydrodictyon- green nets float in sunny and still ponds- join together to form meshes in a net- appears to be like in shape.
• Ulothrix- like Spirogyra unbranched strings of green cells forms a green, fuzzy covering on rocks and sticks on pond water.  The cells are short and somewhat like cubes with rounded corners.  They contain beltlike, green structures and that gives a banded appearance to each strand.  (There is a difference between Ulothrix and Spirogyra. What is it?) Ask this of the students to promote understanding.)
• Nostoc- a slippery mass on ponds and rocks some stick and some float that look like muddy masses of jelly or necklaces of round beads.  ‘Bead’- actually a cell that appears green in color.  Remains attached and surrounded by jelly.
• Oscillatoria- blue-green strings that move (oscillate) slowly back and forth in shallow water.  Disk-shaped cells attached end to end.
• Desmids- beautiful, formed green cells found in many shapes and patterns/boat shaped-crescent shaped- cross-shaped.  Covered with spines, knobs, grooves, markings of various kinds. (pinched in/constricted in the middle so each appears to be composed of two identical half-cells.
• Diatoms- a beautiful gold color and have intricate designs on their cell walls.  Clustered on leaves lying in stagnant pools.  They add a golden color to the leaves.  They are like desmids for they have a variety of shapes and designs.  There are two overlapping halves that fit together almost like a box and cover.

This could be a good ‘pop quiz’ to check for understanding of the material so far.

All of these tiny plants are sometimes called “the grass” of the water.  (food for many of the water animals) the basic food ‘producers’ in water. Several kinds of water weeds may be found rooted in the mud/sand  two to five feet under the surface of the water. 

Write these terms on the blackboard- Elodea, Vallisneria- common water weeds some grow entirely underwater and some have leaves that float on the surface as the the waterlily. 

Fish and aquatic animals as you may know find shelter among such plants.  Ducks eat the roots and the fruits that some of these plants produce.   Plants that grow part on land and part in water- stems and leaves above the water surface or water edge.  Make a list on blackboard: 

• Swamp potato
• Plants
• Cattails
• Rushes

These are food factories for these animals.

“Consumers” in a Pond

There are many consumers like fish, frogs, turtles and there are still many more. Depends where you are located (country) animals like muskrat, beaver, marten, otter, and mink.  These are lung breathers that are holding their breath while underwater (like you do when you swim). 

• Marten, otter, mink----- fish
• Muskrat, beaver, -----parts of plants mainly bark and tender plant shoots (muskrats may also eat small water animals. 
• Ducks and Herons feed at water’s edge - eating plant material and herons eat fish, frogs and other animals. 
• Birds, redwing blackbird live near water, but do not feed on plant life.  (What do birds usually eat?) (Have you ever noticed?)
• Reptiles/turtles live in ponds. Some eat pond plants and some eat the fish, frogs, and insects.  There may be water snakes that eat the fish and frogs.  There are also frogs, toads, salamanders living in ponds too where they lay eggs in the water.  Eggs hatch that are now tadpoles or tiny salamanders.  They breathe through gills like a fish till they change into adult forms then they eat insects and small animals.

List on the blackboard-  All types of Fish

Large and Small

Pike and Bass-  eating smaller fish and are called predatory fish that also eat frogs and other small water animals. 

‘Bottom-feeders’ are catfish/carp that eat dead and decaying animals that sink to the bottom.  Smaller fish live near weed beds where they are protected and get the food they prefer.   Smaller fish like pumpkinseed fish, crappies that eat water insects; worms crayfish and even small young fish.

Larger fish eat smaller fish, snakes, frogs and turtles.  Still other kinds of animals- water snails live in water plants with their filelike tongues.  Mussels are found in mud along with worms and insects along the bottom.

‘Insects’ in and out of the water’ ---- Early and Late stages

Nymph of dragonfly; water bugs and beetles like whirligig beetles - live in water.

New term for notebook (write on blackboard) Larvae-larva- mosquitoes, mayflies, dragonflies, midges, caddis flies; young, immature, forms of some insects. (Butterflies were caterpillars)  Aquatic larvae- eat a variety of tiny water plants and animals; mosquito larvae live on algae-tiny water animals like water fleas and fairy shrimps.  Water fleas and fairy shrimp -cyclops-small animals related to crayfish and lobsters that live on plant life in water.  Serve as food for insect larvae and other small animals in the water- especially tiny young fish.

Still other small animals like the hydra (related to jellyfish in the ocean; the fresh water sponge, crayfish, and different kinds of leeches.  Many (millions) single-celled organisms.  All of these plants and animals form what is called a community of living things is ‘interdependent’ (write this term on the blackboard)- One living thing depends upon the others in the community.)

                                                               End of Part One