Chapter 6 Lesson 3 Part 2"Water Balance Investigations"

Materials:

• Worksheet, Water Balance.
• Investigation Materials (optional) Per Group:

Two fresh eggs.
vinegar (or dilute hydrochloric acid)
straw or glass tube
clear glass
sealing wax
salt
Separate Experiment:
salt
ra sins
A milk bottle or wine carafe (something the egg will not quite fit in)

Objective:

• Students will explain how animals maintain water balance in the sea, in freshwater, and on land.
• Students will explain how animals excrete wastes.
• Students will experiment to determine what affects water movement through a cell membrane and how.

Alaska Content Standards:

• SCI A-10 Students will understand that living things are made up mostly of cells and that all life processes occur in Cells (Cells)
• SCI A-12 Students will distinguish the patterns of similarity and differences in the living world in order to understand the diversity of life and understand the theories that describe the importance of diversity for species and ecosystems.
• SCI A-14 Students will understand the interdependence between living things and their environments; that living environments consists of individuals, populations, and communities; and that a small change in a portion of an environment may affect the entire environment (Interdependence);
• SCI A-15 Students will use science to understand and describe the local environment.
• SCI B-1 Students will use the processes of science: observing, classifying, measuring interpreting data, inferring, communicating, controlling variables, developing models and theories, hypothesizing, predicting, and experimenting;
• SCI- C-8 Students will understand that acceptance of a new idea depends upon supporting evidence and that new ideas that conflict with beliefs or common sense are often resisted.
• SCI- D-2 Students will understand that scientific innovations may affect our economy, safety, environment, health, and society and that these effects may be long or short term, positive or negative, and expected or unexpected;

Anticipatory Set: Review Yesterdays lesson. Then ask the question, "if an animal needs to save water, why does it produce urine? Lead the students to the answer of poisons need to be gotten rid of.

Ammonia is one type of waste that is poisonous to cells and builds up as our body breaks down proteins. Most animals that live in the water ammonia does not build up in the body and moves out into the water.

Land animals need a way of getting rid of ammonia. Ammonia is changed into a less dangerous chemical and then excreted from the body. What organ in the body does this? Show the students a picture of the kidney and sum up this information:

Blood is brought to the kidney in the renal artery. The kidneys filter the blood and then reabsorb useful materials such as glucose. After it has been purified the blood returns to the circulation through the renal vein.
Urine is taken from the kidneys to the bladder by the ureters. The bladder stores the urine until it is convenient to expel it from the body. The main waste product removed in the urine is urea. Urea is a waste product produced in the liver when surplus amino acids are broken down to be used for energy. It is released into the bloodstream until it is filtered out and removed by the kidney.

Urine is produced in microscopic structures in the kidney called nephrons. Each kidney has many millions of nephrons see the function diagram.

Blood is filtered in the glomerulus. The filtrate is collected by the bowman's capsule and enters the tubules. Useful substances such as glucose, some salt and water are reabsorbed into the blood. Reabsorption is done by blood capillaries which are closely wrapped round the tubules. The waste, consisting of water, some salt and urea is urine. The urine is collected by the collecting duct, taken to the ureters and then to the bladder. Here is a complex look.

Guided Practice: Work with the students on the worksheet for Lesson 6-3 review.

Closure: Students and teacher will set up three different osmosis experiments.

Day one:

Independent Practice: Students will research this question. Can you live without your kidneys? For one extra credit point, e-mail me the answer. Have students take lesson 6-3 quiz.

Duration:

30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).