1. Regents Review
Part D
The State Labs

2. Diffusion Through a Membrane

3. Diffusion Through a Membrane
Concepts You Must Know:
The dialysis bag is the “cell”
Diffusion moves materials from high to low concentration, expending no energy
Only small molecules with go through the membrane (selective permeability) … starch is too big a molecule

4. Diffusion Through a Membrane
Concepts You Must Know
Benedict's solution tests for sugar…heat it and it turns red/orange (positive for glucose)
Iodine tests for starch…turns blue/black in starch
Water is used as a control for the indicators
The diffusion of water is osmosis

5. Diffusion Through a Membrane
Procedure:
Make a dialysis tube “cell”…the tube represents the cell membrane
Pour glucose and starch into the cell
Add iodine to the water outside the cell
The cell should turn blue/black
Test the water outside the cell for glucose

6. Diffusion Through a Membrane
Observations and Questions:
Where did the iodine go?
Where did the starch go?
Where did we use Benedict’s?
Where did the glucose go?
The iodine diffused into the cell as evidenced by the liquid in the cell turning black due to the presence of starch inside
The starch remained in the cell or else we would have seen the water outside the cell turn black – the starch molecules are to large to fit through the cell membrane
We used the Benedict’s to test the water outside the cell for the presence of glucose.
The water tested positive because the glucose diffused out of the cell.

7. Diffusion Through a Membrane
Observations and Questions:
Why must we digest starch before we can use it for energy?
Why do they serve free salty pretzels in a bar?
Starch molecules are too large to fit through your body cell’s membranes - we must break them down into smaller molecules (digestion) to get them into the cells
The salt in you mouth makes the environment salty which causes the water in your mouth’s cells to diffuse out of the cells – making you feel thirsty. Thirsty customers buy more drinks!

8. Diffusion Through a Membrane

9. Biodiversity

10. Biodiversity Concepts you must know:
Organisms with structural or molecular similarities may be related
In order for a species to be successful and survive it must contain variety (diversity)
Proteins and enzymes are produced as a result of an organism’s genetic code sequence

11. The DNA code is transmitted from
Biodiversity
The DNA code is transmitted from
DNA → mRNA → tRNA
Base pair codes are as follows:
DNA A --T “always tired”
C -- G “constantly grumpy”
m and t RNA A –U “always ugly”

12. Biodiversity Amino acids are building blocks of proteins
Molecular similarities are the most important evidence of closely related organisms
Organisms evolve much like the branches on a tree
Biodiversity ensures genetic variation

13. Biodiversity Biodiversity increases stability in an ecosystem
Endangered species hold medicinal, agricultural, ecological, commercial and aesthetic value. They must be protected for future generations

14. Biodiversity Questions:
What activities by humans could endanger plants?
Why is Botana Curus so important? How can it be saved?
Why would you not want to save Botana Curus from extinction?
Air, water and land pollution, development, bringing in invasive species
A cure for cancer was developed from an extract of Botana Curus – the area can be legally protected from development or reproduced in a protected environment.
It might be too expensive or there might be other plants (not as rare) that can also be used as a cure.

15. Making Connections

16. Making Connections Concepts you must know:
Resting pulse rates vary with individuals.
By collecting data, scientists can help to answer questions they have proposed.
Pulse rate increases under physical or emotional stress.
Increase in activity produces muscle fatigue.
Use Scientific Method to solve a problem that you have postulated.

17. Making Connections
Be able to prepare a designed experiment with the following format:
Title
Hypothesis
Method/Materials
Data collected
Conclusions
Suggestions for improvements
Suggestions for further research

18. Darwin’s Beaks of Finches

19. Beaks of Finches Concepts you must know:
Certain adaptations give some organisms an advantage to survive.
The environment “naturally selects” which organisms are best suited (fittest) to survive and reproduce.
** In this lab, the type of seeds (food) was the selecting agent in the island environment**

20. Beaks of Finches
Those organisms that survive and reproduce pass these favorable traits on to the next generation. This gives their offspring an advantage to survive.
Competition for resources (food, water, mates and territory) stimulates the struggle for survival.

21. Beaks of Finches Questions:
What other traits will help finches survive besides the shape of their beaks?
What type of beak will be a favorable adaptation to catch mice on the island?
Speed, good eye sight, aggressiveness
A large sharp, strong beak

22. Beaks of Finches Define the following terms: Variation – Competition –
Struggle for survival –
Adaptation –
Environmental selecting agent -
Genetic mutations and sexual reproduction result in different combinations of traits that give species differences (variation)
When niches overlap, organisms have to fight for food, mates or territory.
When there is competition, the strongest will survive (survival of the fittest) or those best adapted to the environment.
How well a trait or characteristic of an organism fits the environment.
It is the environment that determines which traits are the best for adapting, and the organisms with these traits are “selected” to best survive.