Regents Review Part D The State Labs. Diffusion Through a Membrane

Regents ReviewRegents Review

Part DPart D

The State LabsThe State Labs

Diffusion Diffusion Through Through

a a MembraneMembrane

Diffusion Through a MembraneDiffusion Through a Membrane

Concepts You Must Know:Concepts You Must Know:a)a) The dialysis bag is the “cell”The dialysis bag is the “cell”

b)b) Diffusion moves materials Diffusion moves materials from high to low from high to low concentration, expending no concentration, expending no energyenergy

c)c) Only small molecules with go Only small molecules with go through the membrane through the membrane (selective permeability) … (selective permeability) … starch is too big a moleculestarch is too big a molecule


Concepts You Must KnowConcepts You Must Knowd)d) Benedict's solution tests for Benedict's solution tests for

sugar…heat it and it turns sugar…heat it and it turns red/orange (positive for red/orange (positive for glucose) glucose)

e)e) Iodine tests for starch…turns Iodine tests for starch…turns blue/black in starchblue/black in starch

f)f) Water is used as a control for Water is used as a control for the indicatorsthe indicators

g)g) The diffusion of water is The diffusion of water is osmosisosmosis

Diffusion Through a MembraneDiffusion Through a MembraneProcedure:Procedure:

a)a) Make a dialysis tube “cell”…the Make a dialysis tube “cell”…the tube represents the cell tube represents the cell membranemembrane

b)b) Pour glucose and starch into the Pour glucose and starch into the cellcell

c)c) Add iodine to the water outside Add iodine to the water outside the cellthe cell

d)d) The cell should turn blue/blackThe cell should turn blue/blacke)e) Test the water outside the cell Test the water outside the cell

for glucosefor glucose


Observations and Questions:Observations and Questions:a)a) Where did the iodine go?Where did the iodine go?

b)b) Where did the starch go?Where did the starch go?

c)c) Where did we use Benedict’s?Where did we use Benedict’s?

a)a) Where did the glucose go?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.

Diffusion Through a MembraneDiffusion Through a MembraneObservations and Questions:Observations and Questions:

a)a) Why must we digest starch before we can Why must we digest starch before we can use it for energy?use it for energy?

b)b) Why do they serve free salty pretzels in a Why do they serve free salty pretzels in a bar?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!


BiodiversityBiodiversity


Concepts you must know:Concepts you must know:a)a) Organisms with structural or Organisms with structural or

molecular similarities may be molecular similarities may be relatedrelated

b)b) In order for a species to be In order for a species to be successful and survive it must successful and survive it must contain variety (diversity)contain variety (diversity)

c)c) Proteins and enzymes are Proteins and enzymes are produced as a result of an produced as a result of an organism’s genetic code organism’s genetic code sequencesequence


The DNA code is transmitted from The DNA code is transmitted from

DNA DNA → mRNA → tRNA→ mRNA → tRNA

Base pair codes are as follows:Base pair codes are as follows:

DNA DNA A --T A --T “always tired”“always tired”

C -- G C -- G “constantly “constantly grumpy”grumpy”

m and t RNAm and t RNA A –U A –U “always ugly”“always ugly”

C -- G C -- G “constantly “constantly grumpy”grumpy”

BiodiversityBiodiversitye)e) Amino acids are building blocks Amino acids are building blocks

of proteinsof proteins

f)f) Molecular similarities are the Molecular similarities are the most important evidence of most important evidence of closely related organismsclosely related organisms

g)g) Organisms evolve much like the Organisms evolve much like the branches on a treebranches on a tree

h)h) Biodiversity ensures genetic Biodiversity ensures genetic variationvariation


i)i) Biodiversity increases stability in an Biodiversity increases stability in an ecosystemecosystem

j)j) Endangered species hold medicinal, Endangered species hold medicinal, agricultural, ecological, commercial and agricultural, ecological, commercial and aesthetic value. They must be protected for aesthetic value. They must be protected for future generationsfuture generations


Questions:Questions:a)a) What activities by humans could endanger What activities by humans could endanger

plants?plants?

b)b) Why is Botana Curus so important? How Why is Botana Curus so important? How can it be saved?can it be saved?

c)c) Why would you not want to save Botana Why would you not want to save Botana Curus from extinction?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.

Making ConnectionsMaking Connections


Concepts you must know:Concepts you must know:a)a) Resting pulse rates vary with individuals.Resting pulse rates vary with individuals.

b)b) By collecting data, scientists can help to By collecting data, scientists can help to answer questions they have proposed.answer questions they have proposed.

c)c) Pulse rate increases under physical or Pulse rate increases under physical or emotional stress.emotional stress.

d)d) Increase in activity produces muscle fatigue.Increase in activity produces muscle fatigue.

e)e) Use Use Scientific MethodScientific Method to solve a problem to solve a problem that you have postulated. that you have postulated.


Be able to prepare a designed experiment Be able to prepare a designed experiment with the following format:with the following format: TitleTitle HypothesisHypothesis Method/MaterialsMethod/Materials Data collectedData collected ConclusionsConclusions Suggestions for improvementsSuggestions for improvements Suggestions for further researchSuggestions for further research

Darwin’s Darwin’s Beaks Beaks of of FinchesFinches

Beaks of FinchesBeaks of Finches

Concepts you must know:Concepts you must know:a)a) Certain adaptations give some organisms an Certain adaptations give some organisms an

advantage to survive.advantage to survive.

b)b) The environment “naturally selects” which The environment “naturally selects” which organisms are best suited (fittest) to survive organisms are best suited (fittest) to survive and reproduce.and reproduce.

** In this lab, the type of seeds (food) was the ** In this lab, the type of seeds (food) was the selecting agent in the island environment**selecting agent in the island environment**


c)c) Those organisms that survive and reproduce Those organisms that survive and reproduce pass these favorable traits on to the next pass these favorable traits on to the next generation. This gives their offspring an generation. This gives their offspring an advantage to survive.advantage to survive.

c)c) Competition for resources (food, water, Competition for resources (food, water, mates and territory) stimulates the struggle mates and territory) stimulates the struggle for survival.for survival.


Questions:Questions:1.1. What other traits will help finches survive What other traits will help finches survive

besides the shape of their beaks?besides the shape of their beaks?

2.2. What type of beak will be a favorable What type of beak will be a favorable adaptation to catch mice on the island?adaptation to catch mice on the island?

Speed, good eye sight, aggressiveness

A large sharp, strong beak

Beaks of FinchesBeaks of Finches3.3. Define the following terms:Define the following terms:

• Variation –Variation –

• Competition – Competition –

• Struggle for survival –Struggle for survival –

• Adaptation – Adaptation –

• Environmental selecting agent - 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.

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Regents Review Part D The State Labs. Diffusion Through a Membrane