Transcript Regents Review

Regents Review
Part D
The State Labs
Diffusion
Through
a
Membrane
Diffusion Through a Membrane
Concepts You Must Know:
a)
b)
c)
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
Diffusion Through a Membrane
Concepts You Must Know
d)
e)
f)
g)
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
Diffusion Through a Membrane
Procedure:
a)
b)
c)
d)
e)
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
Diffusion Through a Membrane
Observations and Questions:
a)
Where did the iodine go?
The iodine diffused into the cell as evidenced by the liquid in the cell turning black
due to the presence of starch inside
b)
Where did the starch go?
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
c)
Where did we use Benedict’s?
We used the Benedict’s to test the water outside the cell for the presence of glucose.
a)
Where did the glucose go?
The water tested positive because the glucose diffused out of the cell.
Diffusion Through a Membrane
Observations and Questions:
a)
Why must we digest starch before we can
use it for energy?
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
b)
Why do they serve free salty pretzels in a
bar?
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!
Diffusion Through a Membrane
Biodiversity
Biodiversity
Concepts you must know:
a)
b)
c)
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
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”
C -- G “constantly grumpy”
Biodiversity
e)
f)
g)
h)
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
Biodiversity
i)
j)
Biodiversity increases stability in an
ecosystem
Endangered species hold medicinal,
agricultural, ecological, commercial and
aesthetic value. They must be protected for
future generations
Biodiversity
Questions:
a)
What activities by humans could endanger
plants?
Air, water and land pollution, development, bringing in invasive species
b)
Why is Botana Curus so important? How
can it be saved?
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.
c)
Why would you not want to save Botana
Curus from extinction?
It might be too expensive or there might be other plants (not as rare) that can
also be used as a cure.
Making Connections
Making Connections
Concepts you must know:
a)
b)
c)
d)
e)
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.
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
Darwin’s
Beaks
of
Finches
Beaks of Finches
Concepts you must know:
a)
b)
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**
Beaks of Finches
c)
c)
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.
Beaks of Finches
Questions:
1.
What other traits will help finches survive
besides the shape of their beaks?
Speed, good eye sight, aggressiveness
2.
What type of beak will be a favorable
adaptation to catch mice on the island?
A large sharp, strong beak
Beaks of Finches
Define the following terms:
3.
•
Variation –
Genetic mutations and sexual reproduction result in different
combinations of traits that give species differences (variation)
•
Competition –
When niches overlap, organisms have to fight for food, mates or
territory.
•
Struggle for survival –
When there is competition, the strongest will survive (survival of
the fittest) or those best adapted to the environment.
•
•
Adaptation –
How well a trait or characteristic of an organism fits the
environment.
Environmental selecting agent It is the environment that determines which traits are the best for
adapting, and the organisms with these traits are “selected” to
best survive.