biology lab - lab 4

How does the paramecium expel excess water?

The excess water is collected into a contractile vacuole which swells and finally expels water through an opening in the cell membrane.

What kind of activity would you expect to see in a the contractile vacuole of a paramecium if you placed it in seawater? seawater is approximately 4% salt, and a paramecium is approximately 1% salt.

Water will move out of the cell to the region with a higher concentration of solute

Why does a paramecium need a mechanism to expel excess water?

When the contractile vacuole stops working it bursts the membrane of the animal, eventually resulting in its death

Define Hypotonic

When the extracellular fluid has lower solute concentration than the fluid inside the cell and the net flow of water will be into the cell

What is a good guideline for when to make a line graph?

a good rule of thumb is when the x-axis has continuous values, make a line graph

Where in the human body does filtration occur?

blood pressure pushes small molecules and ions from the capillaries into the collecting system of the kidney

Explain how substances are separated during filtration

filtration separates molecules based on size -large particles are too big to pass through the membrane -small particles and a solvent are passed through the membrane by pressure

Define selectively permeable membrane

freely allows the passage of water but stops larger particles

What is an example of diffusion?

gases such as oxygen and carbon dioxide move between blood and cells by diffusion

What is the external energy source in the filtration activity?

gravity

In tube "C" a potato core is placed in a hypotonic solution. Will the core shrink, grow, or stay the same?

grow

What is a good guideline for when to make a bar graph?

if the x-axis displays categories, use a bar graph

What is brownian movement?

molecules are in constant motion due to inherent kinetic energy -temperature dependent -the more higher the temperature, the more rapid the movement will be

Define Active transport

requires the cell to expend energy to move the materials

In tube "A" a potato core is placed in a hypertonic solution. Will the core shrink, grow, or stay the same?

shrink

In tube "B" a potato core is placed in an isotonic solution. Will the core shrink, grow, or stay the same?

stay the same

Define osmosis

the diffusion of water across a selectively permeable membrane

Define Isotonic

the extracellular fluid has the same solute concentration as the ell, there is no net movement of water into or out of the cell

In the brownian movement activity if the ink was inside the cell, what would the ink molecules represent?

the ink molecules represent large molecules that can't get through the membrane

Define diffusion

the movement of particles from a greater concentration to a lesser concentration until they are equally distributed

Distinguish between solute and solvent

the particles are the solute, and they are dissolved in the solvent, water

Define osmotic pressure

the pressure that would have to be applied to a pure solvent to prevent it from passing into a given solution by osmosis, often used to express the concentration of the solution

Define filtration

the process of separating suspended solid matter from a liquid, by causing the latter to pass through the pores of a membrane

Intravenous solutions are isotonic with body cells and fluids. A common intravenous solution is 0.9% saline (salt). What would happen to your red blood cells if you received an intravenous solution of distilled water? Which is hypertonic, the distilled water or the red blood cells?

the red blood cells would swell and burst -the distilled water would represent a hypotonic solution

In the brownian movement activity if the water was inside the cell, what would the water molecules represent?

the water molecules represent the cell's plasma membrane that prevents large molecules from passing through

Give an example of active transport in a living cell

water microorganisms have an organelle called a contractile vacuole that collects & pumps out the accumulated water by active transport -this activity requires energy b/c the water is being pumped against a concentration gradient

Define hypertonic

when the extracellular fluid has a higher solute concentration that the cell's cytoplasm and the water will move out of the cell to the region of higher solute concentration