Biology

Using your knowledge of osmosis, explain why it is not a good idea to drink ocean water if you were stranded on a desert island with no freshwater.

By drinking salt water, the concentration of solutes outside the cells will increase causing the water inside the cell to move out making the cell shrink. The solution outside the cell is hypertonic and can cause dehydration.

Describe how the structure of cell membrane allows for passive transport to take place.

Diffusion occurs through the lipid bilayer if the particles are small enough and osmosis diffuses water through the aquaporins (transport proteins). Other particles that are large in molecular structure also travel through the transport proteins.

Explain the difference between diffusion and osmosis.

Diffusion-particles move from an area of high concentration to an area of low concentration. Osmosis - water diffuses from an area of high concentration to an area of low concentration through a semi-permeable membrane

What makes facilitated diffusion (transport) different from regular diffusion?

Facilitated diffusion requires a transport protein to help diffuse materials in or out of the cell and regular diffusion does not require a transport protein because the materials can travel through the lipid bilayer. Neither process requires energy.

Explain at least 3 factors that affect the rate of diffusion.

Factors that affect the rate of diffusion are temperature, size of the molecules and difference in concentration gradient, surface area. Warmer temperatures increase rate of diffusion Larger the molecules, slower the rate of diffusion The greater the concentration gradient between the outside and inside of the membrane the greater the rate of diffusion Greater the surface area, higher the rate of diffusion

Describe how the structure of the cell membrane allows for active transport to take place.

Flexible membrane (lipids) can fold around large particles (endocytosis/exocytosis) and protein pumps in the membrane move particles from areas of low to high concentration.

What is homeostasis?

Homeostasis is the body's ability to maintain constant internal physical and chemical conditions.

Explain why it is important for organisms to maintain homeostasis.

If they can not maintain homeostasis, they can not survive and die.

Explain the differences between passive and active transport.

Passive Transport - no energy required - particles move through diffusion from areas of high concentration to areas of low concentration Active Transport - energy is required - particles move from areas of low concentration to areas of high concentration

Describe the structure of the cell membrane.

Structure of the cell membrane is - lipid bilayer (flexible) - hydrophilic heads (outside membrane) attract water (water-loving) - hydrophobic tails (inside membrane) repel water (water-hating) - transport proteins move particles in or out of the cell

When a person sweats, water and essential solutes called electrolytes are lost from body fluid. If a person drinks a lot of water but does not replace lost electrolytes, what effect will this have on their cells? Explain.

The cell will have more water and less solutes inside the cell than outside causing the cell to swell (hypotonic).

Explain how having too much or too little water in your cells disrupts the homeostasis of the body.

Unicellular organisms use energy to maintain stable concentrations of water and solutes so they can respond to a changing environment. In multicellular organisms, the cells are specialized and work together to carry out specific functions.

The concentration of solute inside of a cell is 20% and the concentration of solute in the solution outside of the cell is 35%. What direction will the water move in? Is the solution hypotonic, hypertonic, or isotonic? What will happen to the cell (swell, shrink, equilibrium)?

Water moves out of the cell and will shrink because it is in a hypertonic solution.

Explain how having too much or too little water in your cells disrupts the homeostasis of the body.

When cells have too much or too little water they are no longer isotonic. Cells become involved in a hypertonic or hypotonic, which can cause them to swell or shrink. This will prevent them from working properly.

Explain the functions of the cell membrane

protect and support the cell regulate what enters and exits the cell