Bell work Sandworms are annelid worms that live on the seafloor. They absorb oxygen and excrete wastes through their skin. Which characteristic will best help the worm carry out these functions? large number of hearts large diameter blood vessels large mouth compared to body volume  large surface area compared to body volume

Science Fact of the Day: The human heart has enough pressure to squirt blood up to 30 feet away.

CO: LO:

All cells are surrounded by a thin, flexible barrier known as a cell membrane.

What is the cell membrane’s function (job)? (2 things)

The two main functions of the cell membrane are: 1) to regulate what enters and leaves the cell and 2) to provide protection and support.

What is the cell membrane made (composed) of? (3 types of molecules)

The composition of cell membranes is a double-layered sheet called a lipid bilayer. carbohydrate DRAW THIS! Lipid Bi- means 2 Phosphate Also called the phospholipid bilayer

Proteins are embedded in the lipid bilayer Proteins are embedded in the lipid bilayer. Proteins form channels or pumps that help move large materials across the cell membrane.

Carbohydrates are attached to many proteins embedded on the outside of the bilayer. The carbohydrates allow individual cells to identify one another.

How do substances move into/out of the cell membrane? (4 ways)

Why does food coloring spread out in water?

Every living thing lives in a liquid environment that it needs to survive.

In a solution, particles are constantly moving In a solution, particles are constantly moving. They collide with one another and tend to spread out randomly.

Particles move from an area of high concentration to an area of low concentration. This process is known as diffusion.

The concentration is the amount of a substance dissolved into water The concentration is the amount of a substance dissolved into water. (Kool-aid demo)

A concentration gradient is a difference between two concentrations A concentration gradient is a difference between two concentrations. Diffusion is the movement of particles down the concentration gradient. High Concentration Low Concentration

When the concentration of a solute is the same throughout a system, the system has reached equilibrium. When equilibrium is reached, particles do continue to move across the membrane.

Substances that diffuse across a membrane do not require the cell to use energy.

If a substance is able to diffuse across a membrane, the membrane is said to be permeable to it. If a substance cannot diffuse across a membrane, the membrane is said to be impermeable to it.

Selectively permeable means that some substances can pass across while others cannot. Biological membranes are selectively permeable.

Diffusion of water through a selectively permeable membrane is called osmosis. Remember: SALT SUCKS

Isotonic means “same strength”. Hypertonic means “above strength” Isotonic means “same strength”. Hypertonic means “above strength”. Hypotonic means “below strength”. Draw This Label: Hypotonic Water: High (outside cell) Solute: Low Label: Hypertonic Water: Low (outside cell) Solute: High Label: Isotonic Water: Same Solute: Same