Diffusion and Selectively Permeable Membrane

Body cells must maintain a certain amount of water within the cell to function properly. The picture represents a cell and water molecules.

When the number of water molecules outside of the cell is greater than inside the cell, which will most likely occur?

• Molecules of water will NOT MOVE either way

• Molecules of water will move OUT of the cell

• Molecules of water will move INTO the cell

• Molecules of water will EVAPORATE

Tags

NGSS.MS-LS1-2

A cell that is unable to import substances required to process chemical energy is most likely a result of a malfunctioning of the ____________________.

• cell membrane

• endoplasmic reticulum

• golgi body

• nuclear envelope

Tags

NGSS.MS-LS1-2

Cell membranes are described as selectively permeable.

Four students were asked to explain what this means and provided the answers given below:

Student 1: Cell membranes prevent all materials from entering the cell.

Student 2: Cell membranes only provide structural support for the cell.

Student 3: Cell membranes regulate which substances can enter and exit the cell.

Student 4: Cell membranes allow water and water-soluble substances to enter the cell.

• Student 1

• Student 2

• Student 3

• Student 4

Tags

NGSS.MS-LS1-2

A cell with a 10% salt concentration is placed into a beaker that contains a 20% salt concentration. The cell shrinks, as shown in the diagram below. Which part of the cell controls the movement of substances?

• mitochondria

• cell membrance

• chloroplast

• nucleus

Tags

NGSS.MS-LS1-2

The thin, semi-permeable membrane that encloses a cell allows nutrients to enter and wastes to be ____________________.

• digested

• recycled

• protected

• removed

Tags

NGSS.MS-LS1-2

All of the following are functions of a cell membrane EXCEPT

• surrounding and protecting the contents of the cell

• releasing waste products from the cell

• producing energy for the cell processes

• allowing gases to enter the cell

A scientist placed an egg in vinegar to dissolve the shell.

After the shell dissolved, only the semi-permeable membrane of the egg remained.

Then she placed the egg in water, and the egg increased in size as water molecules diffused into the egg.

Next, she placed the egg in corn syrup, and the egg decreased in size as the water molecules diffused out of the egg.

Why were water molecules able to enter the egg but NOT the sugar molecules?

• Semi-permeable membranes will allow any type of molecules to enter and exit a cell.

• The holes of the semi-permeable membrane were too small to let sugar molecules through.

• The holes of the semi-permeable membrane needed energy to push sugar molecules through.

• Semi-permeable membranes must be under pressure to work.

Tags

NGSS.MS-LS1-2

Which characteristic of a cell membrane allows it to control materials entering and leaving a cell?

• A cell membrane is surrounded by fluid

• A cell membrane is semi-permeable

• A cell membrane holds organelles in place

• A cell membrane is found in plant and animal cells

Capillary walls are only one layer of cells thick. Passage of oxygen into and out of the capillaries is controlled most by which process?

• collection of waste material

• breakdown of materials

• diffusion of materials

• storage of materials

The processes of diffusion and active transport are both used to

• break down molecules to release energy

• move molecules into or out of cells of the body

• bring molecules into cells when they are more concentrated outside of the cell

• move molecules against a concentration gradient, using ATP molecules