The cell membrane: a selective barrier
Grade 9 Science Worksheet - Building Confidence
Circle the best answer.
Read this first
Use this
Membrane drawing of an animal cell (model, not to scale). A strip with watery fluid outside the cell above and watery fluid inside the cell below. Between them are a top row and a bottom row of round parts, each with two long thin parts hanging from it; the long thin parts of the two rows meet in the middle. Letter A points to one round part in the top row. Letter B points to the long thin parts hanging from one round part. Letter C points to a large protein that reaches from the top fluid to the bottom fluid with a tunnel through it. Letter D points to a small part lying in the middle of the strip, alongside the long thin parts. Letter E points to a short branching chain of sugar units on the outside surface.
Ari studies a membrane drawing. Letter A points to a round part in the top row, touching the watery fluid. What is A?
- A phospholipid tail, which faces the watery fluid
- A phospholipid head, which faces the watery fluid
- A cholesterol molecule, which lies between the tails
- A channel protein, which lets ions through the strip
On Bo’s drawing, letter C points to a large part that reaches from the top fluid to the bottom fluid, with a tunnel through it. What is C?
- A channel protein, which spans the bilayer
- A pump, which moves ions using ATP energy
- A glycolipid, which marks the outside of the cell
- A surface protein, which rests on top of the bilayer
Kira wants a drawing where ions can get from the outside fluid to the inside fluid through a protein. Which drawing shows that?
- Neither drawing, because ions cross the tails alone
- Drawing X, because the protein spans the bilayer
- Drawing Y, because proteins stay on the surface
- Drawing Y, because the protein is next to the fluid
“model, not to scale” Luz sees two drawings of a particle crossing a bilayer with no proteins. Which drawing shows a particle that can cross this way?
- Drawing Y, because ions are small
- Drawing X, because oxygen has no charge
- Neither drawing, because gases need a protein too
- Both drawings, because a bilayer lets any particle cross
Use this
Membrane drawing of an animal cell (model, not to scale). A strip with watery fluid outside the cell above and watery fluid inside the cell below. Between them are a top row and a bottom row of round parts, each with two long thin parts hanging from it; the long thin parts of the two rows meet in the middle. Letter A points to one round part in the top row. Letter B points to the long thin parts hanging from one round part. Letter C points to a large protein that reaches from the top fluid to the bottom fluid with a tunnel through it. Letter D points to a small part lying in the middle of the strip, alongside the long thin parts. Letter E points to a short branching chain of sugar units on the outside surface.
Phospholipid heads are called hydrophilic. Milo wants the meaning. What does hydrophilic mean?
- Water-fearing, so it faces the middle of the strip
- Water-making, so it produces water for the cell
- Water-loving, so it is attracted to water
- Water-carrying, so it moves water across the strip
Noah sees that letter E points to a chain of sugar units carried by glycoproteins and glycolipids on the outside. What job do these chains help with?
- Cell transport, because the chains are tunnels for ions
- Cell energy, because the chains make ATP for the cell
- Cell recognition, because each cell has its own pattern
- Cell support, because the chains make a solid wall
A cell membrane is called selectively permeable. Pia wants the meaning. What does that mean?
- It lets some substances cross and keeps others out
- It makes even gases wait for a protein to cross
- It lets any substance cross whenever it touches
- It keeps substances out, like a solid wall
Use this
Membrane drawing (model, not to scale).
In Ren’s drawing, which lettered protein reaches all the way across the strip and has a tunnel?
- No letter, because proteins stay on the surface
- R, which spans the bilayer
- Q, which rests on the top surface
- P, which spans the bilayer
How many oxygen molecules does Tala’s drawing show outside the cell?
Use the picture in question 8.
- 7 oxygen molecules
- 4 oxygen molecules
- 2 oxygen molecules
- 3 oxygen molecules
Which lettered protein in Zee’s drawing rests on the top surface and does not enter the middle of the strip?
Use the picture in question 8.
- R, which rests on the top surface
- Q, which rests on the top surface
- Q, which spans the bilayer
- P, which rests on the top surface