Cell Structure - Transport Across Cell Membranes - Structure of Cell Membrane and Passive Transport (diffusion) Flashcards
What does the term Diffusion mean?
What does the term Passive Transport mean?
Why is the cell membrane important in Diffusion?
The cell membrane is important in controlling what substances can enter or leave a cell
Some molecules enter or leave the cell via passive transport. Give one example of passive transport (1)
Diffusion or Osmosis
Give two components that cell membranes are made from (2).
proteins
phospholipids
Cell membranes are said to be selectively permeable. Explain what is meant by this (1)
Selectively permeable - it means that some substances are able to pass across the membrane but others are not
Which of these molecules cannot diffuse through a cell membrane?
A - protein
B - oxygen
C - glucose
D - carbon dioxide
A - protein
Put in the correct order to show in which direction the carbon dioxide in the cells will diffuse
A - Carbon dioxide concentration = 0.2%
B - Carbon dioxide concentration = 1.5%
C- Carbon dioxide concentration = 3.0%
From Cell C to
Cell A and B
From Cell B to
Cell A
What are proteins?
What are phospholipids?
In active transport, molecules are moved by membrane….
A - proteins against the concentration gradient
B- lipids down the concentration gradient
C- lipids against the concentration gradient
D - proteins down the concentration gradient
Answer A
proteins against the concentration gradient
The diagram represents molecules present in a magnified fragment of cell membrane.
Name molecules X and Y
X - lipid
Y - protein
Select the correct missing word.
The cell membrane is ? permeable and transports water in and out of the cell be osmosis.
A - selectively
B- Fully
A - selectively
Select the correct missing word.
Osmotic movement occurs ? the concentration gradient.
A - down
B - against
A - down
Select the correct missing word.
Osmosis ? energy.
A- requires
B - does not require
B - does not require
The diagram shows a cell from a piece of plant tissue.
Describe how a piece of plant tissue could be treated so that its cells appeared as shown in the diagram.
Place in a solution of lower water concentration than cell sap.
What is meant be the term Osmosis?
What is meant by the term Osmotic?
What is meant be the term concentration gradient?
The diagram shows the transport of molecule ‘S’ through a cell membrane.
Name the method by which molecule ‘S’ is being moved across the membrane. Give one reason for your answer.
Active transport (the concentration gradient shown by the molecules in the diagram is the clue!)
Reason 1 - moving from a low to high concentration.
Reason 2 - transported by a membrane protein
(Only need to give one reason)
Plot a line graph using the results in the data.
(You will need to physically do this on graph paper with a pencil)
In which of the following scenarios is osmosis occurring?
A - water is moving from the mouth down into the stomach
B - sugar is being taken up into the blood from the gut
C- A plant is absorbing water from the soil
D- Oxygen is entering the blood from the lungs
Answer C
(remember Osmosis involves the movement of water molecules so the answer can’t be B or D. Osmosis occurs across a selectively permeable membrane so it can’t be A)
Explain why the root hair cell needs to use active transport to absorb the mineral ions (2)
The mineral ions are at a higher concentration inside the cell than outside of it (1)
so the ions need to be moved into the cell against the concentration gradient (1)
If an animal cell is surrounded by a solution with a very high water concentration it is likely to:
A - burst, as water will move out of it
B - burst, as water will move into it
C - shrink, as water will move out of it
D - shrink, as water will move into it
The Answer is B
Diffusion, osmosis and active transport all involve the movement of molecules. Which row in the table correctly shows the net movement of the substances in the diagram?
The Answer is row D
(you need to work out the relative concentration of the molecules on each side of the membrane and read the question carefully to see what process is involved in their movement.
A student did an experiment to see the effect of different sucrose solutions on pieces of potato.
Explain why it is important that all the potato pieces come from the same potato (1)
So that all the pieces of potato have the same water concentration.
or
Because different potatoes will have different water concentrations
The mass of the potato chip in beaker 5 was 10.0g before the experiment and 9.3g afterwards. Calculate the % change in mass of the potato chip in beaker 5 (1)
((9.3) - 10) divided 10
multiply 100
= 0.07 x 100 = -7%
Potato cylinders in two of the beakers become turgid. State the numbers of these two beakers. Give a reason for your answer (2).
Beakers 1 and 2
Reason - the cyclinders in these two beakers increased in mass
Describe what you would know about the water concentration of a potato chip if there was no change in its mass when it was placed in a particular concentration of sucrose solution (1)
The water concentratoin of the potato chip was the same as the water concentration of the sucrose solution
what is a sucrose solution?
The diagrams represent the movement of molecules across a cell membrane. Which cell would require the greatest number of mitochondria to allow the movement shown?
Answer D
