Transport in & out of cells

Microscopes are used in biology to see objects too small for the human eye.

A student makes a microscope slide of a layer of onion epidermal cells.

The student uses a coverslip to make the slide.

Describe the function of the coverslip.

When the student looks down the microscope, they see an image like the one below.

Identify subcellular structure X and describe its function.

The student prepared the slide by covering the onion epidermal cells with water.

The student looks at the cells again after one hour and the vacuoles look larger.

Explain why the vacuoles look larger.

Use your knowledge of transport in cells.

Plants and animals have stem cells.

These are cells that have not undergone changes to become specialised cells.

Which process do stem cells go through to become specialised cells?

Tick (✓) one box.

The table gives features of different types of stem cells.

Complete the table by putting one tick (✓) in each row.

One type of specialised cell in a plant is a root hair cell, shown in the diagram.

Give a function of a root hair cell and state how it is adapted for that function.

One role of a root hair cell is to move ions into the plant against the concentration gradient.

State the name given to this type of transport.

Many substances move in and out of cells, maintaining the internal environment of the organism.

State the name given to the type of transport where ions move against their concentration gradient.

Water can move in and out of plant cells.

Potato chips can be used to demonstrate this type of transport.

The mass of three potato chips are measured at the start of the experiment and after 20 minutes in 3 different concentrations of sugar solution.

The table shows these results.

Calculate the percentage change in mass at 0.0 mol / cm³.

Explain the percentage change in mass shown by the potato chip in the 0.5 mol / cm³ solution.

Calculate the surface area to volume ratio of agar cube C.

Write your answer in the table.

One of the times recorded is an anomaly.

Identify this anomalous result.

The anomaly was due to random error.

Suggest one random error that could have caused the anomaly.

Describe and explain the pattern in the results.

Which process allows substances to enter cells against a concentration gradient?

A Active transport

B Diffusion

C Mitosis

D Osmosis

A student investigates osmosis by placing chips of potato and apple into different concentrations of sucrose solution.

The student calculates the percentage change in length for each chip of potato and apple.

The graph shows the student’s results.

Estimate the concentration of sucrose inside the cells of the apple.

0.0 mol/dm³ A

0.3 mol/dm³ B

0.5 mol/dm³ C

1.0 mol/dm³ D

What is the correct definition of water potential?

A The ability of dissolved glucose molecules to move to different areas.

B The ability of dissolved water molecules to move to different areas.

C The ability of free glucose molecules to move to different areas.

D The ability of free water molecules to move to different areas.

A student investigates osmosis. They place potato chips in different sugar solutions.

The table shows their results.

What is the percentage change in mass for the potato chip in sugar solution Z ?

A −7

B −15

C −18

D −30

Some children can inherit a rare kidney condition called ARPKD. It is caused by a recessive allele.

A pregnant woman has ARPKD. The baby’s father is heterozygous for ARPKD.

What is the probability of their baby having ARPKD?

Complete the genetic diagram to explain your answer.

Use the letters:

• R for the dominant allele

• r for the recessive allele.

It is estimated that 1 in 70 people in the UK is a carrier of ARPKD.

The estimated population of the UK in 2011 was 63.2 million.

Estimate the number of people in the UK in 2011 who were carriers.

Explain why this number is only an estimate and not the real number of carriers.

The kidneys in people with ARPKD have not developed normally.

Stem cells could be used to repair the damaged kidneys.

Discuss reasons for and against using stem cells to treat ARPKD.

A student investigates the effect of concentration on osmosis.

He cuts out five potato chips of similar mass. The student measures the mass of each potato chip.

He then places the potato chips in different concentrations of sugar solution.

After 30 minutes he removes the potato chips from the solution. He dries them with a paper towel before measuring the new mass.

The potato chips are dried before the new mass is measured.

Explain why.

The table shows his results.

Calculate the percentage change of mass for the potato chip in 0.8 mol/dm³ sugar solution.

Record your answer to 1 decimal place.

Plot a graph of the percentage change in mass against concentration of sugar solution and draw a line of best fit.

Estimate the concentration of sugars inside the potato cells.

Answer =........ mol/dm³

Use ideas about osmosis to explain the patterns in the results.