Diffusion

Figure 12 shows a beaker containing a potato cylinder in distilled water.

Explain why the mass of this potato cylinder will change when it is placed in distilled water.

A scientist investigated the rate of diffusion using three agar cubes of different sizes.

Each cube contained a pH indicator that changed from pink to colourless when placed in acid.

The cubes were placed in a beaker containing an acid.

Figure 13 shows some information about each cube.

Calculate the volume of cube C.

_........ cm³

Explain the difference in the times taken for cubes A and B to become colourless.

* (c) Liquid agar was poured into a Petri dish and allowed to set.

A well was cut in the centre of the set agar.

Kiwi fruit juice was poured into the well.

Kiwi fruit juice contains an enzyme that causes set agar to break down into a liquid.

Figure 14 shows the results after 30 minutes.

Devise a plan to investigate the effect of different concentrations of kiwi fruit juice on the breakdown of set agar, using the equipment shown in Figure 14.

Your plan should include:

• measurements that need to be taken

• variables that need to be controlled.

Figure 2 shows a beaker containing a potato cylinder in distilled water.

Explain why the mass of this potato cylinder will change when it is placed in distilled water.

A scientist investigated the rate of diffusion using three agar cubes of different sizes.

Each cube contained a pH indicator that changed from pink to colourless when placed in acid.

The cubes were placed in a beaker containing an acid.

Figure 3 shows some information about each cube.

Calculate the volume of cube C.

Explain the difference in the times taken for cubes A and B to become colourless.

A teacher was demonstrating a process to students.

The teacher had a beaker of water and added five drops of food colouring to the beaker.

State the process being demonstrated.

A student asked if different food colourings spread evenly in the same amount of time.

Give two variables that would need to be controlled if the investigation was repeated with different food colourings.

The teacher repeated this process with water at different temperatures. Figure 7 shows the results of this experiment.

Draw a line graph to show the results in Figure 7.

Explain why the time taken decreased.

In humans, gas exchange occurs in the alveoli of the lungs.

Figure 6 shows the structure of an alveolus and its blood supply.

Which process moves carbon dioxide from the blood into the alveolus?

State one adaptation of an alveolus that increases the rate of gas exchange.

Describe how blood is moved from the heart to the lungs.

Figure 7 shows the heart rate of a person before, during and after exercise.

Describe the trend shown in Figure 7.

Use data from Figure 7 to support your answer.

Explain the trend shown in Figure 7 from 5 minutes to 25 minutes.

The stroke volume is the volume of blood pumped during one beat of the heart.

At 25 minutes the stroke volume was 0.13 dm³.

Calculate the cardiac output of the heart of this person at 25 minutes.

Use the equation

cardiac output = stroke volumeheart rate

_........ dm³ per minute

Alcohol is broken down by liver cells.

Which process moves alcohol from the blood into the liver cells?

If a person drinks too much alcohol, liver cells die and the person can develop cirrhosis of the liver.

The relative risk of developing cirrhosis of the liver is affected by two factors.

1. The volume of alcohol a person drinks in one week.

2. Whether the person drinks the alcohol on its own or with a meal.

Figure 5 shows how these two factors affect the relative risk of people developing cirrhosis of the liver.

Number of units of alcohol consumed per week

Figure 5

Person A drinks alcohol on its own.

Person B drinks alcohol with their meals.

Calculate the difference in risk for these two people when each one drinks 28 units of alcohol per week.

Using evidence from Figure 5, state two pieces of health advice for people about drinking alcohol.

Cystic fibrosis is a genetic condition that can also cause liver disease.

State where genes are found in cells.

Figure 6 shows the inheritance of cystic fibrosis in a family.

F represents the dominant allele that does not cause cystic fibrosis.

f represents the recessive allele that causes cystic fibrosis.

person A (Ff) person B

person C person D person E (ff)

Figure 6

A scientist states that the genotype of person B is Ff.

Explain why the scientist is correct.

State the genotype of person C.

Figure 7 shows a single-celled pond organism (Amoeba proteus).

Which row of the table allows the net diffusion of oxygen into Amoeba proteus ?

Amoeba proteus uses oxygen for aerobic respiration.

Complete the equation for aerobic respiration.

glucose + oxygen _........ +_........ (+ energy is released)

Humans breathe faster when they exercise.

Which two changes allow the rate of respiration in the muscle to increase?

Figure 8 shows breathing data for a human at rest and when running at 5 metres per second on a running machine.

Calculate the mean volume of air breathed per minute when running at 5 metres per second.

Give your answer to one decimal place.

_........ dm³ per minute

Devise an investigation to compare the mean number of breaths per minute for men, with the mean number of breaths per minute for women, when running at 5 metres per second on a running machine.

Whilst running, the leg muscles of an athlete tightened up, causing cramp.

Name the product of anaerobic respiration that can cause cramp.

Figure 6 shows the structure and actual size of red blood cells (erythrocytes).

red blood cells side view of red blood cell (cut)

(Source: © N.Vinoth Narasingam/Shutterstock)

Figure 6

Calculate the image size of the top view of this red blood cell if this cell is

Give your answer in mm.

_........ mm

Explain how the shape of a red blood cell is related to its function.

State the role of haemoglobin inside the red blood cell.

Some blood transfusions contain red blood cells.

Red blood cells are stored in a solution containing 5.0% glucose and 0.9% salt.

Explain why red blood cells cannot be stored in pure water.

Figure 1 shows three cells.

What is structure X ?

The bacterial cell in Figure 1 has a flagellum.

State the function of a flagellum.

Give one other difference between the bacterial cell and the animal cell shown in Figure 1.

Substances move into and out of cells.

How does oxygen move into and out of cells?

A plant leaf cell is 0.04 mm long.

Calculate the length of the image after this cell has been magnified 500 times.

length of image =_........ mm

A student placed three different sized cubes of agar jelly into separate beakers containing the same concentration of hydrochloric acid.

The cubes contained a pink indicator.

This indicator becomes clear when in contact with an acid.

Figure 2 shows the results of the investigation after the cubes had been in the acid for 120 seconds.

The distance from the outside of cube B to the pink area was 3 mm.

Calculate the distance diffused by hydrochloric acid in one second.

_........ mm

The student wanted to confirm their results.

Give one improvement the student should make to this investigation to confirm their results.

Devise a method, using cubes of agar jelly, to investigate how temperature affects the rate of diffusion.

Some substances move into and out of cells by active transport.

Which is the correct description of the movement of a substance by active transport?

Some drugs used to treat cancer are taken into cells by active transport.

Figure 3 shows some causes of preventable cases of cancer in 2015.

What is the percentage of preventable cases of cancer that are caused by tobacco?

In 2015, data from Cancer Research UK suggested that 163 440 cases of cancer could have been prevented.

Calculate the number of preventable cases of cancer caused by alcohol.

Give your answer to the nearest whole number.

number of preventable cases of cancer caused by alcohol_........