Cells in Animals & Plants (AQA GCSE Combined Science: Synergy: Life & Environmental Sciences): Exam Questions

Bone cells divide to repair damage.

Give one other reason why bone cells divide.

Students investigated the effect of different concentrations of salt solution on the mass of pieces of potato.

This is the method used.

1. Cut three pieces of potato, each with a mass of 2.00 g.

2. Place the pieces of potato into a salt solution with a concentration of 0.2 mol/${\text{dm}}^3$.

3. After 30 minutes, measure the mass of each piece of potato.

4. Calculate the change in mass.

5. Repeat steps 1 to 4 for five other concentrations of salt solution.

Table 1 shows the results.

Table 1

Give two control variables the students should have used in the investigation.

Do not refer to mass or time in your answer.

Calculate value X in Table 1.

Figure 2 shows a potato cell.

Explain why the mass of the pieces of potato increased in the 0.2 mol/dm³ salt solution.

You should refer to the cell parts labelled in Figure 2.

The image in Figure 2 was made using an electron microscope and not a light microscope.

Give one piece of evidence to support this.

The potato cell in Figure 2 contains starch grains.

A starch grain on a different image had a diameter of 1.2 cm.

The starch grain had a real diameter of 0.008 mm.

Calculate the magnification of the image.

Starch is digested in the gut.

Why is digestion of starch needed?

Select your answer.

Describe the process of starch digestion.

Explain one advantage to the starfish of reproducing by cloning rather than reproducing by sexual reproduction.

Figure 5 shows a green pepper growing on a pepper plant (a leaf and a green pepper are labelled).

Water is lost from the leaves.

Complete the sentences.

Choose answers from the box.

1. Water is lost through tiny holes in the leaves called _______________.
   

2. The size of each hole is controlled by_____________________ .

Figure 6 shows a drawing of a cell from a pepper.

Cell part A contains a green pigment.

Label parts A, B and C on Figure 6.

Choose answers from the box.

An image of one cell from a pepper has a width of 32 mm.

The real cell has a width of 0.08 mm.

Calculate the magnification of the image of the cell.

Use the equation:

$\text{magnification}=\frac{\text{size of image}}{\text{size of real cell}}$

Magnification = × ____________________

Water can move into cells and out of cells.

A student investigated how different concentrations of sugar solution affect the mass of pepper tissue.

Method:

1. Cut three pieces of pepper 1 cm wide and 1 cm long.

2. Dry each piece.

3. Record the mass of each piece.

4. Leave each piece in sugar solution for 1 hour.

5. Remove the pieces from the sugar solution and dry each piece.

6. Record the mass of each piece.

7. Repeat steps 1 to 6 using different concentrations of sugar solution.

Before the investigation, the pepper was wrapped in plastic and kept at 5 °C.

Which are two reasons for keeping the pepper wrapped in plastic at 5 °C?

Tick (✓) two boxes.

The student calculated the mean percentage change in mass at each concentration of sugar solution.

Figure 7 shows the results

In some concentrations of sugar solution, the mass of the pieces of pepper increased.

The mass increased because water moved into the cells.

What process moved water into the cells?

What concentration of sugar solution would cause a mean percentage change in mass of 0%?

Use Figure 7.

Concentration of sugar solution = __________arbitrary units

The cells of the pepper have wrinkled cell walls.

What is the advantage of wrinkled cell walls to the pepper plant?

Tick (✓) one box.

Why is an electron microscope and not a light microscope used to view the soot particle?

Oak trees reproduce by sexual reproduction to produce seeds.

An acorn is a nut that contains a seed.

The seed may become a new oak tree.

Which process produces the cell that grows into the seed?

Figure 6 shows a green pepper growing on a pepper plant .

The cells of the green pepper contain water.

Water cannot enter the cells through the waxy waterproof coating on the outside of the pepper fruit.

Describe how water reaches the green pepper cells.

A pepper cell was viewed using a microscope.

The image of a pepper cell had a width of 32 mm.

The magnification of the image was ×400.

Calculate the real width of the cell in micrometres.

Real width = ____________ micrometres

A student investigated how different concentrations of sugar solution affect the mass of pepper tissue.

Method used:

1. Cut three pieces of pepper 1 cm wide and 1 cm long.

2. Dry each piece.

3. Record the mass of each piece.

4. Leave each piece in sugar solution for 1 hour.

5. Remove the pieces from the sugar solution and dry each piece.

6. Record the mass of each piece.

7. Repeat steps 1 to 6 using different concentrations of sugar solution.

8. Calculate the mean percentage change in mass at each concentration of sugar solution.

Before the investigation, the pepper was kept at 5 °C.

Suggest why.

Describe why calculating the percentage change in mass is more valid than only calculating the change in mass.

Figure 7 shows the results

Determine the concentration of the solution inside the pepper cells before the investigation.

Concentration = ______________mol/dm³

Explain the mean percentage change in mass of pepper when the concentration of sugar solution was 0.5 mol/dm³.

As peppers develop, the vacuoles of the cells increase in volume.

Figure 8 shows the shape of a pepper cell before it is fully developed

Suggest two reasons why the cell walls of pepper cells are wrinkled.

Figure 4 shows a light microscope.

The eyepiece lens has a magnification of ×10

The high power objective lens has a magnification of ×40

Which calculation shows the total magnification?

Tick (✓) one box.

Write down the equation which links magnification, size of image and size of real object.

A student used a different microscope to view a cell.

The cell was viewed with a magnification of ×250

The size of the image of the cell was 1.5 cm.

Calculate the real size of the cell.

Give your answer in mm.

Real size of cell = _______mm

The student focused the image for the low power objective lens and then changed to the high power objective lens.

The high power objective lens should not be moved towards the stage to focus the image.

Give one reason why.

Viruses are approximately 100 times smaller than animal cells.

What type of microscope is used to view viruses?

Chilli plants can be infected with tobacco mosaic virus (TMV).

Farmers grow chilli plants and sell chilli fruits.

Figure 5 shows chilli fruits growing on a chilli plant.

Figure 5

Figure 6 shows how infection with TMV affects the number of chilli fruits produced on chilli plants.

Figure 6

Determine the decrease in the mean number of chilli fruits produced when plants are infected with TMV.

Decrease = ________ fruits

Mineral ions are at:

• a low concentration in sea water

• a high concentration in algae.

Name the process algae use to absorb mineral ions from sea water.

Figure 5 shows a light microscope.

Figure 5

A student was given a prepared slide of cells.

Describe how the microscope in Figure 5 could be used to view the cells with the high power objective lens.

Light microscopes are not used to view viruses.

What are two reasons why electron microscopes are used to view viruses?

Tick (✓) two boxes.

The concentration of potassium ions in the soil is 3.9 μg/cm³.

The concentration of potassium ions in the root tissue is 2500 μg/cm³.

Explain why the concentration is so much higher in the roots than in the soil.

Cells divide in a series of stages called the cell cycle.

Figure 13 shows a cell cycle for a human cell.

Figure 13

What happens during the mitosis stage of the cell cycle?

Tick (✓) one box.

Before a cell divides by mitosis, the mass of DNA in the cell is 6 picograms.

What mass of DNA will be in each of the new cells at the end of cell division?

Tick (✓) one box.

One cell takes 16 hours to divide and form two new cells.

Estimate the total number of cells produced from one cell at the end of 48 hours.

Use the following steps.

Calculate the number of divisions in 48 hours

Calculate the number of cells after 48 hours

Number of cells = --------------

Give one factor that can cause a mutation in DNA.

Do not refer to ionising radiation in your answer.

A mutation in DNA may cause cells to become cancerous.

Figure 14 shows the change in the number of cancerous cells and non-cancerous cells during 6 days.

Figure 14

Describe three patterns shown in Figure 14.

Use data from Figure 14.

1

2

3

Predict the number of non-cancerous cells on day 7 if the pattern from day 4 continued.

You should extend the line for non-cancerous cells on the graph in Figure 14.

Number of cells =------------------ thousand

All living organisms are made of cells.

Figure 15 shows two types of cell.

Figure 15

Calculate how many times longer the liver cell is than the bacterial cell.

Number of times longer = ---------------------

Compare the structure of cell A with the structure of cell B.

You should include similarities and differences in your answer.

Do not refer to cell size.

A scientist investigated the effect of different concentrations of sugar solution on red blood cells.

Figure 16 shows the effect of placing a red blood cell into a sugar solution.

Figure 16

What conclusion can be made from the result in Figure 16?

Tick (✓) one box.

A student investigated the effect of different concentrations of sugar solution on the change in mass of plant tissue.

The student used pieces of potato.

Describe a method the student could use to produce valid results.

The student used a valid method.

The student calculated the percentage change in mass of the pieces of potato.

Table 5 shows the results.

Table 5

Complete Figure 17.

You should:

• plot the data from Table 5

• draw a line of best fit

Some of the results have been plotted for you (the points at 0.3 mol/${\text{dm}}^3$ = −5, 0.4 mol/${\text{dm}}^3$ = −10 and 0.5 mol/${\text{dm}}^3$ = −12 are already marked).

Determine the concentration of sugar solution that would cause no change in the mass of a piece of the potato.

Use Figure 17.

Concentration of sugar solution = ----------mol/${\text{dm}}^3$

Bacteria can cause disease.

Bacterial cells do not have a nucleus.

Which term describes bacterial cells?

Tick (✓) one box.

Bacterial cells have no nucleus and are smaller than animal cells.

Give one other difference between bacterial cells and animal cells.

This question is about plant tissues.

Plant meristem tissue is found in the growing tips of shoots and roots.

Name two processes in plants that only occur in meristem tissue.

An acorn is a nut that contains the seed of an oak tree.

When one type of insect lays an egg in an acorn, the acorn grows abnormally. The abnormal growth is called a gall. An insect embryo grows inside the gall.

Figure 8 shows a normal acorn and an acorn that has grown a gall.

The seed in an acorn forms from one original cell with two sets of oak tree chromosomes.

The original cell in each seed was produced by sexual reproduction.

The gall has cells that contain two sets of oak tree chromosomes.

Compare the process that produced the original cell in each seed with the process that produced cells in the gall.

Sexual reproduction in humans involves the joining together of an egg cell and a sperm cell.

The sex of an embryo is decided by the chromosomes they inherit from their mother and father.

Where in the cell are the chromosomes?

Tick one box.