Mineral ions in plants

A student uses this apparatus to investigate the effect of nitrate ions on the growth of plants.

● A young plant is grown in a sterile solution containing all the mineral ions needed for growth.

● The student repeats the experiment with other young plants.

● The student also carries out the experiment with young plants grown in a sterile solution that contains all the mineral ions except nitrate.

● The student measures the length of the stem of each plant every five days. Some of the student’s results are shown in the table.

Describe the growth of the plants in each solution.

Explain why young plants absorb more mineral ions when air is bubbled through the solutions.

Suggest why each solution is sterilised at the start of this investigation.

Suggest why the glass jar is surrounded by cardboard during this investigation.

Identify the dependent variable in this investigation.

Name one biotic (living) variable that should be controlled in this investigation.

4 (a) Nile tilapia are fish. Their body colour is controlled by a single gene. The allele N produces normal body colour and the allele n produces pink body colour. Diagram 1 shows the phenotypes and the genotypes of Nile tilapia. normal body colour (NN) normal body colour (Nn) pink body colour (nn)

Diagram 2 shows all the possible crosses between the phenotypes and genotypes of Nile tilapia parents.

The table gives some descriptions of offspring. Complete the table by giving the number of crosses that would produce each description of offspring. The first one has been done for you.

Tilapia are farmed in many parts of the world to provide a source of protein. Farmers build large ponds and fill them with fish. The ponds are exposed to sunlight and the farmers add manure to help the growth of the fish. Some of the water in the ponds is changed every day.

Suggest how sunlight and manure help the growth of the fish.

Suggest why some of the water is changed every day.

A fish farm contains 6000 fish. The average (mean) increase in mass of a fish over a period of 32 weeks is 700 g. Estimate the total mass of fish, in kg, that the fish farm could produce after 32 weeks.

Plants make food by the process of photosynthesis.

Write a balanced chemical symbol equation for photosynthesis.

The leaf of a plant is adapted to carry out photosynthesis. Explain how the following parts of the leaf are adapted for photosynthesis.

palisade mesophyll layer

spongy mesophyll layer

guard cells

A student uses this method to show that starch is produced during photosynthesis. Step 1 put a potted plant in a dark cupboard for 24 hours Step 2 then put the plant in bright sunlight for 12 hours Step 3 remove a leaf from the plant and put it in a beaker of boiling water for 30 seconds Step 4 put the leaf in a boiling tube containing hot ethanol for 10 minutes Step 5 wash the leaf in cold water and put it on a white tile Step 6 add enough iodine solution to cover the leaf and observe the change in colour

Explain why the student put the plant in a dark cupboard for 24 hours in step 1.

Describe how the student could carry out step 4 safely.

State the colour of the leaf observed in step 6.

The student concludes that starch is produced by photosynthesis in the leaf. State a suitable control that she should use to make her conclusion valid.

Plants need to absorb mineral ions from the soil to enable them to produce other biological molecules. Complete the table by giving the missing information.

The table shows the concentration of sodium ions and chloride ions inside a plant root hair cell and in the water in the soil.

The ratio for the concentration of sodium ions in the root hair cell compared to the water in the soil is 71:1

Calculate the ratio for the concentration of chloride ions in the root hair cell compared to the water in the soil.

Adding too much water to soil will fill all the air spaces in the soil with water. Suggest why this will prevent root hair cells from absorbing sodium or chloride ions.

The table lists two other mineral ions. Complete the table by naming a molecule that is made in plants using the mineral ion.

Farmers in Asia add fertiliser to their crops to increase the yield. Fertilisers usually contain nitrate, phosphate and potassium. The table shows the farmers’ crop yield when the crops are given a fertiliser lacking one of these three minerals. A figure of 100% is the maximum yield with all three minerals given.

State the mineral that has the greatest effect on crop yield.

Explain why this mineral has the greatest effect on crop yield.

Which crop is most affected by the lack of potassium?

Suggest why the minerals had different effects on lowland rice and upland rice.

The yield is the mass of the useable part of the crop and is measured in kg per m². The yield is often measured in dry mass rather than fresh mass.

Suggest why dry mass is used.

Suggest how the dry mass of 10 kg of fresh potato tubers could be determined.

The table gives data as a percentage of the yield with all minerals present. Explain why a percentage is used rather than changes in kg per m².

A farmer grew another crop with all three minerals added. The maximum yield obtained was 12 kg per m². He grew the same crop with no nitrate and the yield was 5 kg per m². Calculate the percentage of the maximum yield when the crop was grown with no nitrate. Show your working.

Scientists want to compare the growth of the same species of plant in three different areas. The graph shows the biomass of the plants in each area in g per m² each year for a period of 20 years.

The table shows the increase in biomass in each area in g per m² per year for the 20-year period for areas A and B.

Calculate the increase in biomass in g per m² per year for area C Show your working.

Increase in biomass =_........ g per m² per year

After 20 years, the plants in area A had a greater biomass than those in area B.

Explain how abiotic (non-living) factors could cause this difference.

Explain how biotic (living) factors could cause this difference.

The scientists wanted to find out how efficient plants in area A were at converting light energy and using it to make biomass. The scientists knew the following information: the increase in biomass for the plant growth in area A is 115 g per m² per year one gram of the plants in area A contains 22 kJ of energy the amount of light energy available in area A is 3 200 000 kJ per m² per year The formula for calculating the percentage energy transfer efficiency is

Use this information to calculate the percentage energy transfer efficiency of the plants in area A. Show your working.

Energy transfer efficiency =_........

The diagram shows how water flow is controlled in a fish farm to maintain water quality.

Name a waste product produced by the fish.

Explain how the removal of fish waste helps to maintain water quality.

Explain how adding antibiotics would also help to maintain water quality.

The fish waste from step 2 is used by the plants in steps 3 and 4. Describe how the fish waste helps the plants to grow.

Suggest what could be done on this fish farm to prevent interspecific predation.

The diagram shows the apparatus used to investigate how quickly water passes through two different types of soil.

Each funnel contained 200 g of dry soil. Water was poured into each funnel to make the soil completely wet. Then 100 cm³ of water was poured on to the wet soil in each funnel and allowed to drain into the measuring cylinders. The volume of water collected in the cylinders was measured every two minutes until all 100 cm³ had been collected. The table shows the results.

Soil type is an independent variable in this investigation. What is meant by the term independent variable ?

What is the dependent variable in this investigation?

Tick the box to show the correct controlled variable in this investigation.

Calculate the average rate in cm³ per minute at which water drained through the clay soil. Show your working.

_........ cm³ per minute

The photographs show two stop clocks, A and B, that could be used to measure the time taken for water to drain through the soil in this investigation.

Which of these two stop clocks would give a more precise reading? Explain your answer.

Sandy soil contains large soil particles with big air spaces between them. Clay soil contains very small soil particles with small air spaces between them and most of these air spaces are filled with water.

Suggest why many plants may find it difficult to grow in sandy soil.

Use your knowledge of how plant roots absorb mineral ions to suggest why some plants may find it difficult to grow in clay soil.