Bioenergetics

A scientist investigated the rate of photosynthesis of one type of tomato plant. The tomato plants were grown in a greenhouse. **Table 2** shows the results. Give **two** control variables the scientist should have used in the investigation.

Which range of carbon dioxide concentrations caused the rate of photosynthesis to change the most?

How could the scientist have improved the validity of the results?

Explain the change in the rate of photosynthesis when the concentration of carbon dioxide increased between 0.00% to 0.08%.

A farmer decided **not** to use a concentration of carbon dioxide higher than 0.08% to grow tomato plants. Suggest **two** reasons for the farmer's decision. Use information from **Table 2** and your own knowledge.

Plants take up water from the soil through their roots. Some of the water is used for photosynthesis. Complete the word equation for photosynthesis. Choose answers from the box. **fat, glucose, nitrogen, oxygen, protein** carbon dioxide + water → ______ + ______

Suggest one reason why the leaves of the deadly nightshade plant have chlorosis.

This question is about exercise. During vigorous exercise, anaerobic respiration occurs in a person's body. Explain two effects of anaerobic respiration on the person's body.

This question is about photosynthesis. Complete the symbol equation for photosynthesis. 6 ______ + 6 ______ → C₆H₁₂O₆ + 6 ______

Figure 8 shows how the rate of photosynthesis changes with light intensity. Which part of the graph could be represented by the equation y = mx + c ?

A student investigated the effect of colour of light on the rate of photosynthesis in leaves. Figure 9 shows how the investigation was set up. Give one way the student could change the colour of the light shining on the leaf discs.

Give the independent variable and the dependent variable in this investigation.

All of the air had to be removed from the leaf discs before placing them in the beaker. Suggest one reason why.

The leaf discs were placed in a beaker of sodium hydrogencarbonate (NaHCO₃) solution. Explain why sodium hydrogencarbonate solution was used instead of water.

Explain why the leaf discs moved to the surface of the solution during the investigation.

There are two types of chlorophyll in leaves. Figure 10 shows the percentage of different wavelengths of light that the two types of chlorophyll absorb. Table 6 shows the colour of different wavelengths of light. Suggest the advantage to a plant of having two types of chlorophyll.

Table 5 is repeated below. The leaf discs in the investigation are green. Explain the results in Table 5 for blue light and for green light. Use data from Figure 10 and Table 6.