Biology Quiz on Plant Physiology

When Ismail placed onion cells in a dilute solution, what effect did this have on the turgor pressure of the cells?

• It decreases

• It increases

• It remains unchanged

• It fluctuates

Kushagra uses a solution of known solute concentration to plasmolyze onion epidermal cells in his biology lab. Microscope observations reveal plasmolysis in 50% of cells. What does this observation determine?

• Water potential of the solution

• Osmotic potential of the cell sap

• Turgor pressure in cells

• Rate of diffusion

Anant is conducting an experiment using a potometer to measure water uptake in an excised twig under sunlight. He notices that the rate of water loss correlates with which factor?

• Soil moisture

• Light intensity

• Wind speed

• Air pressure

During a biology class, Raghav and Farhan conducted an experiment under constant temperature. They noticed that transpiration was faster when the excised twig was exposed to direct sunlight. This is due to an increase in:

• Root pressure

• Stomatal closure

• Stomatal opening

• Water absorption

During a biology lab, Mridul examines a mesophyte leaf under the microscope and counts 25 stomata and 100 epidermal cells in a microscopic field. What is the stomatal index?

• 10%

• 20%

• 25%

• 30%

Kushagra measured the stomatal frequency of a xerophyte leaf and found it to be 50 stomata per mm². Xerophytes typically have:

• Higher stomatal frequency to conserve water

• Lower stomatal frequency to conserve water

• No stomata

• Larger stomatal pores

Kavya conducts an experiment in her biology class where she places a piece of potato tissue in hydrogen peroxide solution. Bubbling occurs immediately. The bubbles indicate the release of:

• Oxygen

• Carbon dioxide

• Hydrogen gas

• Nitrogen gas

Aarush, Ismail, and Raghav are conducting an experiment to observe the activity of catalase, an enzyme that breaks down hydrogen peroxide. They notice that the bubbling rate decreases at pH 2 and increases at pH 7. This suggests catalase activity is:

• Inhibited at neutral pH

• Optimal at acidic pH

• Optimal at neutral pH

• Independent of pH

Raghav and Ismail are conducting an experiment with isolated chloroplasts exposed to light in the presence of DCPIP dye. They observe that the color changes from blue to colorless. What does the color change indicate?

• Photosynthesis

• Electron transport

• Respiration

• Starch breakdown

During a biology experiment, Ismail and Raghav observed that in the absence of light, no color change occurred in their Hill's reaction setup. What does this demonstrate?

• Hill's reaction requires respiration

• Hill's reaction is independent of light

• Hill's reaction depends on light

• Chloroplasts are inactive in darkness