Homeostasis Bundle 3

Fig. 1 shows a cross section of a leaf as viewed through a light microscope at x250 magnification. Fig. 1 indicates that the image size of a palisade mesophyll cell is 2 cm. Calculate the actual length of a palisade mesophyll cell.

• 0.08 mm

• 0.8 mm

• 8 mm

• 80 mm

Identify structures P, Q, and R in Fig. 1.

• P: Structure 1, Q: Structure 2, R: Structure 3

• P: Structure 2, Q: Structure 3, R: Structure 1

• P: Structure 3, Q: Structure 1, R: Structure 2

• P: Structure 1, Q: Structure 3, R: Structure 2

Which two features of structure R help it to carry out its function?

• Feature A and Feature B

• Feature C and Feature D

• Feature E and Feature F

• Feature G and Feature H

Suggest how the features given in part (i) help structure R to carry out its function.

• By providing a framework for data analysis

• By enhancing the graphical capabilities

• By improving the speed of computations

• By offering a wide range of statistical techniques

State the role of the stomata in plant homeostasis.

• Regulate water loss through transpiration

• Absorb nutrients from the soil

• Facilitate photosynthesis by capturing sunlight

• Anchor the plant to the ground

Fig. 1 shows an electron microscope image of two guard cells. Which two features other than the stomatal pore help to identify the cells in Fig. 1 as guard cells?

• Thickened inner walls

• Presence of chloroplasts

• Large vacuoles

• Thin outer walls

If the guard cells in Fig. 1 were living, suggest the environmental conditions that might be present.

• High humidity

• Low light intensity

• High temperature

• Low carbon dioxide levels

The process that would cause the size of the stomatal pore to increase is:

• Increase in turgor pressure in guard cells

• Decrease in light intensity

• Reduction in water availability

• Increase in carbon dioxide concentration

State the conditions in which abscisic acid (ABA) plays a role in plant physiology.

• Drought stress

• High humidity

• Excessive sunlight

• Nutrient-rich soil

Which two inorganic ions play a role in the action of abscisic acid in leaf function?

• Calcium and Potassium

• Sodium and Chloride

• Magnesium and Sulfate

• Iron and Zinc