Stomata Density Experiment
Background
Most angiosperms have large numbers of stomata on the underside of leaves to allow for the exchange of gases. Leaves of different age (and therefore size) may have different rates of photosynthesis and so different densities of stomata. This experiment aims to discover whether young/small leaves have a different density of stomata to older/larger leaves.
Research Question
Is there a relationship between the age (size) of ivy leaves and the density of stomata on the underside?
Variables
Independent Variable:
Age/Size of leaf
Dependent Variable:
Density of stomata on the underside of the leaf
Controlled Variables:
The Same Technique will be used throughout. All counts will be made using the same microscope at the same magnification to ensure a standard sized field of view. All leaves will be from the same individual ivy plant, so any other environmental factors will not have an influence.
Hypothesis
It’s hard to predict the outcome as there are several possibilities. Young growing leaves will probably have a higher metabolic rate, so may require a higher rate of photosynthesis and need more stomata for exchange. Alternatively, it could be argued that larger leaves are fully mature to carry out their job of photosynthesis, so require more stomata. It is likely that the density is related to some other factor and is not influenced by photosynthesis, or that the rate of photosynthesis is the same regardless of leaf size.
Equipment
1. An ivy plant
2. A microscope
3. A paper graticule
4. Clear nail varnish
5. 3 microscope slides
6. Clear tape
7. Graph paper
Method
1. Remove 3 leaves of different size from a single ivy plant. Leaf size should be large, medium and small.
2. Place the first leaf on graph paper that has squares measuring 0.5 cm x 0.5 cm, and draw around the edge with a pencil. Try to keep the leaf as flat as possible and do not include the stem....