1. How does the basic leaf structure suit its function?
A leaf is a plant organ that is very crucial for a plant survival. It has a structure that makes it suitable to perform its functions. A leaf normally has a larger surface area so that they are able to absorb sunlight more easily. Sunlight is required by plants for the food making process. A leaf is normally very thin. This allows the carbon dioxide to travel and diffuse in a short distance. Also, oxygen which is usually a by-product, diffuse out easily. A leaf has a green coloring matter known as chlorophyll. This helps in converting the sunlight energy absorbed into chemical energy. There is normally networks of veins within leaves. These provide support to the leaf and enable transportation of food and waste to and from the leaves of plants. A leaf has several openings that allow gasses to diffuse in and out of them. These are known as stomata.
A leaf has cuticle. The cuticle is a wax-like substance that covers a leaf. It protects a leaf from excessive water loss through evaporation. It also protects the leaf from being infected by bacteria and fungi (Traverse, 2005, p. 106). A leaf has upper and lower epidermis that allow gaseous exchange and protect a leaf from mechanical damage as well as preventing transpiration. A leaf has guard cells that automatically open and closes the stomata when required by a leaf. It has palisade layer that contains chlorophyll, arranged in a regular manner to allow absorption of more sunlight. Some leaves have trichomes. These are hair-like structures that prevent insects or herbivores from feeding on leaves. Also, they reflect excess sunlight, enabling protection against the increase of internal temperature within a leaf that may denature enzymes. The spongy mesophyll is arranged in an irregular way with air spaces between then to allow for maximum diffusion of gasses in and out of the cells in a leaf.
2. How does the leaf organization differ between C4 and C3 plants and how is this difference adaptive?
In C3 plants, Krans anatomy is not possessed by the leaves. They possess broad leaves. The leaves in these plants have chloroplasts which lack peripheral reticulum. Also. The chloroplast of these plants is monomorphic. Their leaves are not very efficient in the photosynthesis process since there is normally no chloroplast in the bundle sheath. The leaves of these plants also perform photosynthesis process during stomatal opening only. As their leaves have loosely packed spongy mesophyll, no chloroplasts in bundle-sheath, and perform photosynthesis when the stomata open, they are adapted to growing in a temperate environment where plants only carry out photosynthesis during daytime where the pathway for carbon dioxide fixation is through the C3 cycle.
In C4 plants, their leaves show Krans anatomy (Sinha, 2004, p. 220). They normally have reduced leaves. Their chloroplast does possess peripheral reticulum unlike in C4 plants. Their leaves are very efficient in photosynthesis since their bundle sheath contains chloroplast. Also, the chloroplast in their leaves is dimorphic. The leaves of these plants can perform photosynthesis in both stomatal opening and closure. These features enable these plants to grow well in environments experiencing high temperatures and light intensity like arid and deserts. These plants have a lot of chloroplasts to maximize on photosynthesis that helps in the availability of plant’s food easily as they normally grow under stress. Also, a special adaptation of these plants is that they can perform carbon dioxide fixation through either C3 or C4 cycles. In the C3 cycle, it takes place in bundle sheath while in C4 cycle, it takes place in the mesophyll cells.
References
Sinha, R. K. (2004). Modern plant physiology. Pangbourne: Alpha Science.
Traverse, A. (2005). Sedimentation of organic particles. Cambridge: Cambridge University Press.
