CAM (Crassulacean acid metabolism) is one of the three photosynthetic pathways of vascular plants and special photosynthetic metabolic adaptation to environmental stress. Such a modification is based on the C3 pathway that increases the concentration of carbon dioxide around the RuBisco hence suppressing photorespiration.
The CAM pathway includes a temporal separation of carbon fixation from the atmosphere majorly at the time of the night by opening stomata and later imbibing such carbon dioxide into carbohydrate at the time of the day. The surrounding carbon dioxide at the time of the night is fixed into malic acid through phosphoenolpyruvate carboxylase (PEPC) and oxaloacetic acid accumulating in mesophyll cells having chloroplasts.
Cacti – Example of CAM Plant
Cacti is the stereotypical desert plant. Such plants are ideally designed to exist in deserts. They appear very different from other average leafy green ones. Typically, a cactus has a round shape that minimizes the surface area through which it loses water at the time of the day. Most of them also possess spines to stab animals that may want to consume it and its water. They utilize the CAM cycle to prevent it from opening its stomata to lose water at the time of the day.
These plants have succulent pads, stems or branches possessing spines and scales instead of leaves. Their pads are nothing but modified stems having a waxy coating. The pricking spines are altered leaves that break up the evaporative wind that blows across the surface of pads and renders shade to the stem.
Typically, the root systems are shallow and broad while rainwater is quickly soaked up. The tiny rain roots grow when the soil gets moistened by rain and dries up later. Generally, plants photosynthesize by accumulating carbon dioxide through tiny pores dominantly found in the leaves referred to as stomata. It converts it into oxygen and sugar. Cacti make use of CAM photosynthesis – a special and unique process to succulents. In this process and type of photosynthesis, stomata open at night when plants are comparatively cooler for less moisture to be lost in the process of transpiration.
But, the process of photosynthesis also needs sunlight. The process of CAM includes a way to store chemically the carbon dioxide till the sun comes out when it can be utilized to finish the process of photosynthesis.
Although it has prickly armor, cacti are not immune to predators. Several rodents chew on pads of cacti while other mammals such as humans and bears relish the sweet red fruit of the prickly pear.
The most common cactus is the prickly pear in the Arches. These are distinguished by wide, flat pads. It tends to grow horizontally sprawling across the desert floor. It produces flowers of differing hues ranging from yellow to pink in spring. When it is late summer, it provides edible fruits. Due to the special antifreeze chemicals in cells, it is capable of surviving through the cold temperatures in winter.
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