Photosynthesis in Higher Plants Test - 8

The C₄ plants respond to higher temperatures and show higher rate of photosynthesis while C₃ plants have a much lower temperature optimum.

Synthesis of glucose molecules during photosynthesis involves utilization of ATP molecules. In C₄ plants, 30 ATP molecules are required to fix one molecule of glucose.

RuBisCO that is the most abundant enzyme in the world and is characterised by the fact that its active site can bind to both CO₂ and O₂ hence the name.

Photosynthesis consists of light reaction and dark reaction. During light reaction, ATP molecules are formed along with H₂ and O₂ . Synthesis of PGAL occurs during dark reaction.

Photoperiodism is the response of different organism to environmental change of light and dark period of light. In plants, flowering takes place after certain period of light.

In the photorespiratory pathway there is no synthesis of ATP or NADPH. Therefore, photorespiration is a wasteful process. In C4 plants photorespiration does not occur. This is because they have a mechanism that increases the concentration of CO₂ at the enzyme site.

Dark reaction of Carbon dioxide fixation in CAM plants is called as ocification because it produces Malic acid. These plants open their stomata during night to prevent transpiration.

Blackman proposed the law of limiting factors in 1905. According to this law, when a process depends on a number of factors, its rate is limited by the pace of the slowest factor. Blackman's law of limiting factors determines the rate of the photosynthesis.

Succulents plants have stomata sunken deeply in leaf epidermis to prevent loss of water by transpiration. These plants open their stomata during night and follow the CAM pathway for fixation of carbon dioxide.

The plant factors include orientation of leaves, mesophyll cells and chloroplasts and the amount of chlorophyll.The external factors would include the availability of sunlight temperature, CO₂ concentration and water. As a plant photosynthesizes,all these factors will simultaneously affect its rate.