Question

1. What is the main RuBisCO inhibitor? How frequently does RuBisCO bind to the wrong substrate? What effect does this have on the plant when there is adequate CO2 and when there is very little CO2?

2. What is the full scientific name of Zea mays?

3. Describe the typical environment that Zea mays naturally lives in.

4. What does it do with its stomata during the day and during the night? Why?

Answer 1

1. RuBisCO stands for Ribulose-1,5-bis Phosphate Carboxylase/Oxygenase. The most abundant protein found, carries out the assimilation of CO2(Carbon dioxide) by the carboxylation of Ribulose-1,5-bisphosphate. This enzyme has a low turnover number i.e, a high amount of this protein is needed to carry out the photosynthesis in plants efficiently. The main inhibitor of RuBisCO is CA1P(2-carboxy-D-arabinitol-1-phosphate) which is found in the chloroplast of plants and is formed by phosphorylation of 2-carboxy-D-arabinitol and this binds to the active site of RuBisCO. This inhibitor is generally produced in dark and it is found in most of the plants but not in all. To relieve CA1P inhibition Rubisco activase enzyme is used.RuBisCO is a highly inefficient enzyme with a low turnover rate and apart from this, it lacks specificity. Oxygen and Carbon dioxide being similar in shape and chemical properties makes it difficult for RuBisCO to identify between these two. Oxygen easily binds to the active site of RuBisCO as it is smaller in size than carbon dioxide. RuBisCO when it attaches oxygen with a sugar molecule, it leads to the production of the faulty oxygenated product. If there is adequate CO2 present that means more substrate is present for photosynthesis so RuBisCO will carry out the production of C3 end products i.e glycerate-3-phosphate. If little CO2 is present that means there are higher chances the RuBisCO binds to the oxygen and leads to the production of C2 compounds like phosphoglycolate.

2. Zea mays scientifically known as Zea mays itself or Maize which belongs to the family of grasses of Plantae kingdom. Commonly also known as Corn.

3. Zea mays are cold intolerant, so it should be planted in temperate zones in spring. Its root system is shallow so it depends on the soil moisture and it uses C4 carbon fixation. Zea mays are most sensitive to drought.

4. Since Zea mays are C4 plants so during the day time, Zea mays close their stomata to minimize the photorespiration process and they become hardier in dry and hot environments. While during night time they open their stomata to collect the CO2 for photosynthesis. This opening and closing of stomata is done to preserve water inside the cells of the Zea mays.